Cats frequently have heart disease without clinical signs for months to years. Cats are private and elusive creatures by nature choosing solitude often. Unsurprisingly, cats are not let on that they are sick until they are often at the point of severe illness. This trait likely developed to elude predators. One can imagine that the weakest appearing prey is the most likely to be chased. Noticeable signs typically do not appear until the heart decompensates and cannot adequately pump blood forward resulting in congestive heart failure (CHF).
Lethargy, anorexia, and weight loss as Clinical Signs of Heart Disease in Cats
Clinical signs of heart disease in cats are very subtle and vague at first. Cats may eat slightly less (anorexia), hide more often, or be less active (though, for a cat that sleeps 18 hours a day, how exactly does one notice a less active cat? This author’s own cat’s typical day consists of sleeping on the bed until being fed at night, and then sleeping on the couch until the morning when the bed is free. Less active is his M.O.) Other signs include decreased muscle mass, weight loss, and occasionally vomiting.
Increased respiratory effort and rate as a Clinical Sign of Heart Disease in Cats
Heart failure is a term that essentially means the heart cannot move blood forward properly.
As a result, fluid will leak out of the vessels and into the lungs (pulmonary edema), chest cavity (pleural effusion), or abdomen (peritoneal effusion). As a result, the lungs cannot properly maintain normal oxygen levels in the blood. The body eventually cannot tolerate these low levels of oxygen and signs of respiratory distress begin. One may notice increased respiratory rate and effort. It is not unusual for these signs to appear suddenly as the body cannot keep up with the energy requirements needed for all of that extra breathing effort. Treatment needs to be started immediately as these cases can decompensate severely and quickly.
Fluid accumulation in the abdomen is usually a more favorable clinical sign of heart disease in cats. It will cause some respiratory difficulty, but not nearly to the degree that fluid in and around the lungs will cause. Most often, owners will notice
the back bones become very prominent and the belly is distended. Cats may even gain weight as fluid builds up in the vessels that would be normally be cleared by the kidneys and eliminated from the body.
Coughing is an unusual Clinical Sign of Heart Disease in Cats
Unlike dogs where fluid accumulation in the lungs from heart failure results in coughing, cats rarely cough from this condition.
Acute onset of hind leg paralysis
Cats with heart disease will occasionally present in extreme pain, vocalizing and be unable to move their hind legs. This devastating event is due to a clot having developed in the diseased heart which, often with no warning, travels down the aorta and becomes lodged where the aorta splits into the femoral arteries of the rear legs (aortic trifurcation). This results in complete or nearly complete occlusion of the blood supply to the rear legs. The back feet are cold, the gastrocnemius (calf) muscles are hard, swollen and painful. It is also common for the cat to also be or develop other signs of heart failure at the time of this event or soon thereafter.
Management of this complication of heart failure in cats requires intense treatment and advanced veterinary expertise. Unfortunately, this devastating disease is still a challenge to treat successfully. The most recent unpublished data this author is aware of suggests that the recovery rate is less than 20%. There is significant research going into this disease with the FAT CAT project. Despite new medications coming to be available, preliminary unpublished data from that project is not promising for further useful therapies. Though this is a devastating disease, cats that are not in congestive heart failure at time of presentation have a better prognosis.