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Protozoan Diseases in Dogs

Coccidiosis continued...

Coccidiosis is a particular problem in neonatal puppies who are overstressed by filth, crowding, chilling, and poor sanitation. Puppies acquire the infection from contaminated premises or from their mother, if she is a carrier. When kennel sanitation is poor, puppies reinfect themselves from their own feces. An outbreak of coccidial diarrhea can also occur in association with roundworm infestation or the trauma of shipping. Coccidiosis is an opportunist. Always look for another precipitating cause.

Five to seven days after ingesting oocytes, infective cysts appear in the feces. The first sign is mild diarrhea that progresses until the feces become mucuslike and tinged with blood. The diarrhea is accompanied by loss of appetite, weakness, and dehydration. Dogs who recover become carriers. Infected dogs and carriers can be identified by finding oocysts in a microscopic slide of fresh stool.

Treatment: Treatment in adult dogs usually is not necessary, due to the mild nature of the diarrhea. Puppies with severe diarrhea may need to be hospitalized for fluid replacement. Antibiotics that are effective against coccidiosis include sulfadimethoxine, trimethoprin-sulfa, furazolidone, and amprolium.

Prevention: Known carriers should be isolated and treated. Wash down infected quarters daily with boiling water and/or dilute bleach or chlorhexidine solution to destroy oocysts. Coccidiosis can be prevented by maintaining clean quarters and providing an appropriate whelping environment.


This disease is caused by a protozoan of the giardia species. Dogs acquire the infection by drinking water from streams and other sources that are contaminated with infective oocysts.

Most infections in adult dogs are subclinical. Young dogs can develop a diarrhea syndrome characterized by the passage of large volumes of foul-smelling, watery, or “cow-pie” stools. The diarrhea maybe acute or chronic, intermittent or persistent, and may be accompanied by weight loss.

Diagnosis is made by finding the protozoan or its characteristics oocysts in saline smears of fresh stool. Smears from rectal swabs are satisfactory. A negative smear does not exclude giardia, as oocysts are shed only intermittently. Three negative fecal smears collected at least two days apart should be obtained before the diagnosis is excluded. Serology tests (ELISA, IFA) are now available.

Treatment: Giardiasis responds well to Flagyl (metronidazole). Because Flagyl causes developmental malformations in the fetus, it should not be administered to pregnant bitches. Other effective drugs are available. There is now a vaccine available for giardiasis, but this is rarely recommended because the disease is usually mild and responds well to treatment.

WebMD Veterinary Reference from "Dog Owner's Home Veterinary Handbook"

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