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An Urban Experience
M. Lappin1
1The Kenneth W. Smith Professor in Small Animal Clinical Veterinary Medicine, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins Colorado, USA
Multiple vector-borne diseases can affect cats; those transmitted by ticks (multiple agents), fleas (multiple agents), mosquitoes (Dirofilaria immitis), and sandflies (Leishmania spp) are among the most common. The Companion Animal Parasite Council (www.capcvet.
org), European Scientific Counsel Companion Animal Parasites (, and Companion Vector-Borne Diseases ( are excellent sources of information about vector-borne diseases in cats.
Most of the tick-borne diseases diagnosed in dogs have now been found in cats. Many of these tick-borne agents have been grown or amplified from blood or have induced serum antibodies in the serum of normal cats or those with clinical signs such as fever. In some countries, however, thorough evaluation of cats for tick- borne disease agents has not been completed. In those situations, dog results can be used as evidence for the presence of individual agents in the region that could potentially infect cats. Results of studies from regional ticks can also be used as evidence for risk in cats.1-3
The purpose of this review is provide an update on the diagnosis and management of feline tick-borne diseases of significance. Anaplasma phagocytophilum, Borrelia spp, Cytauxzoon spp, Ehrlichia spp, and Rickettsia spp are discussed. It is less clear how important Hepatozoon spp infections are in cats4 and how often Francisiella tularensis infections are transmitted to cats by ticks and so they are not covered in depth.
Feline Granulocytotropic Anaplasmosis
Canine anaplasmosis has been recognized for
many years. Cats have shown to be susceptible
to A. phagocytophilum infection after experimental inoculation.5 The DNA of A. phagocytophilum has
been amplified from blood of naturally exposed cats in multiple countries.6-11 The easiest way to remember the distribution of A. phagocytophilum infections in cats is to remember the range of Ixodes spp or Lyme disease in people or dogs. In the United States, Ixodes scapularis transmits both A. phagocytophilum and B. burgdorferi but some of the current evidence suggests that A. phagocytophilum is the more likely cause of the clinical and laboratory abnormities (Figure 1).
Figure 1. Replete Ixodes scapularis adult ticks after a 7-day feeding period on an experimentally infested cat
While the pathogenesis of disease associated with
A. phagocytophilum in cats is unknown, some cats experimentally inoculated with A. phagocytophilum developed anti-nuclear antibodies and increased interferon–gamma (IFN-ɣ) mRNA suggesting that an immune pathogenesis of disease may contribute to the clinical findings.12 Fever, anorexia, and lethargy are the most common clinical abnormalities in naturally infected cats.11 Whether this agent is associated
with chronic recurrent fever in cats is unknown. In
a recent experimental study, cats infected with A. phagocytophilum by exposure to wild-caught adult Ixodes scapularis from Rhode Island remained clinically normal over the 70-day study period despite being PCR positive for A. phagocytophilum DNA in blood
for several weeks.5 In a larger unpublished study, we infested 10 cats with I. scapularis twice and induced A. phagocytophilum or Borrelia burgdorferi infection in all 10 cats.13 While repeated or new infections with both organisms occurred, all cats remained clinically normal. Both studies were performed using ticks from the same region so it is possible a less pathogenic strain of the organism was present.14
Cats with fever in endemic areas can have blood smears examined cytologically but morulae are not always detected in cats with clinical signs of anaplasmosis (Figure 2).

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