RESUMO
Four trials were conducted in which laboratory-reared Dermacentor variabilis nymphs were exposed to Ehrlichia canis by feeding on experimentally infected dogs as soon as classical morulae were detected in peripheral blood monocytes. After molting 25, 50 or 90 adult tick pairs were permitted to feed on 7 Ehrlichia-naive dogs. Transmission occurred in trials 1 (1/1 dog), 3 (1/1 dog) and 4 (2/2 dogs) but not in trial 2 (0/3 dogs), with 4 of 7 dogs becoming infected. Successful transstadial transmission was demonstrated by detection of morulae in peripheral blood lymphocytes and by seroconversion to Ehrlichia canis 30 d post-exposure. Incubation periods ranged between 17 and 22 days (mean = 19). Clinical signs, typical of ehrlichiosis, included mucopurulent ocular discharge, lymphadenopathy and malaise with accompanying pyrexia, leukopenia and thrombocytopenia. Pyrexia, thrombocytopenia and erythrophagocytosis and vacuolization of the cytoplasm of monocytic cells were observed 1-4 d prior to detection of morulae. This is the first demonstration that a tick other than Rhipicephalus sanguineus is capable of transstadial transmission of this important pathogen of dogs.
Assuntos
Vetores Aracnídeos/microbiologia , Dermacentor/microbiologia , Doenças do Cão/transmissão , Ehrlichia/fisiologia , Ehrlichiose/veterinária , Anestésicos Dissociativos/farmacologia , Animais , Cães , Ehrlichia/efeitos dos fármacos , Ehrlichiose/transmissão , Técnica Indireta de Fluorescência para Anticorpo/veterinária , Ketamina/farmacologia , Contagem de Leucócitos/veterinária , Pulmão/microbiologia , Ninfa/microbiologia , Contagem de Plaquetas/veterinária , Xilazina/farmacologiaRESUMO
Nine dogs meeting the diagnostic criteria for canine atopic dermatitis were enrolled in a double-blind, placebo-controlled, cross-over clinical trial. In this pilot study, zileuton (a 5-lipoxygenase inhibitor) given orally at 2 mg kg(-1) three times daily for 4 weeks significantly decreased erythema in dogs with atopic dermatitis but had no effect on pruritus. Zileuton was well tolerated and no adverse clinical signs were noted. However, one dog developed mild alanine aminotransaminase elevation, which resolved within 1 week of discontinuation of therapy. Monitoring of alanine aminotransaminase may be necessary in dogs receiving zileuton. Further studies with larger number of dogs are needed to evaluate the efficacy of zileuton as treatment for canine atopic dermatitis.