Carnitine Deficiency in Dogs

Carnitine, specifically L-carnitine, is an amino acid that aids with nutrient transportation in the bloodstream and helps cells metabolize fat. It is found in high quantities in red meat and dairy products. Carnitine is produced in the liver, so dietary deficiency isn’t normally a problem, but in some cases dogs, with congestive heart failure (CHF) also develop carnitine deficiency. This is most often seen in dogs with CHF from an inherited condition called dilated cardiomyopathy (DCM) that causes the left heart chamber to expand or dilate. Stretching of the muscles weakens the heart’s ability to pump blood and causes gradual heart failure. In most cases, veterinarians aren’t sure if carnitine deficiency is the primary problem, or if it develops secondary to DCM. Some families of Boxers have been diagnosed with primary carnitine deficiency, while Cocker Spaniels with inherited DCM have also responded well to carnitine supplementation. Carnitine works with another amino acid, taurine, so the two are often given together. This treatment doesn’t reverse heart dilation, but it can help to support heart function and aid with nutrient transportation. Treatment with carnitine supplements may reduce the symptoms of CHF and make other medications less necessary. Remission can last for a period of months or years.

Carnitine is a naturally occurring substance that helps the body transport and metabolize fats. Deficiency is rare in dogs and usually corresponds with inherited dilated cardiomyopathy. Veterinarians call this myocardial carnitine deficiency. Carnitine supplements can sometimes reduce symptoms.

There aren’t any known symptoms directly related to carnitine deficiency. Some dogs with inherited DCM develop a heart murmur up to 4 years before CHF become a problem. In other cases, symptoms of CHF are the first sign. See a veterinarian right away if you notice any of the following signs of heart failure.

• Abnormal heart rhythm
• Tiredness
• Reduced ability to exercise
• Poor appetite
• Shortness of breath
• Panting or coughing
• Greyish mucus membranes in the mouth
• Enlarged abdomen

Types

True carnitine deficiency  This means that carnitine deficiency is the primary problem. It has only been diagnosed in some families of Boxers, probably as a result of genetic abnormalities in carnitine production or absorption. Carnitine levels are difficult to test, so low-level carnitine deficiency could be more common than veterinarians are aware.

Secondary carnitine deficiency  Carnitine deficiency occurs in combination with many forms of CHF related to DCM. This type of deficiency is believed to be the result of heart failure rather than the cause.

Since carnitine is manufactured by the body, veterinarians don’t know exactly what causes deficiency. Breeds with inherited DCM are more likely to be at risk.

• Boxers
• Cocker Spaniels
• Doberman Pinschers
• Great Danes

Other factors, like obesity and diabetes can also increase the risk of CHF.

A definitive diagnosis of carnitine deficiency requires a biopsy of the heart, called an endomyocardial biopsy. This is an invasive procedure that isn’t often done on dogs. It’s more likely that the veterinarian will evaluate your dog’s symptoms to determine the need for carnitine supplementation.

In some cases, an electrocardiogram test will pick up an abnormal heart rhythm before a dog develops symptoms. This finding might appear on a routine examination. Once CHF has developed, the veterinarian will be able to hear abnormal sounds by listening to your dog’s heart and lungs with a stethoscope. The pulse will usually be fainter and crackles related to fluid in the lungs will be audible. The veterinarian will order chest x-rays or ultrasound to confirm the state of the heart. Dogs with DCM usually show an enlarged heart chamber on one or both sides, and dense fluid-filled lungs.

The veterinarian will need to check for other conditions that could be causing the problem such as a heart infection or a blood clot. Blood tests will also help to determine the degree of heart failure. Since many forms of carnitine deficiency are inherited, your dog’s breed and family history will be very important. DCM often runs in specific families within the breed. It also develops at a younger age than other forms of heart failure (4-10 years).

The recommended treatment for carnitine deficiency is a supplement containing l-carnitine (other forms of carnitine are not effective). This is often accompanied by a taurine supplement since the two amino acids work together to transport necessary fats throughout the body and help cells metabolize these nutrients. Taurine is somewhat less expensive than carnitine, so it could be prescribed alone instead if the vet thinks this will be effective.

Since a definitive diagnosis of carnitine deficiency is rare, l-carnitine supplements are often prescribed for dogs with heart failure whether the direct cause is known or not. Higher levels of carnitine can assist weak heart muscles with transporting nutrients, even if the condition is not caused by carnitine deficiency. Other medications may often be prescribed at the same time and tapered off if the carnitine supplement seems to be effective.

Carnitine supplements are used to treat other conditions in humans, including ketoacidosis that occurs with diabetes, hyperlipidemia, and some cognitive problems. It’s believed that this treatment could help dogs with these conditions as well, and some veterinarians might recommend this treatment. Since l-carnitine already occurs naturally in the body, these supplements are very safe for dogs, either taken alone or combined with other medications that treat these diseases.

Dogs with a true carnitine deficiency may respond well to carnitine supplementation. Unfortunately, this condition is rare, and most dogs with DCM have only a mild reduction in their symptoms. Treatment has been most effective in Boxers and Cocker Spaniels, so if your dog belongs to one of these breeds there may be a higher chance of recovery or remission. This will have to be evaluated by a veterinarian.

Keeping your dog on a diet high in foods that contain carnitine may also be beneficial. While dietary deficiency isn’t believed to be a problem, low-level deficiencies with no symptoms aren’t easy to diagnose. Red meat, especially lamb, fish, poultry, and dairy products are all high in carnitine and also part of a healthy diet. Making these foods part of your dog’s diet, especially if DCM runs in the family, could be helpful. In any case, this type of diet won’t harm your dog.

Some forms of carnitine are available as an over the counter medication. Discuss the effectiveness of these with your veterinarian, especially if your dog is obese, has diabetes or may develop DCM. Don’t use any supplements designed for humans, unless the veterinarian says definitively that they are safe.