Equine

Core Vaccines Every Horse Needs

Published

6 years ago

March 19, 2020

There are many possible dreadful diseases that horses can contract through various insect vectors, ticks, wildlife and even wounds that are rather easy to prevent with routine core vaccinations. Oklahoma has just about every insect known to man to offer, as all Oklahomans are fully aware of especially in the spring and summer, making it a very good environment for some of these key viruses to spread. The five types of diseases that will be discussed in this article are commonly referred to as the deadly five, and that is why they make the core vaccine list because if one of these diseases is contracted it can be game over for your horse. Before spring arrives, the core vaccines should be on every horse owners to do list as a common health care checklist that should be just as routine as deworming and dental care.

The American Association of Equine Practitioners (AAEP) and American Veterinary Medical Association (AVMA) have established key guidelines for vaccinations for horses that are required based on risk to the public and to the horse themselves. The five diseases listed as core vaccines are Rabies, Tetanus, Eastern equine encephalomyelitis virus, Western equine encephalomyelitis virus and West Nile virus.

The AVMA defines core vaccinations as those “that protect from diseases that are endemic to a region, those with potential public health significance, required by law, virulent/highly infectious, and/or those posing a risk of severe disease. Core vaccines have clearly demonstrated efficacy and safety, and thus exhibit a high enough level of patient benefit and low enough level of risk to justify their use in the majority of patients.” (AAEP website)

The reason these deadly five diseases are listed as core vaccines is because they pose a possible public health risk, are highly virulent or infectious, have a high mortality rate and can be effectively controlled with routine vaccination with great efficacy. It’s important to remember that vaccines are not 100% effective for every disease but well worth that risk when it comes to protect against these five deadly diseases.

There are many other diseases that horses may or may not need to be protected against with vaccinations. These diseases are listed under “risk based” immunizations depending on travel, environment, geographic circumstances and even competition/racing venue requirements before entering into an event. With recent localized outbreaks of equine herpes virus at race tracks, shows and barrel races, many venues and race tracks require very recent vaccinations for these viruses before permitted onto the grounds. Here is a list of risked based diseases vaccinations are available for: Anthrax, botulism, equine herpes virus 1 & 4, equine viral arteritis, influenza, rotaviral diarrhea and strangles. These diseases and the risk of contracting them must be weighed on an individual horse bases versus the risk of the vaccine itself.

Many vaccines today that are available for horses have all core vaccines in one shot except rabies. One vaccine provider has developed the first all five core diseases in one single vaccine. Horses just like other species require multiple boosters to generate an appropriate immune response to be protective. Unvaccinated horses or horses that don’t have a documented vaccine history it is recommended to have at least one booster four to six weeks after the first dose to get an adequate response and then annually after that. In some endemic areas of the country with higher cases of West Nile and other viral encephalomyelitis diseases due to prolonged mosquito vector season it is often recommended to have a booster in the mid-to-late summer to have added protection against these particular viruses.

Below is a breakdown of each disease and its importance for your horse and even yourself to be protected against.

Rabies –

Highly deadly virus that is unsurvivable for any mammal that contracts the disease and begins to show clinical signs, even for humans. As of 2016 only four people have survived rabies infection after showing clinical signs, so the odds are very poor. One of the most difficult aspects of rabies in horses is the variability of clinical signs. Horses can display two clinical manifestations of the disease: Furious/Mad form or Dumb/Stuporous but really it can look like anything early on. Veterinarians are trained that rabies can display almost as anything and should always be on the list for a horse that presents with neurologic symptoms, especially horses with no vaccine history for rabies. Horses can display colic, ataxia, blindness, hypersalivation, depression, weakness and even lameness. Also there is no ante-mortem test meaning there is no test to confirm rabies until the horse is dead or euthanized and the brain is collected for testing. Rabies is transmitted via bites from infected rabid wildlife such as skunks (highest transmitter in Oklahoma), raccoons, fox and bats.

EEE/WEE –

Eastern and Western equine encephalomyelitis is transmitted like other viral enchephalitides via the mosquito vector. Clinical signs are neurologic signs of ataxia, blindness, head pressing or head tilt, recumbency, seizures and paralysis of the throat/tongue. Only up to 15% of horses survive EEE. WEE has a better survival rate up to 50% and has very similar sign as EEE. Birds are common carriers of EEE/WEE and are the reservoir for these viruses.

