Lungworm, also known as lung fluke or parasitic bronchitis, is a disease caused by parasitic roundworms of the genus Dictyocaulus that affect the respiratory tract of animals. The duration of lungworm infection depends on several factors, including the species of lungworm, the host animal affected, and the severity of infection.
Quick Answers
In cattle, lungworm (Dictyocaulus viviparus) infections typically last 2-3 weeks if mild, but severe infections can last over a month.
In dogs and cats, canine and feline lungworm infections (e.g. Oslerus osleri, Aelurostrongylus abstrusus, Capillaria aerophila) can last anywhere from 2 weeks to several months if left untreated.
In sheep and goats, Muellerius capillaris lungworm infections can last around 4-12 weeks in mild cases, but severe infestations may not resolve without treatment.
Horses with Dictyocaulus arnfieldi lungworms may have coughing spells lasting 2-3 weeks, but some horses can remain infected for months.
In wild animals, lungworm infections vary by species but often last 1-2 months.
What are lungworms?
Lungworms are parasitic roundworms (nematodes) that live in the respiratory system of their host. The main lungworm genera that infect domestic animals are:
- Dictyocaulus – common in cattle, sheep, goats, horses, deer
- Metastrongylus – affects pigs
- Muellerius – common in sheep and goats
- Aelurostrongylus, Capillaria, Eucoleus – infect cats
- Oslerus, Filaroides – infect dogs
Lungworms have a direct lifecycle, meaning they do not require an intermediate host. Adult worms living in the lungs produce larvae or eggs that are coughed up, swallowed, and passed in the feces. Larvae migrate through the intestinal wall, travel to the lungs via blood, and mature into adults in approximately 2-3 weeks.
How long do lungworm infections last in cattle?
In cattle, the most common lungworm is Dictyocaulus viviparus. Mild lungworm infections in cattle typically resolve within 2-3 weeks. However, heavy infestations that cause severe respiratory disease can last over a month if not treated.
The main symptoms of lungworms in cattle include:
- Coughing
- Increased breathing rate
- Nasal discharge
- Loss of appetite
- Reduced milk production in dairy cows
- Weight loss
Coughing caused by lungworms in cattle may start 2-3 weeks after ingesting infective larvae. The cough becomes more severe and frequent as adult worms multiply in the lungs. Breathing rates increase as inflammation and fluid build up in the airways.
In mild cases, symptoms may resolve after the animal’s immune system reacts to the infection and kills off the worms over 2-3 weeks. The cow’s airways and lungs show extensive healing over 1-2 months.
In severe cases, symptoms steadily worsen over 3-5 weeks and may last over a month. The cow becomes emaciated and struggles for breath. Bacterial pneumonia often occurs secondary to lungworm disease. Without treatment, some heavy infestations can be fatal.
Treatment and Prevention
Several dewormers are effective against lungworms in cattle, such as ivermectin, moxidectin, and albendazole. Treatment kills the worms and allows the cow to recover over the next few weeks. Supportive care like fluids, rest, and nutrition help recovery.
Strategic deworming and pasture rotation helps prevent lungworms. Vaccines are also available in some countries to protect cattle from infections.
How long do lungworms last in sheep and goats?
Sheep and goats are mainly affected by Muellerius capillaris lungworms. In milder cases, symptoms may resolve within 4-12 weeks. Severe infestations can persist much longer without appropriate treatment.
Symptoms of lungworms in sheep and goats include:
- Coughing
- Rapid breathing
- Nasal discharge
- Weight loss
- Poor wool growth in sheep
Heavy breathing and coughing starts 2-4 weeks after ingesting lungworm larvae. The cough becomes harsher as worms multiply and irritate the airways. Breathing may be labored. Infected sheep and goats lose condition.
Mild infections may resolve in 4-12 weeks as the animal’s immune system reacts to the worms. But severe, chronic infections can persist for months, causing debilitation, secondary pneumonia, and even death if untreated.
Treatment and Prevention
Several anthelmintics treat lungworms in sheep/goats, like albendazole, ivermectin, levamisole, and morantel. After treatment, coughing and breathing should improve within 1-2 weeks.
Rotational grazing, quarantine of incoming animals, and regular deworming help control lungworms. Some countries have sheep vaccines available.
How long do lungworms last in dogs?
Dogs are affected by several lungworm species, most commonly Oslerus osleri and Filaroides hirthi. Infections typically last 2-12 weeks but may become chronic if left untreated.
Symptoms of lungworms in dogs include:
- Coughing
- Gagging or retching
- Exercise intolerance
- Breathing difficulties
- Nasal discharge
- Weight loss
Coughing starts about 2-3 weeks after ingesting larvae. Coughing spasms may produce gagging as the dog tries to clear its airways. Breathing becomes labored as inflammation damages the lungs. Infected dogs tire easily.
Mild cases may resolve in 2-3 weeks as the immune system kills worms. More severe infections can last 6-12 weeks. Chronic cases may persist for several months with continuous larvae ingestion.
Treatment and Prevention
Several dewormers treat canine lungworm effectively, like milbemycin, moxidectin, and fenbendazole. Coughing and breathing improve within 1-2 weeks of treatment as inflammation subsides.
Picking up feces promptly, deworming every 2-3 months, and avoiding ingestion of slugs/snails can help prevent lungworm infection in dogs.
How long do lungworms last in cats?
The most common feline lungworms are Aelurostrongylus abstrusus and Capillaria aerophila. Lungworm infections typically last 2-16 weeks in cats if untreated.
