lab notes

ANS 242?Introductory Horse Management Lecture 8/25/08 Horse Industry Pleasure Horses: own/enjoy horses, not for profit Largest number of horses in the US Business Enterprises: -Service Orientation: Boarding Training Riding Lessons Reproduction (goal get mares pregnant) Sales Companies: commissions/sales *Boarding Stable: base of industry *Training Stables: value added boarding stables -Product Orientation: Breeding Stock (create own demand) Racing Stock Show Stock Pleasure Horses Stallion Services (good stud, service to the breed, improve next generation) Horse Value?NO BASELINE MARKET Meat Industry- reduced market, change in slaughter laws, no place to send unwanted horses *Most farms are combination of services or services and products Lecture 8/27/08 Historical Perspective of the US Horse Industry 15-1600 Spanish horses dispersed to the plains Indians 17-1800 A number of breeds of horses developed in New England and Eastern US. 1873 American Thoroughbred Studbook (Currently called Jockey Club) 1908 Arabian Horse Club Registry 1917 American Horse Show Association (Currently USEF (US Equestrian Foundation)) 1940 American Quarter Horse Association 1920-1930 Tractors and automobiles began to replace the horse as a means of power 1950 Rapid decline in horse numbers 1960 Resurgence of horse ownership for pleasure, show and racing. New horse breeds developed (pintos, paints, palominos, buckskins?colored breeds) 1975-85 ??Peak numbers of pleasure horses in US?? (during economic boom, leisure time increasing, horseman began to develop) 1987 Income Tax Reform and Economic Recover Act (Regan), eliminated tax benefit (depreciation on breeding livestock), blessing and a curse to the horse industry, most significant amount of animal abuse to horses because of abandonment 1985-94 Decline in horse numbers, resulted in considerable animal abuse Present Horse population relatively stable, far fewer ?breeders? than in the 70?s and 80?s, more people than ever are involved in horse organizations, reduced horse value (no outlet for lower end horses) *Morgan Horse-only case a breed developed from an individual animal (Figure) *Thoroughbred- more influence than any other breed, most popular among fans *Arabian- in Poland been being bred for over 500 years *Quarter Horse- most numerous in the US *American Horse Council and USEF two main political arms of Horse Industry?lack of unity problem *Horse major part of the military prior to the use the automobiles *MSU has been breeding horses for over 100 years upon induction of becoming a college (starting with draft horses and Belgians, only program to breed an international Belgian champion as well as a daughter international champion) *Silhouette- sold for $56,000 in AZ 1972, largest payout ever for an Arabian horse, by the sire (Bask) who changed the breed, flea-bitten gray, sold 5 times, last time in 1984 for over 1 million, only bred to the most popular stallion *In the present, more people own horses but fewer horses, more variety in breeds, horse population is becoming more geriatric and what to do with them Lab 9/2/08 Nature vs. nuture?50/50 Always want to run if unsure Vision?monocular to see sides, binocular to see straight ahead, eyes high on head to see over grass, can?t see what they are eating or when jumping, don?t have good depth perception, want vertical flexion to see where they are stepping, lower head to see up close Smell?if they have a choice will stay away from poisonous plants Hearing?excellent, ears tell you what horse is thinking, ear tell where area of interest is Touch?sensitive around face, withers (make sure of good saddle fit), flank, mouth (get proper bits), move into pressure but you want them to move away (must train that behavior) Ignore things that spook the horse Contractual?herd animal, can cross over between species (dog, goat) Ingestive?bad behaviors (cribbing, weaving) often management issues, feed less than they want, want to graze for longer, need to know eating behaviors Coprophagy?foal eating mares manure (okay) for short period of time Horses eating other horses manure?bad, nutrient deficiency Mimicking?do not mimic cribbing (may be result of gastric ulcers), but wood chewing could be relaxing to horse Epilmeltic?interaction with foal Et-epimeletic?signaling for care Weaning?need to be eating grain first, fence line weaning is the best method When turning the horse while leading always turn the horse inside towards you, don?t wrap around hand When tying a slip knot, make the four make a complete circle, then pull the rope through When putting on a halter, flip the buckle over the top of the head slip muzzle in and buckle up Lecture 9/3/2008 Current US Horse Industry American Horse Council (AHC) estimates 9.2 million horses in the US 844,000 racing or race horse breeding 2,718,000 showing or show horse breeding 3,906,000 recreation (these horses don?t make money) 1,752,800 farm and ranch work, rodeo, polo, police work, etc. 4.6 million Americans are involved in the horse industry 2.0 million people own horses (4.6 horses/owner) 1.4 million full-time equivalent jobs Horses contribute $102 billion to the gross domestic product Racing, showing and recreation each contribute more than 25% (>75% of total) of the total value of goods and services produced by the horse industry Registration Numbers *In recent years, there is a downturn in breeding. *The Quarterhorse by far has the largest registration *Horse industry has either remained stagnant or declined in registration numbers Michigan Horse Industry *Survey Numbers -Numbers are increasing from 1996 to 2007 (130,000?155,000) -Paint numbers increased dramatically -Standardbreds, Quarter horses, Paints, and Arabians are leaders in MI Michigan Horse Industry -most recent survey 2007, previously done in 1996 -annual surveys in other species funded by the USDA -the horse is not a food producing animal -therefore numbers are of little concern to the USDA -surveys are important for the horse industry -establish numbers so needs of the industry can be identified & met -health concerns -economic concerns -important in legislative initiatives relating to the horse industry -demonstrate the economic importance of the industry in MI -number of citizens involved -lameness number one health concern -most horse located in the lower lower peninsula (mostly around Detroit area and thumb area) -draw a line across above Mount Pleasant and down most of the horse are ?have a lot of forage therefore a lot of cows (part of the forage belt) Lecture 9/8/2008 Comparison of Inventories by Farm Size Operations Inventory 1991 2007 1991 2007 1-2 head 14,700 15,400 24,000 24,000 3-9 head 11,500 16,600 54,000 76,000 10-29 head 2,150 2,650 33,000 38,000 30 + head 360 350 19,000 17,000 Michigan 28,700 35,000 130,000 155,000 *Horse farms with 3-9 head have dramatically increased in MI since 1991 to 2007 (most horses in Michigan are on farms with less than 9 head) Inventory by Principle Use Breeding 21,000 Competition 19,400 (Show/Rodeo) Work 12,600 Racing 5,700 Trail Riding 17,300 Recreation/pleasure 57,500 Idle 21,500 Michigan 155,000 *most horses are for recreational purposes, few horses used for profit *industry based on recreation/pleasure Income Graph -expenses more than doubled the income brought in by horse operations -some loss due to under the table deals (cash transactions) Hot bloods can swing there head in the no fashion Cold bloods do yes motion very well Lab 9/9/08 Bits Snaffle- no leverage, severity depends on width and type of material of mouthpiece The bigger the bit the less severe?more surface area Half cheek- driving bits Pressure points?corners