Eastern equine encephalomyelitis and western equine encephalomyelitis are deadly in horses. These diseases are spread by mainly mosquitos and other biting insects. These diseases classically cause severe swelling and inflammation of the brain and spinal cord. This can manifest as hyperreactivity, head pressing, blindness, severe depression, and ataxia (unsteadiness). Many horses suffer fatal injuries due to the ataxia. Eastern equine encephalomyelitis has a mortality rate of up to 95%. Treatment is usually ineffective and survivors often have residual neurologic signs. Western equine encephalomyelitis has a mortality rate of up to 50%, and horses are more likely to recover completely. Fortunately, both of these diseases are very preventable with vaccines. If horses do get infected they are more likely to have a milder form of the disease and make a complete recovery.

Tetanus is a bacteria disease caused by the organism Clostridium tetani. This disease is found in the soil and the GI tract of the horse. Horses are the most susceptible species of animal to tetanus. Horses can get the disease from any wound, hoof abscess, surgical site, umbilicus of the neonatal foal, or in the post-partum mare. This disease causes a rigid paralysis (unable to relax their muscles). Signs of tetanus include a “sawhorse” stance, prolapse of the 3rd eyelid, wrinkling of the skin of the forehead, and sudden death from respiratory failure. Treatment of tetanus can be difficult, and almost all horses that are unvaccinated for tetanus will die or require euthanasia. Fortunately, the Tetanus vaccine is very effective at preventing infection.

West Nile Virus is another disease that causes severe inflammation of the brain and spinal cord and is spread by mosquitos. Cases of West Nile Virus have been reported in California. The main signs of WNV are muscle fasciculations (muscle twitching) and changes in personality. Other signs include fever, anorexia, depression, gait abnormalities, weakness, and difficulty eating. The mortality rate of West Nile Virus is up to 30%. This disease is also preventable with vaccination and can lessen the severity of the disease.

Rabies is a 100% fatal viral disease that affects almost all mammals including horses. Rabies is transmitted by bite wounds usually from infected wildlife including bats, skunks, raccoons, and others. There are 3 different ways rabies can present called “forms”. There is a “furious form” characterized by aggression, fear of water, hyperreactivity, sensitivity to light, muscle tremors and seizures, a “dumb form” characterized by depression, anorexia, head tilt or circling, unsteadiness, excess salivation, facial paralysis, blindness, incontinence, and self-mutilation, and a “paralytic or spinal form” that is characterized by progressive paralysis starting in the hind end and moving to the front end, incoordination, and shifting lameness. Horses most commonly present with the paralytic or dumb form, but all 3 forms have been documented in horses. Rabies is rare, but still occurs across the US and in California. Fortunately, the rabies vaccine is very effective and preventing this disease.

Strangles is a bacterial infection caused by the organism Streptococcus equi equi. This disease is caused by nose-to nose contact with other horses, or through contaminated objects such as shared bedding, brushes, blankets, food and water containers, or even human that have interacted with an infected horse. Signs of strangles include Swelling of the lymphnodes under the jaw, fever, nasal discharge containing mucus, reluctance to swallow, and depression. In severe cases the lymph nodes can become so large, they block a horse’s airway and tracheostomy may be necessary to allow a horse to breathe. In very rare cases, strangles can cause metastatic abscesses (abscesses spread throughout the body). Treatment of strangles includes isolation, draining the abscesses if possible, and anti-inflammatories. Only in severe cases are antibiotics used to treat this disease. About 10% of strangles infections are fatal. After horses recover, they can become carriers of strangles, as collections of harden pus can accumulate in their guttural pouches, and they may intermittently shed the disease. Strangles while not deadly, can take horses a significant amount of time to recover from. Horses are highest risk are young horses, and horses going to competitions, sales, or other events. The strangles vaccine can help lessen the severity of the disease, but doesn’t always completely prevent it. Talk to us today about whether the strangles vaccine may be the right choice for your horse.

In horses, Influenza is mainly a respiratory disease. Influenza is most common in young horses and is spread through aerosolized droplets from infected horses up to 50 yards away. Signs include fever, depression, anorexia, lymphadenopathy, and serous nasal discharge. Influenza damages the lining of the respiratory tract that helps sweep out pathogens. Because of this, secondary bacterial infections are not uncommon. During recovery from influenza it is recommended horses be rested 1 week for every day of fever. There is a vaccine available to prevent influenza. Call us today about whether the influenza vaccine is right for your horse.

Equine Herpes Virus, also called rhinopneumonitis, is a viral disease that can cause respiratory disease, neurologic disease, and abortions or neonatal death in foals. Signs of the respiratory form include: fever, depression, anorexia, lymphadenopathy, and nasal discharge. Most horses recover well from the respiratory form. Signs of the neurologic form include symmetric weakness and incoordination, ascending inflammation of the spinal cord. The hind limbs are more affected than the front limbs, as well as, urine dribbling and prolapsed penis in males. The prognosis is good if the horse remains standing. There is no vaccine currently labeled for the neurologic form. In pregnant mares, EHV can cause late term abortions or early neonatal death in foals. This is often the same from as the respiratory virus can be prevented with vaccination during pregnancy. Contact us today to see if the EHV vaccine is right for your horse.