Page 402 - WSAVA2017
P. 402

An Urban Experience
cats every month of the study.14 Ticks are tenacious parasites and not easily dislodged, particularly when attached to areas that are more difficult for the cat to reach. In the absence of tick control, cats are also likely to become infected with severe, potentially fatal tick- borne infections such as Cytauxzoon felis transmitted
by Ambylomma americanum (Figures 2 and 3) or Anaplasma phagocytophilum transmitted by Ixodes spp.15 Data continues to accumulate showing that cats, like dogs, would benefit from routine tick control.
been described, including novel Borrelia spp, Ehrlichia spp, and Rickettsia spp, as well as tick-transmitted
viral pathogens. Protozoal tick-borne disease agents including Babesia spp, Theileria spp, Hepatozoon spp, and C. felis have also been reported from new areas and appear more widespread than previously recognized. Fortunately, for many of these agents, tick control – including treatment with systemic isoxazolines – has been shown to prevent or dramatically reduce the risk of infection.
New Strategies for Controlling Ticks and Mites
Controlling ticks and mites can be difficult. Until recently, persistent tick control options for dogs were limited to topical products, such as amitraz, fipronil, and pyrethroids, and choices in cats were even further restricted. The recent advent of systemic isoxazolines, which provide safe and long-lived efficacy against both ticks and mites, offers new opportunities for protecting pets from the blood loss and dermatitis associated with infestation as well as reduced risk of disease transmission.
Isoxazolines have been shown capable of blocking infection with several tick-borne disease agents. Although ticks must attach to the host and begin to feed in order to acquire these systemic acaricides, some of these compounds appear to act quickly enough to interrupt transmission. For example, sarolaner has been shown to block transmission of Borrelia burgdorferi and A. phagocytophilum from Ixodes scapularis,16 while fluralaner and afoxolaner have been shown to interrupt transmission of Babesia canis from ticks to dogs.17,18 Not all pathogen transmission, however, appears to be blocked by the use of isoxazolines. A comparative study showed that afoxolaner and fluralaner reduced, but did not eliminate, the number of dogs infected with Ehrlichia canis by R. sanguineus feeding in an experimental infestation study.19
Isoxazolines have also proven effective at eliminating
mite infestations. Published studies to date support
the use of these compounds for the treatment of demodectic mange,20-23 ear mites,22,24,25 and sarcoptic mange.26-29 In addition, the isoxazolines provide excellent flea control, reducing flea populations and evidence of flea allergy dermatitis in naturally infested dogs.
The trend of increasing tick populations and a greater risk of tick-borne infections will likely continue for the next several decades. Mite infestations will similarly remain
a common issue for pets. Because ticks and some
mites are also zoonotic, controlling these ectoparasites effectively has important One Health implications. Incorporating isoxazolines into routine parasite control programs for dogs and cats brings with it the benefits
 Figure 2. Macrophage containing Cytauxzoon felis schizonts from lung impression smear (Romanowsky stain.) Image provided by the National Center for Veterinary Parasitology, Oklahoma State University.
 Figure 3. Adult male (left) and female (right) Amblyomma americanum, primary vector of Cytauxzoon felis to cats in North America. Image provided by the National Center for Veterinary Parasitology, Oklahoma State University.
Increasing Risk of Tick-Borne Infections
Tick-borne infections continue to pose new and greater challenges to both veterinary and public health. As ticks spread geographically they carry with them the threat of infection and disease. Recent years have
seen a steady onslaught of areas where Lyme disease caused by Borrelia spp has been reported or confirmed for the first time. In addition, new disease agents have

   400   401   402   403   404