of mouth, bar of the mouth, tongue Curb- based on leverage Pressure points?pole, chin groove, roof of mouth, corners/bar of mouth, tongue Shorter curve shank, the less severe the bit The bigger the port, the more severe the bit (has shank means combo) Want spit?dry mouth bad Combo- combination between curb and snaffle Hackamore?tough, squeeze nose Saddles Buy expensive, synthetic ones fall apart Lecture 9/10/08 Light Horse Breeds (900 lbs-1500 lbs, 14-17 hands) (hand=4 in) Arabians Oldest breed (~1000 years old), Hot blood (higher quality, triangular head, one less lumbar vertebrae, and 1-2 less vertebrae in the tail, round over angular eye socket) Developed in deserts of Egypt Selected as war horse Excellent endurance horse Half-Arabian registry (now more expensive then full bred) Thin skin, fine mane and tail, gay tail carriage (hold tail up/away) Stallions more arch in the carrying of the head Light harness breed (light equipment) Black Arabs rare, gray are nothing special for show Lecture 9/15/08 Thoroughbreds Second oldest breed, hot blood Developed in England (Arabian influence) Selected for speed on the flat Very athletic Refined (not fine or frail) American Quarter Horse Breed registry started in 1940 Developed in southwestern US Ranch horse (bred for sprinting in short distances) Greatest numbers in the US Forgiving dispositions Standardbred Developed in the US in the late 1800?s Harness race horse (attached to a cart) Strongest racing industry in Michigan 2 beat gaited horse (horse may be elevated as certain times) trot- two beat diagonal gait pace- two beat lateral gait (halfway between a natural and unnatural gait), faster than a trotting horse Morgan Developed in Northeastern US (3 main pockets) Developed from one outstanding stallion (Figure owned by Justin Morgan) Admired for its versatility Flat profile, short broad faces, large crest in the back of the neck American Saddlebred Developed in the Eastern US Known for its animation at the trot Five-gaited (full mane/tail) and three-gaited (clipped mane/tail) Most brilliant movement Want to get away from nicking Tennessee Walking Horse Developed in the South Plantation horse Very comfortable to ride Performs the running walk (4 beat gait feet rise and fall separately- extremely comfortable for rider) Lab 9/16/08 Components of Conformation Balance, structure, muscling, quality, travel (same for all breeds) Most weight carried on the front end Dressage- higher in front Cow horse- lower in front Lameness more often occurs in front Horse has 3 parts of symmetry Head- large nostrils (take in air), want flat head, with slight ditch if anything mares larger, short ears Neck- look for proportion, longer topline than shorter topline, want a not thick throat latch) Hip- level breed differences, tail set low (croup rounded) Shoulder- angle of shoulder liked to the angle of the pastern Hind leg- need to be slightly toed out Quarter Horse- talk about muscling but in the Arabians not at all Hair should e fine, bone defined, no meat in head Lecture 9/17/08 Color Breeds: (Color requirement for registration, Some allow non-colored horses of the breed to be used as breeding horses) Paints Spotted color pattern Developed in the 1960?s Must have stock horse conformation (resemble a Quarter Horse) Appaloosa Registry started in the late 50?s, early 60?s Developed in the US Distinctive spotting pattern, small spots Generally of stock horse type Blanket pattern could go up to mid back, with base color staying on the legs Registry allows horses that don?t color to be apart of the breeding group, allows quality horses to remain apart of the breed Sex-link coloration traits Pintos Spotted color only requirement for registration May be of any breed or type Paints may be registered as Pintos Not all Pintos may be registered as Paints Palominos and Buckskins True Buckskins (base color: bay) and Palominos (base color: sorrel and chestnut) are similar in genetic makeup Just different base color Buckskin hard color to produce Palomino-golden body with white mane and tail, occurs in all breeds, but usually stock type Buckskin-golden body with black mane and tail No such thing as an albino horse Warm Bloods: many different breeds, a cross between hot and cold bloods, very athletic, usually good minded horses, usually large, trainable, go to hot bloods for sensitivity Lippanzaners (white aren?t really?mostly gray) Draft Horse Breeds: Belgians Most numerous in US Always chestnut in coat color Developed in Belgium Most numerous in number in the draft horse category More forgiving disposition, many work for a living Now horses are growing about 1-2 hands taller (17-18 hands high) Percherons Black or Gray (bays can occur just not popular) Developed in France Born black go gray, while being born mousy will turn black Clydesdales Most recognized in US (Budweiser Team) Developed in Scotland Leg feathering Bay, Black or Roan in color (Roan starts from the center of body and move out while gray starts at the tip of the nose) Not very numerous in the US Lecture 9/22/08 Shire Developed in England Largest breed in terms of stature (17-18 hands) Not many in US Often black and gray Pony Breeds: Shetlands Developed in the Shetland Isles Bred to be a mining pony (larger horses were too large from small/narrow tracks) Later become used as a youth mount Old Shetlands grew long winter coats Crossed with a hackney for higher trot Hackney Developed in England Very animated Bred to be a small coach horse Good trotters Docked tails or long tails POA Pony of the Americas Miniature Appaloosa (have the same patterns) Youth Mount Put together like a stock horse Welsh Developed in Wales Miniature Arabian Youth mount Many sires were purebred Arabian Not many in the Midwest?strong pocket in CA, FL, and the East Connemara Developed in Ireland Youth mount Cross with thoroughbreds to make intermediate sport horse Two Colors in Horses: -Blacks (tip of the nose to the end of the tail), rare because so many genes can altered -Sorrels *every other color are variations EXAM 2 Lab 9/23/08 Unsoundness vs. Blemish Blemish can start as unsoundness Splint more likely to be seen on crooked legs, usually not on outside or hind leg Bowed tendon typically very lame Ring bone- between long and short pastern bone Difference between ringbone and sidebone is location Get both through injury, concussion or deviations Thoroughpin?strain in hock Posty legged horse, see lot of joint fluid Blemish unless causing lameness Curb- happens about a hand width down from hock (thumb size bump) OCD (osteochondritis dissecans)?see in young horses, growth issue Travel-want ground covering long stride Snap and flexion determines animation Navicular disease?hard to diagnose Lecture 9/29/08 Colors: White- some, but not numerous, often mistaken as a true gray/cremello horse) Blacks/Bays: black skin Chestnut: brown skin Gray is dominant gene, doesn?t matter what base color is, head will gray first, legs will stay base color longest Browns different from Black by lighter coloration on nose and flanks Grays from base blacks/browns turn steel gray, some dapple depending on gene Grays from base chestnut/sorrel turn rose gray Bay/Cinnamon gray from base color bay, mane, tail, legs are black Roans: difference between roans and gray where roans gray from rear flank and outward, never get gray in head, legs, or mane/tail, seems homozygous gene is lethal because it never exists in population Blue Roan: if base is black, and then turn to roan variation Red Roan: Palomino: gold body, white mane/tail, base color chestnut Buckskin: gold body/ black mane/tail, base color bay, gene selected for buckskin is wild patter