W A A V P guideline for evaluating the efficacy of anticoccidials in mammals (pigs, dogs, cattle, sheep).

This guideline is intended as an aid in the design, implementation and interpretation of studies for the assessment of drug efficacy against Eimeria in cattle and sheep, Cystoisospora in pigs and dogs, and Cryptosporidium in cattle. It deals with the most important aspects of how to conduct both experimental and field studies for dose determination, dose confirmation and assessment of field effectiveness. Also, guidance on the selection of animals, diagnostic techniques, statistical evaluation and methods for the preparation, maintenance and use of parasites is provided. The specific management conditions that may influence the course of natural infections and consequently determine treatment schemes are mentioned and suggestions for best practice in sampling and evaluation of data prior to conducting of efficacy studies are given. The guideline is also intended to assist investigators in carrying out specific studies, provide relevant information for registration authorities involved in the decision-making process, assist in the approval of anticoccidial drugs in the target species, and facilitate the world-wide adoption of standard procedures. Although currently not implemented, issues of drug resistance testing and alternative methods for drug testing are also discussed as future issues in drug testing against mammalian coccidia.

Treatment of naturally occurring, asymptomatic Giardia sp. in dogs with Drontal Plus flavour tablets.

The administration of three consecutive daily doses of the recommended 1x dose of Drontal Plus flavour tablets (Bayer) was examined for its effect on Giardia sp. cyst-shedding in 7 treated and 7 untreated random-source dogs. Dogs were treated on study days 0, 1 and 2. Cysts were quantified using direct immunofluorescent labelling on days -7, -5, -3 and -2, and daily from day 1 through 11. Three treated dogs never shed cysts again during the study, one shed again only on day 4, and the remaining three dogs started to shed again on days 8, 9 and 11. The mean numbers of cysts per gramme in the faeces of the treated dogs were significantly reduced (t-tests using log(10)(counts)) on days 1 and 2 (geometric means: controls = 447,000; treated = 1,050; p = 0.004) and days 3 to 8 (geometric means: controls = 23,400; treated 5.0; p < 0.001). Four controls that had been consistently positive, changed to negative status on day 11, and thus, on the final day of the trial, there were only three positive control and three positive treated dogs. Three consecutive days of treatment with Drontal Plus flavour tablets halted Giardia sp. cyst shedding by dogs. But starting six days post third treatment, some of the dogs started shedding cysts again. Since the prepatent period of Giardia sp. can be as short as 4 days, shedding of Giardia sp. cysts 6 days after treatment could be caused by a reinfection.

Cystoisospora canis Nemeséri, 1959 (syn. Isospora canis), infections in dogs: clinical signs, pathogenesis, and reproducible clinical disease in beagle dogs fed oocysts.

Canine intestinal coccidiosis is a cause of diarrhea in young dogs and dogs that are immunocompromised. Reports in the literature indicate that experimental reproduction of clinical coccidiosis with Cystoisospora canis (syn. Isospora canis) is difficult, and few studies have been done with C. canis. Experimental oral infections were attempted in 22, 6- to 8-wk-old female beagles with 5 x 10(4) (n = 2) or 1 x 10(5) (n = 20) sporulated C. canis oocysts. Diarrhea was observed in all inoculated dogs. Diarrhea began 2-3 days before oocyst excretion. Five of the 22 dogs were given an anticoccidial (sulfadimethoxine) because of their clinical signs. The mean prepatent period was 9.8 days (range, 9-11 days, n = 22 dogs), and the patent period was 8.9 days (range, 7-18 days, n = 20 dogs). Two dogs exhibiting clinical coccidiosis were examined at necropsy 10 days after infection. Developmental stages of C. canis were present in cells in the lamina propria throughout the entire small intestine in both dogs. Microscopic lesions observed in both of these dogs were villous atrophy, dilation of lacteals, and hyperplasia of lymph nodes in Peyer's patches. Results of bacterial and viral examinations of these 2 dogs were negative, indicating that intestinal coccidiosis was the cause of the diarrhea. Our study indicates that C. canis can be a primary cause of diarrhea in young dogs.