Symptoms include:
- Coughing/gagging
- Sneezing
- Breathing difficulties
- Lethargy
- Weight loss
Coughing starts about 2-3 weeks after ingesting larvae. It may progress to gagging or retching. Breathing becomes rapid and shallow. Infected cats are less active and have poor appetites.
Mild infections may resolve after 2-4 weeks. More severe cases can last 10-16 weeks. Chronic infections may persist for several months in cats continuously exposed to larvae.
Treatment and Prevention
Several broad-spectrum dewormers are effective against feline lungworms, including ivermectin, milbemycin, and moxidectin. Coughing and breathing improve 1-2 weeks after treatment.
Prompt feces removal, regular deworming, and preventing hunting can protect cats from lungworms.
How long do lungworms last in horses?
Horses are most commonly infected by Dictyocaulus arnfieldi lungworms. Lungworm symptoms in horses typically last 2-12 weeks.
Signs include:
- Coughing
- Breathing difficulty
- Nasal discharge
- Poor performance
- Weight loss
Horses develop a cough around 2-3 weeks after ingesting infective larvae. Coughing spasms become more frequent and severe as adult worms accumulate in the lungs. Breathing rate increases. Infected horses exhibit poor exercise tolerance.
Mild infections may resolve after 2-3 weeks of coughing bouts. However, chronic cases can cough for 2-3 months with continual larval exposure. Some horses remain infected for years.
Treatment and Prevention
Ivermectin, moxidectin, and fenbendazole clear lungworm infections in horses. Coughing and breathing improve within 2 weeks after treatment.
Deworming every 2-3 months, manure removal, and pasture rotation help prevent lungworms. Some countries have equine lungworm vaccines available.
How long do lungworm infections last in wild animals?
Many wild animal species can suffer from lungworm infections. Duration varies by species, lungworm involved, and infection severity. However, symptoms often last 1-2 months in untreated wild animals.
Examples include:
- Deer infected with Dictyocaulus spp. experience coughing for ~1 month.
- Elaphostrongylus cervi in deer causes pneumonia for 1-2 months.
- Protostrongylus spp. in hares leads to pulmonary disease for 1-2 months.
- Crenosoma vulpis in foxes causes coughing for 1-2 months.
- Filaroides martis in martens leads to pneumonia for 1-2 months.
Infection severity varies depending on lungworm dose and other stressors. Debilitated or starving animals may show symptoms for longer periods. Secondary bacterial pneumonia is common and can be fatal if untreated.
Key Factors Affecting Lungworm Duration
Some key factors that influence how long lungworm infections last include:
- Lungworm species – Some species are more pathogenic and persistent.
- Parasite burden – Heavy infestations cause more severe, prolonged symptoms.
- Host immunity – Weakened animals struggle to clear infection.
- Nutrition status – Well-nourished animals recover better.
- Co-infections – Co-infections like pneumonia prolong illness.
- Re-exposure – Continued larval ingestion causes chronic disease.
Prompt treatment and supportive care are key to minimizing lungworm disease duration. Preventive measures like deworming and pasture control help limit parasite burdens.
Diagnosing Lungworms
Lungworms are notoriously difficult to diagnose. Signs like coughing are vague. Fecal egg counts are often low and intermittent. However, options include:
- Fecal exam – May reveal lungworm larvae in some cases.
- Tracheal swabs – Can isolate larvae from airways.
- Bronchoscopy – Allows visual identification of worms.
- Serology – Blood tests detect antibodies against lungworms.
- Molecular tests – PCR detects lungworm DNA in feces.
Where available, serology and molecular tests are the most reliable methods to diagnose lungworm infection.
Treatment of Lungworms
Several deworming medications clear lungworm infections. Options for different species include:
| Animal | Medications |
|---|---|
| Cattle | Ivermectin, moxidectin, albendazole, levamisole |
| Sheep/Goats | Albendazole, ivermectin, levamisole, morantel |
| Dogs | Milbemycin, moxidectin, fenbendazole |
| Cats | Ivermectin, milbemycin, moxidectin |
| Horses | Ivermectin, moxidectin, fenbendazole |
After treatment,symptoms like coughing and breathing difficulty should steadily improve over 1-2 weeks as inflammation resolves.
Supportive care like rest, fluids, and good nutrition aids recovery. Severe cases may need anti-inflammatories or antibiotics.
Preventing Lungworm Infection
Steps to prevent lungworm transmission include:
- Deworm livestock regularly, at least 2-4 times per year.
- Use preventive dewormers like ivermectin in horses.
- Avoid overcrowding and contaminated pastures.
- Rotate or rest pastures between grazing animals.
- Pick up feces promptly to remove parasite eggs.
- Isolate and deworm incoming animals.
- Control snails/slugs around livestock facilities.
- Follow veterinary advice on vaccines where available.
Prognosis for Lungworm Infections
With prompt treatment, the prognosis for full recovery from lungworms is generally good. However, complications can occur, including:
- Secondary bacterial pneumonia – Worsens cough and breathing difficulties.
- Permanent lung damage from inflammation.
- Malnutrition and emaciation from chronic disease.
- Severe cases may still be fatal if treatment is delayed.
Lungworm prevention is key to avoid productivity losses, complications, and animal deaths. Coughing lasting over 2 weeks warrants veterinary examination and lungworm testing.
Conclusion
In summary, lungworm infections typically last 2-16 weeks in domestic animals. Exact duration varies by species, parasite load, host health, secondary issues, and continual exposure. Prompt veterinary attention, deworming treatment, and supportive care aid recovery. Prevention through regular deworming, pasture management, and biosecurity is critical to avoid lungworm transmission.
