Introduction: Canine Herpesvirus (CHV) is a fairly common and widespread disease in dogs. It poses very little threat to adult dogs, but is very serious in puppies. CHV usually causes death in puppies that are about 1-2 weeks old. Puppies this young have a weak, immature immune system and are unable to create the fever response to fight off CHV.
Causative Agent: CHV is caused by a virus that inhabits the upper respiratory tract and reproductive tract of dogs. The virus thrives at a temperature of about 100° F. This characteristic may explain why it tends to kill new born puppies and not older dogs; older puppies and dogs have a body temperature over 101°F, while one to two week old pups have a lower body temperature.
Clinical Signs: Puppies infected with CHV become weak and depressed. They will often stop eating, cry continuously, and have greenish diarrhea. Death usually follows within 24 hours of the puppy first showing signs of this disease. If the infected puppy does survive, there is a chance that he/she will have blindness and neurological problems such as incoordination. The puppy may also have damaged lymph and kidney tissue.
Adult dogs can be carriers of the virus and show no visible signs of being infected. However, they may produce nasal secretions or blistery vesicles on their genitals that indicate the presence of CHV.
Disease Transmission: CHV can be transmitted in a variety of ways. It can be airborne or passed along from direct or indirect contact with infected secretions from the dog’s respiratory or reproductive system. The virus can be sexually transmitted between adult dogs during breeding. Also, a mother can pass on the virus to her puppies through the placenta, before the puppies are born. If the mother has developed antibodies to fight the virus in her own body, she can pass the antibodies onto the puppies prior to birth. These antibodies may help prevent the virus from killing her puppies.
Puppies may contract the disease from the mother during the birth process, while they are in contact with the mother’s infected vaginal secretions. CHV can also be transmitted to the puppies after birth from contact with nasal discharge or aerosols (such as a sneeze) from any infected dog. Every dog that carries the virus can pass CHV along both directly (by physical interaction) and indirectly (by sharing the same water dish or toys) to another dog.
Diagnosis: Since CHV acts so rapidly in young puppies, the diagnosis is usually made by doing an autopsy on the deceased puppies. An autopsy usually reveals lesions in the kidney and liver that are strong indicators of CHV. The virus can be detected in adult dogs by taking two serum samples, two weeks apart, and testing for a changing titer.
Treatment: There is currently no treatment for CHV. However, an antiserum given when the first signs of CHV appear may help prevent puppy death. In addition, infected puppies can be given anti-diarrheal medication and force-fed to keep them from dehydrating. Keeping the puppies in a warm environment with temperatures a little over 100° F can also help.
Prevention: Since 1-2 week old puppies suffer the harshest effects of this disease, prevention is aimed at keeping them CHV-free. If a mother dog does not test positive for having CHV, she and her puppies should be kept isolated from other dogs for at least 3 weeks before and 3 weeks after the birth of the pups. If the mother does test positive for CHV, she will hopefully be able to pass on antibodies to her puppies before they are born, and they will be able to fight off the virus.
Since the virus does not do much damage to older puppies and adult dogs, it is generally thought unnecessary and practically impossible to try and prevent them from contracting the disease.