Lungworm is a parasitic infection that affects dogs and other animals. It is caused by roundworms that live in the lungs and airways. There are a few different types of lungworm that can infect dogs, with the most common being Angiostrongylus vasorum and Crenosoma vulpis. Lungworm infection can range from mild to very severe, and in some cases can even be fatal if left untreated. However, with prompt veterinary care most dogs can make a full recovery from lungworm.
What is Lungworm?
Lungworms are parasitic roundworms that live in the heart and pulmonary arteries of infected animals. There are a few different species that can infect dogs:
- Angiostrongylus vasorum – Most common lungworm in dogs, found worldwide
- Crenosoma vulpis – More common in North America
- Eucoleus aerophilus – Less common species
- Filaroides spp. – Rare in dogs
The adult worms live in the pulmonary arteries and right side of the heart. They lay eggs which hatch into larvae, which then migrate to the airways. The dog then coughs up the larvae, swallows them, and passes them out in the feces. The larvae can then infect slugs and snails, where they develop into their infective stage. Dogs become infected by eating infected snails or slugs, or anything that has had contact with slug/snail slime.
The larvae migrate from the intestines through the body to the lungs, maturing into adults along the way. The life cycle then repeats as the adults reproduce. Signs of lungworm usually occur when the larvae migrate through the lungs.
Signs and Symptoms
The main signs of lungworm infection include:
- Coughing
- Breathing difficulties
- Tiring easily
- Bleeding into the airways (coughing up blood)
- Nose bleeds
- Weight loss
- Poor blood clotting
- Bruising easily
- Change in behaviour – lethargy, depression, loss of appetite
- Seizures and neurological signs (with heavy burdens)
The severity of symptoms depends on the worm burden, with heavy infestations being more serious. Some dogs may not show any signs at all, especially in the early stages. Puppies with immature immune systems tend to be more severely affected.
Without treatment, symptoms generally get progressively worse. Secondary bacterial infections may develop in the damaged lung tissue. In severe cases, bleeding into the airways and lungs can become life-threatening.
Diagnosis
Lungworm is diagnosed through:
- X-rays or ultrasound scans of the chest may show signs of lung damage.
- Fecal exam to look for lungworm larvae.
- Blood test to check for elevated white blood cell count, antibodies against lungworms, and biochemistry changes.
A definitive diagnosis is made by finding lungworm larvae in the feces. However, false negatives are common as the larvae are intermittently shed. Multiple fecal exams may be needed to find the larvae. Serology blood tests are also available which look for antibodies against lungworms. Radiography and imaging of the chest may reveal signs of lung disease, but abnormalities may also be missed early in infection.
Overall, diagnosing lungworm can be challenging due to the intermittent shedding of larvae and the vague, non-specific signs. A diagnosis is made based on a combination of clinical signs, fecal exam results, radiographs, and blood tests. Any dog showing respiratory signs or unexplained bleeding should be evaluated for lungworm.
Treatment
The treatment for lungworm involves killing the parasites with deworming medication. There are several effective drugs available:
- Fenbendazole – Kills adult worms and larvae
- Milbemycin oxime – Also kills both adults and larvae
- Moxidectin – Larvicidal dewormer
- Advocate/Advantage Multi – Topical medication containing moxidectin
Most dogs are treated as outpatients with 2-3 doses of dewormer given 2 weeks apart. Severely affected dogs may need hospitalization for more intensive therapy.
Corticosteroids and antibiotics may also be given to control inflammation in the lungs and prevent secondary infections. Severe bleeding may need to be managed with plasma transfusions or vitamin K injections.
After treatment, dogs should make a full recovery as long as irreversible lung damage has not occurred. However, reinfection is common if the dog is still being exposed to the parasite. Prevention with regular monthly deworming is key for dogs at high risk.
Prognosis
With aggressive treatment, most dogs will recover fully from lungworm infection as long as irreversible lung damage has not already developed. However, in some cases permanent lung scarring can occur.
The prognosis is guarded to poor for dogs with heavy worm burdens that cause extensive lung bleeding and secondary infections. If theworms have migrated to the brain and spinal cord, neurological signs may persist despite deworming.
Puppies and young dogs tend to suffer more extensive lung damage before treatment is initiated, and thus have a poorer prognosis. Older dogs with heavier infestations also have an increased risk for complications and death.
With prompt and thorough treatment, the prognosis is good for a full recovery. But dogs in severe respiratory distress will need intensive hospitalization to survive. Regular prevention is key to protect dogs from reinfection.
Survival Rate
There are not any definitive statistics available on the survival rate for dogs with lungworm infection. The prognosis varies considerably based on factors like:
- Severity of infection – Heavy vs light worm burden
- Duration of infection – Treated early vs late
- Extent of lung damage
- Development of secondary infections
- Age and health status of the dog
- Neurological involvement
Based on clinical experience, veterinarians report that the majority of dogs recover with treatment when lungworm is caught early. However, the prognosis declines sharply in severe cases that cause substantial bleeding into the lungs and airways.
