Jan 16, 2015 | Ailments, Breeding
The 5 Panel Genetic Test for AQHA registration
The AQHA offers its members a genetic test for a panel of 5 different genetic diseases affecting Quarter Horses. The panel tests for Hyperkalemic Periodic Paralysis (HYPP), Polysaccharide Storage Myopathy type 1 (PSSM 1), Malignant Hyperthermia (MH), Hereditary Epidermal Regional Dermal Asthenia (HERDA), and Glycogen Branching Enzyme Deficiency (GBED). All these diseases are genetic, and are caused by single mutations in DNA that are easy to test for. The University of California-Davis performs the testing for the AQHA, using mane or tail hair or blood samples.
The panel has been available for years, but just recently AQHA began requiring that results of the panel be on file for stallions before their foals could be registered. This applied at first only to stallions that were bred to more than 25 mares, but after January 1, 2015, ALL breeding stallions will need to have the 5 panel test results on file. This requirement doesn’t restrict the use of stallions that may test positive for one or more of the diseases, but it does give mare owners valuable information to consider when making breeding decisions. Although the requirements for the panel testing only apply to breeding stallions, owners may request testing of any horse if they are interested or have concerns.
HYPP
HYPP stands for Hyperkalemic Periodic Paralysis. This disease affects the electrical impulses within the body that control muscle contraction. The defective gene results in clinical signs of muscle tremors and fasciculations. In some severe cases, horses may be unable to stand, or even unable to breathe. Horses can show symptoms with only one copy of the defective gene, but symptoms are often more severe if they have two copies of the mutation. This disease affects mostly halter horses, and can be traced back to the prolific stallion ‘Impressive’. Since Impressive lines were also used in Paint and Appaloosa halter breeding programs, HYPP is found in those breeds as well. AQHA does not allow registration of foals that test positive for two copies of the defective gene (H/H), but will allow registration of foals that are H/N: one defective and one normal gene.
PSSM 1
PSSM stands for Polysaccharide Storage Myopathy. This disease causes changes in the way sugars are stored and used by the muscles. It causes frequent episodes of ‘tying up’ if not properly controlled by a special diet and regular low intensity exercise. There are two types of PSSM. Type 1 is caused by a genetically identified mutation, which is testable. Type 2 is suspected to be genetic, but that mutation has not yet been identified by researchers. Most Quarter Horses with PSSM have type 1. Horses will show symptoms of PSSM type 1 with one or two copies of the mutation. Like HYPP, PSSM type 1 is more common in halter QHs than in other lines. Some QHs have been shown to have mutations for both HYPP and PSSM.
HERDA
HERDA stands for Hereditary Epidermal Regional Dermal Asthenia. Horses with HERDA have defective collagen, an important protein that is part of skin, cartilage, muscles, and tendons. The major clinical sign is skin that is easily injured, torn, or even sloughed off. The skin is also very slow to heal. There is no treatment for the condition, and horses that have it are often euthanized. Horses will only show symptoms if they have two copies of the mutation for HERDA. Horses with only one copy of the mutation are clinically normal. These animals are called ‘carriers’. They can pass copies of the mutation to their foals, and if one carrier is bred to another carrier, the foal might inherit the mutation from both parents and be symptomatic. HERDA is limited mostly to horses with reining and cutting horse bloodlines.
GBED
GBED stands for Glycogen Branching Enzyme Deficiency. Like PSSM, this disease also affects how sugars are stored, but in a different and more severe way. It results in abortions, stillborn foals, and foals that are alive but weak at birth and die or are euthanized soon after. Like with HERDA, horses may be carriers for GBED – if a horse has only one copy of the mutation it will be clinically normal. Paints and Appaloosas can also carry the GBED mutation.
MH
MH stands for Malignant Hyperthermia. This disease changes the way muscle cells handle calcium, and thus the metabolism of the cell. Horses with MH will appear normal most of the time, but have specific occasions when they show symptoms. During an attack, horses will have a very high fever, profuse sweating, high and irregular heart rate, high blood pressure, and rigid muscles. Attacks are triggered by certain anesthetic agents or stress, and are sometimes fatal. MH is believed to be less common than either HYPP or PSSM, but the percentage of affected horses is not yet known. Several breeds including Quarter Horses and Paints can be affected. Horses may be positive for both PSSM and MH together, and these animals appear to suffer from more severe episodes of tying up than horses that have PSSM alone.
