Q. We have two 19-week-old Miniature Pinschers. They keep getting a parasite that causes blood in the stool and diarrhea. They have both received medicine from the vet several times, and they just continue to get it back. We’ve cleaned the yard to prevent the problem, but it doesn't seem to be working. Do you have any suggestions that might help?
A. Your two Min Pins are likely infected with Giardia, a nasty intestinal parasite that lives in standing water. Dogs often drink from rain puddles, streams or toilet water, where they can become infected with this parasite.
At 19 weeks of age, your puppies' immune systems have not yet geared up enough to eliminate the parasite, so you need to rely on medication. As soon as a round of medication is finished, your dogs can become re-infected by drinking more outside water. Interestingly, some city water has been found to contain Giardia. Most people are resistant to the effects of Giardia at low doses, but it’s not pleasant to consider their presence in your drinking supply, or in your intestines.
Although metronidazole used to be the treatment of choice, newer research indicates that many of these parasites are not affected by metronidazole. A better choice is fenbendazole. Ask your veterinarian about using it.
Eventually your dogs will develop immunity to Giardia, at least at low doses, but monitor the water they are drinking to minimize risk of re-infection. Although dogs don’t become infected with Giardia from stool droppings in the yard, it’s a good idea to keep your yard as clean as possible to avoid infection with other equally unhealthy parasites, such as roundworms and hookworms.