A Different Breed of Calici

When clients at Jefferson Animal Hospital balk at bringing their cats back to the clinic only three weeks after an annual visit for new vaccine booster, practice manager Jodi Michaelson doesn’t argue. “Don’t make me pull out the pictures,” she says quietly.

The photos show cats with grotesque mouth and nose ulcers, hemorrhaging lungs and swollen joints—all result from a vicious mutation of a common cat virus. Every owner who has seen the pictures has eagerly embraced the vaccine protocol to prevent the family pets from suffering a similar fate. In fact, compliance at the Baton Rouge practice is 100 percent.

Still, even though Fort Dodge Animal Health introduced an effective vaccine in 2007, many cats have yet to be vaccinated against the deadly mutation.

Common calicivirus is nothing new. While some cats show no signs and simply pass the virus along, others appear to have a kitty cold with sneezing, coughing, runny eyes and nose and, sometimes, painful mouth ulcers. Researchers have long recognized the virus’ ability to mutate and animals’ susceptibility to each different strain. For 30 years, only one vaccination was available to protect cats from a spectrum of common caliciviruses.

However, within the last decade, a virulent strain (v.s.) calicivirus has appeared with vengeance. Nearly 60 to 70 percent of infected adult cats die from its complications; kittens stand a slightly better chance of survival.

In 2006, feline specialist Gary Norsworthy, DVM, of San Antonio, first encountered the deadly version of the disease. Two adults and a kitten began showing classic calici symptoms. Rather than subsiding, the illness rapidly progressed with mouth ulcers, decreased liver function, severe swelling around the joints, head and neck, loss of hair at the affected sites.

Since there are no anti-viral drugs for v.s. calici, all a vet can do is provide supportive care. Fort Dodge Animal Health staff veterinarian Christine Brady, DVM, explains, “Animals can survive; but it’s up to their immune system and how big a dose they have. Once they’re sick, there’s no specific treatment.”

Unfortunately, Norsworthy’s adult patients died within seven days; the kitten survived only long enough to succumb to a relapse later.

In addition to being fatal, the virus is highly unpredictable. It can appear spontaneously as an isolated incident or decimate entire catteries and shelters.

“We don’t know for sure why it does not spread outside certain populations,” Brady says. “It is spread by secretions from nose and eyes and on the skin and fur. It is very contagious. But, the signs are so severe, the animal does not live for very long and may not have much time to infect others.”

While the new vaccine does not protect against all strains of calici, it represents a tremendous advantage over its predecessor. Norsworthy cites a University of California Davis study that shows the old vaccine to be effective against 23 to 36 percent of 37 different calici strains; the new vaccine prevents 74 percent—providing triple the protection.

So why aren’t all cats vaccinated against the v.s. virus?

As a national lecturer for Fort Dodge, Norsworthy knows the answer. “After (my) presentations, I have talk with veterinarians across the country. I have plotted the stories I hear about cases (on a map). (The spread of v.s. calici) is not geographically bound and in some cases, the vet did not make the diagnosis…because he did not identify it as such at the time.”

The under-reporting of disease creates the illusion the risk of contracting v.s. calici is negligible. So, some professionals believe their clients get adequate coverage with the tried-and-true older vaccine and suspect the excitement over the newer version to be the product of pharmaceutical company marketing tactics. “Not all my colleagues have seen (the v.s. virus) and appreciate what it does,” says Norsworthy. “If they haven’t seen it in their practices, they don’t worry about it.”

In addition, the American Veterinary Association not added the new calici vaccine to its recommendations. And even the most conscientious cat lovers may be unaware of the v.s. calici threat and which vaccine the family cats have received.

Should cat owners seek out a vet who offers the v.s. calici vaccine, even if their current vet does not? “That’s a difficult question,” Norsworthy admits. “But, if their cat comes down with the virus, they certainly will wish they had.”

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