Method for Preventing Diet Induced Carnitine Deficiency in Domesticated Dogs and Cats

The invention relates to the field of pet food compositions and more specifically to pet food enriched with L-Carnitine.

L-Carnitine is a quaternary amine that promotes beta-oxidation of long-chain fatty acids by facilitating their transfer across the mitrochondrial membrane. L-Carnitine has also been shown to promote oxidation of branched-chain amino acids and the utilization of acetyl-coenzyme A.

In mammalian species, L-Carnitine concentration in cardiac and skeletal muscle is much higher than in serum. In these tissues fatty acids are utilized as a major source of energy. Because of L-Carnitine's central role in transporting fatty acids to the site of oxidation, adequate levels of a L-Carnitine are required for normal fatty acid and energy metabolism in mammalian hearts. This is evidenced by the restoration to normal of fatty acid oxidation in muscle homogenates of certain L-Carnitine deficient patients. A relationship between deficient levels of myocardial L-Carnitine and cardiomyopathy has been observed in both hamsters and dogs. Restoration toward normal of such deficient L-Carnitine levels has been shown to result in improved myocardial function in both species.

In mammals, L-Carnitine is derived from the diet and from biosynthesis in the liver, and in some species, kidney and other tissues. Neither cardiac nor skeletal muscle is capable of synthesizing L-Carnitine, however. Thus, the L-Carnitine found in these tissues was either absorbed from the diet or biosynthesized endogenously by other tissues.

The present invention is for a method of preventing diet-induced carnitine deficiency in domesticated dogs and cats using a dietary supplement containing a prophylactic amount of L-Carnitine. The invention is useful in preventing L-Carnitine deficiencies which can lead to a multitude of conditions, including myopathic heart disease, ischemic heart disease, hyperlipidemia, ketosis, muscle weakness and premature aging.

Pets, particularly the carnivores, are at great risk for developing L-Carnitine deficiencies. As Table 1 indicates, dog and cat foods are extremely low in free L-Carnitine levels as compared with that found in raw ground beef. Most pets are maintained strictly on commercial pet food diets and are thus kept chronically deficient in L-Carnitine. This results in a diet-induced carnitine deficiency.

Six apparently healthy Greyhound dogs were determined to be normal by physical examination, fecal flotation, complete blood count, serum biochemical profile, ECG, and echocardiography. They were fed a standard commercial dog food diet free choice for a one-month control period. Control plasma samples (as well as subsequent test samples) were obtained following an eight-hour fast on two consecutive days for analysis of total, free, and esterified L-Carnitine concentration. The average of the plasma L-Carnitine concentration on two consecutive days was taken for each dog and each measuring period.

Following the control period, all of the dogs were continued for two weeks on the standard commercial dog food diet supplemented with L-Carnitine. The L-Carnitine supplement was in the form of 0.5 kg per dog per day of raw frozen lean ground beef. This was equivalent to a daily supplement of 350 mg. of L-Carnitine per dog. Plasma samples were drawn on days 7 and 8 (averaged for the one-week measurement) and days 13 and 14 (averaged for the two-week measurement) for L-Carnitine analysis. Differences between the means of each test period and control were determined by the Student's t test.

The results of the study are shown in Table 2.

The data in Table 2 indicates that the plasma L-Carnitine concentration of a normal, healthy dog, previously maintained on a commercial pet food diet, is significantly increased if such pet food is supplemented with adequate levels of L-Carnitine.

It is clearly evident from the foregoing data that supplementation with a prophylactic amount of L-Carnitine of the standard commercial dog food will dramatically increase the plasma concentration of L-Carnitine in dogs.

It is to be understood that although the foregoing Example details the use of raw frozen lean ground beef as an L-Carnitine source, other sources within the scope of the claims can be readily utilized in the application of the invention with essentially equivalent results. For example, meat or meat by-products may be used other than raw frozen lean ground beef. These meat or meat by-products may be heat processed, dried or frozen and are suitable substitutes provided such meat or meat by-products have an L-Carnitine concentration in the range of 0.2 to 2.0 grams L-Carnitine per kilogram. The term "meat" is understood to apply not only to the flesh of cattle, but also that of other mammals, poultry and fish. The term "meat by-products" is intended to refer to those non-rendered parts of the carcass of slaughtered animals including but not restricted to mammals, poultry and the like.

Also within the scope of the claims would be the use of commercially prepared L-Carnitine such as that obtained from Austin Chemical Company, Inc., 9655 West Bryn Mawr Avenue, Rosemont, Ill.

These L-Carnitine supplements may be administered separately in the form of dietary supplements or they may be added at the time of manufacture of the commercial dog food as an additional ingredient in the commercial dog food. If used as a separate dietary supplement, the L-Carnitine may be combined with other valuable nutritional or prophylactic substances. Examples of this would be a combination of L-Carnitine with a vitamin and mineral preparation. Another example would be the inclusion of a prophylactic amount of L-Carnitine with an anti-heartworm medication such as diethylcarbamazine.

The L-Carnitine supplement may also be administered as a liquid preparation. L-Carnitine is extremely soluble in water. Such a liquid preparation may be prepared by dissolving the appropriate amount of L-Carnitine in a waterbased solution. Flavoring agents or other nutritional or prophylactic substances may likewise be combined in the solution. The liquid preparation may be administered to the pet separately as a dietary supplement. It may be added to the pet's drinking water or to the animal's food. Further, the concentration of L-Carnitine in the liquid preparation may be such that the appropriate amounts in the range of 0.2 to 2.0 grams of L-Carnitine may be easily measured out and administered as above described to the animal daily.