Page 1056 - Small Animal Internal Medicine, 6th Edition

1028 PART VIII Reproductive System Disorders

diagnostic accuracy. Strongyloides stercoralis may be demon- coronavirus, and rotavirus, whereas parvovirus (Feline Pan-
strated by either the Baermann flotation technique or obser- leukopenia), coronavirus, and retroviruses (FeLV, FIV) are
VetBooks.ir vation of larvae in fresh fecal smears. Giardia infections can important in young cats. Bacterial organisms responsible for
neonatal diarrhea can include Salmonella spp., Escherichia
be diagnosed by observation of motile trophozoites in fresh
fecal smears or by detection of cysts using a zinc sulfate fecal
bacter spp. Diagnosis in most patients is usually uncom-
flotation; however, a more recently developed fecal ELISA coli, Clostridium spp., Yersinia enterocolitica, and Campylo-
test that detects Giardia antigen is the preferred diagnostic plicated, and is based on typical clinical signs, serology, or
test. demonstration of virus in feces, or specialized fecal cultures
Parasitic infections also reach pathogenic levels in kittens for certain bacterial organisms. It is often best to run tests
in the first month of life. Coccidia infection, which may be for these disorders at the same time through the use of a
inapparent in adults, can cause severe diarrhea and malnu- “fecal diagnostics panel” now available at many commer-
trition, resulting in rapid weight loss, hypoglycemia, and cial laboratories. A single fecal sample is submitted to the
dehydration. Coccidia are highly contagious and survive in lab, and tests for each of these disorders are done at the
the environment despite extensive decontamination efforts. same time (commonly immunologic tests and PCR tests)
Coccidia infection is readily diagnosed by fecal floatation (see Chapter 27).
and should be considered in kittens that develop diarrhea in Several breeds of dogs have a reported genetic predilec-
this age range or older. Treatment is with sulfadimethoxine tion to small intestinal disease. Normally, the small bowel
(50 mg/kg PO first day, then 25 mg/kg PO every day for 5-20 appears sonographically as four distinct layers (Fig. 57.30, A,
days until asymptomatic and fecal flotation negative), which 57.30, B). The bowel lumen is hyperechoic, as gas and ingesta
is coccidiostatic, not coccidiocidal. Recovery from coccidia are compressed. The layer just outside the lumen is the
infection requires an intact immune response, so treatment mucosa; it is hypoechoic and normally the thickest appear-
failures can often be traced to concurrent immunosuppres- ing section. Outside the mucosa is the submucosa; it is
sive conditions such as malnutrition, overcrowding, and hyperechoic to the mucosa and about one third the thick-
poor hygiene. If coccidiosis is diagnosed in a group of cats, ness. The muscularis, the bowel muscle layer, is outside of
all of the animals should be treated. Ascariasis (round the submucosa and appears as a very thin hypoechoic black
worms) also becomes significant in this age group, and large line. Reactive mesenteric lymph node enlargement is
worm burdens can lead to malnutrition and poor growth. common in puppies (Fig. 57.30, C) An immunoproliferative
Because maternally acquired ascaridiasis is so common, enteropathy is seen in the Basenji breed, which is character-
all puppies and kittens should receive routine deworming ized by lymphangectasia, intermittent diarrhea, weight loss,
treatments with pyrantel pamoate (10 mg/kg orally, repeated hypoalbuminemia and hyperglobulinemia, and lymphoplas-
in 2 weeks), regardless of fecal test results. Control of many macytic mucosal infiltrates throughout the gastrointestinal
helminth infections can be easily accomplished by monthly tract. Histopathology is diagnostic; however, abdominal
administration of combined anthelmintic and heartworm ultrasonography can identify bowel in which disruption of
preventative, for example, ivermectin plus pyrantel pamoate. the normal layering has occurred. Chinese Sharpei dogs have
Treatment of Dipylidium infections must include adequate been identified with a lymphoplasmacytic-eosinophilic infil-
flea control as well as an appropriate anthelmintic such as trative enteropathy characterized by poor weight gain, weight
praziquantel. Coccidial infections are treated with sulfa- loss, or intermittent diarrhea episodes, with onset of signs
containing drugs such as sulfadimethoxine or trimethoprim typically between 2 to 6 months of age. Infiltrative enteropa-
sulfa; although very frequently diagnosed and treated in the thies can be characterized ultrasonographically as having
clinical setting, most canine coccidial infections are likely changes in the normal bowel wall layering.
self-limiting. Fenbendazole is the recommended treatment PSS are congenital malformations of the hepatic portal
for Giardia infection (50 mg/kg PO q24h for 3-7 days); venous drainage system and can have either a familial (i.e.,
although metronidazole is commonly used, it is proven less genetic) or random occurrence. Congenital PSS can be either
effective than fenbendazole and has greater potential for side intrahepatic or extrahepatic; breed predilections for extrahe-
effects in immature animals. A Giardia vaccine is also avail- patic shunts include Yorkshire Terrier, Maltese, Poodle, Min-
able, and it has been suggested that it may be effective in iature Schnauzer, Dachshund, Lhasa Apso, Pekingese, Pug,
clearing refractory infections; however vaccination against and Shih Tzu, whereas intrahepatic shunts are more com-
Giardia failed to decrease incidence of diarrhea associated monly identified in large breed dogs such as Golden Retriev-
with giardiasis in one field study (Payne et al., 2002). ers, German Shepherds, Irish Wolfhounds, Irish Setters, and
Diarrhea not associated with endoparasitism is not Samoyeds. PSS are uncommon in cats. Ultrasonography
uncommon in pediatric patients after weaning; overfeed- provides a rapid and noninvasive method for screening
ing with consequential bacterial overgrowth syndrome is the patients suspected to have congenital PSS. It is noninvasive
most common cause. Decreasing the amount fed, sometimes and requires no anesthesia, however diagnostic accuracy is
with a short course of antibiotics (amoxicillin), is effective. highly operator-dependent, and the PSS will be confirmed
Infectious agents associated with diarrhea in young dogs in only approximately 60% to 80% of cases. The liver may be
and cats are typically either bacterial or viral. Viral infec- small and difficult to image in patients with congenital PSS.
tions in dogs include canine parvovirus, canine distemper, Imaging the liver from the standard ventral approach can be