Canine herpesvirus (CHV)

Test code: S0104 - Ultrasensitive qualitative detection of canine herpesvirus by real time polymerase chain reaction

S0104 is included on P0019 - Canine Respiratory Panel

Canine herpesvirus (CHV) can cause fading puppy syndrome, upper respiratory tract disease (kennel cough) and abortion or stillbirths in dogs. The main route of transmission appears to be oronasal from infected puppies or from nasal or vaginal excretions of adults. The virus spreads rapidly through kennels but usually only causes disease in very young puppies. Infection of newborn puppies commonly results in death. Puppies infected with CHV at the time of birth will generally start to show clinical signs of infection at four to six days of age. Infected puppies will exhibit persistent cry, a diminished suckling response, yellow green diarrhea and abdominal pain. Fever is usually not present. Death frequently occurs within 48 hours after clinical signs are noted. One or all pups in a litter infected at birth may show signs of herpesvirus infection.

Infection of adults or puppies over 3 weeks old results in replication in the respiratory tract without clinical disease. The virus can undergo latent infection and reactivation, and further shedding can be induced by immunosuppression or stress.

CHV infection is a major concern to the breeding kennel because it can result in decreased fertility, small litter sizes, and puppy death. CHV is very environmentally labile and is quickly killed by sunlight or heat, and therefore most transmission occurs when dogs are in close contact as a result of licking secretions or coughing. The virus can be passed to unborn pups in the uterus, or may infect newborn puppies as they pass through the birth canal and come in contact with vaginal cervical secretions. It may also be transmitted during mating. When dogs are under stress, such as during pregnancy (especially three weeks prior to whelping), in the neonatal period (especially the first three weeks of life), in a boarding kennel, or when competing in events, reactivation of latent viruses may occur. Also, any dog undergoing immunosuppressive therapy (cancer treatment or steroid use) is at a higher risk of herpesvirus infection or reactivation. Once infected, the dog usually remains infected for life, and may be capable of shedding virus whenever stressed.

In the adult bitch, new infection or reactivation of CHV results in vaginal infection (vaginitis), and may form pustules (also known as “dog pox”). Fertility is decreased, and abortion or premature birth is common. Infected male dogs may show similar ‘pox-like’ lesions on the base of the penis and prepuce. Many males will have a preputial discharge. Upper respiratory signs may also be noted.

Diagnosis of CHV infection in puppies is usually made at necropsy. Petechial haemorrhage and focal necrosis to produce speckled kidneys are often seen. However, inclusion bodies seen by histological examination and virus isolation are necessary for confirmation. Routine rapid diagnosis by viral culture or serology is very difficult and unreliable because the virus is quite labile and excreted only occasionally and in small amounts. Antibody levels are often very low or undetectable. Molecular detection by PCR, however, offers a highly sensitive, rapid and specific method with which to identify this virus.

Utilities:

• Confirm the disease causing agent
• Ensure that animal groups and populations are free of canine herpesvirus
• Early prevention of spread of CHV among a population
• Minimize human exposure to this virus
• Safety monitoring of biological products and vaccines that derive from susceptible animals

Specimen requirement: Vesicular, nasopharyngeal, conjunctival or throat swab, or 1 ml tracheal wash, or 0.5 ml whole blood in EDTA (purple top) or ACD (yellow top) tube, or fresh or paraffin-embedded tissue, shipped overnight at room temperature; or tissue shipped frozen.

For specimen types other than those listed here, please call to confirm specimen acceptability and shipping instructions.

For all specimen types, if there will be a delay in shipping, or during very warm weather, refrigerate specimens until shipped and ship with a cold pack unless more stringent shipping requirements are specified. Frozen specimens should be shipped so as to remain frozen in transit. See shipping instructions for more information.

Turnaround time: 2 business days

Methodology: Qualitative real time PCR

Normal range: Nondetected