A critical look on anthelmintic treatment of dogs

Abstract

The current recommendation on anthelmintic treatment for dogs is not based on solid evidence in the published literature. To reconsider the current advice on preventive anthelmintic treatment of at least four times a year, the frequency of patent infections of Toxocara was examined in 446 dogs from the Netherlands over a period of 9 months. For this study data from dogs participating in an ongoing longitudinal project were used. The owners submitted a fecal sample from their dog (s) and completed a questionnaire on a monthly base. The dogs did not receive anthelmintic treatment unless being diagnosis of a patent infection, and the feces was tested for Toxocara and other intestinal parasites. The questionnaire showed that the average dog from the study population was treated less than two times a year previous to participation. The most frequently reported reason was the healthiness of the dog. Fecal examination was performed using the centrifuge sedimentation-flotation technique and present and eggs, larvae and (oo)cysts were recorded semi-quantitatively. The most common identified intestinal parasites were: Toxocara (40%), Hookworm type (20%), Giardia (18%), Isospora (12%), Trichuris (5%), Sarcocystis (3%) and Capillaria (2%). The frequency of Toxocara eggs found per dog over 9 months was (0=348, 1=65, 2=22, 3=8, 4=2, 5≤1). The average dog from the research population had less than 1 infection per year. In conclusion, this study found that when the current advice of preventive anthelminthic treatment of four times a year is executed, many dogs did not have a patent infection at the time of treatment. Future studies should focus on identification of risk groups of dogs to enable targeted treatment advice.