which produces striping on legs Grulla: base black Perlino: base black/bay (mistaken for albino),undesirable color, breed palomino/buckskin to each other Cremello: base chestnut (mistaken for albino), with two shots of palomino, undesirable color, undesirable color, breed palomino/buckskin to each other Throat Diagram: 1,2,8,12,15,30,31 soft palate: may have problems but usually resolve Respiratory System Primary function to deliver oxygen to the blood and remove carbon dioxide Upper Airways: Nasal passage- 3 channels divided by turbinate bones, warms and moistens air (can freeze this area by working in cold weather) Pharynx- cavity located at the back of the nasal passage Epiglottis- cartilage trap, prevents food from entering airways Larynx- regulates air flow, prevents inspiration of foreign objects, contains vocal cords (two muscles, paralysis produces roaring) Lower Airways: Trachea- 2 inch diameter cartilage rings, mucous and ciliated cells (clean and lubricate) Bronchi- branches of the trachea (divides further to bronchioles) Alveoli (air sacs)- where gases are exchanged Lungs- series of air sacs, right lung has 3 lobes, left lung has 2 lobes in the horse Resting respiration rate for the horse is 8-16 breaths/minute Heart Diagram: Adult horse resting heart rate- 28-40 bpm (humans ~70 bpm) Maximum horse heart rate- can reach up to 260 bpm (humans 210 bpm) Heart rate really helps detect pain Horses don?t have symptoms, have signs, unable to indicate direct location of pain Lab 9/30/08 Purchasing a Horse Don?t let Veterinarian make decision on behavior Part 1: Pre Trip Ads, call seller (should be easy, personality?not hiding things), vitals (where advertised at? 4-H, breed assoc.)?price, name, sex, age, height Check the name in a database?breed, color, markings, owner?s info Health-ask about soundness issues (watch for fraud), need shoes?, health issues? (worming, colic, colic surgeries?), diet? Personality-sellers perspective (energy) vices (kick, bite, rear, crib) Training- ready to ride (free movement), skills, training (who, when), show record Stable skills- stand for farrier, dominant Breeding mare?make sure vet check (all parts?) Stallion?BSE, behavior Photo-make horse look nice Video-look for edits Part 2: See Yourself Bring friends, trainer evaluation Visuals?first impressions (farm, barns, look of other horses), look for scars Flexion test- make horse lame, see how long it takes to recover Lecture 10/1/08 Horse Health General Care Grooming- Is it needed for animal health? Daily, weekly, never? It depends on the circumstance: before riding, when it?s dirty (at MSU brood mares never get groomed unless being used for something, they groom each other and do self grooming), need grooming to remove debris and enhance circulation to skin, horses that are in stalls a lot should be groomed more than those in the field, and more than those put out in a group Foot Care- trimming and shoeing how often, 8 wks, 6 mths, 1 year, never? It depends: most often hear you should trim every 6-8 weeks, in the summer when ground is hard/dry it wears the feet down Dental Care- floating, periodically, annually, never? It depends: often hear annually, but only need to when you notice problems?losing weight, drop feed out of mouth Economics and Animal Health are the bottom line. Don?t let economics compromise animal health People make decisions Risk Management?is what a health program is all about, this is what all management emphasizes Unique Concerns in Equine Health Care Vaccinations?evolving science FDA doesn?t regulate the vaccinations for horses Vaccines used in really young horses were found to be useless Drug companies are the ones in charge of research therefore often over-vaccinated Horses over 1 year of age- vaccinate annually for most diseases, exceptions during periods of high risk (exposure), in areas of high risk or in high risk horses Summer is flu season for horses, due to the congregation factor Single largest loss of income in the horse industry is downtime or when the horse is not performing Foal Vaccinations Past Way: vaccinate mare 30 days prior to foaling, vaccinate foal 30-60 days of age booster 4-6 weeks later Present Method: vaccinate mare 30 days prior to foaling, vaccinate foal 4-12 months of age depending on vaccine booster 4-6 weeks later -vaccinate mare before foaling because of the passive immunity the foal will receive in the milk, which is the most important, she passes it to the offspring, also immunity to things the mare has seen in her lifetime Coggins (EIA) testing for all animals traveling to events in Michigan and throughout the US Not possible to pass to humans Usually up to the event if they require the coggins test Lecture 10/6/08 Respiratory Diseases (need to know general signs, preferred treatments, handle according to vaccinations) Influenza: Signs Fever up to 107?F (regular temp-100?F), biphasic (fever up/down) Clear nasal discharge?later pus Apathy, loss of appetite Dry cough, later moist cough Recover 1-2 weeks Cause Viral?variety of strains 2-10 day incubation period (isolate new horses to farm ~2-4 weeks) Spread ~35 yards or greater (airborne) Isolate horses if possible by a different barn, separate pasture, and check the winds (put infected horses in the NE corner of barn in MI, wind patterns) Strict quarantine to control outbreaks Treatment Rest, rest, rest (wait until fever drops) Antibiotics for secondary infections Vaccinations available?strain specific (not very efficient) Horses that travel a lot should be vaccinated Viral Rhinopneumonitis (Rhino)?acute viral infection in young (late fall-early winter), seen most frequently on breeding farms Signs Similar to influenza Abortion in pregnant mares (late in pregnancy) Incubation 2-10 days Also is a neurological strain?relatively rare, high death loss Abortion?fresh, minimally autolyzed fetus 3-12 weeks after asymptomatic infection No warning-labor?expulsion of fetus Diagnosis Difficult Lesions in fetus (necropsy) Treatment None Antibiotics for secondary infections in young horses Vaccination available (once per year young horses, 3,5,7,9 or 4,6,8,10 months of pregnancy) appears not to be effective against neurological strain May have negative effects Not very effective ~1-2 abortions a year at MSU due to rhino Equine Viral Arteritis?EVA Signs Similar to influenza May abort early in pregnancy (mares), nothing specific in fetus Treatment Vaccine available, also not extremely frequent in occurrence Strangles/Distemper A disease of young horses (6 months-3 years), almost all have had it Very contagious?can kill reputation for stables Do not vaccinate for strangles at MSU?vets highly recommend More problematic for older horses if they haven?t had strangles yet Cause-bacteria, Streptococcus equi Species specific Spread through horse to horse contact, stay in environment Signs Temperature 104-106?F High respiration rate (difficulty breathing) Depression, off feed? Nasal discharge (pus) Usually swelling of sub maxillary and sub mandibular lymph nodes Rupture- swells, skin dies, hair sheds, skin weakens, pus discharge Lymph nodes in other areas may be affected, recovery more difficult?often cause death if this happens Prognosis Good?