West Nile –

A very commonly know virus that is also transmitted by mosquitoes to horses, humans, birds and other mammals. Birds again are the largest reservoir for this virus. The virus affects the central nervous system by creating inflammation around the brain and spinal cord. Symptoms or clinical signs are fever, depression, muscle fasciculations, weakness and ataxia. The severity of the disease is horse dependent and not all horses get the disease but among those horses that do about 1/3 will die from it. Also almost half of horses will have lasting neurologic effects from the disease.

Tetanus –

The causative bacterium was first discovered in 1884 by injecting wound exudates from humans with tetanus into animals leading to the discovery that Clostridium tetani is the causative bacteria. The bacteria is found everywhere in the environment including the soil and manure of horses. Horses are rather sensitive to the neurotoxin produced from Clostridium tetani that leads to the clinical signs of tetanus. The bacteria enter the horse’s body through wounds, cuts or even surgical wounds such as castration sites. The spores of the bacteria turn into the vegetative form when it begins to grow and replicate. The neurotoxin produced from the bacteria enters the central nervous system by peripheral nerves. The clinical signs of tetanus are muscle spasms, stiffness, prolapsed third eyelids, extended head and neck, elevated tail and retracted lips. As the disease progresses, horses will become recumbent and have difficulty breathing. Life saving treatments can be implemented to save the infected horses but still up to 75% of horses will die.

What all these disease have in common besides death is that these deaths are extremely excruciating, painful and miserable. There is no doubt from seeing these cases personally and from watching teaching videos that these horses are suffering enormously. What makes it even more difficult and disheartening when we see these cases is that they are so easily preventable with vaccination. The bottom line is that vaccines can save your horse’s life from these deadly diseases and vaccines are rather inexpensive especially compared to the expensive of trying to treat the horse once they are ill. Please talk to your veterinarian about getting your horse or horses protected with core vaccinations and if any other vaccinations are necessary based on your situation.

Read more great articles in the March 2020 issue of Oklahoma Farm & Ranch.

Equine

Degenerative Suspensory Ligament Desmitis of the Horse

Published

2 weeks ago

May 26, 2026

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By Dr. Garrett Metcalf

The suspensory ligament is a vital component of the limb of a horse to produce normal locomotion and support. The suspensory ligament is a common area of concern in performance horses of various disciplines and can be single handedly the cause of lameness or performance issues. This article is going to look at a specific degenerative disease of the suspensory ligament and what horses are at risk for this disease.

DSLD or degenerative suspensory ligament desmitis was first discovered in the early 1980’s in Peruvian Paso horses. The name has been changed because the suspensory ligament is not the only organ affected from the disease but the suspensory is ultimately the biggest issue. The newer name, ESPA or equine systemic proteoglycan accumulation, is more correct because other ligaments and tissues are affected by this disease. In this article we will only focus on the suspensory ligament. The most commonly affected breeds are Peruvian Paso, Paso Fino, Morgan, Saddlebred, Warmblood, Paints, American Quarter Horse, and Thoroughbred breeds. The age of onset of the disease is variable among breeds but it is more common to be seen in middle age to older horses. However it has been documented in horses as young as one year of age. The disease generally will have a slow insidious onset that can go undiagnosed for months or years depending on the horses work and discipline.

A horse that begins to show early signs of DSLD may have a vague lameness issue that is difficult to isolate and they most likely will resolve with a period of rest. As the horse returns to moderate level of work the lameness will return. This scenario may go on for several months or more before the discovery of the DSLD is made. The first indication of DSLD is often pain isolated in the suspensory branches or fetlock region when a flexion test is performed. Horses with DSLD will also have a “dropped” fetlock appearance because the suspensory is the main supporting structure of the fetlock joint. DSLD can affect the hind limbs, forelimbs or all limbs at the same time. A unique sign of DSLD is that not just one limb is affected but rather bilaterally affecting the limbs, meaning it will either affect either both forelimbs or hind limbs at the same time. It is my experience that the hind limbs are more commonly affected compared to the forelimbs. Horses will often have enlargement of the fetlock region and increased joint fluid or wind puffs. Horses will often have a straight hock or post legged hind limb appearance. Horses will often shift weight frequently in an effort to get relief from the discomfort and this can be confused with other lameness issues or foot related pain.

