Exercise Intolerance in Cats


Exercise intolerance is defined as the decreased ability to tolerate strenuous exercise. Cats with exercise intolerance want to get up and play or run, but aren’t able to keep up without having difficulty. This symptom is easily confused with lethargy, which is defined as a severe decrease in activity and willingness to exercise or even move.

Exercise intolerance is observed in cats suffering from serious conditions such as heart or lung disease. Cats often hide signs of cardiovascular and respiratory disease until the illness is quite advanced, so exercise intolerance in cats indicates a need for urgent medical care. When present with other symptoms like pale gums, labored breathing, or collapse, exercise intolerance is indicative of a medical emergency. 

Diagnostic tests such as bloodwork and X-Rays are used to determine the underlying cause for this symptom and guide the best course of treatment.


Exercise intolerance is rarely observed in cats, and it is often difficult to notice as adult cats do not typically exercise strenuously. 

It is often associated with serious medical conditions such as heart and respiratory disease and as such warrants urgent medical care. Cats are masters at hiding their symptoms, so it is best to pursue veterinary attention while the exercise intolerance is still mild. Other symptoms of heart or respiratory disease such as pale gums, fainting,  shortness of breath, difficulty breathing, or panting , indicate a need for emergency care.

Possible Causes

Conditions associated with exercise intolerance include:

Heart Disease: cats suffering from congestive heart failure commonly have fluid build up in the lungs, making it harder for them to  breathe and exert themselves.

Respiratory Disease: Conditions such as upper respiratory infections, feline asthma, and allergic pneumonitis interfere with normal breathing and exercise intolerance often results.

Cancer: Cancer in the lungs compromise their ability to properly function, and provide the body with the oxygen needed for exercise.

Brachycephalic airway syndrome: short-faced breeds have abnormal anatomy in the upper airway which compromises breathing.

Risk Factors

Exercise intolerance is classified according to its: 

• Onset: did the intolerance suddenly occur (acute), or has it been observed over a period of time (chronic)

• Severity: How long does it take for the cat to return to normal after exercise?

Testing and Diagnosis

The underlying cause for exercise intolerance is usually determined by performing: 

• Physical exam • Blood work • X-rays • Echocardiogram (ultrasound of the heart)

Treatment and prognosis vary widely depending on the underlying cause.

Similar symptoms

Exercise intolerance is sometimes mistaken for laziness. It is a subtle symptom in cats since many healthy cats are not particularly active. 

Exercise intolerance is commonly confused for lethargy. While very similar, a cat that is lethargic does not want to get up and exercise or play. A cat suffering from exercise intolerance wants to take part in these activities, but is unable to keep up, usually due to inadequate circulation or breathing.

Associated Symptoms

Exercise intolerance is often observed alongside other symptoms such as lethargy, rapid breathing (tachypnea), coughing or panting. In severe cases cats may also experience episodes of syncope (fainting).

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