<2% die After abscesses drain rapid improvement, 70% are immune for 5 years, continue to have increased resistance Treatment Antibiotics?? Pre-abscess, present thought Rest in comfortable environment Help with breathing? Put vaporizer in stall in extreme cases If fever remains may have internal abscesses Vaccination available not as effective as disease Nasal appears to be more effective than injectable Rhinitis, Pharyngitis- inflammation of air passages (cold in humans) Cause Inhalation of fungus or chemicals or bacterial infection Usually responds to penicillin if bacterial Pneumonia Generally of concern in the very young or very old Acute-young (happens quickly) Chronic-old (constantly having respiratory problems) Cause Bacteria-variety of strains Usually secondary to upper respiratory problems already discussed Aspiration pneumonia (medium placed in lungs accidentally) More of a problem in the 70?s/80?s due to people always tubed de-wormed horses (tube through nose every 3 mon) Accidents happen and water/dewormer end up in lungs Now paste wormers exist?much more healthy Signs Nasal discharge (noted for 1 wk, no other signs) Depressed/off feed Increased temperature 102-105? Increased respiration (abdominal breathing, moist cough) Moist rales (listen to breathing, hear moisture in lungs) and congestion (use stethoscope) Pleuritis (pain while breathing) (Rhodococcus?foals, 80% die) occurs naturally in the environment, causes lots of problems Prognosis Acute?favorable if treated early 50% death delayed treatment or becomes chronic Treatment Antibiotics Fluid intake important 2-3 week recovery Heaves- chronic pulmonary emphysema ?like asthma in humans?, usually occurs in older horses, generally not life threatening Cause Not clear, possibly due to one or all of the following Allergies Dust and mold (hay quality) Heredity (predisposition) Over exertion (improper warm-up) Signs Labored breathing Wheeze, cough (especially during exercise) Expiration prolonged Hot, dry weather and dust will increase incidence Heave line develops Stand with elbows out and rib cage expanded Severe cases rectum protrudes on exhale Treatment NO CURE Renders horse essentially useless from performance career May prolong useful life of affected animal Avoid dusty or moldy hays (dunk in water first) Increase concentrate ?Fiber? Green pasture best roughage (allergies) Drugs?aimed a bronchial dilation (antihistamines in feed) Prognosis Poor?especially for performance Progressive problem-minor to much worse Roaring (Laryngeal Hemiplegia)-whistling or roaring heard (on ispiration) when animal is exercised Cause Paralysis of muscles of larynx Most common in light horses (work harder) Paralysis due to degeneration of nerves 92% on the left side of the larynx (thought to happen because nerve that feeds the left side is close to the artery, and pulsates on the larynx therefore causing it to become paralyzed) 6% on the ride side of the larynx 2% on both Diagnose Usually observation May use endoscope to improve diagnosis Treatment Surgical removal of involved in tissue Lecture 10/13/08 Nervous System Diseases Encephalomyelitis- Insect born virus, therefore it is usually seasonal 3 strains: Eastern, Western, Venezuelan All life threatening?no cross immunity between strains Public health concern-reportable disease(report to Department of Agriculture)?humans can become infected with Western and Venezuelan (especially a concern) strains Transmission: mosquitoes?birds/rodents (reservoir multiplies)?mosquitoes?mammals Birds and rodents live long enough to continue spreading Horses are a dead-end host?can spread diseases when infected (through insects), will die shortly after infected Incubation is >24-48 hours, may take up to 1-2 weeks Signs Inflammation of brain and nervous tissue, very depressed, Fever: 104-106?F, Hypersensitive to sound and touch, excitable, blindness, lacking coordination, head pressing, grind teeth, muscle paralysis (can?t hold up head, ultimate cause of death), wandering Prognosis Western Equine Encephal. (WEE) 50% mortality rate Eastern Equine (EE)/Venezuelan (VEE) 90% mortality rate Treatment Antibiotics for secondary infections, Maintain fluids, Lower fever, protect from injury (padded stall), if down, keep sternal, prop them up Prevention Vaccinate?spring, works very well, 3,4,5,6 way?all contain EEE/WEE Diagnosis Blood sample/examine brain West Nile virus?humans and horses (near equine encephalitis) Morbidity and mortality lower than for other EE?s Birds are primary species affected Mosquito vector Signs Lethargy, weakness in hind limbs, stumbling, lack of coordination, head tilt, muscle twitching, convulsions, paralysis, coma, CNS (central nervous system) signs similar to EE Prevention Vaccination available thought to be very effective Reportable Tetanus (lockjaw)?humans, horses, and sheep Very important in horses Bacteria?Clostridium tetani, normally found in horse feces, produces neurtotoxin Cause Infection of wound, puncture or contaminated cut (anaerobic bacteria) Signs 1-4 week incubation (may not find injury) hyper excitiability localized stiffness?jaws, limbs prolapsed third eyelid 108 temperature 80% die 3-6 week recovery Prevention Vaccinate annually?very good one, tetanus toxoid?mare late pregnancy to improve foal immunity through colostrums EPM- Equine Protozoal Myelitis Organism- sarcocystis neurona May invade nervous system Opossum is the definitive host Many secondary hosts Not a reportable disease Signs Unilateral lack of coordination, stumbling, altered movement, lameness, etc., highest percentage don?t show signs Diagnosis Want a test that never gives a false negative, this test very good, may sometimes give a false positive, test available to determine diagnosis (not definitive), need spinal tap to be sure, positive testers may be asymptomatic, >60% of MI horses test positive, Treatment Reduce inflammation (some improvement) Prevention Decrease contact with opossum feces Vaccine not yet effective Lab 10/14/08 Basic Health Care Strategies for Horses A healthy horse has?. Look for horse standing inward?indicate pain When have few guard hairs?spotty coat means something wrong (parasites) Take 20 min or less to eat feed in normal conditions 75% concentrate (if racehorse, pushing hard?not recommended) Need high fiber diet to maintain hind gut fermentation Hay contains 90% dry matter Diet contains 90% dry matter BCS (1-9) 1?s usually can?t be brought back Feed by weight?not volume Thermoneutral zone ~70?F Rotate dewormers Worms?carry weight funny Ascarid?young horses, hard to get rid of up to 5 years after Strongyles- wormers focused on, can be life threatening, mow pastures to get rid of Bots- killed by ivermectin Tapeworms- not killed by ivermecting Praziquantel and moxidectin get tapeworms Older horses get older pastures due to increased immunity against worms Muscle mass in neck in foals not developed enough to vaccinate there Most vaccinations are the killed organisms Lecture 10/15/08 Miscellaneous Diseases Equine Infectious Anemia EIA- seen in horses mules, and donkeys (reportable diseases?but does not affect humans or any other species) ?Swamp Fever? Acute or chronic, intermittent fever, depression, progressive weakness, weight loss, edema (fluid build up?happens in the legs or along the underside of the abdomen), anemia Cause Viral (no vaccination available), may stay in animal in blood and body tissues for years, found in milk, semen, saliva, discharge from eyes and nose, urine, feces, infected animals are lifetime carriers, spread by blood sucking insects or dirty needles or syringes Three types Acute?sudden onset, temperature 105-108, no appetite, increase pulse rate, weak hind limbs (shit weight), yellow mucous membranes, decreased red cell count, after 3-5 days animal appears normal may recur, animal may die during initial bout Chronic/Sub-clinical (carrier)?less severe fever, longer time period between bouts, unthrifty (just doesn?t do well), depressed attitude, muscle weakness, thin Carrier State (sub-clinical)?no signs, may become active at any time, source of infection for others horses