Lungworm in Cats

icon May 8, 2024

Lungworm, a parasitic infection caused by various species of nematodes, can affect cats worldwide. While less common than in dogs, lungworm infestations in cats can lead to respiratory issues and other health complications if left untreated. Understanding the causes, symptoms, treatment, and prevention of lungworm is crucial for cat owners to safeguard the health and well-being of their feline companions. In this comprehensive guide, we'll delve into the intricacies of lungworm infections in cats, providing valuable insights for identification, management, and prevention.

What is Lungworm?

Lungworms are a group of parasitic worms belonging to the class Nematoda that inhabit the respiratory tract of their host animals. These worms primarily affect the lungs and airways, causing inflammation, respiratory distress, and other associated symptoms. While several species of lungworms can infect cats, the most common is Aelurostrongylus abstrusus, also known as feline lungworm.

What Does Lung Worm Look Like?

Lungworms are thin, thread-like parasites that inhabit the respiratory tract of their host animals. Adult lungworms are typically white to pale yellow in color and may measure several millimeters in length, resembling small worms or larvae.

Causes of Lungworm in Cats:

Lungworm infections in cats occur through the ingestion or inhalation of infective larvae, which are typically found in contaminated environments or transmitted through intermediate hosts. The primary causes of lungworm in cats include:

1. Ingestion of Infected Intermediate Hosts:
Cats can become infected with lungworm by ingesting intermediate hosts such as snails, slugs, or rodents that carry the infective larvae. Cats may inadvertently consume these hosts while hunting or scavenging outdoors, leading to the ingestion of lungworm larvae.

2. Environmental Contamination:
Contaminated environments, including outdoor areas frequented by infected animals or containing contaminated feces, can serve as sources of lungworm larvae. Cats that spend time outdoors, especially in areas with high snail or slug populations, are at increased risk of exposure to infective larvae.

3. Transplacental Transmission:
In rare cases, lungworm larvae can be transmitted from an infected mother cat to her kittens through the placenta during pregnancy. This vertical transmission can result in neonatal lungworm infections in kittens, although it is less common than other modes of transmission.

Symptoms of Lungworm in Cats:

Lungworm infections in cats can manifest with a variety of respiratory and systemic symptoms, ranging from mild to severe. Recognizing the signs of lungworm infection is crucial for prompt diagnosis and treatment. Common symptoms of lungworm in cats include:

1. Coughing:
Persistent or intermittent coughing is a hallmark symptom of lungworm infection in cats. The cough may be dry or accompanied by the production of frothy or bloody sputum, indicating inflammation or damage to the airways.

2. Respiratory Distress:
Cats with lungworm may exhibit difficulty breathing, rapid or labored breathing, and increased respiratory effort. Respiratory distress may worsen with physical activity or exertion, leading to open-mouth breathing or wheezing.

3. Exercise Intolerance:
Lungworm-infected cats may show reluctance to engage in physical activity or exercise due to respiratory discomfort or fatigue. They may become lethargic, tire easily during play or movement, and prefer resting in quiet, comfortable areas.

4. Gagging or Retching:
Some cats with lungworm may experience episodes of gagging, retching, or attempting to clear their throat. This behavior is often triggered by irritation or inflammation in the respiratory tract caused by the presence of lungworms or associated secretions.

5. Weight Loss and Poor Appetite:
Chronic lungworm infections can lead to weight loss, reduced appetite, and general malaise in affected cats. Cats may show a decline in interest in food, leading to decreased food intake and subsequent weight loss or muscle wasting over time.

6. Lethargy and Weakness:
Lungworm-infected cats may appear lethargic, weak, or subdued compared to their usual behavior. They may spend more time sleeping or resting and show decreased interest in interacting with their environment or engaging in normal activities.

Is Lungworm in Cats Contagious to Humans?

No, lungworm infections in cats are not considered contagious to humans. The species of lungworm that affects cats, such as Aelurostrongylus abstrusus, is specific to felines and does not pose a risk of transmission to humans. However, other types of lungworms that infect dogs or wildlife may pose a potential risk to human health.

How to Test for Lungworm in Cats?

Diagnosing lungworm in cats requires a combination of clinical evaluation, laboratory testing, and diagnostic imaging techniques. Veterinarians may perform the following diagnostic procedures to confirm a suspected lungworm infection:

1. Physical Examination:
A thorough physical examination allows veterinarians to assess respiratory signs, auscultate lung sounds, and palpate for abnormalities such as enlarged lymph nodes or abdominal masses.

2. Fecal Analysis:
Examination of fecal samples for the presence of lungworm larvae or eggs can help confirm a diagnosis of lungworm infection. However, lungworm larvae may not always be detectable in fecal samples, especially in cases of low-level or intermittent shedding.

