Infectious Agent Prevalence Rates in Dogs with Diarrhea and Response to Administration of Fenbendazole or Nitazoxanide
Diarrhea associated with infectious agents is common in dogs housed in animal shelters. Empirical treatment is often prescribed because of financial limitations. The objectives of this study were to determine infectious agent prevalence rates in dogs with diarrhea and response rates to fenbendazole or nitazoxanide, drugs with a broad-spectrum against some common parasites.
Feces from dogs with diarrhea but no vomiting that were housed in two animal shelters were assayed by fecal flotation using zinc sulfate centrifugation, Giardia spp. and Cryptosporidium spp. by IFA (Meridian Laboratories, Cincinnati, Ohio), aerobic fecal culture, and electron microscopy. Dogs were randomly administered fenbendazole at 50 mg/kg, PO, daily for five days or nitazoxanide at 25 mg/kg, PO, twice daily for five days and a fecal score determined daily.
Diarrhea resolved in 7 of the 10 dogs initially administered fenbendazole; 4 of these dogs were positive for Giardia and the remaining 3 dogs were negative in all tests. The 3 dogs that continued to have diarrhea on day 6 were from the Giardia positive group; diarrhea resolved in the 2 dogs that were then administered a complete course of nitazoxanide. Diarrhea resolved in 7 of the 8 dogs initially administered nitazoxanide. Giardia alone (3 dogs), Giardia, Isospora, Cryptosporidium, and Salmonella spp. (1 dog), Giardia and Cryptosporidium (1 dog), or Cryptosporidium alone (1 dog) were detected in 6 of these 7 dogs; the seventh dog had no detectable infectious agent. The nitazoxanide treated dog with diarrhea on day 6 was normal after administration of fenbendazole; no infectious agents were detected.
Overall, there were no differences between apparent response rates to fenbendazole or nitazoxanide and both drugs were well tolerated. Results of this study suggest that the nitazoxanide protocol utilized may have activity against Giardia spp. and Cryptosporidium spp. infections in dogs.