Diagnosis Coggins test, very effective test, may occasionally produce false positive?horse just retested, tested usually done every 6 months-1 year old Treatment?destroy Prevention Sanitary vet practices Decrease biting insects Lecture 10/20/08 Horses digestive tract is similar to rhinos, elephants, guinea pig, rabbit, zebra Not very successful Horses don?t often practice coprophagy due to large amounts of grazing Consume small quantities of feed relatively constantly Ileium primarily abosportion Cecum and colon extremely large to slow down passage rate?help ferment Duodenum?most important in digestion Digestion?the breakdown of ingesta to absorbable end products by enzymes produced by the animal Fermentation?the breakdown of ingesta to absorbable end products by enzymes produced by microbes Anatomy and Physiology of Digestive Tract Esophagus?passage of food Smooth muscle contractions conduct feed to stomach Inability to regurgitate or freely eructate (belch), can?t vomit Choke Stomach rupture in severe colics Stomach aches Stomach?storage <2 hours Some digestion (few enzymes?can?t digest starch in mouth with salivary amylase) Secretes acid?lower pH (denature proteins, increase digestive rates) Small intestine?duodenum, jejunum, ileum Primary site of digestion Primary site of absorption Fat (lipid) digestion Bile salts?directly from the liver (no gall bladder) Enzymes?pancreas and intestinal secretions Fat?free fatty acids Protein digestion (enzymes) Protein?amino acids Carbohydrate digestion (starches, sugars) Complex CHO?simple sugars Most important energy source in domestic species because it is eventually broken down to glucose Important site of absorption AA, fatty acids, simple sugars Minerals?active and passive absorption Vitamins?fat soluble and water soluble B12: makes horses urinate more, allowed horses to clear system faster to hide drug residues in testing Biotin: taken to help really bad feet Cecum and colon Bacterial fermentation of carbon containing compounds Primary carbohydrates (fiber) Product: energy, volatile fatty acids (VFA) are produced by the microbes, vitamins (water soluble, vitamin K (helps with blood clotting)?comes from the cecum/colon of the fermentation in the hindgut concentrations of feces (H2O absorption) protein?microbial protein produced is not usable by the horse Choke?complete or partial obstruction of the esophagus Cause: generally eating habits, dry food or medicinal boluses Treament: generally nothing, stomach tube? (push to hard, rupture esophagus by hitting the bolus) Prevention: put large rocks in the feedbox to slow horses from eating grain too quickly, soak feed Salmonellosis Usually foals Causes colitis Watery diarrhea, temperature 103-106 May go systemic (get in blood stream)?fatal 24-36 hours Vet clinic?has most problems with it on campus Potomac Fever Recognized 1979 along Potomac River Seasonal May-Oct (July-Aug peak) Snail?insect vector?Ehrlichia risticcii Signs Temperature 103-107 Depression?decreased appetite Decreased white cell count Explosive diarrhea, dehydration Rapid weight loss Infectious but not contagious Treatment?oxytetracycline (don?t usually use in horses?sets them up for salmonella) and fluids Prognosis?good, if treated early, may result in death if not treated (used to be apart of Colitis X not any more) Vaccination available? Provides immunity for only one strain, several strains, therefore not very effective at all Not widely recommended presently Lecture 10/22/08 -Unwanted horses- a horse that no one really wants, owner no longer interested/capable of providing care for them either physically or financially -For the past 15 years, ~1-2% went to slaughter (100,000/year), while 200,000 die/euthanized on-farm each year (buried on the far, cremated, gone to rendering) -Michigan you can bury the horse on farm, many states don?t have option -The demographics of slaughter-bound horses mirror the demographics of the national horse population -Cases of neglect and abandonment are increasing since closing of slaughter plants -Some people guide their moral compass on legislation, others by culture/customs, others on religion (Hindus worship cow, but >90% of American?s eat beef) -Beloved cultural icon in the US, symbol of beauty, grace, power?changes perception of slaughter -Horse industry personnel like to see industry as livestock, while public views as companion animals -Often if horse is healthy, many veterinarians won?t feel comfortable euthanizing horse as a convenience -Rights groups believe that only veterinarian-administered barbiturate overdose as the only acceptable method of humane euthanasia?to many barbiturates in the ground Over the method of shotgun or impact gun -Facts there are too many unwanted horses; economic times are tough, option are very limited -Bill that is getting ready to pass saying that you can?t knowingly transport animals to Canada or Mexico knowing they are going to slaughter?can definitely add to the unwanted horse problem -Bill died in committee due to the economic crisis?but sure that it will get started again -Humane society of the US is one pushing for the bill, as well as PETA and Animal Institute, some Equine veterinarians got together for a group to support this bill as well -Ban against slaughter is actually only existent in Texas and Illinois, so theoretically could start slaughter plant in any state?won?t happen because they anger level too high on this topic (horse slaughterhouse has been burned) Lecture 10/27/08 Nutritional Disorders Anemia Fe deficiency (normally) Difficult to produce with adequate high quality roughage Extremely difficult for horses turned out side to pasture Azoturia ?Monday morning disease? Signs: profuse sweating, abdominal distress, stiffness, reluctant to move, wine colored urine (myglobinuria?protein in muscles, takes O2 off hemoglobin) Occurs at the onset of exercise Cause: failure of carbohydrate metabolism Treatment: rest and quiet, muscle relaxants, keep warm Prevention: bulk up feed (add more fiber) on days of rest, Vitamin E and Se are thought to be involved Problem is too much energy Not the same as tying up syndrome?occurs after exercise (late-post) also been associated with vitamin E and Se, Founder (laminitis)?usually in front feet Cause: excess feed, chronic or acute overfeeding, increase energy, trauma (road founder?excessive trailering), infections (systemic), illness Signs: classic stance, feet hot, increase digital pulse, rotation of the coffin bone, Treatment: antihistamines, bute (phenylbutazone)?anti-inflammatory for chronic pain, hot?cold water (alternating), trim feet to make horse more comfortable Prognosis: guarded?always will hit heal first Lecture 10/29/08 Metabolic bone disease (MBD)/Acquired contracted tendons/Osteochondrosis (OCD) Young horses disorders Large number of bone disorders are lumped together in this category Seen mostly in large fast growing breeds or in the fast growing lines within the breeds Cause Unknown and varied Genetic component Cu-copper?lesions significantly reduced with increased copper Energy intake Treatment Reduce growth rate Colic General term which describes a variety of conditions, there are many causes Signs Pain?two forms Irreversible: severe and unrelenting Reversible: intermittent Decreased fecal passage Gut sounds usually decreased (except with gas colic) Sweating Toxic signs HR increased Pulse rapid and weak Capillary refill slow Color of membranes (muddy really bad?can?t get to surgery fast enough Respiration shallow Treatment Oil, water Surfactants (help break up gas bubbles) Pain relief Surgery Internal Parasites of Horses Strongyles Large and small (blood worms) Large