Dec 23, 2014 | Breeding, Uncategorized
White Horse
Is there really such a thing as a white horse? Many gray horses start out nicely dappled, but then fade to nearly white as they age, and are incorrectly called ‘white’ by non-horsey folks. However there are a handful of other colors, each genetically different, that can result in a horse that looks white.
Blue-Eyed Creams Blue-eyed creams, (cremellos and perlinos), are horses that inherit two copies of the ‘cream’ gene. This gene is a color dilution factor, and when a horse inherits two copies, the result is a horse with blue eyes and an off white or cream colored coat. In the summer when they are slick and shiny these horses can appear white. Cremellos and perlinos can be difficult to tell apart without a genetic test to detect the differences in their underlying coat color. Cremellos are genetically chestnuts with two cream genes, and perlinos are genetically bay with two cream genes.
Lethal White Lethal white is an inherited condition usually seen in paint horse foals. These foals are born either all white, or mostly white, and like the name implies, they heartbreakingly will all die or have to be euthanized shortly after birth. The all white coat color in these foals is associated with a genetic mutation that also produces a problem in the nerves to the gastrointestinal tract, which interferes with motility and causes severe colic. There is no treatment for the condition. Usually, but not always, these foals are a product of breeding two overo paint horses. There is a genetic test available to screen potential breeding animals as carriers for the condition, and all responsible paint breeders should know the status of their breeding stock.
Sabino White Sabino is a description for a collection of white markings, and the word is used by multiple breeds. Horses labeled as sabinos often have extensive roaning, belly spots or large face markings and high white on the legs. Geneticists believe that there are probably several different genes that produce sabino type markings, but one mutation in particular has been identified, and named Sabino1. The Sabino1 gene is found mostly in Tennessee Walkers and Miniature horses, but also in some Paints, Shetland Ponies, and Pony of America’s. One copy of the Sabino1 gene produces the typical roaning, belly spots, high leg white, and large face markings. However, horses with two copies of Sabino1 are at least 90% white, and are referred to as ‘Sabino-white.’ These horses usually have pink skin and dark eyes. Sabino-white foals can look identical to Lethal-white foals, but they will be completely healthy, so it is important not to assume that all white foals should be euthanized at birth.
Dominant White Dominant white is caused by a variety of genetic mutations that affects pigment cells in skin and hair follicles. These mutations produce a horse with pink skin, white hair, and usually dark eyes. One particular such mutation, from the QH stallion GQ Santana, has been identified, and there is now a test available for it. Since it is a ‘dominant’ trait, only one copy of the mutation is needed to produce a white coat color. So far no horses with two copies of the mutation have been identified, so it is not known if foals/fetuses with two copies would be ‘viable’.
Nov 24, 2014 | Athleticism, Competition Horses, Exercise, Hoof Care
Managing your horse for a long athletic career I listened intently Tuesday evening to Dr. Lacher and Dr. Bourke discussing athletic horses and their needs. I like to think of myself as an athlete and I want to be around a long time so here are notes from the cat.
A long career starts at the beginning. A solid education as a youngster gives our horses the right skills to fall back on in a pinch. By spending time putting good footwork and consistent response we set our horses up to succeed later in life. Footwork allows a horse to properly use each of its four legs to balance when we ask them to suddenly change direction to cut a cow, or spin, or jump, or pirouette. Just like football players have to practice footwork so its second nature during a crucial play, our horses have to be very good at the basics. Ask any high level rider what they practice most of the time and the answer will be the basics. Ask any high level rider what they don’t practice and it will be the big tricks whether that be spins and slides, big jumps, extreme collection or extension.
Apparently not only should our horses be educated but the riders should be too. You humans can really affect what happens with your horse. Getting the best quality lessons, using all that technology has to offer, and always learning help you influence your horse in a positive way.