Diagnosis of DSLD is often made by clinical signs, breed and ultrasound findings. Ultrasound imaging of the suspensory ligaments will often show diffuse enlargement of the suspensory body and branches. The suspensory ligament will have a poor heterogeneous fiber pattern with periligamentious soft issue thickening from scar tissue deposition and edema or fluid within the tissue. Radiographs of the lower limb may reveal abnormal bone changes in the sesamoid bones behind the fetlock joints and even osteoarthritis of the pastern and or fetlock joints. A definitive diagnosis can be made from a biopsy of a ligament in the neck called the nuchal ligament, but is not often performed because of the invasiveness of the biopsy.

Treatment is very limited and it is mostly geared towards protection of further damage by prolonged rest. Pain management is also important to attempt to keep the horse as comfortable as possible. Different shoeing techniques can be used with marginal success. In early cases of DSLD, a suspensory shoe that helps engage more work from the deep digital flexor tendon can help elevate the fetlock and offer more protection to the suspensory ligament. The devastating thing about this disease is that there is no cure and there are hardly any good options to slow the progression of the disease. DSLD carries a poor prognosis when the diagnosis is made in any breed of horse or any discipline. Although some cases can be managed better than others, it often progresses to the point of debilitating pain and discomfort to the point of humane euthanasia especially in the Peruvian Paso breed.

Read more in the February 2023 issue of Oklahoma Farm & Ranch.

Equine

Gastric Ulcers

Published

2 weeks ago

May 25, 2026

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By Dr. Devan England DVM

Does your horse have gastric ulcers? Gastric or stomach ulcers are frequently blamed for a variety of things including poor performance, acting ‘cinchy’, weight loss, not eating, poor coat condition, diarrhea and colic. However, gastric ulcers are not always the culprit and the only way to know for sure if your horse has gastric ulcers is to look at the stomach on camera, using an endoscope. Poor appetite and poor body condition are the mostly widely observed clinical signs with gastric ulcers, however, these are non-specific. If you think your horse might have gastric ulcers, the best place to start is to talk to your veterinarian and consider scheduling a gastroscopy. Gastroscopy requires the horse be held off feed for at least 16-18 hours and held off water for at least 6-8 hours. Fasting off feed and water is necessary to allow the veterinarian to see the whole stomach. If restricting feed or water is difficult in your management situation, many veterinarians will allow you to hospitalize your horse the night before gastroscopy for proper fasting.

Gastric ulcers are split into two types, classified by the location of the ulcer in the stomach. Squamous ulcers are ulcers that occur in the squamous or skin like portion of the stomach. This is the top part of the horse’s stomach, is closest to the esophagus, and has squamous tissue to protect this portion of the stomach from stomach acids. The other ulcer type are glandular ulcers. Glandular ulcers occur in the bottom portion of the stomach, which is closest to the small intestine. This portion of the stomach has glandular mucosa with cells responsible for producing stomach acids for digestion as well as cells that produce mucus and buffers to protect the lining from stomach acid. Gastroscopy is important not only for diagnosing whether ulcers are present but also determining the severity and the type of ulcer, because these two ulcer types require different treatments.

Squamous gastric ulcers are common in racehorses both in and out of training, with higher prevalence in racehorses under training. Prevalence in Thoroughbred racehorses in training has been reported to be up to 100% (Sykes 2015). Squamous ulcers are also prevalent in Western pleasure horses, Thoroughbred stallions on breeding farms, and Italian donkeys (Sykes 2015). Glandular gastric ulcer prevalence has not been as well described as squamous ulcers. Glandular ulcers are reported to be most common in Thoroughbred and Standardbred racehorses, Canadian showjumpers and polo ponies, and American Quarter Horses (Sykes 2015).

Risk factors for ulcers vary by ulcer type. Anti-inflammatories (Bute, Banamine) can increase the risk of glandular ulcers in some horses by affecting normal defense mechanisms but are not a high risk in most horses. Horses that display stereotypic behaviors, such as cribbing, have an increased risk of squamous ulcers. Grain fed before hay in non-exercising horses, feeding larger amounts of grain, and increased time between meals increases the risk of squamous ulcers. Increased time with high intensity exercise and housing in single pens is associated with increased risk of glandular ulcers. A straw only diet, lack of water access and lack of direct contact with other horses increases the general risk of gastric ulcers.