are most damaging (damage intestinal blood vessels) 3 types of large strongyles Strongylus equinus Strongylus edentatus Strongylus vulgarus (get these, get other three?dewormers focus on) Strongylus vulgarus?most common Migrate through blood vessels and cause fibrous thickening of vessel walls Large strongyles are 1 inch long at maturity Found mainly in cecum and some in colon Damage gut lining by actively digesting plugs of intestinal mucosa Not major concern?the migration is the major problem Resulting in blood loss, intestinal damage and anemia in sever cases Life Cycle Adults (intestine), 6-12 mos to reach maturity?eggs in feces, 1st and 2nd stage larvae live in feces?3rd stage larvae migrate to grass and are ingested, 4-8 weeks after de-worming eggs reappear in feces (from maturing migrating forms)?migrate through blood vessels Ivermectin will kill all migrating forms Ascarids Parascaris equorum (large round worms) 5-15 inches long when mature Generally seen in horses <2-3 years old Rare in horses >5 years old May cause damage from migration in body Results in pot-bellied, rough coated young horses Food sources not clearly defined extensive damage to gut when large numbers are present De-worming?heavily infected animals need multiple small doses When de-wormed may plug intestines and cause colic First foal de-worming should aim to reduce Ascarid infestation Life cycle Adult ascarids (intestines)?eggs passed in feces, mature to infective stage (10-15 days)?infective larvae ingested?penetrate gut wall?migrate indirectly (blood) or directly (tissue)?lungs and liver?coughed up and swallowed Infective stage may survive for 5 years or more in the environment, contaminated feed, facilities, drinkers and bedding Produces dry, hacking cough Bots-Gastrophilus Mature parasite?stomach, mouth Large numbers?digestive disturbance most damage to stomach, suck blood Early anthometics caused damage to mouth After ingestion migrate through tissues of cheek and gums (may results in mouth soreness in heavy infections) Life cycle: Larvae (gastric parasite) 9-10 mos?Larvae passed in manure in summer, pupate in feces 2-4 days?Adult fly emerges, has 5 days of life, some do not have mouth parts and do not eat?Eggs on hair (legs, neck, lips) species dependent, warmth and moisture on lips causes eggs to hatch (migrate in mouth) Worm one time a year to reduce bot population?not more because used carbon disulfide is the flushing compound Now Ivermectin is used because it destroys bots?use one time in fall after the first frost of the year Lecture 11/3/08 Pinworms?Oxyuris equi Usually young horses Locate in large intestine Adults-feed on vegetable matter Larvae-attach to gut lining No body tissue migration Severe infections may cause irritation of rectum and colon and result in colic Life cycle Mature female migrates to anus and deposits eggs on skin of anus, this causes itching (tail rubbing) Causes horses to rub on other horses or fences allow it to be spread Eggs infective in 3-5 days Picked up from posts, walls, drinkers, or directly from horse Tapeworm?Anoplocephala perfoliata magna Lives in the intestines, causes poor growth and weight loss Live entire life in digestion tract, no migration Not of particular concern until recently Avermectin products don?t get tapeworms Life cycle similar to pin worms Need to direct one de-worming per year at getting this parasite Parasite control management practices in addition to a de-worming programming 1. Provide sanitary feeding and watering facilities, reduce fecal contamination 2. Remove manure from stalls and paddocks (discourage grazing in paddocks) 3. Allow periodic rest of pastures at least 2 months (rotate if have enough land) 4. Avoid over crowding of pastures 5. Never spread fresh manure on pastures (compost at least 2 weeks) 6. De-worm before putting on new pasture 7. Harrow and mow pastures Exam 3 Material Lecture 11/3/08 Reproductive system of the horse?of the mare (look at diagram) Female Reproductive Tract Ovary?produces the egg (follicle)?estrogen After the egg ovulates Corpus Luteum (CL) develops and then produces progesterone Fallopian Tubes (oviducts) Fertilization happens Conducts the ova to the uterus Uterus Maintenance of pregnancy, very muscular and glandular Cervix Muscular sphincter that separates the uterus from external environment Vagina Receive stallion and semen Vulva Separates vagina from external environment, receives stallion Estrogen Produced by the follicle on the ovary Causes mare to show signs of estrus The higher the estrogen levels go up the more receptive she is to the stallion as well as as the follicle is increasing the levels of estrogen Progesterone (Regumate?brand name) Produced by the CL and by the uterus during pregnancy Maintenance of pregnancy, mare not receptive to the stallion Relaxes uterus and makes it quiet (no contractions)?allows embryo to seed itself and become nourished Regulates cycle so mares come into heat at the same time?used for embryo transfer to get two mares cycling together Keep out of heat to make more enjoyable FSH (Follicle Stimulatin Hormone) Produced in the brain Initiates follicle growth LH (Luteinizing Hormone) Causes ovulation of the follicle Produced in the brain (feedback group of hormones) Used to ship semen Prostaglandins Causes lysis of the CL Uses exogenous prostaglandins?produced outside the body Give it to her when she has a CL?kills CL?progesterone drops dramitcally?starts the estrus cycle over Used to short cycle mares, synchronization of mare Non-progressing pregnancies to bring back into estrus to re-breed Accidental breeding to bring back into estrus and promote absorption of the follicle Lecture 11/10/08 Mare Seasonal breeder (seasonally polyestrous) Optimal breeding season for a mare in northern hemisphere and optimal environment is late spring?early summer Anestrous?not cycling in winter Transitional period?late winter through early spring, fall Estrous Cycle 21 days in length Estrus (heat) average ~6 days, range 3-7 days Diestrus (not receptive) average ~15 days Heat detection Teasing Mares will only show estrus in the presence of a stallion Heat detection critical to reproductive performance (often people get lazy at?but very important) Teasing and Teasing Methods Teaser Aggressive Controlled-restraint Stallion/non-breeding, young colt or pony Accuracy and Frequency?most important practices Should tease every other day Know your mares? cycles Record results daily Methods-most farms use some combination Individual teasing?more accuracy Leading mare to stallion?s stall, may produce bad stall manners, urine in aisles Lead stallion to mare?s stall, difficult to detect estrus in protective mares with foals Tease wall, labor intensive, mare and stallion are both handled Group Teasing?less labor, reduced accuracy Fence line, shy or aggressive mares may create problems Pony turned out with mares, clever ponies will get mares bred, pasture teasing?ride or lead stallion, ?Dangerous? Lecture 11/12/2008 Breeding Hygiene?reduce introduction of bacteria Mare?wrap tail, wash vulva and surrounding area, rinse thoroughly Stallion?wash penis with mild soap or just water, rinse thoroughly *Questions regarding the value of this practice, but is done throughout industry Breeding Area Large enough area or 2 horses and handlers Stallion and mares can by very dangerous at this time Surface clean and dust free?almost impossible on farm Free from dangerous objects Close to water supply Close to lab?AI Palpation chutes?not essential but very useful Phantom?artificial insemination, improves safety Indoors?especially if you are breeding large numbers (doesn?t have to be), well