Etiology

• Canine herpesvirus (CHV) is an enveloped DNA virus that primarily affects neonatal puppies.

• Spread mainly through direct contact with infected oral, nasal, or vaginal secretions from shedding dogs.

• Pregnant bitches without prior immunity are at high risk of transmitting the virus to their puppies, either in utero or after birth.

• Puppies under 3 weeks old are most susceptible due to their lower body temperature, which promotes viral replication.

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Clinical Signs

• Neonatal puppies:

  • Sudden death (often within 24 hours of onset).

  • Lethargy, poor suckling, and weight loss.

  • Respiratory distress, including tachypnea and pneumonia.

  • Corneal edema (cloudy eyes) and conjunctivitis.

  • Diarrhea and abdominal distension.

  • Absence of fever, unlike many other infections.

• Older dogs:

  • Mild upper respiratory symptoms, similar to kennel cough.

  • Vesicular vaginitis and posthitis.

  • Ocular issues such as conjunctivitis and dendritic corneal ulcers.

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Diagnosis

• Diagnosis is challenging due to rapid disease progression and nonspecific symptoms.

• Postmortem:

  • Necropsy of deceased puppies reveals characteristic lesions in organs like the lungs, liver, kidneys, and gastrointestinal tract.

  • PCR and virus isolation are the most reliable methods for confirming CHV infection.

  • Histopathology shows necrosis with intranuclear inclusion bodies in affected organs.

• Ante-mortem:

  • PCR assays on tissue or fluids from affected animals.

  • Serologic tests (e.g., ELISA) may help identify exposure to the virus.

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Treatment

• Supportive care is the primary treatment, including:

  • Intravenous fluids with electrolytes and/or dextrose to address dehydration and maintain blood sugar.

  • Oxygen therapy for respiratory distress.

  • Nutritional support (e.g., tube feeding if puppies aren’t nursing).

  • Antimicrobials to prevent or treat secondary bacterial infections.

  • Active warming to combat hypothermia.

• Prognosis for affected puppies is generally poor, and survival is unlikely for those with severe disease.

• Adult dogs with mild respiratory or ocular symptoms may benefit from topical antiviral treatments like cidofovir or trifluridine.

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Prevention

• No vaccine is available for CHV in the U.S.

• Maternal immunity:

  • Bitches that have been previously infected with CHV will pass antibodies to their puppies through colostrum, offering some protection.

• Preventive measures:

  • Isolate pregnant bitches from other dogs during the last 3 weeks of pregnancy and the first 3 weeks postpartum.

  • Maintain strict hygiene practices to reduce exposure risk.

  • Disinfect kennels and veterinary facilities with lipid solvents or standard disinfectants, as CHV is sensitive to these agents.

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