Page 516 - Small Animal Internal Medicine, 6th Edition

488 PART III Digestive System Disorders

involves controlling the intermediate hosts (i.e., fleas and lice the environment. The coccidia invade and destroy villous
for D. caninum). epithelial cells.
VetBooks.ir Public Health Concerns Clinical Features

Echinococcus spp. are a major human health hazard and an
important reason to use anticestode drugs in dogs. Diphyl- Infections with Cystoisospora are very common in puppies
and kittens and may be asymptomatic or may cause copious,
lobothrium spp. and Spirometra spp. can also cause signifi- watery diarrhea with or without blood. Rarely, a kitten or
cant human disease. puppy may lose enough blood to require a blood transfusion.

STRONGYLOIDIASIS Diagnosis
Coccidiosis is diagnosed by finding oocysts on fecal flotation
Etiology examination (see Fig. 31.4). Repeated fecal examinations
Strongyloides stercoralis principally affects puppies, especially may be necessary, and small numbers of oocysts do not
those in crowded conditions. These parasites produce motile ensure that the infestation is insignificant. Diagnosis can be
larvae that penetrate unbroken skin or mucosa; thus the confusing because Cystoisospora oocysts must be distin-
animal may be infested from its own feces even before the guished from Eimeria oocysts (these are “passing through”
larvae are evacuated from the colon. In this manner, animals after the dog was copraphagic) and giardial cysts. If a nec-
can quickly acquire large parasitic burdens. Most animals are ropsy is performed, multiple areas of the intestine should be
infested after being exposed to fresh feces containing motile sampled because the infection may be localized to one area.
larvae. Humane shelters and pet stores are likely sources for
infestation. Treatment
If coccidia are believed to be causing a problem, sulfadi-
Clinical Features methoxine or trimethoprim-sulfa should be administered
Infested animals may be asymptomatic, or they can have for 10 to 20 days (see Table 28.7). The sulfa drug does not
mucoid or hemorrhagic diarrhea and be systemically ill (e.g., eradicate the coccidia but inhibits it so that body defense
lethargy). Respiratory signs (i.e., verminous pneumonia) mechanisms can reestablish control. Amprolium, toltrazuril,
occur if parasites penetrate the lungs. and ponazuril have been reported to be effective, but these
are off label uses in the United States.
Diagnosis
S. stercoralis is diagnosed by finding larvae in fresh feces, Prognosis
either by direct fecal examination or by Baermann sedimen- The prognosis for recovery is usually good unless there are
tation. Strongyloides larvae must be differentiated from underlying problems that allowed the coccidia to become
Oslerus spp. larvae. The feces must be fresh because old feces pathogenic in the first place.
may contain hatched hookworm larvae, which resemble
those of Strongyloides spp. CRYPTOSPORIDIA

Treatment Etiology
Fenbendazole (used for 5 days instead of 3; see Table Cryptosporidium spp. may infect animals that ingest sporu-
28.7), thiabendazole, and ivermectin are effective anthel- lated oocysts. These oocysts originate from infested animals
mintics. This disease is a potential human health hazard but may be carried in water. Thin-walled oocysts are pro-
because larvae penetrate unbroken skin. Immunosup- duced, which can rupture in the intestine and produce auto-
pressed people are at risk for severe disease after being infection. The organism infests the brush border of small
infected. intestinal epithelial cells and causes diarrhea.

Prognosis Clinical Features
The prognosis is guarded in young animals with severe diar- Cryptosporidiosis is a potential cause of diarrhea in dogs and
rhea and/or pneumonia. cats, but determining cause and effect is often difficult
because it can be found in clinically normal patients. Dogs
Public Health Concerns with diarrhea due to cryptosporidiosis are usually younger
Strongyloides stercoralis is zoonotic, but dogs are rarely docu- than 6 months of age, but a similar age predilection has not
mented to be the cause of human infection. been recognized for cats.

COCCIDIOSIS Diagnosis
Diagnosis requires finding the oocysts by fecal flotation
Etiology examination, immunofluorescence assay (IFA), ELISA, or
Cystoisospora spp. are the coccidia infecting cats and dogs. PCR. C. parvum is the smallest of the coccidians and is easy
The pet is usually infested by ingesting infective oocysts from to miss on fecal examination. It is best to submit the feces to