Lungworms are a particulary hot topic at the moment so we thought we’d give you the basics here in the latest MSP blog post. It’s not only dog owners who need to be aware of the facts so read on ….
Lungworms are parasitic nematode worms that infest the lungs of vertebrates.
Lungworms migrate to their hosts’ lungs or respiratory tracts, and cause bronchitis or pneumonia. The lungworm will gradually damage the airways or lung tissue by inciting an inflammatory reaction inside the tissue. Ultimately, the parasites survive and reproduce in the respiratory tissues.
The science bit
Different species are found in cattle and deer (D. viviparus), donkeys and horses (D. arnfeldi), and sheep and goats (D. filaria). These animals have direct life-cycles. The lungworms in the superfamily Metastrongyloidea include species that infest a wider range of mammals, including sheep, goats and pigs but also cats and dogs.These include Metastrongylus elongatus (apri), found in pigs; Oslerus osleri found in dogs; and Aelurostrongylus abstrusus found in cats. Some of these have indirect, and complex, life-cycles; several of them involve slugs or snails as intermediate hosts, where the habit of sniffing at slug trails, or even licking them, causes the parasite egg to enter the dog’s respiratory tract.
The general life cycle of a lungworm begins with an ingestion of infected larvae. The infected larvae then penetrate the intestinal wall where larvae migrate into the lungs through the bloodstream. The infected larvae reside in the lungs until the development into adult larvae. The eggs of the adult larvae hatch thus producing lungworm. These eggs that reside in the lungs are coughed up and then ingested back into the stomach and then into feces.
The most common symptom is coughing and other typical symptoms are wheezing and weight loss. These symptoms are caused by larvae that reside in the lungs where immunity develops and the accumulation of mucus cause blockage of the airway into the lungs.
If an animal is suspected of lungworm infection, there are many ways to detect this parasitic infection such as performing one or more of the following techniques: a complete medical history including lung auscultation (stethoscope examination), doing a chest xray, fecal examination for detection of ova or larvae, examination of respiratory secretions for ova or larvae, and/or a complete blood count (CBC) to check for signs of increase in eosinophils
- Lungworm infestations can cause significant distress to the animal but are usually treatable with drugs. Oxibendazole is commonly used as a prophylactic against these and other nematode infestations.
- If infected with lungworm parasite, an anti-parasite drug must be administered.
- In the case of a severe reaction, an anti-inflammatory drug of corticosteroids may be given for a brief period (3 to 10 days).
- To treat tissue inflammation, Prednisone is usually given (5–10 days). However, there are some side effects such as increased urination or appetite.
- The drug fenbendazole is usually administered to kill the parasite. It is very safe and does not harm the animal.
There are several different Lungworm parasites that have been identified. Although they all originate from the lungworm parasite, they are treated somewhat differently and requires a combination of various drugs to treat the parasite.
Repeat chest X-rays in 2 and 4 weeks after treatment. Also, recheck a fecal sample to monitor for the presence of larvae or ova in 2 to 4 weeks. This will confirm if the parasite is still living inside the respiratory tissue.