All viruses have the potential to impact the health, welfare and survival of those animals they infect. Where a virus causes obvious symptoms, infection may be easy to detect. However, some viruses can cause less obvious and hidden symptoms, or may remain in an animal for the rest of its life. Canine herpesvirus (CHV) has been known about for many decades; but with improved ability to screen for infection, studies have shown that over 80% of dogs in England have been exposed to the disease. With a vaccine available through veterinary clinics in the United Kingdom, dog owners may be offered the option of vaccinating their pet.

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How Could Canine Herpesvirus Affect My Pet?

The impact of CHV on your pet is influenced by their age and gender. Viruses in the herpes family can infect an animal and lead to immediate symptoms (clinical herpes), or they can infect an animal causing it to be a lifelong carrier. Carriers may initially be asymptomatic but develop intermittent symptoms during times of stress (latent infection) and will periodically be infectious to other animals.

CHV primarily impacts the respiratory system and reproductive systems

Adult dogs infected with this virus may develop symptoms in the eye, nose and throat such as a cough or a discharge. During this time, affected individuals are highly infectious to other dogs. This is a particular concern where dogs are in close proximity to each other such as in kennels or breeding facilities.

The biggest concern, however, is the impact of infection on pregnant females and young pups. Infection of a bitch during pregnancy can cause abortion or re-absorption of the foetuses. This may not be outwardly obvious and may show itself as perceived low fertility. If infected when the pregnancy is at a later stage, pups may be carried to term but be stillborn. As the virus can pass through the placenta, surviving pups may be born already infected.

As newborn pups (neonates) have poorly developed immune systems, they are at high risk of disease. Infection before birth may result in eye lesions, reduced birth size, or low survivability. Infection in the immediate weeks following birth can result in the phenomenon of ‘fading puppy syndrome’ where the infected pup fails to gain weight, becomes weak and declines before passing away.

How Can the Vaccine Help?

There is no cure for herpesvirus, but a vaccine is available to reduce the risk of disease in those individuals at highest risk. If you are breeding your dog, the vaccine is designed to be given when the bitch is in heat or 7-10 days after being mated. This is then repeated 1-2 weeks before she whelps (gives birth). The aim is to prevent puppy deaths and to prevent the symptoms of herpesvirus infection in puppies after birth. This is achieved by the mother producing antibodies in response to the vaccine, which are passed through the first milk (colostrum) to the puppies. It is recommended to repeat the vaccine regime at every subsequent pregnancy.

The value of, and risks of, the vaccine in your pet should be discussed with your vet. This vaccine does not effectively prevent infection, and for most healthy adults the benefits are relatively small. Your veterinary team can also advise on hygiene and housing management during pregnancy and whelping to optimise pup health. As with all vaccines, side-effects may occur although severe side effects are rare. Given that the vaccine protects puppies through colostrum, if the mother fails to produce milk or suckling is unsuccessful, the benefit of the vaccine for the pups may be lost.

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Conclusion

CHV infection has the potential to cause recurrent health issues for infected dogs. It also has serious implications for breeding animals. With a vaccine available in the United Kingdom, owners who intend to breed their dog should discuss its use with their vet  as part of a breeding plan.

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