Comment submitted by S. A. Levy

Steven A. Levy, VMD State Police Surgeon- K9 Unit 860- 349-3485 Durham Veterinary Hospital, PC Fax 860-349-8649 178 Parmelee Hill Road email drstevelevy@yahoo.com Durham, CT 06422 October 17, 2006 Environmental Protection Agency Amitraz has been used for many yeas as an acaracide in veterinary medicine. Formadines inhibit monoamine oxidase and block neurotransmitter amines to paralyze ticks resulting in decreased feeding and attachment. Control of acarine ectoparasites of dogs is important both as a primary veterinary medical matter and also as a potential limiting strategy for zoonotic impact on humans. Ticks are the most common vectors of infectious disease for dogs in the United States. In virtually all areas of the United States there are tick species that transmit microorganism such as Borrelia burgdorferi, Anaplasma phagocytophilum, Ehrlichia canis, Ehrlichia chaffeensis, Rickettsia rickettsii, Babesia canis, and other emerging pathogens to dogs. Additionally, mites in the genus Demodex and Sarcoptes often parasitize dogs and cause the clinical syndrome known as mange. Amitraz acts through a rapid neurotoxic effect on ticks and causes a phenomenon known as clinical repellence. That is, dogs treated with Amitraz may be acquired by host seeking ticks but contact with the treated skin and fur of these dogs exposes the ticks to Amitraz thus preventing attachment and resulting in ticks that are both unattached to the treated dog but also neurologically damaged and therefore unable to attach to other hosts (including humans). The result is the appearance of ticks having been repelled by the treated dog but the effect is more significant because rather than leaving healthy ticks with the ability to acquire another (human or animal) host in the environment the ticks have been exposed to a lethal dose of Amitraz and will be unable to acquire new hosts. Prevention of tick attachment and feeding are essential steps in prevention of tick- transmitted diseases of dogs. Some tick-borne diseases may be transmitted very rapidly (Rickettsia rickettsii in as little as 5 hours, Anaplasma phagocytophilum within 24 hours and Borrelia burgdorferi in 24 to 52 hours) and effective prevention of transmission must not just kill ticks but also prevent host acquisition and feeding. The ability of Amitraz to prevent transmission of a tick-borne infection in dogs has been demonstrated Elfassy, Goodman, Levy, et al. JAVMA, 2001; 219:185-189.). Morbidity caused by parasitism with mange mites is a major clinical concern for small animal veterinary practitioners. The availability of a pesticide with activity against ticks and mange mites may eliminate the need for treating dogs with multiple products when control or treatment of various combinations of parasites is required. Demodectic mange often leads to severe secondary bacterial infections and Sarcoptic mange in dogs may lead to the incidental parasitism of humans leading to cutaneous lesions, pruritis and visits to health care providers. Amitraz has been used safely in dogs. A mange dip (Mitaban?) and a tick control collar (Preventic?) have been in the hands of veterinarians for more than a decade. Offering Amitraz in a metered dosing/dispensing container for monthly use will support safety. The availability of an effective antidote for toxicity (yohimbine) should help ensure safe use. I have routinely used both products in my practice since they were released for use. Decreased transmission of tick-borne organisms, blood loss, secondary cutaneous infections and self-trauma have been the benefits of using these products. Further, clinical repellence typical of neurotoxic tick control agents like Amitraz prevents ticks from being transported into human contact by untreated dogs and then potentially leaving the canine and acquiring a human host. A healthy, unattached tick on an untreated dog may be transferred to a human by direct contact with the dog prior to the tick attaching to the dog. Activity against mange mites has successfully treated infested dogs and decreased incidental, temporary transmission of Sarcoptic mites to humans who may suffer pruritis from bites. Amitraz is a proven safe and effective antiparasite agent for use in canine practice.