OklahomaHorses Magazine March 2021

18 OklahomaHorses • March/April 2021 CORE Vaccinations for Horses WRITTEN BY: Grace Owen, DVM Equine Medical Associates | Edmond PHOTOS COURTESY OF: Grace Owen V accinations are important to protecting your horse’s health. It is the cheapest form of “in- surance” you can get. Vaccination protocols are created by your veterinarian to help ensure the best possible health for your horse. There is no single stan- dard of vaccination; instead, protocols are created that consider your horse’s age, use and risk of exposure. It is also important to determine what could happen if the horse was not vaccinated. In some cases, lack of vaccination may equal death if the horse is exposed. Lastly, it is important to consider possible side effects of the vaccine. These parameters are all taken into account when creating a vaccination plan for your horse. There are two categories of vaccinations that horses may need: core vaccines and risk-based vaccines. In this article, we are focusing on core vaccinations. These protect against diseases that are found in our region, are very contagious, can cause severe disease and may cause a public health risk. These vaccines have low risk to the patient and have been proven to be effective. They are recommended to all equines in the United States. The core vaccines are for prevention of Tetanus, Eastern and Western Equine Encephalomyelitis (EEE/WEE), West Nile Virus (WNV) and Rabies. It is important for every equid in the United States to be protected against these diseases. This also includes donkeys and mules. Tetanus is something that all horses are at risk of developing. Tetanus is a frequently fatal disease that is caused by a spore-forming bacterium, Clostridium tetani. These organisms are present in the digestive tract and fecal output of horses, as well as abundant in the soil. Tetanus is not a contagious disease; it is contracted by contamination of an open wound with the bacteria. The incubation time from contamination to symptoms averages about 10 to 14 days. Localized stiffness that frequently affects the jaw muscles and the muscles in the neck is usually first seen. General stiffness develops with associated muscle spasms that creates a “sawhorse” stance with ears and head held up high and back end rigid with tail extended. Often, the third eyelid is protruding. The spasms continue to strength- en in nature, and the horse is often very reactive to external stimuli. In the end, about 80% of affected animals die. EEE, WEE and WNV are all zoonotic (affecting humans) diseases that are transmitted by mosquitos. In the horse, they cause brain and spinal cord inflammation. Clinical signs may include twitching of muscles (especially in the neck, shoulder and pectoral regions), muzzle and lower lip twitching, incoordination, difficulty swallowing, behavioral changes, recumbency and death. Horses that are affected with WNV have a 60% survival rate; however, those with EEE and WEE often die or must be euthanized. Rabies in horses is usually transmitted by skunks, bats, foxes and raccoons. Affected wild animals behave abnormally and will potentially encounter and bite horses even if they are normally not seen in the envi- ronment. Once a horse develops signs of rabies, it is a rapidly progressive disease of which death is inevitable. Mild early signs can include colic, lameness or depression. As the disease progresses, horses may become extremely aggressive or recumbent. There is no cure for rabies in horses or humans. Human exposure does not require a bite to occur. It is possible for the horse’s saliva to contact mucosa or bro- Vaccination appointments are a good time to have a wellness exam for your horse by your veterinarian.