Fitness is not a subject I’m particularly fond of. I like to hold down the counter at the office and be sure everyone in the office offers me a bit of their lunch. But I digress. Different types of horses require different levels of fitness. A rail horse, for example, will need stamina to keep consistent gaits both directions of the rings and potentially come back for a final but is unlikely to need extreme cardiovascular fitness. An event horse or a reiner, on the other hand, will need to be cardiovascularly fit to perform at even modest levels. Designing an appropriate fitness program for your horse’s career will keep tendons, ligaments, muscles, and lungs ready to handle anything we throw at them. Spoiler alert: there will be a bit about injury later on. Mental fitness should also be taken in to account. Horses, just like people, like to cross train. Oh and they like a vacation every now and then too. Personally, I like summer to vacation. As a black cat summer gets a bit hot so I stay inside, listen to the latest tunes, and catch up on Facebook.
Fitness is again important for the humans. You are more likely to make all the right moves if you aren’t too tired to make the right decision at the right moment. Assess your own strengths and weaknesses. Most of us favor one side or the other. Do you find all the horses you have ever ridden on a consistent basis are similarly one sided? Do you have a go to move when you get in trouble? A few sessions with a personal trainer every now will help you manage those weaknesses. Oh and don’t forget mental fitness for humans. Ten Minute Toughness by Jason Selk and other similar books are great introductions to sports psychology.
Well that’s a wrap for this blog since I need to go supervise the office. Stay tuned for my next installment about the equine athlete. Until then may your litter box be clean and your food bowl full.
Nov 10, 2014 | Breeding, Uncategorized
Welcome to part 2 of Equine Coat Color Genetics: Gray, Roan, and Dun
This blog builds on the information presented in the previous blog: Equine Coat Color Part 1. We recommend you read that post first to best understand this one.
The Gray Gene
We all know that gray horses aren’t born gray, but they are not all born black. A gray horse can start out any color at birth, and then they fade as they age, sometimes slowly, and sometimes rapidly. The ‘gray’ gene is simple. ‘G’ stands for ‘gray’, and ‘g’ for ‘NOT gray’.
GG = horse goes gray
Gg = horse goes gray
gg = horse stays whatever color it is at birth
The color that a gray horse is born with is determined by the other color genes. For example:
EE or Ee (black-based), with aa (unrestricted black), with GG or Gg (gray) = Horse born black, then goes gray.
EE or Ee, with AA or Aa (restricted black), with GG or Gg (gray) = Horse born bay, then goes gray.
ee (red-based) with GG or Gg (gray) = Horse born chestnut, then goes gray.
Roaning
The roan gene is a color modifier that causes an intermixing of white hairs with the base coat color, with more white over the neck and body and less white on the head and legs. Black based horses with roan have black and white hairs, and are called blue roans. Chestnut based horses with roan have red and white hairs, and are called red roans. Bay horses with roan have brown and white hairs, and are either called bay roans or strawberry roans.
The roan gene is a dominant trait, meaning that ‘Rn’ for ‘roan’ is dominant to ‘rn’ for ‘NOT roan’. The famous cutting horse mare Royal Blue Boon is an example of a blue roan, and her son, the famous sire Peptoboonsmal, is a red roan.
EE or Ee (black-based), with aa (unrestricted black), with RnRn or Rnrn = Blue Roan
EE or Ee (black-based), with AA or Aa (restricted black), with RnRn or Rnrn = Bay Roan
ee (red-based), with RnRn or Rnrn = Red Roan
Dun Dilution – Dun, Red Dun, and Grulla
The dun gene is a color dilution factor that causes a horse to have a diluted coat color, a dorsal stripe, and other ‘primitive’ markings, such as bars on the legs, and sometimes dark marks near the withers. The dun gene is responsible for grulla, dun, and red dun horses. Dun is a dominant trait. ‘D’ for ‘dun’ is dominant to ‘d’ for ‘NOT dun’. The other color genes determine what shade the base coat color is.
A grulla is a black horse with the dun dilution factor.
EE or Ee (black-based) with aa (unrestricted black) with dd (not dun) = Black.
EE or Ee (black-based) with aa (unrestricted black) with DD or Dd (dun) = Grulla.
A dun is a bay horse with the dun dilution factor.
EE or Ea (black-based), with AA or Aa (restricted black), with dd (not dun) = Bay.
EE or Ea (black-based), with AA or Aa (restricted black), with DD or Dd (dun) = Dun.
A red dun is a chestnut horse with the dun dilution factor.
ee (red-based), with dd (not dun) = Chestnut.
ee (red-based), with DD or Dd (dun) = Red Dun.
