Canine Herpesvirus

What is Canine Herpesvirus?

Canine herpesvirus (CHV) is a condition specific to canines including dogs, wolves, and coyotes. CHV is primarily a reproductive disease, which means many of our canine companions (and their pet parents) do not have to worry too much about it.  

However, CHV is a significant problem for breeders because it can have a high mortality rate for puppies 3 weeks old and younger and is a major cause of spontaneous abortion and stillbirths. After 3 weeks, a puppy’s body temperature begins to rise and her ability to fight the virus improves. Puppies over 6 months old rarely succumb to the virus. 

Exposure usually occurs through the nose, mouth or genitals. For puppies (and canine fetuses), the virus can replicate and can spread throughout the lymphatic system and blood stream causing widespread harm.  

Herpesviruses also travels to the nerve cells where they can “camouflage” themselves, lying dormant and causing infection in times of stress. Dogs can then shed the virus intermittently throughout their lives.  

Symptoms of Canine Herpesvirus

Given the seriousness of the virus, for many pet parents or breeders, the only sign they may notice is unfortunately, a deceased puppy. For others, signs can include: 

• Failure to thrive, such as failing to nurse or gain weight 

• Excessive crying 

• Listlessness 

• Body temperature lower than normal 

Other signs include diarrhea, runny nose, pneumonia, and petechiae (pin-point hemorrhages) on the belly, inner ears, conjunctiva, or gums.  

Adult dogs suffering from the virus may not exhibit any clinical signs or may exhibit mild signs associated with a common cold (i.e., cough, runny nose, or lethargy). Some may also exhibit infertility, lesions on their genitalia, and dogs that are pregnant may exhibit a sudden loss of their litter or stillbirth(s).

Causes of Canine Herpesvirus

CHV is often spread from one dog to another via direct contact, either through saliva, nasal, or vaginal discharge/secretions or by sexual contact. Rarely, the virus can be transmitted by fomites (objects carrying the virus, such as clothes, water, and food bowls). Usually, the virus spreads between puppies and dogs that co-mingle, such as those in a litter. The virus also can also be passed from mother to offspring.

How Veterinarians Diagnose Canine Herpesvirus

A veterinarian may suspect canine herpesvirus with a puppy that is 3 weeks or younger and shows clinical symptoms (or has passed away).  

A PCR test may be done on tissue samples or fluids, but unfortunately most diagnoses are done after the puppy has died by looking for lesions associated with canine herpesvirus. 

Treatment of Canine Herpesvirus

Unfortunately, once diagnosed or even suspected, the outcome for most infected puppies is poor. In many cases, a puppy will have already passed, or the veterinarian will recommend euthanasia. It is important to examine the puppy even after she has passed so precautions can be taken to limit the virus’ transmission and protect siblings or other dogs in the household. 

It’s important to remember that the virus is sensitive to heat so maintaining a warmer ambient temperature for the surviving pups may help prevent transmission. Some antivirals and antibody serum injections have been reported as a form of treatment and other forms of treatment often utilized are usually supportive care measures such as rehydration, getting the puppy to eat, or medications administered to alleviate pain, nausea, and diarrhea.  

Recovery and Management of Canine Herpesvirus

Unfortunately, most affected puppies do not survive, but those that do often lead a life with long-term debilitating effects such as blindness, kidney disease, or neurologic dysfunction.  

Many adult dogs and puppies older than 3 weeks of age go on to lead a relatively normal life. Some may be affected with fertility issues and females that are infected prior to becoming pregnant, or have already suffered an abortion from the virus, can go on to have healthy litters in the future (assuming the pups do not acquire the infection elsewhere).