Rat lung worm

Aug 9, 2022

Unfortunately for our pets there are many unusual parasites in Australia that can cause serious health issues. Some are common, such as paralysis ticks and intestinal worms and some are uncommon, but just as deadly, such as the rat lung worm.

Rat lung worm normally inhabits the heart and pulmonary arteries of wild rats, where it rarely causes disease, as expected for an efficient parasite. To complete its lifecycle, however, the rat lung worms’ eggs are passed in the rat’s stool and ingested by an intermediate host – normally slugs or snails, where they develop into larvae. When these slugs or snails (or infected rats carrying the larval stages of worms) are ingested by accidental hosts such as dogs, serious disease can occur.

After ingestion of the larval stages of rat lung worm, the microscopic larvae migrate from the gut via the blood vessels to the peripheral nerves and then to the spinal cord. From here the parasite can travel up the spinal cord and into the brain causing serious neurological disease along the way. Damage is inflicted both by migration of the parasite but also by the hosts’ inflammatory response. Sadly, the use of deworming medication at this stage can cause worsening of disease due to an increase in inflammation prompted by death of the migrating larval stages of rat lung worm. Common symptoms of rat lung worm include urinary incontinence, neck pain, difficulty walking and loss of nerve function in the tail and/or parts of the face.

Rat lung worm can be treated in some cases with steroid anti-inflammatory medication, analgesics and careful nursing care. For some patients, however, the damage can leave permanent neurological deficits.

Puppies are more commonly affected than adult dogs due to their tendency to eat slugs, snails and rats. Cases of rat lung worm peak during the winter months due to increased prevalence of slugs and snails. Prevention is far more effective than cure and all dogs (and children) should always be prevented from eating slugs and snails. For further information contact our hospitals.