Horse Owner Today | Ask A Vet

Horse Owner Today | Ask A Vet

Good management and nutrition are the foundation of horse health. New homes, new herd mates, new careers and new routines. “It’s important that people know that the MLV has been in use for decades, has proven to be reasonably safe, and in — my opinion — it should be the vaccine of choice, at least in non-pregnant animals,” said Klaus Osterrieder, associate professor of virology in the College of Veterinary Medicine at Cornell. General Directions: Vaccination of all horses on the premises is recommended to enhance herd immunity. It was with the help of this discovery that Smallpox was eradicated from the world population, existing now only in vials and experimental conditions. Annually thereafter, 4 to 6 weeks prepartum Only in endemic areas. • keep all horses at least 50-100 feet away from that horse who should be isolated, • your horse can be boostered with the high antigen load killed vaccines licensed for abortion control (Pneumabort-K or Prodigy with Havlogen) or the Modified-live vaccine (Rhinomune, Boehringer Ingelheim Vetmedica, which causes greater side effects and reactions), • take your horses temperature 2 or more times a day (normal is 102F), • monitor your horse for any signs of not feeling well, being too quiet, not eating/drinking, dribbling urine, acting uncoordinated or wobbly, or any other neurological signs.

Both EHV-1 and EHV-4 spread via aerosolized secretions from infected coughing horses, by direct and indirect (fomite) contact with nasal secretions, and, in the case of EHV-1, contact with aborted fetuses, fetal fluids, and placentae associated with abortions. The veterinarian must provide the date of vaccination, the brand, serial number, and the expiration date of vaccine. Only recently has the full complement of horse Ig heavy (H) chain constant region genes (one δ, one μ, seven γ, one α and one ɛ) been described (Wagner et al., 2004). RNA analyses revealed that these proteins are expressed from two different late (γ2) transcripts, an unspliced 5.5-kb and a spliced 4.3-kb mRNA that are translated into proteins of 985 and 611 amino acids, respectively. In contrast, horses are not protected against the abortigenic or neurologic forms of the disease, even after repeated exposure, and mature horses are in fact more commonly affected by the neurologic form of the disease than are juvenile animals. The neurological form of rhinopneumonitis is less common. This mutation results in the presence of either aspartic acid (D) or an asparagine (N) residue at position 752.

With mosquito-borne diseases, such as Encephalitis and West Nile, the foal needs typically needs three doses in the first year of life to get adequate protection. It is important to understand that both isolates can and do cause neurological disease, it is just more common for the D752 isolates to do so (it is estimated that 80-90% of neurological disease is caused by D752 isolates, and 10-20% by N752 isolates). Experts do not currently advise any specific management procedures for horses based on which isolate they are latently infected with, and it is possible that 5-10% of all horses normally carry the D752 form (this estimate is based on limited studies at this time). In the face of an active outbreak of EHV-1 disease, identification of a D752 isolate may be grounds for some increased concern about the risk of development of neurological disease. Primary indications for use of equine herpesvirus vaccines include prevention of EHV-1-induced abortion in pregnant mares, and reduction of signs and spread of respiratory tract disease (rhinopneumonitis) in foals, weanlings, yearlings, young performance and show horses that are at high risk for exposure. Many horses do produce post-vaccinal antibodies against EHV, but the presence of those antibodies does not ensure complete protection. Consistent vaccination appears to reduce the frequency and severity of disease and limit the occurrence of abortion storms but unambiguously compelling evidence is lacking.

