Protozoan Diseases in Dogs
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
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.