One study in Ireland found that 4.3% of untreated dogs with lungworm died suddenly or required euthanasia. With treatment, most dogs even with severe initial signs can recover with aggressive therapy. Overall, most veterinarians report a good prognosis for survival if lungworm is caught and treated promptly before irreversible lung pathology develops.
Regular deworming and prevention is critical for dogs at high risk of lungworm exposure. While lungworm can potentially be fatal, timely diagnosis and treatment provides dogs with the best chance at making a full recovery.
Prevention
Lungworm infection can be prevented through regular monthly use of dewormers that are effective against the parasite. The following preventatives will kill lungworm larvae and prevent disease:
- Milbemycin oxime
- Moxidectin
- Selamectin
- Advocate/Advantage Multi
Dogs should be dewormed monthly during seasons when slugs and snails are active. Winter is typically a low risk period in temperate climates since the mollusks hibernate.
Environmental control can also help reduce exposure to the intermediate slug and snail hosts:
- Clean up areas of dog feces promptly
- Use molluscicide baits in the yard to kill slugs/snails
- Avoid areas with slugs and snails when walking dogs
- Pick up toys, bowls outside that might collect slime
- Keep dog’s food and water bowls inside
Dogs that hunt, eat slugs/snails, or have access to areas with these mollusks are at highest risk and need vigilant prevention. Make sure all new puppies are started on monthly lungworm prevention. With consistent deworming and environmental control, lungworm can be prevented in most dogs.
Conclusion
Lungworm is a serious parasitic infection in dogs that can be fatal if left untreated. The worms live in the heart and lungs, causing respiratory distress, bleeding, and secondary bacterial infections. However, most dogs can survive lungworm and make a full recovery with prompt veterinary treatment that kills the worms and controls lung inflammation.
The prognosis depends on factors like worm burden, lung damage, and secondary infections. Generally puppies, debilitated dogs, and those with heavy infestations have the poorest outcome. But even severely affected dogs have a fair prognosis with aggressive hospitalization. The keys are early diagnosis through fecal and blood testing, and quick treatment with appropriate dewormers.
Preventing lungworm by avoiding mollusks and using regular monthly dewormers is vital for any dog at risk. While lungworm can potentially be deadly, most dogs survive infection with appropriate treatment and have an excellent prognosis. Continued prevention is then needed to protect dogs from reinfection by this challenging parasite.
Frequently Asked Questions
How do dogs get lungworm?
Dogs get infected by eating slugs or snails carrying lungworm larvae. The larvae then migrate through the body to the lungs where they develop into adult worms. Dogs can also become infected just by contact with slug/snail slime on toys, food bowls, grass, etc.
What are the first signs of lungworm in dogs?
The first signs are usually respiratory in nature – coughing, tiring easily, difficulty breathing. The dog may also show poor appetite, weight loss, sluggishness and bleeding tendencies as other early signs.
How is lungworm diagnosed in dogs?
Lungworm is diagnosed through fecal tests to look for larvae, blood tests for high white blood cell count and antibodies, and chest x-rays/ultrasound to visualize lung changes. Multiple tests are usually needed for diagnosis.
How are lungworms treated in dogs?
Lungworms are treated with dewormers like fenbendazole, milbemycin, moxidectin, and selamectin. Dogs usually need 2-3 doses given 2 weeks apart to fully clear the infection. Supportive care like steroids and antibiotics may also be needed.
What is the survival rate for dogs with lungworm?
There are no definitive statistics on survival rates, which vary based on worm burden, lung damage, and overall health of the dog. However, with prompt treatment most dogs recover fully. Severely affected dogs have a poorer prognosis but aggressive hospital care can still save many of them.
How can lungworm be prevented in dogs?
Prevention involves monthly use of dewormers effective against lungworm and reducing exposure to slugs/snails through environmental control. Dogs in endemic areas should stay on preventatives year round and avoid contact with slugs/snails.
Can lungworm infection come back after treatment?
Yes, reinfection is common if the dog continues to be exposed to slugs/snails carrying lungworm larvae. This is why consistent monthly prevention is so important even after treatment.
Are lungworms always fatal in dogs if untreated?
No, not always. Some dogs can live with low levels of infection without treatment for some time. But eventually the worms will multiply and cause worsening symptoms. Without treatment, lungworms are often fatal especially in cases with heavy worm burdens.
What does lungworm do to a dog?
Lungworms live in the pulmonary arteries and heart of infected dogs. The migrating larvae damage the lung tissue, causing bleeding, respiratory issues, and secondary infections. Worms can even migrate to the brain in severe cases. Left untreated, they can be fatal.
Can lungworm go away on its own?
No, lungworm infection will not go away on its own without treatment. The parasite will complete its lifecycle inside the dog and the worm burden will continue to increase. Prompt medication is necessary to kill the worms and prevent potentially fatal consequences.
Do dogs recover fully from lungworm?
Yes, with prompt treatment most dogs make a full recovery without any long term effects, as long lung damage has not progressed too far. However, permanent lung scarring can develop in some cases. Dogs with heavy worm burdens have the poorest prognosis for full recovery.