Look for the next installment of Equine Coat Color Genetics coming soon for info on Palomino, Buckskin, and Smokey Black!
Oct 31, 2014 | Ailments, Events, Herpes, Vaccines
Why Vaccines are SO Important for your horse!
“Do I really need to vaccinate my horse?” YES. Absolutely. In an era where more and more people are turning to a more holistic approach to health care for both themselves and their horses, it is important to remember that vaccines are still an extremely important part of protecting your horse from harm.
All horses in Florida need at minimum to be vaccinated against Rabies, West Nile Virus, Eastern Encephalitis, and Tetanus. These are called ‘core’ vaccines because ALL horses should have them, regardless of their age, use, travel, or geographic location. The list of core vaccines and recommended vaccine schedule is put together by experts in immunology and equine medicine within the American Association of Equine Practitioners, the nationwide organization of horse vets. Why these four, and not others? Here’s the criteria used to qualify a vaccine as ‘core’, or a ‘MUST have’:
The disease causes severe symptoms or death.
- Rabies: A variety of neurologic symptoms leading to certain death.
- West Nile: Muscle twitching, hyper excitability, in-coordination, sometimes inability to stand or death.
- Eastern Encephalitis: Fever, severe in-coordination, inability to stand, seizures, coma, death.
- Tetanus: Muscle spasms/rigidity, inability to eat or drink, inability to rise, death.
The disease is difficult or impossible to treat.
- Rabies: 100% fatal regardless of treatment.
- West Nile: Supportive care only. Up to 1/3 of horses die despite treatment, and others have lasting neurological problems.
- Eastern Encephalitis: Supportive care only. Up to 90% of horses die despite treatment.
- Tetanus: Antibiotics, muscle relaxants and supportive care are used. 50-75% of horses die despite treatment.
The way the disease is spread puts all horses at risk, regardless of the horse’s lifestyle.
- Rabies: Through bites from rabid animals.
- West Nile: Spread by mosquitoes.
- Eastern Encephalitis: Spread by mosquitoes.
- Tetanus: Bacteria lives in the soil, horses exposed through wounds or hoof abscesses.
The vaccine is safe and effective.
- Rabies vaccine: 99% effective in preventing disease
- West Nile vaccine: 95-99% effective in preventing disease
- Eastern Encephalitis vaccine: 95-99% effective in preventing disease
- Tetanus vaccine: 95-99% effective in preventing disease
“But my horse doesn’t ever leave the property or interact with other horses.” Doesn’t matter. Your horse doesn’t have to go anywhere to get bit by a raccoon, a mosquito, or injure himself.
“But I’ve never heard of a horse getting Rabies.” Yes, Rabies in horses is rare. But when it does, there’s always a long list of people who get exposed in the process of diagnosing and caring for the horse prior to its death. Those people then have to go through the expensive and painful process of post-exposure therapy. Vaccinating your horse is a $20 insurance policy to protect you and your family from the possibility of exposure.
“But there haven’t been any cases of West Nile/Eastern Equine Encephalitis in my area recently. Those diseases are not here anymore.” WRONG. Just this year there have been 10 cases of EEE in horses in central Florida (Alachua, Gilcrest, and Levy counties). Our practice personally diagnosed 3 cases of EEE this season, all of course in un-vaccinated animals. The reason there haven’t been even MORE cases is because we have done a good job protecting horses by vaccinating them.
“But I’m worried about vaccine reactions.” This is a valid concern. Like all decisions in veterinary medicine, the decision to vaccinate should be one of risks-versus-benefits. For most horses the benefits of vaccination far outweigh the risks of vaccine reactions. The most common form of vaccine reactions are very mild – either a brief fever or local swellings, easily controlled by a few days of anti-inflammatories. If your horse has a history of a more severe reaction, then it may be safer to withhold that vaccine from that individual horse.
“My horse has had vaccines plenty of times before. He doesn’t need any more. My small animal vet says we only need to vaccinate my dog every 3 years.” Horses are not dogs. Unfortunately horses do not mount the same level of an immune response to vaccination as people or dogs. The scientists who did the research on extending the time between vaccines for small animals are clear that this won’t work in horses because of the different way their immune systems function. To be properly protected, horses in Florida should be vaccinated yearly against Rabies and West Nile Virus, and every 6 months against Eastern Equine Encephalitis.
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