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Whipworm Infection 1049

hypoadrenocorticism-like illness related to • Histoplasmosis (large bowel) Possible Complications
whipworm infection. • Neoplasia (carcinoma, lymphoma) Possible adverse reaction with milbemycin
VetBooks.ir Etiology and Pathophysiology • Protein-losing enteropathy Recommended Monitoring Diseases and Disorders
oxime in heartworm-positive dogs
• Hypoadrenocorticism
• Intussusception
• Direct life cycle begins with ingestion of
embryonated eggs.
• Ova hatch in small intestine, and larvae Initial Database Frequent fecal exams for recurrent infections
burrow into mucosa for a 1-week period. • Serial fecal flotations to identify character- PROGNOSIS & OUTCOME
• Young adults emerge, relocate to the cecum/ istic eggs (shed intermittently, often in low
colon, and deeply embed the threadlike head numbers). Dense flotation solution (specific • Excellent with appropriate therapy
(the whip) into the mucosa to feed on blood gravity > 1.200, such as for sugar or zinc • Reinfection likely as a result of environmental
and tissue fluids. sulfate) is required. contamination with resistant ova.
• A 3-month prepatent period (range, 70-107 • CBC: occasional eosinophilia and mild to
days) precedes appearance of ova in feces. moderate anemia PEARLS & CONSIDERATIONS
• Host response varies from mild localized • Serum biochemistry profile: hyponatremia,
inflammation to mucosal hyperplasia to hyperkalemia, azotemia, hypoalbuminemia, Comments
granulomatous inflammation, resulting in metabolic acidosis are occasionally seen. • T. vulpis is a common cause of large-bowel
variable degrees of gastrointestinal (GI) • Rectal cytologic exam (p. 1157): insensitive diarrhea in dogs in the eastern and southern
clinical signs. for ova but may demonstrate clostridial United States.
• Affected animals can develop large-bowel spores, inflammatory cells, neoplastic cells, • Empirical treatment is recommended in
diarrhea that ranges in severity from intermit- or fungal (Histoplasma) organisms uncomplicated cases before pursuing a
tent soft stool to severe, copious mucoid or • Measuring basal cortisol concentration and lengthy, expensive diagnostic workup.
hemorrhagic diarrhea with tenesmus. following with ACTH response testing if • The potential for hypoadrenocorticism-like
• Whipworm-related enteritis may produce basal cortisol is < 2 mcg/dL is recommended findings with trichuriasis must be recognized.
biochemical changes falsely suggesting to rule out hypoadrenocorticism in dogs with • Seizures have been reported in dogs with
hypoadrenocorticism. hyponatremia and hyperkalemia (pp. 572 trichuriasis, most likely associated with
○ Hyponatremia: due to concurrent and 1300). profound hyponatremia.
diarrhea-associated sodium loss, water
consumption, and anorexia Advanced or Confirmatory Testing Prevention
○ Hyperkalemia: due to metabolic acidosis, An ELISA is available for coproantigen detec- • Monthly administration of antiparasite
decreased kaliuresis from reduced flow in tion and offers a more cost-effective alternative products incorporating milbemycin oxime as
the distal renal tubules, and/or laboratory than finding on colonoscopy. a component is ideal in endemic areas and for
+
artifact (normal platelet K release when chronic infections due to contaminated envi-
clotting) TREATMENT ronments. These combination antiparasite
○ Primary enteritis-associated hyponatremia medications often have the advantage of also
and hyperkalemia are not caused by Treatment Overview preventing infection with Dirofilaria immitis
aldosterone deficiency (hypoadrenocorti- Therapeutic goal is elimination of parasites from and other endoparasites and ectoparasites.
cism), as confirmed by normal ACTH the GI tract. Three treatments are needed to • Moxidectin-containing antiparasite com-
stimulation test results. completely eliminate parasites due to prepatency binations can prevent T. vulpis, Dirofilaria
• Whipworm infection has been suggested as period. immitis, and endoparasite and ectoparasite
a cause of cecocolic intussusception. infections.
Acute General Treatment • In field trials, the cyclooctadepsipeptide
DIAGNOSIS • Anthelmintic therapy emodepside has been effective against adult
○ Fenbendazole 50 mg/kg PO q 24h × 3 and immature forms of T. vulpis and other
Diagnostic Overview days is preferred. intestinal nematodes and cestodes.
Whipworm infection should be suspected in ○ Febantel 10 mg/kg PO q 24h × 3 days
any dog with clinical signs of chronic colitis. is an acceptable alternative. Technician Tips
Multiple fecal analyses should be pursued but ○ Drontal Plus (contains febantel) is also Characteristic microscopic appearance is large,
may yield negative results despite infection appropriate. ovoid, golden brown eggs with an operculum
(intermittent shedding). Monitoring the • Current recommendations are to repeat on each end. Eggs are heavy but can be found
initial response to two courses of anthelminthic treatment at 3 weeks and 3 months due to on fecal float using dense flotation solution
treatment (2 weeks apart), even with negative the long prepatent period and possibility of (>1.020).
fecal analysis results, is an important step before larval resistance.
pursuing costly diagnostics for any patient • Supportive care (e.g., intravenous fluids) Client Education
with solitary signs of intermittent large-bowel for electrolyte abnormalities and azotemia Environmental contamination is the source for
diarrhea. in severe cases reinfection and is difficult to eliminate. Monthly
• Typhlectomy for granulomatous typhlitis or prophylaxis is recommended after treatment.
Differential Diagnosis cecocolic intussusception (rare)
• Capillaria spp infection (ova appear similar, SUGGESTED READING
but Capillaria spp do not cause enteritis) Chronic Treatment Hall EJ: Diseases of the large intestine. In Ettinger
• Dietary-responsive large-bowel diarrhea Milbemycin oxime is an effective preventive SJ, et al, editors: Textbook of veterinary internal
• Clostridium perfringens enterotoxicosis for chronic, recurrent trichuriasis. medicine, ed 8, St. Louis, 2017, Saunders, pp
• Inflammatory bowel disease (large intestine) 1565-1592.
• Chronic colitis (e.g., histiocytic ulcerative Drug Interactions AUTHOR: Saralyn Smith-Carr, DVM, PhD, DACVIM
colitis) Dogs should be evaluated for heartworm EDITOR: Rance K. Sellon, DVM, PhD, DACVIM
• Eosinophilic colitis infection before instituting milbemycin oxime.

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