A few weeks ago, I wrote about a new test for canine parvovirus that can detect an emerging strain of the virus (2c) while also testing for the “older” 2a and 2b strains. I quoted from the Kansas State University press release saying that “researchers are seeing that parvovirus can infect cats.” TheOldBroad commented, “This definitely struck fear in my heart. Do you know if it's the same virus or a mutated form? Will canine vax protect a cat/kitten from this?”
I’ve done a little research into these questions since I’m admittedly ignorant about the details of canine parvovirus infecting cats. Here’s what I’ve found.
First of all, the fact that canine parvovirus can infect cats isn’t that big of a surprise. The most widely accepted theory about how canine parvovirus suddenly erupted on the scene with such disastrous results in the 1970s is that it originated (mutated) from the feline panleukopenia virus or another type of closely related parvovirus. So, the reports of cats coming down with canine parvovirus that started emerging in the last decade or two are most likely a case of canine parvovirus redeveloping the ability to infect cats rather than developing it anew.
A paper published in 2010 describes two cases of kittens diagnosed with canine parvovirus.
Unlike the original canine parvovirus type 2 (CPV-2), CPV-2 variants have gained the ability to replicate in vivo in cats but there is limited information on the disease patterns induced by these variants in the feline host. During 2008, two distinct cases of parvoviral infection were diagnosed in our laboratories. A CPV-2a variant was identified in a 3-month-old Persian kitten displaying clinical sign of feline panleukopenia (FPL) (acute gastroenteritis and marked leukopenia) and oral ulcerations, that died eight days after the onset of the disease. Two pups living in the same pet shop as the cat were found to shed a CPV-2a strain genetically identical to the feline virus and were likely the source of infection. Also, non-fatal infection by a CPV-2c strain occurred in a 2.5-month-old European shorthair kitten displaying non-haemorrhagic diarrhoea and normal white blood cell counts. By sequence analysis of the major capsid protein (VP2) gene, the feline CPV-2c strain showed 100% identity to a recent canine type-2c isolate. Both kittens had been administered multivalent vaccines against common feline pathogens including FPL virus. Whether and to which extent the FPL vaccines can protect cats adequately from the antigenic variants of CPV-2 should be assessed.
Another recent study shows that the prevalence of canine parvovirus infections in cats may be more widespread than you might think. It found that “Canine parvovirus was demonstrated in 32.5% (13/50) of faecal samples in a cross sectional study of 50 cats from a feline only shelter, and 33.9% (61/180) of faecal samples in a longitudinal study of 74 cats at a mixed canine and feline shelter.” None of these cats were showing any symptoms of disease. The authors concluded, “These results suggest that in some circumstances, clinically normal cats may be able to shed CPV for prolonged periods of time, and raises the possibility that such cats may be important reservoirs for the maintenance of infection in both the cat and the dog population.”
Perhaps dogs have more to fear from cats with regards to parvovirus than the other way around.
Dr. Jennifer Coates
Characterisation of canine parvovirus strains isolated from cats with feline panleukopenia. Decaro N, Buonavoglia D, Desario C, Amorisco F, Colaianni ML, Parisi A, Terio V, Elia G, Lucente MS, Cavalli A, Martella V, Buonavoglia C. Res Vet Sci. 2010 Oct;89(2):275-8.
Canine parvovirus in asymptomatic feline carriers. Clegg SR, Coyne KP, Dawson S, Spibey N, Gaskell RM, Radford AD. Vet Microbiol. 2012 May 25;157(1-2):78-85.