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480.e2 Hookworm Infection

Hookworm Infection Client Education
Sheet
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BASIC INFORMATION
• Melena
• Diarrhea • Feline leukemia virus infection (kittens)
• GI ulceration
Definition • Ova may be found incidentally on fecal exam. • GI neoplasia (older animals)
Infection with bloodsucking nematode parasites • Hemolytic anemia (any cause)
of dogs and cats that colonize the gastrointestinal PHYSICAL EXAM FINDINGS • Anemia due to ectoparasites (e.g., fleas,
(GI) tract and cause blood loss anemia • Pale mucous membranes are the hallmark ticks)
due to the blood-sucking activity of adult
Epidemiology hookworms causing blood loss anemia. Initial Database
SPECIES, AGE, SEX • Poor body condition and haircoat Fecal flotation: diagnostic test of choice:
• Cats: Ancylostoma tubaeforme, Ancylostoma • Melena on rectal exam • Eggs of Ancylostoma species and U. steno-
braziliense, Uncinaria stenocephala (rare) • Heart murmur due to anemia (systolic, cephala appear similar (eggs of U. stenocephala
• Dogs: Ancylostoma caninum; less commonly left-sided, soft) are slightly larger). Characteristic hookworm
U. stenocephala, A. braziliense • Tachycardia, tachypnea, weakness, or ova are ellipsoidal and contain an eight-cell
• Young animals of both species are primarily obtundation if in hemorrhagic shock morula.
affected. • Clinical signs vary based on degree of blood • Highly sensitive fecal antigen testing has
loss and chronicity of parasitism. recently become available as an alternative
RISK FACTORS • Physical exam may be normal if worm burden to fecal flotation.
Small body size (smaller blood volumes of is low (typical in adult animals).
puppies and kittens) increases risk for dispro- Advanced or Confirmatory Testing
portionately greater anemia with high worm Etiology and Pathophysiology CBC:
burdens. Puppies born to bitches in stressful • Hookworms attach to the small-intestinal • Regenerative anemia (most cases)
and crowded environments are at increased risk, mucosa. Host blood travels through hook- • Nonregenerative anemia with microcytic
especially at 2-8 weeks of age. worm gut; attached worms essentially mimic hypochromic red cells may occur second-
open blood vessels, causing persistent GI ary to chronic blood loss and subsequent
CONTAGION AND ZOONOSIS blood loss. The buccal cavity of hookworms iron deficiency, especially likely in young
• Contagion: arrested larvae in the female naturally secretes a potent anticoagulant, and animals.
dog become reactivated during pregnancy previous attachment sites continue to bleed • Eosinophilia
and migrate to the placenta and mammary after worm detachment/reattachment. • Thrombocytosis
glands, where they are transmitted to pups. • A. caninum consumes more of the host’s Serum biochemistry profile:
No similar transplacental or transmammary blood than other hookworms. U. stenocephala • Hypoproteinemia/hypoalbuminemia
transmission of A. tubaeforme in the cat rarely causes clinical disease or significant • Hyponatremia/hypochloremia in polydipsic
• Zoonosis: A. braziliense and less commonly A. anemia. animals
caninum can cause cutaneous larval migrans • Life cycles of hookworm species are similar. Urinalysis: generally unremarkable
in humans. Infective larvae penetrate and Prepatent periods (incubation period, from
migrate through the skin, causing intensely the time of ingestion to the appearance of TREATMENT
pruritic elevated tracts. ova in feces) ≈12-28 days. Inoculation occurs
through oral ingestion or skin penetration Treatment Overview
GEOGRAPHY AND SEASONALITY from infective third-stage larvae in the envi- Rapid eradication is important in affected
• A. tubaeforme: worldwide ronment or transmammary or transplacental puppies and kittens (anthelmintics). Severe
• A. caninum: worldwide subtropical and transmission (puppies). cases may require transfusion.
temperate regions ○ Oral: swallowed infective third-stage larvae
• A. braziliense: tropical and subtropical penetrate stomach and intestinal wall, Acute General Treatment
climates in North and South America, Africa; where they become arrested in submucosa • Severe anemia ± weak, depressed patient
near coastlines or other tissues, are reactivated, and return warrants transfusion with blood products
• U. stenocephala: temperate to cooler climates, to intestine to attach to mucosa. (p. 1169)
North and Central America, Europe, Asia ○ Skin: third-stage larvae penetrate skin, • Iron supplementation may be required due
• Eggs develop into infective third-stage larvae migrate through lungs and up trachea, to GI blood loss, especially in juveniles
only above 15°C (59°F), and infection occurs are swallowed, and ultimately attach to (relatively iron deficient).
primarily in warmer months in temperate intestinal wall. ○ For severe iron-deficiency anemia, iron
regions. dextran 10-20 mg/kg IM once (dogs) or
DIAGNOSIS 50 mg/CAT IM once, followed by oral
ASSOCIATED DISORDERS supplementation
Co-infection with other nematodes (particularly Diagnostic Overview ○ Ferrous sulfate 100-300 mg/DOG PO
Toxocara canis and Toxocara cati) is common A small, young animal with evidence of blood-loss q 24h (dogs) or 50-100 mg/CAT PO q
in young animals. anemia should trigger the consideration of hook- 24h; may cause gastric irritation; should
worm infection, particularly in warm climates. be given with food
Clinical Presentation Basic fecal flotation is the preferred diagnostic • Anthelmintics should be administered until
HISTORY, CHIEF COMPLAINT test, although empirical treatment without testing 6 months of age
• Weight loss (subclinical infection) is also reasonable. ○ Pyrantel pamoate 5-10 mg/kg PO q 2
• Lethargy weeks, or
• Polydipsia Differential Diagnosis ○ Fenbendazole 50 mg/kg PO q 24h for 3
• Poor growth and unthriftiness (puppies/ • Foreign body ingestion days (1-2 treatments usually sufficient),
kittens) • Canine parvovirus (puppies) or

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