Feline Lungworm

24 05 2011

Feline Lungworm

The feline lungworm or Aelurostrongylus abstrusus is a nematode (type of roundworm).

Feline lungworms are obtained through the ingestion of infected snails or slugs which are intermediate hosts.  Lungworms may also be obtained following the consumption of a bird, reptile, amphibian or rodent that has fed on an infected small or slug and is termed a transport or paratenic host.

Adult lungworms reside in the bronchioles and alveoli where the female lays its eggs approximately 25 days following ingestion of the paratenic host.  The eggs or ova hatch and become larvae which migrate to the bronchi and trachea were they are coughed up, swallowed again and are then passed through the host in the feces from an infected individual.  Once the eggs are shed on the ground they are picked up by snails and slugs to infect yet another host cat.

Many infected cats will be asymptomatic (show no clinical signs of illness) while others will show clinical signs of bronchial and pulmonary (lung) disease.  Common clinical signs include coughing, possible harsh lung sounds on auscultation, in rare cases pleural effusion (fluid in the chest), and often the host will appear depressed and lethargic.

Serologic testing may demonstrate an elevation in eosinophils levels on a CBC or complete blood count.  Eosinophils are a type of white blood cell that is characteristically found in elevated levels with parasitic and allergic conditions.  Serum globulin levels may also be slightly elevated which is characteristic of an infection.

The condition is definitely diagnosed through microscopic fecal analysis. When seen the ova have a football-like appearance with opercula at apposing ends. The larva measure 360 to 390 µm in length and have a curved tail characteristic of the parasite. The larvae are shed intermittently therefore when suspected serial fecal analysis should be conducted.

Treatment consists of fenbendazole at a dose of 25 to 50 mg/kg orally every 12 hours or one dose of ivermectin at 0.4 mg/kg by subcutaneous injection or orally.  Supportive treatment should include the administration of corticosteroids and the use of bronchodilators to ease breathing and decrease the lung inflammation.  Ivermectin has been used but is not considered as effective as fenbendazole.

The prognosis for A. abstrusis infection is generally thought to be good with treatment.  Some cases of infection may be self-limiting (resolve on their own).

References:

Ettinger, Stephen. And Edward Feldman.  Textbook of Veterinary Internal Medicine. Vol 2. W.B. Saunders.  5th Edition  2000.  Pp. 1068-1070.

Feeman, William.  “Feline Lungworm.”  Veterinary Forum.  May 2007.  Pp. 74-75.

Norsworthy, Gary.  The Feline Patient.  3rd Ed.  Blackwell Publishing.  2006. P. 175-176.

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