If your horse is diagnosed with ulcers, the mainstay of treatment is a buffered formulation of omeprazole (Gastrogard, Ulcergard). Over the counter Omeprazole and compounded Omeprazole are not effective because without buffering, the acidic stomach quickly breaks down the drug before absorption. Most horses with squamous ulcers will have healing of these ulcers after a 4-week course of Gastrogard or Ulcergard at treatment dose (whole tube for the average horse). Some horses may be healed by 3 weeks of treatment, but all horses should undergo a recheck gastroscopy before stopping treatment. Horses diagnosed with glandular ulcers need combination therapy with Gastrogard/Ulcergard and Sucralfate for 4 weeks. About 2/3 of horses with glandular ulcers will heal in this time, but some horses may require longer treatment times so a recheck is always recommended before discontinuing treatment.

Horses at higher risk of gastric ulcers may benefit from preventative (low) doses of Ulcergard (1/4 tube in average sized horse) given for a few days before and during high stress situations like long distance travel and competitions. Sea buckthorn berry supplement may be protective against formation of glandular ulcers. Dietary management to decrease the risk of ulcers includes providing more frequent small hay meals if pasture access is not available, limiting high sugar grains as much as possible and adding vegetable oil to the feed.

Sykes BW, Hewetson M, Hepburn RJ, Luthersson N, Tamzali Y. European college of equine internal medicine consensus statement – equine gastric ulcer syndrome in adult horses. J Vet Internal Med 2015; 29:1288-1299.

Equine

Trailer Safety Checklist

Published

1 month ago

May 8, 2026

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By Janis Blackwell

As the season arrives to gear up for participation in your equine event of choice, one thing remains a constant for all horse owners. That constant is our responsibility to insure the safety of our horses by being diligent to maintain the integrity of the trailers in which we haul them. There are a number of things that can be dangerous both inside and outside of your trailer. Whether you traveled all winter long or whether your trailer sat unused or was used very little through the cold weather months, at least once a year your trailer is due a thorough going over. So here we go with a checklist that will help you insure a happy and safe trip for you and your equine partner.

A sound floor is absolutely imperative. Whether your floor is aluminum, steel or wood, it should be cleaned regularly after use to preserve it. Urine and manure will erode and weaken all types of floors. Even rubber mats will not prevent erosion of your floor. (Maintenance tip: remove mats and wash aluminum floors often to prevent erosion.)
Especially check wooden floors for rotten boards. Immediately replace questionable flooring before hauling. (Maintenance tip: For wood, remove mats and wash out manure and debris. Coat wooden floor in a cheap motor oil. Allow to sit in hot summer weather until the oil soaks in. Be careful—floor will be slippery until oil cures into the wood. This treatment yearly will preserve a wooden floor for much longer than normal as it repels urine and protects the wood).

Keep the interior and exterior washed to enable you to check for rusted out places, leaks, etc.
Have a professional check your brakes at least once yearly to be sure they are operating properly.
Be sure tires are inflated to the proper air pressure, and check the inside of each tire for hidden unusual wear that could cause a blowout. Replace worn tires before leaving home.
Wheel bearings must be checked and packed at least once a year. This should be done even if the trailer has been rarely used since the last time the wheel bearings were packed. In fact, trailer maintenance professionals say that sitting stationary and unused is even worse for the bearings. Improper care and maintenance of wheel bearings can cause a wheel to seize up and actually twist off while in use. Use a horse trailer professional for this maintenance task.
Axles should be checked for bowing. A bent or bowed axle can cause excessive tire wear and damage wheel bearings.
There should be no more than two inches in height difference from the front of the trailer to the back. More difference than that causes the bulk of weight of the trailer and its contents to ride mostly on the rear axle causing it to bow and wear on both tires and wheel bearings.
Another critical part of the trailer to keep an eye on are the butt chain or bar and the back door. The butt chain or bar should be firmly attached to the wall and its keeper and should always be latched. The door should have a strong secure latch with a pin to insure it stays latched while in motion.
Finally, but certainly not of least importance is a thorough check of the trailer hitch including ball and coupling. Keep the ball well greased. Periodically, check to see that the ball is still securely tightened and the latch on the coupling is working properly.

These few critical safety check points can save you money, stress and the wellbeing of your horse. Until next time, happy trails and safe traveling.

This article was originally published in the April 2016 issue of Oklahoma Farm & Ranch.