Many species of coccidia infect the intestinal tract
of cats and dogs. All species appear to be host-specific. Cats have
species of Isospora, Besnoitia, Toxoplasma, Hammondia, and Sarcocystis. Dogs have species of Isospora, Hammondia, and Sarcocystis. Neither dogs nor cats have Eimeria.
Hammondia has an obligatory 2-host
life cycle with cats or dogs as final hosts and rodents or ruminants as
intermediate hosts, respectively.
Hammondia oocysts are indistinguishable from those of
Toxoplasma and
Besnoitia but are nonpathogenic in either host.
The most common coccidia of cats and dogs are
Isospora. Some
Isospora spp
of cats and dogs can facultatively infect other mammals and produce in
various organs an encysted form that is infective for the cat or dog.
Two species infect cats:
I felis and
I rivolta; both can be identified easily by oocyst size and shape. Almost every cat eventually becomes infected with
I felis. Four species infect dogs:
I canis,
I ohioensis,
I burrowsi, and
I neorivolta. In dogs, only
I canis can be identified by the oocyst structure; the other 3
Isospora overlap in dimensions and can be differentiated only by endogenous developmental characteristics.
Clinical coccidiosis, although not common, has been
reported in kittens and puppies. In kittens, it is seen primarily during
weaning stress. The most common clinical signs in severe cases are
diarrhea (sometimes bloody), weight loss, and dehydration. Usually,
coccidiosis is associated with other infectious agents,
immunosuppression, or stress.
Treatment may be unnecessary in cats because they
usually spontaneously eliminate the infection. In clinically affected
cats, trimethoprim-sulfonamide (30–60 mg/kg/day for 6 days) can be used.
In kennel conditions when the need for prophylaxis
might be predicted, amprolium is said to be effective, although it is
not approved for use in dogs. In severe cases, in addition to supportive
fluid therapy, sulfonamides such as sulfadimethoxine (50 mg/kg the
first day and 25 mg/kg/day for 2–3 wk thereafter) can be used.
Sanitation is important, especially in catteries and kennels, or where
large numbers of animals are housed. Feces should be removed frequently.
Fecal contamination of feed and water should be prevented. Runs, cages,
and utensils should be disinfected daily. Raw meat should not be fed.
Insect control should be established.