Exercise Intolerance in Dogs

Key Takeaways

Exercise intolerance is a decreased ability to endure sustained exercise. 

• A dog suffering from exercise intolerance wants to move and take part in the activity but is unable to do so

• Obesity is one of the most common causes of exercise intolerance

• Exercise intolerance is a symptom of a number of serious underlying medical conditions such as heart disease, anemia, and diabetes

• Diagnostics for a dog with exercise intolerance include physical examination, blood tests, and diagnostic imaging

• Treatment and prognosis depend on the underlying cause of the symptoms and vary greatly

A Closer Look: What is Exercise Intolerance in Dogs?

Exercise intolerance is commonly confused with lethargy, which is defined as an extreme decrease in the willingness to exercise or move. Exercise intolerance most commonly presents in association with obesity, which has multiple negative impacts on a dog’s health.  Exercise intolerance is also a symptom of other serious medical conditions, such as heart disease, anemia, or diabetes mellitus. Most cases of exercise intolerance require prompt veterinary care. Dogs that collapse suddenly, are severely lethargic, or unable to rise require immediate, emergency veterinary care. 

Maintaining a healthy lifestyle, including frequent exercise, reduces the risk of exercise intolerance due to obesity. Regular, year-round use of heartworm prevention is an effective way to prevent exercise intolerance due to heartworm disease. Regular dental cleanings also help minimize the risks for heart disease and subsequent exercise intolerance. Frequent veterinarian visits can help identify other potential causes of exercise intolerance early, improving their prognosis.

Possible Causes

Causes of exercise intolerance vary widely but include:

• Obesity • Anemia • Toxicoses • Heart disease, including heartworm

• Respiratory conditions such as pulmonary hypertension

• Muscular disorders such as myasthenia gravis • Bone and joint disorders such as arthritis

• Endocrine disorders such as hypothyroidism, hypoadrenocorticism and diabetes mellitus

Risk Factors

Exercise intolerance may be categorized in accordance with the severity of symptoms. Mild cases may present as an unwillingness to walk or participate in activities. Severe cases of exercise intolerance may result in collapse, pale gums, and cyanosis with exercise. The collapse may be total or only affect the rear legs causing the appearance of poor coordination or balance.

Testing and Diagnosis

A dog presenting symptoms of exercise intolerance will likely undergo the following diagnostics to determine the underlying cause:

• Physical examination • Blood test  • Diagnostic imaging • Urinalysis

Exercise intolerance is a symptom of an underlying medical problem and not a condition in itself. Treatment depends on the underlying condition. Prognosis depends on the underlying cause and varies greatly. In all cases, prompt veterinary treatment increases the probability of a positive outcome.

Similar symptoms

Exercise intolerance may be mistaken for:

• Lethargy • Exercise-Induced Collapse (EIC) • Reduced activity or mobility associated with aging

Associated Symptoms

Symptoms associated with exercise intolerance:

• Lethargy • Rapid breathing (tachypnea) • Pale/Blue gums • Coughing

• Excessive panting • Collapse

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