American Shorthair Health Care (HCM & Obesity)

HeartBreed HealthMeongsiljang Veterinary Advisory Board

American Shorthairs are particularly prone to hypertrophic cardiomyopathy and obesity, so regular heart check-ups and weight management are essential.

What Breed Is the American Shorthair?

A veterinarian listening to the heart of an American Shorthair cat with a stethoscope.

American Shorthairs are a medium-sized, short-haired breed that requires particular attention to two conditions: hypertrophic cardiomyopathy (HCM) and obesity. The most critical aspects to never overlook are regular cardiac screenings and weight management. Although they may appear robust on the outside, the disease characterized by thickening of the heart muscle can progress silently. Additionally, their strong appetite makes them prone to rapid weight gain after neutering. Starting at three years of age, it is recommended to undergo an annual echocardiogram along with a body condition score (BCS) assessment.

Top 3 Health Concerns for American Shorthairs

Here are the key health concerns every American Shorthair owner should be aware of.

Hypertrophic Cardiomyopathy (HCM): This is the most common heart muscle disease in cats, characterized by the thickening of the heart muscle, particularly the left ventricular wall. This thickening can impair the heart’s ability to relax and fill properly. While a hereditary predisposition has been reported in several cat breeds, the progression and prognosis vary significantly from individual to individual.

Obesity: After neutering, cats often become less active, leading to rapid fat accumulation. Since excess weight can strain the heart, joints, and overall body, maintaining a healthy weight is essential.

Feline Lower Urinary Tract Disease (FLUTD): A combination of insufficient water intake and stress can lead to bladder and urinary tract issues. Therefore, it is important to monitor your cat’s daily water consumption and manage their environment to reduce stress.

Understanding Hypertrophic Cardiomyopathy (HCM)

Hypertrophic cardiomyopathy is a condition in which the left ventricular wall thickens, preventing the heart from relaxing properly, and it is the most common myocardial disease in cats. A familial (genetic) predisposition has been reported in several cat breeds. It is characterized by few or no symptoms in the early stages, with sudden onset of emergency signs such as respiratory distress, hindlimb paralysis (arterial thromboembolism), and syncope. According to veterinary cardiology textbooks, echocardiography is the most accurate diagnostic method, and early lesions are often missed when relying solely on auscultation or radiography.

A cat undergoing an echocardiogram examination

Seek Immediate Veterinary Care If These Symptoms Appear

If your cat shows any of the following signs, it may indicate that hypertrophic cardiomyopathy (HCM) has progressed to an emergency situation. Seek immediate care at a 24-hour emergency veterinary clinic, even if it’s nighttime. - Open-mouth breathing or gasping for air - Sudden inability to use the hind legs or cold hind limbs - Pale or purple gums - Collapse or altered consciousness Thromboembolism is a life-threatening emergency. If you notice any of these symptoms, seek veterinary treatment immediately without delay. Prompt intervention is critical to the outcome.

Why Obesity Worsens HCM

Obesity is not merely a matter of gaining weight; it can place significant strain on the entire body and the heart. According to veterinary nutrition textbooks, body condition is assessed using a 9-point scale (Body Condition Score, or BCS), with 5 being the ideal score for cats (whereas 4–5 is ideal for dogs). For every one-point increase in BCS, body weight attributable to fat increases by approximately 10–15%. A score of 6–7 indicates overweight, while 8–9 signifies obesity. If you cannot easily feel the ribs under your fingertips, or if the waistline disappears when viewed from above, your cat is likely already overweight.

Assessing Your Cat’s Condition Using Body Condition Score (BCS)

Item	Abnormal body condition (5 points)	Overweight (6–7 points)	Obese (8–9 points)
Rib palpation	Easily felt with fingertips	Hard to feel due to fat layer	Not felt at all
Waistline (viewed from above)	Distinct	Faint	Gone, even bulging outward
Abdominal line (viewed from the side)	Slightly tucked up	Nearly horizontal	Sagging downward
Versus ideal weight	Baseline	+10–30%	+30% or more

Based on the Purina 9-point scale — the optimal BCS for cats is 5 points (see veterinary nutrition textbooks)

Health Care Tips You Can Do at Home

Here are key care tips to help extend the healthy lifespan of your American Shorthair.

Portion-controlled feeding: Instead of free-feeding, divide the daily ration into two to three meals. Use the weight-based feeding guidelines on the food bag as a baseline, adjusting portions according to your cat’s activity level.

Hydration: Place multiple water bowls around the home or use a circulating water fountain to encourage voluntary water intake.

Playtime: Engage your cat in two 10- to 15-minute sessions daily, using a wand toy to stimulate full-speed sprints.

Weight monitoring: Weigh your cat every two weeks using a home scale and keep a record of the results.

An active American Shorthair playing with a fishing rod toy

Essential Regular Check-ups for This Breed

American Shorthairs often develop heart disease silently, even without outward symptoms, making regular check-ups during the asymptomatic stage the most important. - Age 1–2: Initial baseline echocardiogram - Age 3–7: Echocardiogram and blood pressure measurement every 1–2 years - Age 8 and older: Annual echocardiogram, including kidney and thyroid blood tests Genetic testing to identify HCM-related mutations in advance can also be helpful.

Reviewed by a veterinarian

Dr. Tony — Punnawat Phongkittirak

Veterinarian

A veterinarian who majored in veterinary medicine at Khon Kaen University, Thailand, and completed the IVSA program at North Carolina State University in the United States. Drawing on clinical experience at animal hospitals, he works in the pet healthcare field and is dedicated to building a digital care environment that connects pet parents with veterinarians.

Frequently Asked Questions

Do all American Shorthairs develop HCM?

Not all cats develop HCM. It is the most common cardiomyopathy in cats, and a genetic predisposition has been identified in certain breeds. Early detection through regular echocardiograms allows you and your veterinarian to create a management plan tailored to the specific stage of the disease.

My pet is gaining weight too quickly after being spayed or neutered. What should I do?

After spaying or neutering, your pet’s energy requirements decrease, making them more prone to weight gain. Maintaining their previous food intake can lead to overweight conditions, so it’s important to regularly assess their body condition score (BCS) and consult with your veterinarian to adjust their diet accordingly.

Do I need to give my pet heart medication for the rest of their life?

HCM currently has no cure, so it’s a lifelong condition managed by controlling symptoms. However, if detected early, some cases may only require monitoring without medication. It’s important to consult with your veterinarian to create a management plan tailored to the stage of the disease.

Which is better, dry or wet food?

When considering conditions such as hypertrophic cardiomyopathy (HCM), obesity, and lower urinary tract disease, it may be worth increasing the proportion of wet food in your pet’s diet. Wet food can help boost water intake and, due to its lower caloric density, may also support weight management.

Is there a way to check my pet’s heart condition at home?

Counting your pet’s resting respiratory rate (SRR) can be helpful. If their chest rises and falls noticeably faster or with more effort than usual while they’re sleeping or resting comfortably, it may indicate a heart issue, so please consult your veterinarian.

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References

[1] Applied Veterinary Clinical Nutrition, 2nd Ed — Chapter 9: Nutritional Management of Body Weight

[2] Clinical Medicine of the Dog and Cat, 4th Ed — Chapter 26: Management of the Obese Dog or Cat

[3] Ettinger's Textbook of Veterinary Internal Medicine — Feline Hypertrophic Cardiomyopathy