Normal dogs require not less than 5 per cent of fat in their diet if they are to remain comfortably plump, and carry good coats. As much as 10 per cent can be fed, temporarily, to a dog that has lived on a fat-deficient diet, or half-starved, without causing digestive upsets, except perhaps in a few individual cases in which there is fat-sensitivity so- called chronic gastritis case, to use a common expression.
Every dog, however, appears to have its own special fat requirement; while some appear to be unable to digest fairly high proportion of beef fat added to their regular diet. In the absence of a fat ration, the dog uses up fat already stored in its body, until the fat content of the whole body falls to 6 per cent, after which emaciation becomes observable.
It is being able to maintain the balance between the laying down of fat and its regular rate of absorption that spells success not a particularly easy thing to do in these days of building congestion and motor traffic, which limit the possibility of either man or dog taking sufficient exercise.
The type of fat within the body depends in large measure upon the diet. If it comes from the food in the form of butter, beef fat, cream or lard, the dog’s fat remains soft and the dog appears unduly obese.
If, however, the source of the fat is digested carbohydrate, the fat in the body is much harder, and it is possible for the dog to carry a considerable quantity of such fat, firmly moulded into or around the body, with the clog looking fairly normal, certainly not obese.
Although both fat and carbohydrate foods provide energy, they play quite different parts in the metabolism of the body, and the one cannot be substituted for the other, both fat and carbohydrate being necessarily present in the same diet.
The inclusion of sufficient fat in the diet appears to have a definite value in maintaining bitch fertility but at no time should the proportion of fat fed to brood bitches exceed 5 per cent of the total ration. This applies also to lactating bitches during the summer, though rather more can be fed to them when the weather and the accommodation are cold.
Fat is very necessary in connection with the nourishment and well-being of the skin, and in this connection one must include the ears, which are lined with skin even down the ear canal. It has been proved that a number of skin diseases, including a fair proportion of cases of so-called chronic tear-canker’,’ respond to treatment consisting of feeding fat, or unsalted bacon in the feed daily, while the benefit derived from quite small amounts of pure, fresh linseed oil (not boiled oil) is well known to many breeders.
A shortage of fat in the diet may give rise in some dogs, principally the long-eared varieties, to a purulent form of ear canker.
Excess of fat fed to dogs lessens the appetite for other necessary foods and, even if it fails to excite biliousness and vomiting, it may retard growth in young animals.
Young dogs and recently weaned puppies are far less able than older animals to digest either meat proteins or fats. Rancid fats such as stale lard and rancid cod-liver oil, are capable of destroying vitamins A and E in the body. One useful effect of a store of fat within the body is that it may help to combat certain types of infection, especially those attacking the skin.