Herpes viruses are a major cause of disease for both animals and humans. In fact a herpes virus was responsible for the disease outbreak at the National Cutting Horse Association’s Western National Championship in Ogden Utah in 2011. This outbreak caused the deaths of several animals and resulted in the quarantine of affected horses in numerous states.
In animals herpes virus infections occur in multiple species including dogs, horses, elephants, nonhuman primates, guinea pigs, tortoises, and cats; for this article I will focus on infection in cats, horses, and cattle.
Understanding viral infection is important to preventing the spread of these significant viruses. A hallmark of herpes virus infection is that there is no cure and infection often results in chronically infected, apparently healthy carriers. This means even if an animal appears healthy they can serve as a source of infection for other animals. These chronically infected animals can also break with clinical disease at any time especially during periods of stress. Chronic infection is usually a result of the viruses’ ability to remain latent within nerve bundles.
Infection in cats:
Feline herpes virus causes eye infections and respiratory disease in cats1. Kittens are commonly infected and clinical signs include nasal discharge, sneezing, and discharge from the eyes1. Clinical signs may clear up on their own, but secondary bacterial infection requiring antibiotics is common. Infection can also lead to pneumonia or bronchitis. Up to 80% of cats that recover will become chronically infected1.
Human antiviral medication can be administered, but is usually reserved for severe infection or for chronically infected cats with frequently recurring infections1. Remember antivirals do not eliminate the virus, but can help shorten the course of illness or diminish clinical symptoms.
Infection in horses:
Infection in horses results in respiratory infection, abortion, or neurologic disease. In the case of the outbreak in Ogden those horses died from the neurologic form2. Clinical signs for each of the syndromes reflect the affected system. With the respiratory form you will usually see, coughing, nasal discharge and fever3. With neurologic disease the horse will stagger, may have a difficult time eating and in serve cases will lapse into a comma and die3. In the case of abortion unfortunately no clinical signs are evident until the mare aborts3.
Infection in Cattle;
Cattle suffer from two types of viral infection; respiratory and reproductive. Clinical signs of respiratory infection mimic those of both cats and horses. Reproductive infection is known as pustular vulvovaginitis and infects the genital tract of both bulls and cows. Painful pustules develop in bulls in the sheath (prepuce) and vagina and vulva of females.
Prevention and control;
Prevention and control are based on vaccination and preventing exposure to infected animals. Herpes viruses are short lived in the environment and as such, spread is most often dependent on contact with an infected animal. Remember that even if there are no signs, they can still infect other animals.
While vaccines are not available for all species vaccine manufactures have produced very good vaccines for cats, horses and cattle. See your veterinarian for advice on specific vaccines and vaccine protocols to help control infection with your pets or livestock.
1. Herpetic Keratoconjunctivitis in a Cat Caryn E. Plummer, DVM, DACVO
2. http://voices.yahoo.com/equine-herpes-virus-myeloencephalopathy-8561129.html?cat=70
3. Equine Herpes Virus; American Association of Equine Practitioners 2006
4. Chapter 2.4.13. – Infectious bovine rhinotracheitis/infectious pustular vulvovaginitis; OIE Terrestrial Manual 2010