Lungworm is a parasitic infection that affects the lungs of various animals. It is caused by different species of roundworms depending on the host animal. Lungworm can cause severe respiratory distress and even death if left untreated. Thankfully, there are effective medications available to treat lungworm infestations in domestic animals like dogs and cats as well as livestock animals.
What is Lungworm?
Lungworm refers to a parasitic infection of the lungs by a species of roundworm. The most common lungworms that infect dogs and cats belong to the genus Oslerus or Filaroides. In cattle, the lungworm Dictyocaulus viviparus is most prevalent. Other livestock animals like sheep and goats can be infected by Muellerius and Protostrongylus species of lungworms. Wild animals are also susceptible to lungworms with different species affecting foxes, badgers, deer, etc.
These parasitic worms live inside the lungs, breathing passages, and sometimes the heart of the host animal. The female adult worms lay eggs which hatch into larvae. These larvae are then coughed up and swallowed by the infected animal. They migrate to the intestines where they mature into adult worms and the cycle starts again. The larvae can also be swallowed by another host to spread the infection.
The presence of lungworms causes significant pathology to the respiratory system of the infected animal. It can lead to coughing, breathing difficulties, nasal discharge, weight loss, lethargy, and secondary pneumonia. Severe infestations can permanently damage lung tissues and even cause death due to asphyxiation.
Common Lungworms in Animals
Dogs and Cats
- Oslerus osleri – Also known as the canine nasal worm, it primarily infects membranes of the trachea.
- Filaroides hirthi – Known as the canine lungworm, it inhabits the bronchi and bronchioles.
- Aelurostrongylus abstrusus – The feline lungworm that inhabits the alveoli.
Cattle
- Dictyocaulus viviparus – The bovine lungworm which causes parasitic bronchitis.
Sheep and Goats
- Muellerius capillaris
- Protostrongylus rufescens
Horses
- Dictyocaulus arnfieldi – The equine lungworm responsible for disease symptoms.
Pigs
- Metastrongylus species
Signs and Symptoms
The clinical signs associated with lungworm infection vary between animal species but commonly include:
- Coughing
- Breathing difficulties
- Nasal discharge
- Lethargy and reduced exercise tolerance
- Loss of appetite and weight loss
- Secondary pneumonia
- Bleeding into the lungs
In severe cases, collapsed lungs, heart failure, and death can occur if treatment is not given in time. The onset of symptoms also depends on the lungworm species but can take 2 to 8 weeks after the initial infection.
Diagnosis
Lungworm infection is diagnosed through:
- Medical history – Information about the animal’s health, exposure risk, and clinical signs can indicate lungworms.
- Fecal examination – Larvae or eggs of lungworm may be detected in the feces.
- Blood tests – May reveal eosinophilia (increased eosinophils).
- Imaging – Radiographs or CT scans can reveal lung pathology.
- Bronchoscopy – Direct examination of lower airways to view parasites.
- Biopsy – Microscopic examination of lung tissue for larvae.
Ideally, diagnosis should be confirmed by identification of larvae/eggs or with imaging/endoscopy before starting treatment.
Treatment
Several broad-spectrum dewormers and anthelmintic drugs are available to effectively treat lungworm infections in domestic and livestock animals. These include:
| Drug | Animal Uses |
|---|---|
| Fenbendazole | Dogs, cats, cattle, sheep, horses |
| Albendazole | Sheep, cattle |
| Ivermectin | Dogs, cats, horses, sheep, cattle |
| Moxidectin | Dogs, sheep, cattle |
| Levamisole | Cattle, sheep |
| Pyrantel | Dogs, cats, horses |
These drugs paralyze and kill the adult lungworms and migrating larvae. Most are given orally but some like ivermectin can be injected. The veterinarian will decide the suitable medication based on the animal, symptoms, and type of lungworm suspected.
Usually, 2-3 doses are given at intervals of 1-2 weeks to kill all life stages. Supportive care like antibiotics, cough suppressants, and bronchodilators may also be prescribed. Severely affected animals may need hospitalization for intensive treatment.
In livestock, mass deworming using medicated feed/water is useful to treat entire herds during outbreaks. Strict follow-up and re-dosing if needed is key to completely eliminate the lungworms.
Prognosis and Complications
With prompt treatment, the prognosis for full recovery is generally good. However, certain complications can arise:
- Permanent damage to lung tissue leading to chronic respiratory disease.
- Reinfection if larvae persist in the environment.
- Bacterial pneumonia due to damage of lung epithelium.
- Inflammation and scarring obstructing airways.
In severe infestations, death can occur even after treatment due to irreversible lung pathology and pulmonary hemorrhage. Puppies and kittens are more vulnerable due to their smaller lung capacity.
Preventive measures like regular deworming, hygiene, and lungworm vaccination (dogs) are key to protecting animal health.
Prevention
Lungworm prevention revolves around limiting exposure to infective larvae and routine deworming:
- Avoid areas where intermediate snail/slug hosts are found. These include slug/snail-infested yards, swamps, ponds, and feeds contaminated with slug slime.
- Pick up dog feces regularly from the yard to remove potentially infectious larvae.
- Keep livestock housing clean and dry to discourage molluscs.
- Regular deworming every 2-3 months, especially during high risk seasons like warm, wet weather.
- Yearly fecal exams to check infection status.
- Vaccination against lungworms for dogs using products like Nobivac L4.
Combining diligent prevention measures, prompt treatment, and close monitoring is key to protecting animal health against the serious consequences of lungworm disease.
Conclusion
Lungworm poses a real threat to the well-being of domestic pets and livestock animals across the world. Thankfully, modern anthelmintics provide an effective solution to eliminate these parasites. Fenbendazole, ivermectin, and other broad-spectrum dewormers can eradicate lungworm infestations with proper dosing and follow-up.
While most cases have a good outcome, prevention is always better than cure when dealing with opportunistic parasites. Through lifestyle adjustments to avoid exposure, routine fecal screening, regular deworming schedules, and even vaccination, animal caregivers can successfully protect the respiratory health of their furry companions and livestock against damage from insidious lungworm disease.
