Overview

• Physaloptera spp. occur in dogs and cats; adults attach to the stomach mucosa; there is no larval migration outside the gastrointestinal tract.
• Infection can be asymptomatic or cause gastritis, vomiting.
• Typically few worms are present; single worm or all-female infections are common.
• Transmitted by ingestion of infective larvae in intermediate hosts (e.g., coprophagous grubs, beetles, cockroaches, crickets) or in paratenic hosts (e.g., birds, rodents, frogs, snakes, lizards).

Signalment

Dogs and cats; any breed, age, or sex. Infected animals often undergo extensive work-ups for suspected inflammatory bowel disease/ulcers, only to discover the nematodes at the time of endoscopy.

Signs

• Vomiting, often chronic and intermittent; occasionally find worms in vomitus.
• Weight loss can occur, especially with chronic infection.
• Signs can occur without egg production during pre-patent period, single worm, or female-only infections.
• Possible melena.

Causes & Risk Factors

• Outdoor exposure; access to insect intermediate hosts or small vertebrate transport hosts.
• Access to habitat occupied by wildlife species (raccoon, fox, coyote, bobcat, cougar, badger, skunk) infected with Physaloptera.

Differential Diagnosis

• Other infectious causes of vomiting including parasite, viral, or bacterial infections.
• Spirocerca, the esophageal worm, produces similar smaller eggs (11–15 × 30–37 µm).
• Ollulanus, a trichostrongylid nematode, can cause chronic vomiting; seen mainly in colony and feral cats; larvae and adults (<1 mm long) but no eggs present in vomitus or feces.
• Roundworms (ascarids) in puppies and kittens; worms can be present in feces and vomitus; larger than Physaloptera; characterized by three lips and cervical alae.
• Other non-infectious causes of vomiting including dietary indiscretion, foreign objects in the stomach, noxious substances accidentally ingested, gastrointestinal neoplasia, metabolic diseases.

CBC/Biochemistry/Urinalysis

Mild anemia and eosinophilia can occur.

Other Laboratory Tests

N/A

Imaging

Abdominal radiography, including contrast studies, to eliminate other causes of vomiting.

Diagnostic Procedures

• Endoscopy (gastroscopy) to visualize and remove worms, usually attached to stomach or duodenal mucosa; careful, thorough exam necessary to detect all worms; typically few are present and they can be hidden by mucus, ingesta, stomach rugae; pinpoint hemorrhages from prior attachment sites can be seen.
• Physaloptera spp. are small (2.5–5 cm long), stout, white or pink, with an anterior cuticular collar; male and female P. praeputialis have a posterior prepuce-like cuticular sheath.
• Direct smear, wet mount, or fecal flotation to detect eggs in vomitus or feces; eggs are dense and can be difficult to detect by fecal flotation using low specific gravity solutions; use flotation solution with s.g. >1.25.
• Eggs are small (42–58 × 29–42 µm), thick-shelled, larvated, ovoid to ellipsoidal, and colorless.

Drug(s)

• With no migration beyond the stomach wall, use adulticide anthelmintic released in stomach.
• Fenbendazole (dogs), 50 mg/kg PO q24h for 3–5 days; repeat if signs persist.
• Pyrantel pamoate (dogs/cats), 5 mg/kg twice at 3-week interval or 15–20 mg/kg once; repeat if signs persist.
• Ivermectin (cats), 0.2 mg/kg PO or SC once.
• Medication to reduce gastritis-histamine H2-antagonists (e.g., famotidine 0.5 mg/kg PO q24h); sucralfate 0.25–1 g PO q8–12h in the dog; 0.25 g PO q8–12h in the cat.

Patient Monitoring

Recheck 1–2 weeks post-treatment and re-treat with anthelmintic if eggs still present on fecal exam and/or if vomiting persists.

Prevention/Avoidance

• Prompt removal and disposal of feces to prevent infection of arthropod intermediate hosts.
• Keep pets from roaming freely outdoors; prevent hunting and scavenging.

Expected Course and Prognosis

Clinical signs and/or shedding of eggs in feces should resolve within 2 weeks of treatment.