3. Baermann Technique:
The Baermann technique is a specialized method used to concentrate and recover lungworm larvae from fecal samples. This technique involves placing a fecal sample in a funnel apparatus with water, allowing larvae to migrate out of the feces and collect in a container for examination under a microscope.

4. Radiography (X-rays):
Chest radiographs (X-rays) can reveal characteristic signs of lungworm infection, such as pulmonary inflammation, consolidation, or nodular lesions. Radiographic findings may aid in the diagnosis and assessment of the severity of respiratory involvement in affected cats.

5. Tracheal Wash or Bronchoalveolar Lavage:
Collection of respiratory secretions through tracheal wash or bronchoalveolar lavage allows for direct visualization and analysis of lungworm larvae, inflammatory cells, and other cytological or microbial components. These procedures may be performed under sedation or anesthesia for thorough evaluation.

Cat Lungworm Treatment

The treatment of lungworm in cats typically involves antiparasitic medications to eliminate the parasites and supportive care to manage respiratory symptoms and complications. The following treatment modalities may be utilized in cats with lungworm infection:

1. Anthelmintic Medications:
Anthelmintic drugs such as fenbendazole, moxidectin, or milbemycin oxime are commonly used to treat lungworm infections in cats. These medications target the adult worms and larvae in the respiratory tract, disrupting their lifecycle and eliminating the parasites from the host.

2. Anti-inflammatory Therapy:
Cats with lungworm-associated respiratory inflammation may benefit from anti-inflammatory medications such as corticosteroids or nonsteroidal anti-inflammatory drugs (NSAIDs). These medications help reduce airway inflammation, alleviate respiratory symptoms, and improve lung function.

3. Oxygen Therapy:
Severely affected cats with respiratory distress or hypoxemia may require supplemental oxygen therapy to support respiratory function and alleviate breathing difficulties. Oxygen can be administered via nasal prongs, oxygen cages, or oxygen tents in a veterinary hospital setting.

4. Fluid Therapy:
Cats with lungworm infection may require fluid therapy to maintain hydration, support organ function, and address electrolyte imbalances associated with respiratory distress or systemic illness. Intravenous or subcutaneous fluid administration may be indicated in cases of dehydration or compromised fluid balance.

5. Nutritional Support:
Providing adequate nutrition and supportive care is essential for cats recovering from lungworm infection. Encourage appetite with palatable food offerings, and consider syringe feeding or appetite stimulants if necessary to ensure adequate calorie and nutrient intake during recovery.

Lungworm in Cats Prevention

Preventing lungworm infection in cats involves minimizing exposure to infective larvae and implementing preventive measures to reduce the risk of transmission. Consider the following strategies to help prevent lungworm infection in cats:

1. Limit Outdoor Access:
Minimize your cat's exposure to outdoor environments where they may encounter snails, slugs, or other potential intermediate hosts of lungworm larvae. Supervise outdoor activities, provide secure outdoor enclosures, or transition to indoor-only living arrangements to reduce the risk of exposure.

2. Practice Good Hygiene:
Maintain a clean and hygienic living environment for your cat, including regular removal of feces from litter boxes or outdoor areas. Dispose of fecal matter properly to prevent contamination of the environment with lungworm larvae and other parasites.

3. Control Intermediate Hosts:
Take measures to control populations of snails, slugs, or rodents in and around your home to minimize the risk of exposure to infective larvae. Remove potential habitats for intermediate hosts, such as stagnant water sources or debris piles, and use pet-safe methods for pest control if necessary.

4. Regular Veterinary Care:
Schedule routine wellness exams and preventive healthcare visits with your veterinarian to monitor your cat's health and assess their risk of parasitic infections. Follow your veterinarian's recommendations for parasite prevention, including appropriate use of anthelmintic medications and parasite screening tests.

5. Administer Parasite Preventatives:
Use veterinarian-recommended parasite preventatives, including monthly broad-spectrum dewormers or spot-on treatments that target lungworms and other intestinal parasites. Discuss the most suitable preventive options for your cat based on their lifestyle, risk factors, and medical history.


Lungworm infections pose a significant health risk to cats, leading to respiratory distress, inflammation, and other associated complications if left untreated. By understanding the causes, symptoms, diagnosis, treatment, and prevention of lungworm in cats, pet owners can take proactive measures to protect their feline companions from this potentially debilitating parasitic infection. Prompt veterinary intervention, including accurate diagnosis and appropriate treatment, is essential for managing lungworm infections and supporting the health and well-being of affected cats. As advocates for our feline friends, let us remain vigilant in safeguarding their respiratory health and providing them with the care and attention they deserve.

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