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Feline Asthma

Feline Asthma is one of the most commonly diagnosed respiratory conditions in cats. Cats at any age can be affected but the condition is most commonly appreciated in middle-aged adults. Both males and females are susceptible to feline asthma and, while there’s not an overwhelming breed predilection, Siamese cats appear to be overrepresented.


What is Feline Asthma?

Feline Asthma is a recurring respiratory condition defined by 3 key features: airway inflammation, airway hyper-responsiveness, and reduced airflow.


Asthmatic episodes begin with excess mucus accumulation in the cat’s airway. The airway detects the abnormal mucus and recruits inflammatory cells to clear the material. In normal cats the excess mucus would be cleared without incident, however, in cats with asthma the otherwise normal inflammation of the airway wall becomes hyper-responsive.        The exaggerated inflammatory response leads to airway wall muscle spasms, constriction of the airway lumen, and reduced airflow. With proper intervention and monitoring, some of the airflow reduction can be reversed; cats presenting with a low-grade chronic cough are experiencing the residual, irreversible airway inflammation that remains after such a hyper-reactive inflammatory response. 


Clinical Signs

Though not all symptoms may be present at the same time, cats may experience:

  • Inability to draw a deep breath

  • Exercise intolerance

  • Coughing

  • “Wheezing”


In many patients it’s not uncommon for the only sign to be a low-grade chronic cough. Seemingly benign most of the time, it’s important to remember asthmatic airway constriction can happen without stimulation or warning, sending the cat into a life-threatening asthmatic crisis. During an asthmatic crisis, cats may experience:

  • Inability to draw an adequate breath

  • Cyanosis (blue-tinged gums and skin)

  • Open mouth breathing

  • Breathing with increased abdominal effort

  • Weakness

  • Collapse

Open mouthed breathing in a feline patient is always a medical emergency! Contact your veterinarian immediately.


Diagnostics

Feline asthma should be on the list of potential diagnoses for all coughing cats. Coughing, wheezing, and difficulty drawing a full breath are all suggestive of a positive diagnosis.


If the cat is stable enough for further diagnostics, chest radiographs is the next step. Classic feline asthma radiographs reveal small, constricted airways. The tiny airways are often observable in finer detail in these cases, as the inflammation of the airway and excess mucus make the usually thin walls appear markedly thicker. The over-inflated lungs appear larger than normal because inhaled air is unable to be exhaled through the constricted airways. 


In a perfect world, sick patients would “read the textbook” and demonstrate classic signs, symptoms, and diagnostic results consistent with their illness. Unfortunately in the case of feline asthma, up to 23% of patients will have completely normal chest radiographs. Further confusion comes when considering multiple conditions can cause cats to cough, which can easily trip up veterinarians trying to track down the source of respiratory distress.


When diagnostic tests are not accessible or leave room for question, your veterinarian might recommend seeing how your cat responds to medical treatment based on the presumptive diagnosis of feline asthma; response to medication can confirm the diagnosis and guide further maintenance. 

Radiograph of asthmatic feline showing thickened airway walls, enlarged lungs with flattened diaphragm, and multiple air bronchograms.


Treatment/Management


Emergency Diagnosis and Treatment

If your cat is showing signs of respiratory distress (ie, open mouthed breathing, blue-discoloration to gums, collapse, etc), it needs to be assessed by a veterinarian right away. If the patient is experiencing an asthmatic crisis, a small dose of epinephrine or terbutaline (a bronchodilator) will be administered; these drugs can reverse an asthmatic crisis in as little as 15 minutes, whereas injectable corticosteroids generally establish clinical results in 25-30 minutes.


Treatment Options: Corticosteroids

Because the underlying problem in cases of feline asthma is airway inflammation that results in airway constriction, targeting the inflammation is critical when forming a treatment plan. Injectable, oral, or inhaled corticosteroids are all effective in reducing airway inflammation.


Oral: Your veterinarian will consider your cat's unique situation when determining if oral corticosteroids need to be continued long-term, supplemented with other medications, or used only during flare ups or when known triggers are present. While long-term corticosteroids have the potential for causing side effects, feline patients tend to be more resistant than other animals. Despite being well tolerated, corticosteroids are started at an anti-inflammatory dose to establish the necessary therapeutic effect but then tapered to the lowest effective dose for continued maintenance; this dose adjustment helps avoid unnecessary side effects and the possible formation of resistance to the drug.


Injectable: If administering pills is not feasible, your veterinarian might recommend long-acting corticosteroid injection to control asthma symptoms. Unfortunately, cats appear to be more sensitive to potential side effects from these injections.


Inhaled: In certain cases, corticosteroids can be administered via an inhaler attached to a spacer. Your veterinarian will consider your cat's case prior to recommending a twice/day inhaler for long term therapy or an inhaler exclusively used during flare ups. Inhalers aren’t appropriate for all feline asthma patients, as many cats will not tolerate the spacer’s mask remaining snuggly over their nose for the full 7-10 breath dose.

Inhaler attached to spacer and mask.


Other Treatment Options:

  • Airway Dilators: Terbutaline and theophylline are two bronchodilators proven beneficial in mitigating inflammation-induced airway constriction.

  • Immunomodulator: Cyclosporine is occasionally used in cats with asthma that are unable to achieve adequate inflammatory control with the use of corticosteroids and/or airway dilators, or in cats that have concurrent illnesses that inhibit the use of corticosteroids (ie, infection, history of calcium oxalate bladder stones, diabetes mellitus, etc.).


Other Management Strategies:

Many feline asthma patients can be successfully managed with medications but life-long flare-ups are possible. Adjusting your cat's environment can help your cat maintain healthy airways. Recommendations of environmental modification include: 

  • Do not expose your cat to cigarette smoke

  • Use dustless litter

  • Use non-topical insecticides

  • Regularly replace air filters in your home

  • Avoid plug-in diffusers (yes, even Feliway)

  • Keep the stress level in your cat’s life as low as possible


Regardless of whether or not your asthmatic cat is well-managed, it’s important to realize even stable asthma patients can experience life-threatening respiratory crises with little warning. Signs of an emergency situation can include open-mouthed breathing or excessive abdominal movement (tummy breathing) not contributed to purring.

           

If you suspect your cat is in respiratory distress or crisis, contact your veterinarian immediately.

  • Candlewood Veterinary Clinic: 785-537-0537

  • KSU Veterinary Health Center: 785-532-5690

 

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