Domestic Cats Succumb to Lethal Tick Disease
Written by Steve Dale   

ImageIf being hit by cars, chased by coyotes or stray dogs or clashing in a cat fight aren’t compelling enough arguments to keep your kitty indoors, check out cytauxzoonosis.

     It seems this protozoan infection is really meant to infect bobcats rather than domestic cats, according to internal medicine specialist Dr. Leah Cohn, assistant professor at the University of Missouri College of Veterinary Medicine – Columbia. Bobcats get sick, but they almost always recover on their own. Just the opposite is true in domestic cats; they get sick but rarely recover (even with veterinary treatment). The Cytauxzoonosis protozoa have no effect on dogs, people or other animals who are not of the feline persuasion.

      While bobcats and ticks have always been around, no one knows why cytauxzoonosis appears to be far more prevalent today, described as an emerging disease.  No one’s done a tick census, but arguably there are more ticks today than ever. Dr. Michael Dryden, veterinary parisitologist at Kansas State University College of Veterinary Medicine – Manhattan, says, “Ticks are a big fan of global warming, or at least the unseasonably warm winters.”

      Another factor is that with sprawling suburbia, and burgeoning population of deer (who help to spread ticks), more people than ever before are getting up close and personal with nature. Also, bobcat populations are on the rise.

      “No doubt this is a result of a culmination of many factors, but all combined they are the perfect storm for ticks,” says internal medicine specialist Dr. Adam Birkenheuer, assistant professor at North Carolina State University College of Veterinary Medicine – Raleigh.

      The good news is that cytauxzoonosis only seems to appear where a genus of tick called Dermacentor is found, but that still accounts for about a third of the country; throughout central and southern U.S., but not West of Kansas or Texas (All the states where cytauxzoonosis seems to appear are listed in the sidebar below).

      Once infected, a speedy diagnosis is required, since the disease can spread and kill in a week. “That’s a problem since early symptoms might be lethargy and the cat going off food, owners might wait a few days before seeing their veterinarian,” Cohn says.

      Despite generalized symptoms, vets can first begin to think about cytauxzoonosis if they’re in an endemic region and if the cat ever goes outdoors, even if only in the backyard. About half of the cats with cytauxzoonosis have the organism clearly seen their blood. If a diagnosis can’t be determined with a blood test, an aspirate of the liver, spleen or lymph nodes usually reveals the organism.

      Once a diagnosis is made, most cats have already begun to decline quickly. They may become anemic, have problems breathing, run high fevers, and some lapse into a coma. Only a miniscule per cent (about two or three percent) survive. It’s thought with supportive veterinary car the chances of survival only increases only ever so slightly. No one knows why some cats – a miniscule per cent - are able to beat cytauxzoonosis on their own.

      “Of course, we realize people want to do everything they can for their cat, and to increase the odds of survival,” says Cohn. “While there is no proven treatment, fluid treatment to maintain hydration and general nursing care makes sense.”

      Cohn and Birkenheuer are trying out various drug therapies to determine effectiveness – and they’re seeking real life subjects they may be able to help. Veterinarians who regularly see cytauxzoonosis in their practices are encouraged to contact Cohn or Birkenheuer. The good news is that the drug therapies being tried do seem to have an impact, increasing survival rate to about fifty per cent.

      Actually, from a feline public health perspective, an increased number of survivors could be a mixed blessing. No one knows if it can be spread by those survivors. Say a cat that has survived cytauxzoonosis moves from South Carolina to Colorado (where currently cyauxzoonosis is not known to occur). Since even cured cats might still carry infective agents in their blood, once bitten by a tick the pattern of re-infection could begin. And the disease could move to a place where it previously hasn’t occurred.

      “There’s certainly no need to panic,” says Cohn. “We don’t even know if cats can transmit the organism. And we don’t know all the specific ticks who are capable of transmitting the disease either. And, at least now, most cats don’t survive in the first place. But if more cats are able to survive (cytauxzoonosis), potentially this can be something to seriously worry about.”

      Meanwhile, where cytauxzoonosis exist today, Birkenheuer reiterates the best possible protection is to keep cats indoors. If a cat must go outside, at least attempt to protect the cat with a tick control product. Be careful since many products used to deter ticks on dogs can’t be used on cats.

      “The efficacy of over-the-counter products is questionable,” says Cohn. Even if eventually the tick falls off as a result of the product, no one knows if the tick was able to transmit disease before dying.  Frontline Plus is the only veterinary approved product used for tick control in cats, but still its effectiveness to deter cytauxzoonosis appears to be inconsistent. “Certainly, dosing a cat with Frontline Plus is suggested as opposed to doing nothing at all,” Cohn adds.

      “We really are having some success with the drugs we’re looking at,” says Birkenheuer. “So I’m hopeful that soon we’ll be able to save most cats with cytauxzoonosis.”  
 

Where Cytauxzoonosis Occurs 

      Here are the states where Dr. Adam Birkenheuer, assistant professor at North Carolina State University College of Veterinary Medicine – Raleigh says cytauxzoonosis is presumed or confirmed to occur:

      Alabama, Arkansas, Florida, Georgia, Kansas, Kentucky, Louisiana, Missouri, North Carolina, Oklahoma, South Carolina, Tennessee, Texas and Virginia. He adds that probably cytauxzoonosis is on the move, and will soon be identified in additional states.  

 
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