A young dog imported from South Korea to western Canada last fall brought a dangerous hitchhiker: the Asia-1 strain of canine distemper virus (CDV), which has never been reported in North America.
Scientists at Cornell’s Animal Health Diagnostic Center (AHDC) identified the virus in samples from the dog that they suspect were part of a shipment of animals rescued from a Korean meat market by an animal welfare organization. Dogs already immunized against CDV are unlikely to be at risk from the Asian strain. However, when the virus comes into contact with wildlife, it can severely impact wild carnivore populations.
“Well-intentioned people try to save animals, but when you move animals, you move their infectious disease,” said Dr. Edward Dubovi, Director of the Virology Laboratory at AHDC and Professor of Population Medicine and Diagnostics. “If that particular Asia-1 strain got into the wildlife population, they’ll be here forever because they can’t be got rid of when they meet the wildlife.”
About two weeks after the sick dog arrived in Canada in October 2018, he developed a cough and was sluggish. Ten days later she developed muscle twitches, then seizures, and was finally put to sleep. When the AHDC tested animal samples they were negative for canine influenza virus but gave strongly positive results for CDV. Genetic Analysis by Randall Renshaw, Ph.D. ’92, a research fellow at AHDC, stated the virus was nearly identical to the Asia-1 CDV strain circulating in East Asia.
Canine distemper virus is highly contagious and often migrates between hosts through the aerosols released when dogs bark and cough, as well as through urine and feces. The disease begins with respiratory symptoms such as coughing and pneumonia and leads to gastrointestinal disorders and neurological problems. Most dogs in the US are given CDV vaccines to protect against native North American tribes.
Although CDV outbreaks occasionally occur in animal shelters, the virus persists mainly in wildlife populations, particularly in the northeast where cases of CDV in dogs are extremely rare. It circulates among numerous carnivores and causes raccoons, gray foxes, skunks, coyotes, wolves, and other animals to die.
Although Dubovi was unable to get any further information on how the dog got to Canada, he expects it to have come from a Korean dog meat farm. Animal rescue organizations have been working for years to remove dogs from farms that supply dog meat markets in South Korea and some other Asian countries. With the change in attitudes towards dogs, the demand for dog meat is falling, allowing welfare groups to buy up farms and ease the transition to new careers for farmers.
While these efforts are well-intentioned, they put animals in North America at risk for foreign strains of the disease. The United States receives rescued pets from around the world, and any of these animals could carry viruses, bacteria, and parasites that are not common in North America. Animals raised in countries with lax antibiotic regulations for meat are at particularly high risk of carrying drug-resistant strains of bacteria.
The canine influenza virus, which first appeared in the Chicago area in 2015, can be traced back to rescued Korean dogs. “Genetic analysis has clearly linked the virus to the most recent Korean H3N2 influenza strains,” Dubovi said. “This particular strain of flu was likely circulating in Asia, China and Korea 10 years before it arrived in the US.” He estimates the recent canine influenza outbreak cost US dog owners up to $ 75 million nationwide in diagnostic tests and vaccinations.
Keeping new infectious organisms out of the US is a challenge, however, as there is virtually no federal oversight of pet imports. The U.S. Department of Agriculture only oversees trade in animal products to protect U.S. ranch and dairy farms. A rabies certificate is the only requirement for dogs entering the United States and Canada. However, in some countries, people are buying fake certificates, as demonstrated by a handful of rabies-infected dogs that have traveled from India, Iraq and Egypt over the past two decades.
Rescue dogs flown in from other countries often pass through airports in New York City and Los Angeles. In theory, California and New York could regulate
Import of pets, but these laws would not apply to border crossings in other states. “It’s a 50-state free-for-all when it comes to pets,” Dubovi said. “It is a very unsatisfactory situation when you are trying to control infectious diseases in our domestic cats and dogs.”
Affected pet owners could also put pressure on rescue groups to adopt better transport and quarantine protocols when transporting foreign animals to the United States.
It is not yet known whether the Asia-1 strain of the distemper virus is included or whether it should stay here in North America, but Dubovi views this case as a “canary in the mine shaft”.
“There are probably a number of other things that we haven’t tested for,” said Dubovi. “If we don’t look for it, we won’t find it until it’s too late.”