Canine influenza strikes the Southeast: Another outbreak?

Shutterstock.comHere we go again-canine influenza is back in the headlines. H3N2, the same viral strain identified in a March 2015 outbreak in the Chicago area, seems to have gone south for the summer: This time it's hitting the southeastern United States, especially Georgia and Florida so far.

Two years ago the virus swept through Chicago-area animal shelters, making dogs sick with fever, coughing, sneezing and other respiratory signs. Many of these dogs experienced decreased appetite and some even progressed to secondary pneumonia. The virus is highly contagious, and dogs seem to be able to spread it even before they are clinically ill.

In early June, the American Kennel Club (AKC) issued a statement to all dog show exhibitors in the Southeast warning that there were reports of sick dogs from Georgia and Florida dog shows. The AKC recommended that if a dog seemed at all ill, it should not be exposed to other dogs and should see a veterinarian concerning the possibility of influenza.

The North Carolina Veterinary Medical Association also warned dog show participants about the outbreak because the dog show rotation was scheduled to place potentially exposed dogs in that state next.

The University of Florida has confirmed that this current outbreak of influenza is strain H3N2. The College of Veterinary Medicine in early June positively confirmed seven dogs as being infected, and several other suspected cases were pending identification at press time. The University of Georgia's Athens Veterinary Diagnostics Laboratory identified two cases of canine influenza, but the strain had not been subtyped. Another Georgia lab positively confirmed one case of H3N2 during this outbreak so far.

By mid-June, canine influenza had been reported in a number of other states besides Flordia and Georgia. Local media outlets reported that the disease was affecting dogs in North and South Carolina, Tennessee, Kentucky, Texas and Illinois, and other states were on alert for the virus.

One veterinarian says these reports aren't telling the whole story. Richard Hawkes, DVM, of Moorehead, North Carolina, participates in dog shows and says he knows of more than 300 dogs that became ill in association with AKC events in Florida in mid- to late May. He himself had 10 dogs become sick, he says, one of which died in early June. A PCR test confirmed the presence of H3N2, Hawkes says.

During the 2015 outbreak, one study looked at the duration of shedding of active virus in order to guide isolation protocols for infected dogs. Dogs were shown to shed the virus for 20 to 24 days after infection.1 Spread of the virus was slowed significantly when shelters implemented a 21-day isolation protocol, so owners of infected dogs should plan for extended isolation.

But isolation is only a part of disease containment. Vaccination can also play a role in stopping disease transmission dogs. Dogs considered to be at highest risk are those that participate in social activities or encounter groups of other dogs: boarding and grooming facilities, dog parks, dog shows and shelters are all potential venues for transmission.

“Dogs at risk should be vaccinated at least yearly with both influenza strains, H3N8 and H3N2,” says Ronald Schultz, PhD, professor of pathobiological sciences at the University of Wisconsin School of Veterinary Medicine, in a release from Merck Animal Health, which offers a canine influenza vaccine. (Zoetis also manufactures a vaccine.)

Here are a few tips for veterinarians and pet owners:

> Any dog showing signs of respiratory disease should see a veterinarian as soon as possible.

> Veterinarians with patients that may travel, especially into or out of the southeastern United States, should consider offering a canine influenza vaccine.

> Any dog that resides in (or has recently traveled to) the Southeast should be closely observed for signs of respiratory disease.

> Any dog that becomes ill with canine influenza should be isolated for at least 21 days after illness to limit spread of the virus.

Reference

1. Newbury S, Godhardt-Cooper J, Poulsen KP, et al. Prolonged intermittent virus shedding during an outbreak of canine influenza A H3N2 virus infection in dogs in three Chicago area shelters: 16 cases (March to May 2015). J Am Vet Med Assoc 2016;248:1022-1026.