Canine influenza spreads easily, often damages lungs

A recent study found that canine influenza virus spreads easily among dogs and can cause lung damage in many cases. 

The study appeared Aug. 26 in the journal Veterinary Microbiology. The study was conducted by researchers at Intervet/Schering-Plough Animal Health, which makes the only vaccine for canine influenza.

The researchers infected four dogs with canine influenza virus and, after a day, co-mingled the dogs with a group of eight CIV-negative dogs. All four of the experimentally infected dogs and six of the eight contact-exposed dogs excreted virus in nasal secretions. Nasal swabs from contact-exposed dogs were first CIV-positive as early as day 4 to as late as day 14.

The study found that virus excretion precedes the onset of peak clinical signs in CIV-positive dogs. This finding indicates that clinically normal dogs can infect other dogs in shelters, kennels, clinics, and other settings.

The experimentally infected dogs and five contact-exposed dogs were euthanized on day 10, and the remaining three dogs were euthanized on day 21. All four experimentally infected dogs had one or more lung lobes with 50 percent consolidation. Two of the five contact-exposed dogs euthanized on day 10 had 50 percent consolidation in one or more lung lobes, while two had mild lung consolidation. All three of the contact-exposed dogs euthanized on day 21 had 50 percent consolidation in one or more lung lobes.