Dogs can get herpes, and have their own form of the herpes virus. Canine herpesvirus—also known as canine herpes—is a disease that is nearly 100% fatal in young puppies. It does not typically cause serious illness in older puppies and adult dogs. This virus is found worldwide. Canine herpesvirus only infects dogs and cannot infect humans.
How Do Dogs Get Canine Herpesvirus?
Canine herpesvirus is transmitted between dogs and puppies through direct contact with ocular, nasal, oral, or vaginal secretions. Nose-to-nose contact and sexual transmission are the usual routes of infection. This virus does not survive long in the environment and is easily killed by disinfectants.
After the initial infection, dogs become carriers of canine herpesvirus for life. They may experience periods of recrudescence (shedding of the virus). These dogs can transmit the virus to other dogs and puppies when they are actively shedding the virus in their tears or other secretions.
Puppies Are Extremely Susceptible
A pregnant dog that is exposed to canine herpesvirus in the last three weeks of her pregnancy may transmit the virus to her unborn puppies. These puppies may be delivered stillborn. Puppies that are born alive will often die within the first few days of life.
Puppies that are exposed to canine herpesvirus in the first three weeks of life are the most likely to die from this disease. Canine herpesvirus is able to replicate rapidly in a puppy whose body temperature is cool (about 95 degrees Fahrenheit).
Puppies younger than three weeks of age are unable to maintain their own body temperature. They rely on their mother, the additive warmth of their litter mates, and a warm cozy environment to maintain a normal body temperature between 96 and 100 degrees Fahrenheit. Puppies less than three weeks old that are not kept sufficiently warm are at the highest risk of dying from canine herpesvirus.
Symptoms of Canine Herpesvirus
Puppies younger than three weeks of age may develop a bloated belly, difficulty breathing, weakness, and be cool to the touch. This illness is painful and they will cry inconsolably. Death comes quickly, usually within 24-48 hours of becoming ill.
Adult dogs and puppies older than three weeks of age may develop signs of an upper respiratory infection, including coughing, sneezing, and nasal discharge. Signs of conjunctivitis—such as teary eyes, green or yellow ocular discharge, squinting, or corneal ulcers—may also develop. Blisters on the vulva of female dogs or the prepuce of male dogs may be observed.
Symptoms in adult dogs are typically mild and resolve without complications. Puppies older than three weeks of age may see their upper respiratory symptoms progress into a potentially life-threatening bronchopneumonia. Adult dogs that have been exposed to other viral or bacterial infections at the same time may also develop bronchopneumonia that can become serious or fatal.
Some adult dogs may become infected with canine herpesvirus but are asymptomatic. This means that they have no symptoms of illness when they become infected.
Survivors of canine herpesvirus will become carriers of the virus for life. The virus hides and lies dormant in the trigeminal nerve of the face and in lymph nodes and salivary glands. Viral replication and shedding will begin during periods of stress or illness—this is called recrudescence. Dogs that are receiving immunosuppressive doses of prednisone may also begin shedding the virus.
Carrier dogs that are experiencing recrudescence may squint one or both eyes and have increased tear production. They may sneeze and have nasal discharge. Some may develop corneal ulcers. And then there are dogs that are actively shedding the virus but have no symptoms at all!
Any dog that is actively shedding the virus can transmit canine herpesvirus to puppies and other dogs. This includes dogs that are showing symptoms of canine herpesvirus, dogs that are acutely infected but asymptomatic, and carrier dogs that are actively shedding the virus in their oral, nasal, and ocular secretions.
Diagnosis
Canine herpesvirus can be diagnosed with a simple blood test. A blood sample from your dog can be submitted to an outside laboratory for a PCR test. It can take several days to run this test, so your veterinarian may begin treatment for canine herpesvirus before knowing the results of the test.
A puppy that dies acutely for an unknown reason can undergo a necropsy to help determine the cause of death. A necropsy is like an autopsy, but for animals instead of people. Samples from the puppy’s organs can be tested for canine herpesvirus and other infectious diseases.
Treatment for Young Puppies
Treatment for puppies less than three weeks of age that become ill with canine herpesvirus is typically unsuccessful with a nearly 100% fatality rate. The following interventions may be able to save the remaining puppies in a litter that have not yet become ill:
- Keep all of the puppies warm with a body temperature between 96 and 100 degrees Fahrenheit. You can achieve this by making sure their environment stays a toasty 85 to 90 degrees Fahrenheit during the first 4 days of life. The ambient temperature can be gradually lowered to 80 degrees Fahrenheit by 7 to 10 days of age and then gradually to 72 degrees by the start of the fifth week of life. Keeping them warm will lower the replication rate of the virus inside their bodies. Use warming devices made for puppies, such as incubators or heat lamps. Do not use heating pads made for people as this may cause thermal burns.
- Serum from an adult dog that has antibodies against canine herpesvirus can be administered to each puppy. This provides them with antibodies that can fight a canine herpesvirus infection.
- There is limited evidence that antiviral medications—such as famciclovir and acyclovir—are effective against canine herpesvirus. Not much is known about effective dosages and potential adverse effects of these medications. Use them with caution and only under the direction of a veterinarian.
Treatment for Dogs and Older Puppies
Treatment for dogs and puppies older than three weeks of age is largely supportive. Symptoms and complications are treated as necessary. Dogs and puppies with corneal ulcers caused by canine herpesvirus may benefit from ophthalmic antiviral medications, such as idoxuridine, trifluridine, or cidofovir.
Prevention
Canine herpesvirus is easily transmitted between dogs and rarely causes serious illness in adult dogs and mature puppies. The only way to truly prevent your dog from getting canine herpesvirus is for your dog to never have contact with other dogs. This is just not possible nor advisable.
Prevention tactics are aimed at the most vulnerable of our population—young puppies and puppies not yet born. Pregnant dogs should be isolated from other dogs in the last three weeks of their pregnancy. Puppies and their mothers should be isolated from other dogs in the first three weeks following whelping.
There is no vaccine for canine herpesvirus currently available in the United States. A vaccine has been available in Europe since 2001.
