Causes of Canine Herpesvirus Infection
Puppies normally become infected with canine herpesvirus in utero or during whelping. In other words, they become infected because their mother is infected. The optimal temperature for canine herpesvirus replication is fairly low – typically about 91 degrees Fahrenheit, which is the temperature of the outer genital and upper respiratory tracts in dogs. Very young puppies with low body temperature (those that are hypothermic) are extremely susceptible to infection by this virus and tend to develop severe, often fatal disease. Also, very young puppies have immature immune systems and a poor ability to regulate their body temperature, which contributes to their susceptibility to CHV infection. Once puppies are exposed to the virus, it takes several days for symptoms to appear. The signs in adults are slower to appear and are normally caused by physical contact with an infected dog (often through breeding), or by inhalation of viral particles. Direct contact with saliva or secretions from the urogenital tract of an infected animal is highly likely to transmit infection.
Preventing Canine Herpesvirus Infection
Good hygienic practices, including rigorous attention to hand washing or the use of protective gloves, especially during whelping, can reduce the risk of transmitting infection from mother to puppies. A warm and clean environment for the whelping and for the subsequent care of puppies is equally important. Infected animals should be spayed or neutered and never bred, so that they do not spread the disease through sexual contact. Reducing an adult dog’s stress and providing good nutritional support and regular exercise may also help to limit future outbreaks by strengthening the dog’s immune system. There currently is no vaccine approved in the United States for canine herpesvirus. However, a European vaccine seems to have good results when administered to a bitch before a breeding takes place.
Canine herpesvirus infection can be a manageable disease, and a preventable one. The prognosis for adult dogs infected with CHV is quite good if future outbreaks can be controlled. For very young puppies who become infected, the prognosis unfortunately is grave. The CHV is inactivated quite readily by heat, drying and disinfectants such as bleach. This is not an infection known to be transmittable to humans.