Page 523 - Small Animal Internal Medicine, 6th Edition

CHAPTER 31 Disorders of the Intestinal Tract 495

appreciable weight loss). In cats hematochezia is the most Prognosis
common clinical sign, and diarrhea is the second most Prognosis is good if the patient is diagnosed before it is
VetBooks.ir common sign. Feline LPC may occur by itself or concur- sumptive treatment for “IBD” with glucocorticoids is associ-
cachexic and antibiotics are administered long enough. Pre-
rently with small bowel IBD, whereas canine large bowel IBD
ated with mortality.
seems to be infrequently associated with small bowel IBD.
Diagnosis
Diagnosis requires excluding other causes (e.g., parasites, PROTEIN-LOSING ENTEROPATHY
dietary-responsive diarrhea, fiber-responsive diarrhea, Clos-
tridial colitis, and fungal/algal colitis) plus demonstrating CAUSES OF PROTEIN-LOSING
colonic mucosal inflammation. In particular, Tritrichomonas ENTEROPATHY
must be eliminated in cats. Any intestinal disease producing sufficient inflammation,
infiltration, congestion, or bleeding can produce a PLE (or
Treatment gastropathy if it affects the stomach) (see Box 26.10). In dogs,
Antiinflammatory glucocorticoid (i.e., prednisolone) therapy lymphangiectasia and alimentary tract lymphoma seem to
is usually effective. Dogs sometimes benefit from sulfasala- be the most common causes in adult dogs, whereas hook-
zine, mesalamine, or olsalazine therapy. Feeding a fiber- worms and chronic intussusception appear to be more
supplemented diet may enhance therapeutic effectiveness. common in very young dogs. If IBD is responsible, it is
usually a very severe form. ARE has also been noted to cause
Prognosis PLE, which is reasonable since IBD may originate from ARE.
The prognosis for patients with colonic IBD tends to be Immunoproliferative enteritis of Basenjis, GI ulceration/
better than for small bowel IBD. erosion, and bleeding tumors may also produce PLE. Cats
have PLE less frequently than dogs, and the major cause is
GRANULOMATOUS/HISTIOCYTIC lymphoma although severe IBD can occasionally cause it.
ULCERATIVE COLITIS
INTESTINAL LYMPHANGIECTASIA
Etiology
This disease principally affects Boxers and French Bulldogs, Etiology
but other breeds can be affected. It is caused by adherent- Intestinal lymphangiectasia (IL) primarily affects dogs. Lym-
invasive E. coli and may reflect immune system idiosyncra- phatic obstruction causes dilation and rupture of intestinal
sies in the commonly affected breeds. lacteals with subsequent leakage of protein, lymphocytes,
and chylomicrons into the intestinal submucosa, lamina
Clinical Features propria, and lumen. Because these proteins may be digested
Affected animals initially often appear just like any other dog and resorbed, there must be sufficient loss so that the intes-
with chronic colitis (i.e., healthy except for the diarrhea ± tine’s ability to resorb the protein is exceeded. Rupture of
hematochezia). However, this disease tends to be progres- lymphatics in the intestinal wall or at the mesenteric border
sive; chronic cases can develop weight loss and hypoalbu- can produce lipogranulomas, which exacerbate lymphatic
minemia and eventually die. obstruction. A common misconception is that most of the
intestine must be affected, but many severely symptomatic
Diagnosis patients only have segmental disease (e.g., just jejunum or
Although colonoscopy is often delayed to see how patients just ileum affected). Most cases of canine IL are idiopathic.
with chronic colitis will respond to anthelmintic, dietary, and
antimicrobial therapeutic trials, early endoscopy should be Clinical Features
considered for Boxers and French Bulldogs with chronic Yorkshire Terriers, Soft-Coated Wheaten Terriers, and
large bowel signs. Histopathology is required for diagnosis. Lundehunds appear to be at higher risk than other breeds.
Finding PAS-positive macrophages in the mucosa (usually Soft-Coated Wheaten Terriers may have concomitant
the deeper mucosa) is diagnostic. protein-losing nephropathy. Diarrhea is inconsistent and
may not occur; low protein transudative ascites is the only
Treatment sign in a substantial number of dogs. These dogs can be
This is an antibiotic-responsive disease, but increased bacte- hypercoagulable; pulmonary thromboembolism occasion-
rial resistance to commonly used antibiotics is making it ally occurs.
difficult to treat. Therefore colonic mucosal biopsy for culture
is strongly recommended. It is critical to treat for at least 8 Diagnosis
weeks (even if the patient seems normal by week 2). Stopping Clinical pathologic evaluation is not diagnostic. Severe
antibiotics before 8 weeks has been associated with recur- hypoalbuminemia (serum albumin < 2.0 g/dL) and hypo-
rence of infection and resistance to previously used cholesterolemia are expected, but panhypoproteinemia
antibiotics. is inconsistent. Lymphopenia is inconsistent. Finding