Veterinary Medicine - February 2008 - (Page 88) ClinQuiz A NS W ERS 1) A—Incorrect. Although adult B. procyonis (10 to 20 cm) are somewhat larger than adult Toxocara canis (10 to 15 cm) and Toxascaris leonina,1,2 Baylisascaris species do not pose a greater risk of impaction than the other, more common canine ascarids do. On casual inspection, both the adults and the eggs of B. procyonis may be mistaken for T. canis, a mistake that may contribute to a failure to recognize the raccoon roundworms in domestic dogs.1 B—Correct. Baylisascaris procyonis is considered a serious zoonotic disease threat. The larvae of this ascarid are particularly neurotropic and can induce visceral larva migrans characterized by severe neurologic disease.1 This parasite is one of the reasons keeping raccoons is discouraged. (Rabies is another major zoonotic risk from raccoons.) C—Incorrect. Adults of B. procyonis usually develop in the intestinal tract of dogs. Although aberrant migration of B. procyonis larvae has been reported in dogs,3 the disease is generally limited to the central nervous system. necessary to prevent reinfection.6 B—Incorrect. Although highly effective against Giardia species in dogs and cats, albendazole has been associated with bone marrow toxicosis and aplastic anemia when administered in companion animals.8,9 The use of albendazole for any application in dogs and cats is not recommended.8,9 C—Incorrect. Although widely used extralabel for treating giardiasis in companion animals, the efficacy of metronidazole for treating Giardia species infections in dogs is poor.6,9 In addition, this drug has been associated with neurotoxicosis in dogs.9 However, a symptomatic response to metronidazole administration along with the impression that efficacy may be enhanced when it is combined with a more effective drug leads some practitioners to administer it with fenbendazole in cases of giardiasis that are refractory to fenbendazole treatment alone.10 characteristic of D. immitis. C—Correct. The size of these microfilariae is characteristic of D. immitis, the canine heartworm. However, because the prepatent period of D. immitis is six to seven months,2 this puppy was most likely born to a microfilaremic dam and acquired the microfilariae in utero. Without treatment with macrocyclic lactones, microfilariae will survive in the circulation of a dog for several months. However, these microfilariae will not develop into adult heartworms unless they are picked up by a mosquito, molt into the infective third-stage larvae, and are then reintroduced to a dog when the mosquito subsequently feeds. 4) A—Incorrect. Figure 2 shows amastigotes of Leishmania infantum, which is transmitted to animals via a sandfly bite or, rarely, by fomites such as contaminated needles.11 Leishmania species do not have an environmental cyst form. B—Correct. Figure 2 shows Leishmania species amastigotes. The dog’s travel history suggested that this dog was most likely infected with L. infantum, which is transmitted to dogs and people by the bite of sandflies in the genus Phlebotomus. Other sandfly genera transmit 3) A—Incorrect. Although the morphology of these microfilariae is characteristic of Dirofilaria immitis, which is transmitted via mosquitoes, the prepatent period is six to seven months.2 Since this puppy was only 2 months old, adult worms would not be present and producing microfilaria. Antigen would also not be present in a puppy this young because the adult female worms do not produce the antigen detected by commercial assays until at least five to six months after infection. B—Incorrect. Acanthocheilonema (Dipetalonema) reconditum is transmitted to dogs via fleas. Its prepatent period is about three months, and the microfilariae are generally narrower (< 5.6 µm wide) than those of D. immitis are. The morphology of these microfilariae is 2) A—Correct. Figure 1 shows Giardia species cysts, which can be identified by their small size (10 to 15 µm), an internal axostyle, and two or four nuclei. Fenbendazole is considered the treatment of choice for giardiasis in dogs. The efficacy of fenbendazole in published studies is greater than 90%, compared with the relatively poor efficacy of metronidazole.4-6 Febantel, a probenzimidazole that is metabolized to fenbendazole after ingestion, is also effective.7 Removing Giardia species cysts from the environment through the careful cleaning of fecal-contaminated areas and bathing of dogs immediately after treatment may be This quiz was provided by Susan E. Little, DVM, PhD, DEVPC, Department of Veterinary Pathobiology, Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK 74078. 88 February 2008 VETERINARY MEDICINE
For optimal viewing of this digital publication, please enable JavaScript and then refresh the page. If you would like to try to load the digital publication without using Flash Player detection, please click here.