Heart Muscle Disease in Cats

The heart has four chambers: two chambers at the top, the right and left aorta; and two chambers on the bottom, the right and left ventricles. Dilated cardiomyopathy (DCM) is a heart disease that affects the ventricular muscle. It is characterized by dilated, or enlarged heart chambers, and reduced contraction ability. That is, a reduced ability to push blood out of the respective ventricle. DCM causes the heart to become overloaded, and will often lead to congestive heart failure. Before 1987, DCM was one of the most common heart diseases in cats. This is suspected to have been related to a dietary deficiency of the amino acid taurine. DCM in cats is now relatively rare, since most cat food manufacturers began adding taurine supplements to their foods, further confirming the relationship.

Some breeds, such as the Burmese, Abyssinian, and Siamese, are more commonly affected by DCM. The disease will usually affect cats between the ages of 2 to 20 years, but the average age of onset is ten years old.

Symptoms and Types

Cats suffering from reduced cardiac blood flow due to DCM will exhibit symptoms of depression, loss of appetite, and weakness. Reduced flow due to blockage of a blood vessel, thromboembolism, may be apparent as sudden onset of pain and partial paralysis (paraparesis). A physical exam may discover a low, high, or normal heart rate, a soft heart murmur, a galloping rhythm, hypothermia, a weak left cardiac impulse, and quiet lung sounds.

Causes

While taurine deficiency greatly contributed to the onset of secondary feline DCM in the past, the underlying cause in the majority of DCM cases today remains unknown. In some families of cats, a genetic predisposition has been identified.

Diagnosis

In addition to a thorough physical examination of the heart, certain medical tests are needed to diagnose DCM and exclude other diseases. An electrocardiogram (or EKG) recording can be used to examine the electrical currents in the heart muscles, and may reveal any abnormalities in cardiac electrical conduction (which underlies the heart’s ability to contract/beat), and can also help your veterinarian to determine the origin of the abnormal heart rhythms, if they are present. X-ray imaging of the chest (thoracic radiographs) may reveal heart enlargement and accumulated fluids in the chest. Echocardiograph (ultrasound) imaging is required for a confirmed diagnosis of DCM. This test will enable your veterinarian to visually examine the size of the heart and the ability of the ventricular muscle to contract. An echo cardiograph may reveal thin ventricular walls, an enlarged left ventricle and left atrium, and low contraction ability, confirming a diagnosis of DCM.

Pneumonia, an infectious lung disease, can be blamed on a host of organisms — bacteria, viruses, and fungi. Symptoms include fever, coughing, runny nose, labored or loud breathing, and a lack of appetite. If your cat comes down with pneumonia, medications to treat the underlying cause and supportive care are usually recommended. Keeping your cat current on vaccinations and in general good health is the best prevention for this disease.

Overview

Pneumonia is a relatively common respiratory condition that can result following one or more of a variety of insults to the lung’s tissue. It can involve a small segment of a lung lobe or the entirety of the lungs, depending on the cause of the process.

Most lung tissue is made up of tiny clusters of air “balloons” (called alveoli). Each balloon is lined by a thin layer of cells and surrounded by a network of very small blood vessels. When you breathe in, air fills the balloons. The cells in the lining and the small blood vessels exchange oxygen from the air for carbon dioxide, which you then breathe out. The main pathway from the lungs to the outside of the body consists of the trachea (the large airway that begins at the back of the throat and continues down into the lungs) and the nostrils.

When foreign organisms, such as certain bacteria, viruses, and fungal organisms, invade the nostrils or trachea, they sometimes cause infection and inflammation there. If this infection and inflammation continues down the respiratory tract to involve the alveoli, material such as fluid, pus, and cellular debris can accumulate in the lungs. At this point, the patient is said to have developed pneumonia.

A variety of bacterial, viral, and fungal organisms can cause pneumonia in cats. Examples include feline calicivirus, feline infectious peritonitis (FIP) virus, Mycoplasma bacteria, and the fungus Cryptococcus.

Sometimes, a virus or fungus can cause such damage to the respiratory tract that a secondary bacterial infection can take hold so that pneumonia may be complicated and exacerbated by multiple organisms. The condition can also occur if fluid is present in the lungs, such as after a near-drowning incident or as a result of heart failure or when a pet inhales vomit or any type of caustic or irritating substance. Cancers can also lead to pneumonia.

Signs and Identification

Pneumonia can be confined to a small area of the lungs, or it can spread throughout them. Depending on the severity of the pneumonia, clinical signs can range from relatively mild to severe and can include the following:

• Difficult (labored) or rapid breathing
• Loud respiratory sounds
• Discharge from the nostrils
• Lethargy (tiredness, malaise)
• Reduced appetite
• Fever
• Coughing

Because a variety of organisms can cause pneumonia, additional clinical signs may be associated with the causative agent. For example, FIP virus can cause pneumonia but additional clinical signs might include vomiting, diarrhea, or other complications.

Obtaining a medical history and performing a physical examination are the first steps in diagnosing pneumonia. When a veterinarian examines a cat, he or she will listen to the chest with a stethoscope to determine whether the air sounds in the lungs and airways are normal and whether there are any audible cardiac abnormalities.

Many veterinarians use the results of chest radiographs (X-rays) to help confirm a diagnosis of pneumonia. Once pneumonia is diagnosed, additional testing may be recommended to help identify the organism(s) responsible and to look into possible underlying causes for the illness.

Affected Breeds

Although pneumonia is relatively uncommon in cats, all breeds of cats are susceptible. Those with brachycephalic (flat-faced) features (such as Persians, Ragdolls, and Himalayans) are more likely to experience upper respiratory tract infections, which may put them at risk for complications, such as pneumonia.

Treatment

Pneumonia is treatable in most cases. However, the outcome for a cat with pneumonia can depend heavily on the cause of the pneumonia and the overall health status of the pet. If the cat is very young, very old, or already sick with another condition, the prognosis may not be as favorable as if the patient was healthy before pneumonia developed.

Additionally, if the underlying cause of the pneumonia is FIP virus or another potentially fatal illness, the patient may recover from pneumonia but die from other complications of the underlying disease.

Treatment for pneumonia will necessarily have several goals:

• Stabilization of the patient: If the patient is having significant trouble breathing or is otherwise unstable, oxygen therapy and other treatments may be necessary to stabilize the pet.
• Treating the pneumonia: Antibiotics are often prescribed to begin treating bacterial infections while additional test results are pending. If a pet is seriously ill from pneumonia, hospitalization may be recommended so that the patient can be supported and monitored as treatment is progressing.
• Addressing any underlying illnesses: If specific bacteria, viral, or fungal organisms are identified, additional medications may be prescribed to address the infection. A veterinarian may also recommend repeating chest X-rays periodically to monitor how well the pneumonia is resolving.

Prevention

Prevention of pneumonia is possible only to the extent that infectious diseases are prevented through routine vaccination and regular wellness exams. Prevention of severe pneumonia is possible with early treatment of any signs of respiratory disease. This is especially true for brachycephalic breeds and cats with preexisting underlying diseases.

This article has been reviewed by a Veterinarian.