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Granulomatous Enteritis/Colitis 395

tick-borne disease, should not be used as • Tick prevention remains important in SUGGESTED READING
blood donors. previously/subclinically infected animals to Little SE: Ehrlichiosis and anaplasmosis in dogs
VetBooks.ir Client Education may result in more severe clinical illness AUTHOR: A. Rick Alleman, DVM, PhD Diseases and Disorders
avoid co-infections with other agents that
and cats. Vet Clin North Am Small Anim Pract
40:1121-1140, 2010.
• There is essentially no risk of contracting
and to prevent transfer of pathogens from
these infections directly from a pet. However,
to feed on infected dogs has the potential
people share the same environment with their subclinical carriers to ticks. Allowing ticks EDITOR: Joseph Taboada, DVM, DACVIM
pets, and they should also make efforts to to increase the pathogen burden in the tick
reduce the risk of tick exposure to prevent population.
tick-transmitted diseases for themselves and
family members.

Granulomatous Enteritis/Colitis Bonus Material Client Education
Sheet
Online
Clinical Presentation
BASIC INFORMATION lymphocytic plasmacytic colitis seen in
DISEASE FORMS/SUBTYPES other breeds
Definition • GC: associated with AIEC and character- ○ Additional evidence suggests GC
Uncommon cause of persistent (>3 weeks) ized by mucosal infiltration with periodic may not be IBD but rather a unique
signs of small-intestinal or, more often, colonic acid–Schiff (PAS) stain–positive macrophages and specific form of infectious colitis
inflammation associated with mucosal infiltra- • Other infectious causes of granulomatous (AIEC).
tion of macrophages enteritis • Granulomatous enteritis
• In the colon, the most common cause is ○ Heterobilharzia americana ○ Mucosal disease caused by fungi, parasites,
mucosal invasive Escherichia coli infection ○ Histoplasma capsulatum (p. 476) oomycetes, or algae
(i.e., adherent/invasive E. coli [AIEC]). ○ Pythium insidiosum (p. 860) ○ Can involve large and/or small bowel
Affected animals have large-bowel diarrhea ○ Prototheca spp ○ Dissemination to other organs is common
and systemic signs (fever, anorexia, weight with systemic mycotic and algal infections.
loss). HISTORY, CHIEF COMPLAINT
• Other types of infections (e.g., algal, fungal, • GC: persistent large-bowel diarrhea, tenesmus DIAGNOSIS
parasitic) can cause granulomatous inflam- (straining to defecate), increased frequency
mation in small or large bowel or in both of defecation, mucoid feces, and fresh blood Diagnostic Overview
segments. (p. 1215) The diagnosis may be suspected based on
• Cachexia, anorexia, and weight loss are history of signs of chronic colitis and weight
Synonyms common with GC, in sharp contrast to loss, prompting endoscopic or full-thickness
Boxer colitis refers to the old inflammatory bowel other causes of colonic inflammation. intestinal biopsies (definitive confirmation).
disease (IBD) variant; granulomatous colitis (GC) • Infectious causes of GC can be associated
is the contemporary term describing E. coli with small-intestinal gastrointestinal (GI) Differential Diagnosis
infection in boxers and French bulldogs. signs (e.g., vomiting, melena) or other organ Other differential diagnoses: severe colonic IBD,
signs (e.g., blindness, cutaneous lesions, neoplasia (p. 604)
Epidemiology central nervous system signs).
SPECIES, AGE, SEX Initial Database
• Granulomatous enteritis is much more PHYSICAL EXAM FINDINGS • CBC, serum biochemistry, and urinalysis:
common in dogs than cats. • Colonic mucosa may feel thickened or evaluate involvement of diverse organ
• GC seen with AIEC appears to be most cobblestone-like on rectal palpation. Fresh systems.
prevalent in young male dogs. blood or mucus may be recognized after • Fecal flotation and direct examination for
palpation. GI parasites, including Heterobilharzia
GENETICS, BREED PREDISPOSITION • Fever, cachexia, weight loss, and peripheral/ • Exfoliative cytology (e.g., rectal scrape [p.
• Predisposition in boxers and French bulldogs mesenteric lymphadenomegaly are observed 1157]) is easy and inexpensive and can some-
is associated with defective clearance of with infectious causes. times confirm infection with Histoplasma or,
intracellular bacteria and GC. • Dogs with AIEC may not have mesenteric less often, with Prototheca spp or Pythium
• Large-breed dogs are more commonly lymphadenomegaly. in endemic regions.
affected with systemic fungal infections. • Other examination abnormalities can be • Urinary Histoplasma antigen (highly sensi-
• Hunting/sporting dogs more often infected related to pathogen infection of other tive and specific assay [p. 1365]): simple
with schistosomiasis (i.e., Heterobilharzia) tissues (e.g., uveitis, paresis, head tilt, ataxia noninvasive test for GI histoplasmosis
and pythiosis. with Prototheca spp infection; respiratory • Abdominal imaging (survey radiographs,
• German shepherd, collies, and boxers over- effort, peripheral lymphadenomegaly with contrast radiography, and/or ultrasonog-
represented for protothecosis histoplasmosis). raphy): diffuse colonic wall thickening,
loss of wall layering, and/or mesenteric
GEOGRAPHY AND SEASONALITY Etiology and Pathophysiology lymphadenomegaly indicative of infiltra-
Geographic or seasonal influence important for • GC tive mural disease, but these changes
several fungal, algal, and parasitic infections ○ Chronic enteropathy of boxers and are not specific for any specific cause of
(see specific chapters for detail) French bulldogs, much less common than colitis.

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