Hundreds if not thousands of racing greyhounds in 11 states have been diagnosed with a respiratory illness that has caused fatalities and prompted track closures over the last few months. Symptoms include a soft, gagging cough that lasts from 10 to 21 days. Clinical signs are similar to an outbreak in racing greyhounds reported in Florida last year that was linked to the equine influenza virus. Arkansas, Arizona, Colorado, Florida, Iowa, Kansas, Massachusetts, Rhode Island, Texas, West Virginia and Wisconsin have reported similar cases in racing greyhounds.

Respiratory disease outbreaks, like this one, are not exclusive to greyhounds and can affect groups of dogs in close contact, such as shelters, kennels and show dogs, said experts. Researchers at the University of Florida, Cornell and the University of Wisconsin are working with the Influenza Branch of the Centers for Disease Control and Prevention on influenza virus as one of the causes for these respiratory infections in dogs. Goals include confirmation of the influenza virus as a causative agent, the future development of preventive vaccines, rapid diagnostic tests and treatment protocols, said Cynda Crawford, DVM, PhD, who is coordinating the effort. “At this time we have no reason to believe that influenza virus infection is restricted to greyhounds,” she said. “We are currently investigating the potential susceptibility of any dog.” A paper detailing the group’s efforts will be published by a scientific journal in the next few weeks but details were not released.

In Colorado, about 1,000 racing greyhounds at one track started showing signs of respiratory infection in late April. Lori Scott, DVM, a state veterinarian for the Colorado Racing Commission, said the situation is now under control. She believes that Colorado has avoided national outbreaks in the past by closing borders to traveling greyhounds when reports of respiratory disease outbreaks surface.

This year, some dogs developed a secondary bacterial infection identified as Pasteurella multocida, according to Scott. It is the same bacteria identified in some Florida dogs that Crawford examined. The Florida dogs spiked fevers of 105-107 degrees Fahrenheit associated with development of pneumonia, Crawford added. Sixteen dogs died in Florida, all dogs that developed severe cases of pneumonia. Crawford is now testing dogs at tracks in Massachusetts, West Virginia and Wisconsin.

Across the country dogs that presented with minor symptoms were treated with injectable penicillin and doxycycline for potential bacterial infections like Pasteurella, Bordetella bronchiseptica and Streptococcus canis, Crawford said. Unlike traditional kennel cough due to Bordetella bronchiseptica bacteria, recovery from the infection seen in many of the greyhounds is not hastened by treatment with doxycycline and cough suppressants, Crawford added.

Researchers are investigating viral and bacterial components of the disease. “I don’t think it would be wise to wear blinders,” Crawford said. “We need to think outside the box and not always presume that it’s the same virus or bacteria over and over. Anything is possible.”