Veterinary Medicine - August 2008 - (Page 424)

ClinQuiz 4) A client with a 4-year-old spayedtofemale American Staffordshire terrier calls your ofﬁce report a tick infestation in his home. He describes bites on both himself and the dog, especially at night (the dog sleeps with him). Later that day, he brings in the organism shown in Figure 4 and requests a tick-control product to eliminate the infestation. What organism Figure 4 is this? Cimex species, the common bedbug Rhipicephalus species, the brown dog tick or kennel tick Ornithodoros species, a soft tick common on bats, rodents, birds, and reptiles 5) The organism seen in Figure 5 was found on a skin scrape from a hyperkeratotic patch on the elbow of an extremely pruritic 6-yearold mixed-breed dog. Which of Figure 5 400X the following products is labeled in the United States to provide safe, effective treatment of infestations with this parasite? Selamectin, 6 mg/kg, applied topically at the base of the neck Ivermectin, 0.2 mg/kg, administered orally or subcutaneously; repeat in two weeks Amitraz, 250 ppm dip, applied to the entire animal topically; repeat in two weeks A NS W ERS 1) A—Incorrect. To date, only Ixodes species ticks (black-legged ticks or deer ticks) have been shown to be capable of transmitting B. burgdorferi.1 B—Correct. In 2004, a foci of transmission of Rocky Mountain spotted fever was identiﬁed in dogs and people in Arizona. Surprisingly, the vector tick was identiﬁed as Rhipicephalus sanguineus, the brown dog tick.2 This report, the ﬁrst time this association had been shown in the United States, is important since the existence of such a cycle increases the risk of transmission of this important, potentially fatal disease. The agent of Rocky Mountain spotted fever is most commonly transmitted to people and dogs by Dermacentor species. C—Incorrect. Trypanosoma cruzi is transmitted to people and dogs by reduviid (kissing) bugs3 and not by tick bites. 2) A—Correct. The inﬂammation caused by Cuterebra species larvae migrating to the brain or spinal cord can produce severe neurologic disease in infected cats.4 Prevention recommendations include keeping cats indoors where they will not come in contact with the Cuterebra species larvae and routinely applying residual insecticides, such as imidacloprid and ﬁpronil, which may limit the duration of infestation.5 B—Incorrect. The Cuterebra species larvae enter the mouth or nares to begin their migration; usually there is not a discernible reaction to this initial penetration.6 C—Incorrect. Although Cuterebra species could theoretically migrate anywhere in cats, clinical disease is most commonly associated with the presence of larvae and associated inﬂammation in the central nervous system.4 3) A—Correct. The organism depicted in Figure 3B is a morula of Ehrlichia ewingii, which is transmitted to dogs by lone star ticks (Figure 3A). The organisms are morphologically identical to Anaplasma phagocytophilum, which is transmitted by black-legged ticks, or deer ticks (Ixodes species).7,8 Patients usually respond to doxycycline within two or three days. 9 However, infections can recrudesce; 28 days of treatment is recommended to better eliminate chronic infections.10 B—Incorrect. This organism is a morula of Ehrlichia ewingii within a neutrophil. Penicillins are not effective against rickettsial infections. C—Incorrect. This organism is a morula of Ehrlichia ewingii within a neutrophil. Fluoroquinolones are not effective against rickettsial infections. 424 August 2008 VETERINARY MEDICINE

Table of Contents Feed for the Digital Edition of Veterinary Medicine - August 2008

Veterinary Medicine - August 2008 Contents Editors' Note Leading Off ClinQuiz Idea Exchange Practical Matters Diagnosing and Treating Canine Copper-Associated Hepatopathies Canine and Feline Demodicosis CE Form Advertiser Index Product Preview Marketplace/Classifieds Mind Over Miller

Veterinary Medicine - August 2008

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