Respiratory disease caused by parasites (Proceedings) - Veterinary Healthcare


Respiratory disease caused by parasites (Proceedings)


Linguatula serrata

Epidemiology: Pentastomid parasites that represent a group of specialized crustacean-like arthropods.

  • Adult female is approximately 8 to 10 cm long and 1 cm in diameter; the male is about 2 cm long. The body appears superficially annulated, and the worms tend to be tan to brown in color.
  • Life cycle requires an intermediate host. The eggs that are passed by the female contain a four-legged larvae. Eggs do not appear in the feces of the dog but instead are found in the nasal secretions
  • Suspected that most dogs obtain their infections by the ingestion of sheep offal. When dogs ingest infected tissues, the nymphs migrate up the back of the throat into the nasal turbinates. Once swallowed, the nymphs do not migrate back up the esophagus.
  • Prepatent period (PPP) is about 6 months. Adult worms live about 2 years.

Clinical signs: Sneezing, slight nasal discharge sometimes containing blood. The parasites become large, lie in the recesses of the nasal turbinates, and attach themselves firmly to the mucous membranes with their four hook. The adults apparently feed on respiratory mucosal cells and blood. When fully grown, the parasites are capable of causing nasal obstruction.

  • Humans may also become infected but not from dogs.

Diagnosis: Eggs (yellowish oval, 80 m, surrounded by bladder-like envelope and containing a four-legged larva) in the nasal secretions. - identifying larvae during rhinoscopy.

Treatment: Physical removal only treatment described. Ivermectin (200 g/kg, PO, once) may be efficacious.

Eucoleus boehmi

Epidemiology: Capillarid nematode parasite of nasal mucosa of the dog. Adult worms live threaded through the mucosa of the nasal sinuses. Adults appear as very fine threads seen grossly as very fine transparent hairs.
Clinical signs: Sneezing, nasal discharge.
Diagnosis: Identifying eggs in feces (eggs can be recovered in nasal washings).
Treatment: Fenbendazole (50 mg/kg, PO, q24h, 7 days). Ivermectin (200 g/kg, PO, once).

Parasites of the lung parenchyma

Aelurostrongylus abstrusus

Epidemiology: Metastrongyloid nematode parasite of cats.

  • Adult female (9 to 10 mm long) and males (4 to 6 mm) worms coil in the terminal respiratory bronchioles and alveolar ducts. The females lay eggs that contain a single cell when laid and which embryonate within the alveolar ducts and the surround alveoli. The larvae hatch from the eggs, are carried up the ciliary escalator, swallowed, and passed in the feces.
  • Larvae: approx. 360-390 um long, characteristic dorsal spine on the tail.
  • Cats infected when ingest infected snail intermediate host or, more likely, paratenic hosts (mice, birds).

Clinical signs: Heavy infestations (100 larvae) can cause severe pulmonary disease and radiographic changes by 2-wks PI. Most severe disease occurs 5 to 15 weeks after infection.

  • Presents as alveolar lung disease (no pulmonary hypertension or associated RVH disease).
  • Most infections are asymptomatic with the cat recovering uneventfully.
  • May get signs of severe bronchopneumonia (rapid open-mouthed abdominal breathing with) - eosinophilia rare. - radiographs: diffuse interstitial pattern. After a week of treatment, the radiographic pattern may appear worse (more peribronchial infiltrates with areas of alveolar consolidation) in spite of clinical improvement in signs.

Diagnosis: Identifying typical larvae in the feces or in a trans-tracheal wash.

Treatment: Fenbendazole (20 mg/kg, PO, q24h, for 5 days, then repeat after 1 week).

  • Ivermectin (400 g/kg, PO, once, followed by a second dose of 400 g/kg, PO, one week later).
  • Prednisone (1 mg/kg, PO, q12h, 5 days) alleviates signs during recovery.


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