ventilated, and easy to clean Breeding and Breeding Methods Age May breed mare at 2 years, with good nutrition Typical initial breeding age 3-4?most breeds Range 3-16 years (do cultures/biopsies to see if they are able to breed) If uterus too bad to conceive and horse is valuable use embryo transfer Breeding Breed 20-24 hours before ovulation Breed every other day or every 36 hours beginning on 2nd day of heat Don?t over breed?increase possibility of infection Breed to follicles more palpations, AI, shipped semen (becomes much more invasive) Pasture breeding?Coral breeding Advantages Horses determine time of breeding Increased conception rate Decreased labor Disadvantages Limited book 25-30 mares Increased chance of injury to both stallion and mares Inaccurate breeding dates, markers not very Stallion temperament?may not separate easily Hand breeding?Natural cover Advantages Increased number of mares bred (allow to track number of times bred) Decreased injury to horse Increased accuracy Disadvantages Humans determine time of breeding Increased labor Increased cost Requires experienced personnel Increased injury to people Advantages -Increase number mares per stallion -Decreased injury to stallion and mares -This is the main reason in horses-every other species does it to improve genetics in the population -Evaluate semen -Decreased mare handling Disadvantages -Humans determine time of breeding -Increased labor -Increased cost -Experienced personnel (technical) -Registry, breed rules and paperwork Lecture 11/17/08 A.I. Advantages Increase number mares per stallion Decreased injury to stallion and mares This is the main reason in horses?every other species does it to improve the genetics of the population Evaluate semen Decreased mare handling Disadvantages Humans determine time of breeding Increased labor Increased cost Experienced cost Experienced personnel (technical) Registry, breed rules and paperwork Differences in estrus Puberty?18 months, earlier if well fed, later if not well fed (don?t often breed at this time?wait till about 3 years of age) Anestrous?infertile, may show estrus signs Foal heat?7-9 days after foaling, may be bred if delivery normal, increased incidence of early pregnancy losses Foals born a monogastric digester, foals often get extreme scours nothing to worry about often the changing to a hind-gut fermentor Silent heat?no signs, frequently man-made Light therapy?mimic spring, hormone assistance, approximately 16 hours Give them two more hours of light at the end of the day Combination of artificial and natural light Classification of mares?predicts how you are going to manage them on farm Maiden?never bred and still relatively young Open/Barren?not pregnant, but was bred previously (Open?left open from the year before) (Barren?bred the previous year but did not conceive or aborted) Foaling?lactating, foaling annually (better off to keep them bred) Conception rates?conceptions/breedings (estrus) Not mares bred Conception rates in horses are relatively low (~50%) Want good numbers for taking individual horse too Pregnancy rates?conceptions/mares bred (often given to clients) Foaling rates?births/number of mares exposed to a stallion Want high numbers if a breeding farm?indicates good care Birth date is always January 1st Breeding season (Feb 15-June 30, use artificial lighting) Don?t breed anything before February 15th Standardbreds made November 1st the birthdate of all horses?but changed after many problems Gestation is 342 days Range: 336-370 days Most embryonic loss occurs at <60d not to often after except maybe viral loss Pregnancy detection 1. Failure to return to estrus 2. Rectal palpation 3. Ultra sound 4. Blood test (PMSG) Stallions are also seasonal Most fertile in the spring May begin breeding at 2 years of age Most start at 3 Hand Mating Guide 2 year old?????.10-15 mares/season 3 year old?????.20-40 mares/season 4 year old?????.30-60 mares/season Mature??????..60-80 mares/season >18 year old????.20-40 mares/season *How old is too old?? 2 stallions producing after 30 years old Often a problem with testicular degeneration due to something produced in the brain?testicle often atrophies *Based on every other day breeding *Don?t over breed Cryptorchadism?retained testicle(s) Unilateral?one testicle?often still successful breeders, pose a genetic problem pass on to offspring Bilateral?both testicles Lecture 11/19/08 Common Name Scientific name Chromosome No. Przewalskii?s Horse Equus caballus przewalskii 66 Horse Equus caballus 64 Donkey, Ass Equus asinus 62 Asiatic Wild Ass Equus hemionus 56 Grevy?s Zebra Equus grevyi 46 Burchell?s, Grant?s, Chapman?s Equus burchelli 44 Damara, Boehm?s Zebra Mountain Zebra Equus zebra 32 Hartmann?s Zebra (true zebra) *All breeds and types of horses can interbreed even though look very different?variants for speed and function *Large number of donkeys are infertile *Know generalizations Definitions: Chromosome: threadlike structure that carries genetic information Gene: located on chromosome, regulates body functions, by regulating protein production, occurs in pairs on different chromosomes Locus: where gene is located on chromosome, loci-plural Allele: member of a gene series, may be several alleles of a given gene that appear on the same locus Meiosis: reduction of chromosome numbers to ½ during sperm and egg production, only one allele of a pair is passed to the next generation Dominant: the dominant allele masks the effect of the other allele present Recessive: if present with dominant it will not be expressed, but is still present Homozygous: when the two alleles present are identical Heterozygous: when the two alleles present are different Incomplete Dominance (Co-dominance): when one allele is present, partial masking of other allele, when both alleles are present, more extreme effect is noted Phenotype: outward characteristics (height, color, lengths of neck, racing speed) Genotype: genetic make-up (genes that are present) Environment: affects the expression of he genes present, therefore genotype and phenotype may differ (lack of feed may result in an animal not reaching its genetics for height) *in a breeding program, only interested in genotype but reliant on phenotype to select for breeding C locus: the color gene, allows animal to have pigment, there are 3 alleles that occur at this locus C dominant ccr dilution gene, co-dominance (occurs rarely) c recessive C or ccr will have skin, hair and eye pigment cc (both recessives) no pigment is the true albino, albinos do not exist in horses, thought to die in utero ccr is thought to a mutation of the c allele has an additional effect which will be discussed with other dilutions *one ccr produces the palomino/buckskin *two ccr produces the cremello/perlino (NOT ALBINOS) B locus: only two alleles possible B dominant, produces black pigment B recessive, produces brown (chestnut) pigment *Pigmentation includes eyes, skin, and hair *There are only two base colors in horses (black and chestnut) *All other colors are variations on those two base colors *equal chance of having black or chestnut foal Lecture 11/24/08 A locus: the wild pattern gene, affects distribution of black pigment, **has no effect on chestnut Four alleles A, A+, a+, a (in order of dominance) A bay pattern A+ controversial, thought to produce the color pattern of Przewalski?s Horse, dark spinal stripe, dark vertical bar on each shoulder, dark horizontal bars on front legs a+ seal brown coat color, lightening in flanks, rear, and muzzle a uniform coat color, fading black E locus: these alleles works jointly with the alleles present at the B and C loci to control intensity of