Many horse owners are unaware that there are at least four types of equine herpesvirus. The ones we associate the most are EHV-1 and EHV-4. EHV-1 is the most prevalent and often the most destructive to the horse. EHV-1 causes respiratory problems, miscarriage in Meres and neurological disease. EHV-4 only causes upper respiratory infections. Most horses contract EHV-1 and are usually first diagnosed with runny nose, fever, cough, and brooders who are having an abortion.
The neurological disease of EHV-1 is mutant strain and has caused quarantine of many stables and racetracks across the country. The University of Findley in Ohio has reported the most devastating outbreak of EHV-1, where in 2003 one-third of 140 horses showed neurological symptoms. Twelve horses died from the disease.
Once the virus infects the horse, the horse will become a lifelong carrier. This is similar to herpes in humans. Horses may not show signs of being sick, but they will continue to produce the virus, especially during high stress. Sporadic shedding of horses in this disease is often thought to be the cause of many outbreaks that occur randomly. Many veterinarians believe that about three-quarters of the equine population are thought to be carriers of the EHV-1 neurological form of the virus.
The disease is transmitted by infected horses through their respiratory secretions. Horses can also contract the disease through nose-to-nose contact, buckets, bits, lip chains, and handlers. Once the virus makes it horse, the virus passes through the bloodstream. Early symptoms include nasal discharge and a slight increase in temperature. The fever is not consistent, so if you think your horse is showing symptoms, you should check their temperature every six hours. Nasal discharge will start clearly, but will turn to thick and milky. Your veterinarian may obtain a discharge and blood sample swab to diagnose the disease.
If the horse is infected with neurological stress, the horse will begin to show symptoms in six to twelve days. Early progression of the disease can occur quickly and within 24 to 72 hours. Favors are usually more than 102 degrees Fahrenheit and other symptoms include nasal discharge, depression and loss of appetite. The first neurological symptoms may begin in hinderwater and may include leg cramps, floppy tails, incontinence, and weakness in the hind legs. Eventually, the horse will not be able to stand. If a horse is down for more than twenty-four hours, it is unlikely that they will survive the infection.
As the disease is caused by a virus, there is no cure. Many veterinarians will give horses immune modulator shots that will help boost their immune system and help attack the disease through their own immunity. Only many horses with respiratory problems will do well with shots. Antibiotics usually won’t help these horses, because they don’t kill the virus, just the bacteria. When a horse is sick with a respiratory condition, owners and veterinarians can do all they can to treat their symptoms. Your veterinarian will provide you with a strong anti-inflammatory that reduces swelling and pain.
There is also no vaccine that is capable of preventing the neurological form of the disease. Studies have been conducted on small groups of horses to compare the effects of a modified-live vaccine against a passive killing vaccine. An improved-live version of the vaccine seemed to be more effective in preventing respiratory disease, while both had no effect on preventing neurological symptoms. This vaccine will help reduce the spread of the virus.
To prevent your horses from becoming infected with EHV-1, it is recommended that your horses be placed on a food vaccination program as well as good herd management. The American Association of Equine Practitioners recommends that all pregnant women be vaccinated to prevent miscarriage. Foals, weanlings, and even years should be vaccinated. Falls should take the first dose in four to six months, the second dose in five to seven months, and the third dose in six to eight months. They should also be vaccinated at three-month intervals. Annuity and Performance Horses should receive booster shots every three to four months or annually depending on the amount of stress. Broodmeres should be vaccinated with the inactivated EHV-1 vaccine in their fifth, seventh and ninth months of pregnancy. You can also give them an alternate dose in their third month if I am stressed. Vaccination should be done before breeding and pepper four to six weeks before. Breeding strains should be vaccinated before the start of their breeding season as well as every six months.
Other preventative strategies include cleaning your barn at least three times a year. Barnes that have erupted can be cleaned six times a year. If you show horses and suspect that the horses in the show are sick with the virus, you may want to keep your own horses separate from the rest of the herd for twenty-one days. You may also want to disinfect each area of the barn for those who suspect that sick horses have been kept or worked.
If there is an outbreak in your pantry, you may want to instruct all owners, handlers, and visitors to wear leather or rubber boots that can be disinfected with chlorine or bleach. You should have disinfectant tubs at each entrance to the barn. You want to disinfect all stalls, floors, walls and possibly even arenas and fencing. Disinfect all grooming supplies, buckets, water troughs and whatever may be shared. A horse from a large herd can spread the disease throughout the herd.