Cats and ferrets are latest to succumb to H1N1
posted December 1, 2009
If people weren't worried enough already about the 2009 H1N1 influenza virus, news that even pets aren't safe from the novel flu bug certainly didn't help.
Iowa state officials confirmed Nov. 4 that a 13-year-old indoor cat had the dubious distinction of being the first feline known to have contracted the H1N1 viral strain. As word of additional feline H1N1 infections spread, the Oregon state public health veterinarian announced that a pet cat sick with the virus had died Nov. 7.
News of the first known H1N1 feline infection followed on the heels of another first: A pet ferret in Portland, Ore., had tested positive for H1N1 in early October. Later that month, the virus was confirmed in three ill ferrets owned by a different family that were taken to a veterinary clinic in Roseburg in the southwest part of the state. The owners of the cats and ferrets reported that family members had been suffering from flulike symptoms just prior to the pets' illnesses. The animals were treated by their veterinarians and recovered.
Not all ferrets infected with the H1N1 virus recovered, however, and the virus is known to have contributed to the death of a pet ferret in Nebraska. Yet again, the owners had been sick first.
H1N1 continues cropping up among domestic livestock. Notably, the U.S. Department of Agriculture confirmed the first novel H1N1 infections in commercial swine. Dr. Bret D. Marsh, Indiana state veterinarian and AVMA treasurer, said in an announcement Nov. 2 that the affected animals had recovered from the illness, and a private practice veterinarian was caring for the Indiana herd.
The herd owner reported to agriculture authorities that workers at the farm displayed flulike symptoms shortly before the infection was discovered.
And at least six samples from pigs at the Minnesota State Fair have also tested positive for the H1N1 virus, according to the USDA, but it was not immediately clear whether each sample was taken from a different pig.
"My concern is I don't want people to overreact and take their pet to be euthanized because they're worried they're going to get H1N1 from cats."
—DR. ALBERT E. JERGENS, PROFESSOR,
IOWA STATE UNIVERSITY COLLEGE OF VETERINARY MEDICINE
On the other hand, it isn't yet known whether dogs are susceptible to the H1N1 virus. They are, however, prone to the H3N8 canine influenza strain.
Meanwhile, the Centers for Disease Control and Prevention announced Nov. 11 that at least 4,000 Americans had likely died of H1N1 infection.
The number of H1N1 animal cases is small, and the evidence so far suggests that the animals were infected by people and not the other way around. Therefore, when presented with an ill animal, veterinarians may want to determine whether it has had contact with a person with the flu.
Possible H1N1 infection was not on Dr. Albert E. Jergens' mind when he examined the 13-year-old cat brought in late October to the Lloyd Veterinary Medical Center at Iowa State University's College of Veterinary Medicine.
The cat, whose name and sex were being withheld, was presented with a three- to four-day history of lethargy and lack of appetite, recalled Dr. Jergens, a professor of veterinary clinical sciences at the veterinary college. An examination revealed the cat had an increased respiratory rate and harsh lung sounds, particularly in the caudal lung areas, he said.
"I was thinking pneumonia. Aspiration pneumonia, bacterial bronchial pneumonia, or feline allergic airway (asthma) disease. Those were some of the big differentials that went through my mind," Dr. Jergens said.
Because the cat was kept indoors and was the only cat in the home, Dr. Jergens figured an infectious disease was unlikely. Cardiac illness was considered as a possible cause of the cat's signs but dismissed when Dr. Jergens found no heart abnormalities.
Thoracic radiography confirmed abnormalities in the lungs, and after a blood sample was taken for routine analysis, Dr. Jergens performed a bronchiolar lavage on the animal. Cytology results were consistent with a chronic inflammatory process, possibly bacterial pneumonia, but results of the bacterial culture were negative.
Dr. Jergens admits he wasn't sure what he was dealing with until the cat's owner gave him a clue. "Actually, it was the client who said, 'Well, my husband and I have had these flulike symptoms. Is there a possible association?' I said, 'To be honest with you, it's possible, but I think it's really unlikely,'" he recalled.
So they tested the cat for influenza, and when the test came back positive, they went a step further. "We have a team of investigators that had an H1N1-specific PCR assay, and so we said, 'Let's screen the cat,'" Dr. Jergens said, and added, "We were all quite surprised the cat tested positive."
Dr. Ann Garvey, the Iowa public health veterinarian, doesn't consider the 2009 H1N1 diagnosis all that remarkable. "This is not completely unexpected, as other strains of influenza virus have been found in cats in the past," she said.
The cat had been receiving antimicrobials, supportive treatment, and subcutaneous fluids. A re-examination in early November showed the cat's condition had substantially improved, despite some persistent radiographic abnormalities Dr. Jergens attributes to slow resolution of the viral infection.
"It's important for people to know that this cat's responding positively to therapy, and the prognosis on the cat is excellent," he said. "My concern is I don't want people to overreact and take their pet to be euthanized because they're worried they're going to get H1N1 from cats."
"There are no published reports that a cat could infect a person. In this case, we are suspicious that the people with histories of influenza possibly infected the cat," he added.
Iowa also performed follow-up tests on a 14-year-old domestic shorthair cat in Park City, Utah, the second known feline H1N1 case. Although the 2009 H1N1 virus was not detected, antibodies for the virus were. Dr. Kyoung-Jin Yoon, a professor at the ISU veterinary college who participated in the testing of both cats, sees this development as good news. "This implies that cats develop immunity to the virus once they recover," Dr. Yoon said.
The AVMA is monitoring all reports of H1N1 in animals and posting updates on the Association's Web site. For updates and helpful resources, go to www.avma.org and click on "Influenza" under the Public Health section.