Page 435 - Cote clinical veterinary advisor dogs and cats 4th

Colitis, Chronic 191

may cause chronic colitis if not detected • Hematochezia indicates severe mucosal colonic disease because of the obstructive
disruption of the distal colon and rectum.
early. Some helminth parasites (Trichuris spp, • Parasites, including helminths and protozoa: effect of air in the colonic lumen on the
VetBooks.ir spp, potentially zoonotic; Tritrichomonas spp, T. vulpis (dogs), T. foetus (cats), Giardia Advanced or Confirmatory Testing Diseases and Disorders
ultrasound beam and because colonic wall
potentially contagious) and protozoa (Giardia
thickness is difficult to standardize.
lamblia (dogs, cats)
potentially contagious) also may cause persistent
• Dietary causes: incriminating antigens or
signs of colitis in pets.
dietary ingredients (nonimmunologic) • Colonoscopy with procurement of multiple
GEOGRAPHY AND SEASONALITY • Specific bacterial pathogens: cause colonic mucosal biopsy specimens may be required
Midwestern and southern United States for inflammation by invasion or enterotoxin to diagnose infiltrative diseases. Collection
GI histoplasmosis production. Adherent/invasive E. coli (AIEC) of biopsy specimens from all colonic regions
is a recently recognized enteropathogen (full colonoscopy) will allow neoplasia to be
ASSOCIATED DISORDERS associated with GC. ruled out and differentiation between the
Colonic motility disorders (e.g., irri- • Infiltrative mucosal disorders: benign, different types of colonic inflammation.
table bowel syndrome in dogs and colonic malignant, or infectious (e.g., fungal) • Fluorescence in situ hybridization (FISH)
constipation/obstipation in cats) may mimic performed on colonic biopsy samples from
mucosal inflammation and cause signs of DIAGNOSIS dogs with GC confirms the presence of
large-bowel diarrhea with tenesmus. These AIEC.
diseases are due to functional disturbances Diagnostic Overview • Urine antigen testing for histoplasmosis (p.
in colonic motility and have no significant Diagnoses of many causes of chronic colitis 1365)
contribution from inflammatory/structural will require histologic evaluation of mucosal • Colonic biopsies should not be obtained by
disease. biopsy specimens. laparotomy because the bacterial content
of the colon and attendant risk of bacterial
Clinical Presentation Differential Diagnosis peritonitis after biopsy of a diseased colon are
DISEASE FORMS/SUBTYPES • Specific causes: see Etiology and Pathophysi- markedly greater than with small intestinal
• Diet-responsive disorders (p. 347): includes ology above. biopsies.
food intolerance (nonimmunologically medi- • Occasionally, patients with rectal diseases
ated) and dietary sensitivity (immunologically (e.g., perineal hernia, perianal fistula, TREATMENT
mediated). Food-responsive causes of GI diverticula, rectal polyps or masses) will
signs, including large-bowel diarrhea, are present with signs of large-bowel disease. Treatment Overview
common in dogs and cats. These are generally distinguished by digital Treatment is based on the specific definitive
• Infectious disorders: includes selected examination and careful inspection; normal diagnosis because empirical therapies are often
nematode/protozoal parasites, bacteria, and perineal and rectal structure on examination inadequate or deleterious (e.g., use of gluco-
fungal organisms (especially GI histoplasmo- more strongly suggests large-bowel disease corticoids in animals with GI histoplasmosis).
sis). T. foetus may cause chronic intermittent in such cases.
colitis in young cats. • Colonic motility disorders can be mistaken Chronic Treatment
• Infiltrative mucosal diseases: includes fungal, for colitis, but motility disorders are not • Treatment for suspected nematode and
idiopathic benign (e.g., IBD), and malignant associated with inflammation. protozoan parasites is often warranted before
(e.g., mucosal neoplasia) diseases completing expensive or invasive diagnostic
Initial Database testing, even if fecal exams are negative for
HISTORY, CHIEF COMPLAINT • Physical examination: abdominal palpation parasites. Use appropriate broad-spectrum
Persistent large-bowel diarrhea, which is char- and digital rectal examination, with collection anthelmintics or antiprotozoal (e.g., fenben-
acterized by tenesmus (straining to defecate), of feces dazole 50 mg/kg PO q 24h for 3-5 days)
increased frequency of defecation, mucoid feces, • Fecal examination for nematode and pro- medications. Confirm efficacy of therapy
and fresh blood (p. 1215). Some disorders (e.g., tozoal parasites. Fecal flotations and fecal with repeat follow-up fecal examinations
IBD, GI histoplasmosis, GI lymphoma) may smears should be performed. Multiple (three) or, if no parasites were identified, response
affect the small intestine as well, causing mixed zinc sulfate flotation tests using fresh feces to therapy.
large- and small-bowel signs. may be required for identification of Giardia • Feed an appropriate diet to animals with
spp trophozoites (p. 386). dietary-responsive disorders and IBD.
PHYSICAL EXAM FINDINGS ○ Commercial ELISA kits are also sensitive This may range from a hypoallergenic/
• The animal is often well fleshed without for the detection of Giardia antigen. hydrolysate diet, to a highly digestible diet,
systemic signs (e.g., unthriftiness, weight • Rectal cytology may demonstrate evidence or to a homemade diet. Reduction in the
loss) of illness unless the small bowel is also of bacterial pathogens (e.g., vegetative spores quantity of dietary antigens will assist in
affected. Fungal disease, severe IBD, and of Clostridia) or increased numbers of fecal reducing mucosal inflammation with these
colorectal neoplasia may cause weight loss, leukocytes indicative of mucosal inflamma- disorders. Other animals with colitis, but
fever, alterations in appetite, and peripheral/ tion. Exfoliative cytology (e.g., rectal scrape not requiring a specific antigen-restricted
mesenteric lymphadenopathy. using a uterine curette or a curette of the diet, will benefit from being fed a low-fat,
• Rectal examination: evaluate the character of same type used for bone graft harvesting [p. fiber-enriched commercial ration.
the feces, obtain fecal samples for parasitic 1157]) is also a useful tool for confirming the • Avoid all treats and supplements containing
examination, procure exfoliative cytologic presence of Histoplasma organisms contained protein or flavors during the dietary trial
specimens, and evaluate the rectum for within colonic macrophages. period.
mucosal abnormalities, possible mass lesions, • Polymerase chain reaction (PCR) for detec- • Use diets with added soluble or mixed fiber,
and sublumbar lymphadenomegaly. tion of T. foetus infection (p. 997) or add small to moderate amounts of soluble
• Abdominal imaging (survey radiographs, fiber to the diet to reduce tenesmus and
Etiology and Pathophysiology pneumocolonography, ultrasonography) may facilitate colonic epithelial repair.
• Large-bowel diarrhea is characterized by identify fecal impaction, mass lesions, bowel • Use antibiotics only in animals with con-
increased amounts of mucus because of the wall thickening, and/or evidence of significant firmed bacterial causes (e.g., colonization
large numbers of mucus-secreting goblet cells mesenteric lymphadenomegaly. Generally, with enteropathogenic bacteria) of clinical
in the colon. ultrasonography is a poor screening tool for signs. Antimicrobials used in this fashion are

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