the pigment present (how you get dark bays and liver chestnuts) Three alleles ED, E, e in order of dominance ED increases the intensity of dark pigment E allows normal pigment of expression e increases the intensity of light pigment (yellow-red) suppresses dark pigment ED ED will mask the action of the A locus, i.e. bay horse will be black ee produces light bays and sorrels (doesn?t necessarily mean flaxin tail?has some white in the tail) example: CCBbAaEDe?dark bay -Has pigment at C locus, B means black base, A adjusts to bay, e adjusts intensity CcbbAAee?sorrel -has pigment at c, chestnut at B locus, A locus doesn?t matter its chestnut, sorrell ccBBAAED ED?albino or non-existent CCBBaaEE?fading black Has pigment at C, black at B, not affected at A, not affected at E Chestnut crossed with a bay (both unknown genetics) possible colors? Black Bay Brown Chestnut Sorrel *at the A locus, chestnut masks everything, blacks masks things at that B and E locus Dilution genes (speculative) D locus: causes dilution of base color Two alleles D, d D dilutes base color d base color unaltered Dd, DD black to grulla, mouse, or smoky blacks Bay to yellow dun with dark mane and tail Brown to redden Chestnut and sorrel to yellow dun with dun man and tail ccr allele at the C locus has one effect in the heterozygous state (co-dominance), more complete effect in the homozygous state Cccr Chestnuts and sorrels?palominos Bay?buckskins Seal brown or black?little change, may appear bay ccr, ccr, cccr chestnut and sorrel?cremello bay, black and seal brown?perlino *cremello with a chestnut get 100% palomino Modifying Genes G locus: produces gray coat color from any base color, overruns everything! G dominant, produces gray g recessive, base color unchanged 2 solid color horses can not produce a gray Chestnut crossed with a chestnut with give you 100% chestnut Lecture 11/26/08 CCBbAaEEddGg?bay gone gray (cinnamon gray) ccBBaaEdEdddGg?steel gray cross the top two?which percent will be gray? Gg xGg (1/4 of foals will not be gray) CCbbAAEEddGG?chestnut gone gray (rose gray) CC=has pigment bb=chestnut AA=doesn?t affect EE=color unchanged dd=color unchanged GG=gray (if stallion, 100% of offspring will be gray) CccrBbAaEeddGg?gray buckskin (UGLY!) C=has pigment, has dilution gene for buckskin B=black A=bay E=no change in color D=no change in color G=gray Rn locus: produces roaning (Arabians ignore the roaning pattern?register as base) Rn dominant, produces roan pattern rn recessive, base color remains unchanged RnRn homozygous dominant, thought to be lethal in-utero as this horse doesn?t exist in the population Rnrn x Rnrn roaning happens 66% of the time W locus: produces white horses (whites in Saddlebreds & Tennessee Walkers) W dominant, white w recessive, base color WW lethal in utero (doesn?t exist) Whiter than cremellos and perlinos Gray- graying starts at he head and move towards the leg?in the end all gray mane and tail include Steel gray- come from black/browns Cinnamon gray-come from bay Rose gray- come from chestnut/sorrel Blue roan- come from base black/brown (head, legs, mane, tail black) Bay roan- head red, mane/tail black Degree of roaning controlled at a different loci Tobiano 1. White Crosses the back 2. Head is marked like that of a solid colored horse 3. All legs are white, at least below the knees and hocks 4. Body spots are regular, oval shaped and distinct 5. One or both flanks are usually dark (usually not a lot of white on underline) Overo 1. White does not cross the back (topline) 2. One or more legs are dark 3. The head is often bald (cover the whole area of the face), apron (downward over the muzzle/eye), or bonnet-faced (big splotch up high). 4. White body markings are irregular or splashy 5. The tail usually one color Paints and Pintos?Tobiano or Overo Piebald black base Skewbald brown base (chestnut) Tobiano simple dominant TT or Tt are tobiano Overo dominant, homozygous lethal ?lethal white? OO dies shortly after birth Oo overo oo solid The amount of white for both patterns is controlled by several genes. Lecture 12/1/08 Examples: CCbbAAEdeddggRnrnwwTtoo?spotted chestnut roan C=has pigment B=chestnut A=doesn?t affect E=dark/liver chestnut D=doesn?t affect G=doesn?t affect Rn=roan W=not white T=tobiano O=not overo ccrccrBbAaEeddggrnrnwwttoo?perlino C=double dilution B=black A=bay E=all recessive D=doesn?t affect G=doesn?t affect Rn=recessive W=not white T=not tobiano O=not overo CCBBAaEeddGgRnrnwwttoo?cinnamon gray (can?t see the roan) C=has pigment B=black A=bay E=normal pigment D=no dilution G=gray?cinammon Rn=roan W=not white T=not tobiano O=not overo Palomino mare bred to Chestnut stallion Possible Offspring colors: palomino, chestnut Concerned about the C, B loci Mare: Cccrbb Stallion: CCbb Possible Outcomes: Cccrbb?palomino CCbb?chestnut Could have: ccrcbb?cremello (don?t worry about, happens too infrequently) Appaloosa Blanket controlled by at least 3 pairs of genes Ap allows expression (dominant genes) Wb blanket occurs Sp spots on blanket Can have genes for a blanket but not expressed if the dominant gene not present Wb and Sp must be homozygous to be expressed in female *The breed allows non-colored horses to be registered as breeding horses Leopard pattern may be controlled by a dominant gene Genetic Disorders SCID (severe combined immuno-deficiency) Arabians, young horses die from the inability to produce antibodies Autosomal recessive Occurs rarely in thoroughbreds 4-6 weeks old foal gets cold, eventually flu like symptoms, then eventually die, test available, can still breed if bred to non-SCID stallion *As long as you don?t select for undesired trait, it doesn?t increase in the population. *MSU SCID free Both sexes can carry, mare carrier then breed to non-SCID stallion, if stallion is carrier often doesn?t get bred HERDA (hereditary equine regional dermal asthenia) also HA (hyperelastosis cutis) Quarter horses (Poco Bueno Syndrome), slough skin, not seen until older Autosomal recessive Most recently discovered, traced back to Poco Bueno, when put saddle on them the back skin will separate and slough off, extremely painful, often euthanized HYPP (hyperkalemic periodic paralyis) Quarter Horses (Impressive Syndrome), muscular disorder causing spasms and seizures Codominance?heterozygote shows slight effect, homozygote shows extreme effect Traced back to one horse, Impressive, horses that are carriers often did better in the show ring than non-carriers (typically halter horses), thought to be the constant tremors enhance muscle mass Heritability: the percentage/amount of the variation in an individual compared to the average of the population that can be passed on to the next generation Something?s have heritability of 100%?not usually concerned about, traits that are not influenced as much by the environment Hard to reproduce, traits that are influenced greatly by environment may not be highly heritable In general, reproductive traits are very lowly heritable (<.25) Traits that have to do with speed?mildly heritable (.25-.3) growth often highly heritable, cow sense (desire of individual to look/work cattle)?highly heritably (.35-.5) 365-day weight?very highly heritable (some environmental influences) height at 365 days?very highly heritable Jumping ability, dressage, 3-day event?based on enviro, low heritability Horse Breeding What does it mean to be a breeder? 1. Have a goal (decide by you) Improve the breed Leave the breed better than you found it Stay with your goal Don?t respond to trends ?magazine breeders? Don?t let others dictate your goals 2. Be honest and stand by your product (only need to get caught once) 3. Be a student of practical genetics