Horse Owner Today | Ask A Vet
Management of pregnant mares is of primary importance for control of abortion caused by EHV-1. that large numbers of animals per affected premise are developing severe clinical disease. Abortion rates can be as high as 70% and an entire foal crop can be lost. Performance of the inactivated high antigen load respiratory/abortion vaccines is superior, resulting in higher antibody responses and some evidence of cellular responses to vaccination. “The current recommendations by the Influenza International Surveillance Panel from April 2005 recom-mend the current vaccines contain updated strains (A/eq/South Africa/4/03 or A/eq/Ohio/03, and A/eq/Newmarket/2/93, A/eq/Suffolk/89, or A/eq/Borlange/91),” he says. Sellon weighs in: “Strangles IN vaccine is used in horses at risk of exposure to strangles. “There are some widely available commercial extenders that have, in my view, insufficient amounts of antibiotics to control the bacteria,” says Varner.

All available vaccines make no label claim to prevent the myeloencephalitic form of EHV-1 (EHM) infection. As researchers have worked with MLV technology, they have gained “better recognition of mutants that work,” Horohov says. “None of the vaccines in either of the two studies in this relatively small number of horses demonstrated any adverse effects of vaccination,” said Lunn. The vaccines with the greatest ability to limit nasal shedding include the 2 high-antigen load, inactivated vaccines licensed for control of abortion (Pneumabort-K®: Pfizer; & Prodigy® Merck), a MLV vaccine (Rhinomune®, Boehringer Ingelheim Vetmedica) and an inactivated vaccine, (Calvenza®, Boehringer Ingelheim Vetmedica). Two horses at the facility had to be euthanatized, and two horses at a nearby private farm were put down. Small abscesses were present in muscle and liver tissue. Horses housed at facilities with frequent equine movement on and off the premises, thus resulting in an increased risk of exposure.

But the toxin is not limited to these areas. In addition, HRP-conjugated goat polyclonal anti-horse IgG H + L chain (kindly provided by Bethyl Laboratories) and goat anti-horse IgG Fc (Rockland) were tested in ELISA. An outbreak of Equine Viral Arteritis (EVA) occurred on a Quarter Horse breeding farm in New Mexico in June of this year and the ensuing dissemination of infection to farms both within and outside the state raises significant issues and conclusions. A 4 to 6 week interval between doses is recommended. Pregnant mares: Vaccinate during the fifth, seventh, and ninth months of gestation using an inactivated EHV-1 vaccine licensed for prevention of abortion. Many veterinarians also recommend a dose during the third month of gestation and some recommend a dose at the time of breeding. Bürki F., Rossmanith W., Nowotny N., Pallan C., Möstl K., Lussy H., Viraemia and abortions are not prevented by two commercial Equine herpesvirus 1 vaccines after experimental challenge of horses, Vet.

Maternal antibody passively transferred to foals from vaccinated mares may decrease the incidence of respiratory disease in foals, but disease can still occur in those foals and infection is common. Foals: Administer a primary series of 3 doses of inactivated EHV-1/EHV-4 vaccine or modified-live EHV-1 vaccine, beginning at 4 to 6 months of age and with a 4 to 6 week interval between the first and second doses. Administer the third dose at 10 to 12 months of age. The benefit of intensive vaccination programs directed against EHV-1 and EHV-4 in foals and young horses is not clearly defined because, despite frequent vaccination, infection and clinical disease continue to occur. In nonvaccinated controls, challenge with BVD Type 1 resulted in 100% fetal infection, and challenge with BVD Type 2 resulted in greater than 85% fetal infection. Influenza is not only expensive to treat, but results in a lot of “down time” and indirect financial loss, not to mention discomfort to your equine. The simplest approach is to vaccinate all horses in the exposure area—independent of their vaccination history.

If horses are known to be unvaccinated, the single dose may still produce some protection. There remain concerns that heavily vaccinated horses may be more susceptible to developing neurological disease caused by EHV-1. This possibility is unsubstantiated and a subject of active investigation. To date, the use of a single vaccine immediately before exposure has not shown any association with an increased incidence of neurological disease. Horses having been naturally infected and recovered: Horses with a history of EHV infection and disease, including neurological disease, are likely to have immunity consequent to the infection that can be expected to last for 3 to 6 months (longer in older horses). Young horses that come into contact with lots of other horses may need to be vaccinated every six months.

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