Meat is a good source of protein as well as being highly palatable. However, pets can not live on a meat diet only due to the very high amount of phosphorus and low amount of calcium. The ratio of calcium to phosphorus in a pets diet should be in the order of 1.2-1.4 calcium to 1.0 phosphorus. Meat also does not contain enough iron, copper, magnesium, iodine, or sodium. Meat should not exceed 25% of the pets diet.
Milk is good source of protein, fat, vitamin D, vitamin A, vitamin B12, calcium, phosphorus, potassium, and iodine. In the wild, when puppies are weaned from the mother, they never drink milk again. It is not necessary for their growth or maintenance of a healthy state. Many pets older than 12 weeks of age cannot metabolize milk and consequently suffer from diarrhea, because they lack the enzyme called lactase. Those pets that do not have the lactase enzyme and can drink milk without developing diarrhea may be fed milk as a part of their diet.
Liver is a good source of protein. It is very high in phosphorus and vitamin A, vitamin B1, niacin, chorine, and cobalt. Although it is low in calcium.
Fish is a good source of protein, magnesium, iodine, and selenium. Raw fish contains an enzyme called thiamin's which will destroy vitamin B1. Vitamin B1 deficiency can lead to brain damage. Early signs include weight loss, not eating, vomiting, and weakness in the hind quarters, followed by irritability, wobbliness, and walking with the head and neck downwards. Excess fish can result in the diet being high in unsaturated fatty acids.
Eggs are an excellent source of protein, vitamin B12, vitamin D, iron, sulfur, and chorine. Raw egg white contains an enzyme which destroys biotin. Biotin deficiency cause dry flaky skin and hair. Raw egg yolks are not a problem. A cooked egg is an excellent source of protein for the pet.
Kidney is a very good source of protein, very high in phosphorus and low in calcium. It is also a good source of vitamin B1 and cobalt. pets that are fed a kidney only diet, can develop a disease called nutritional secondary hyperparathyoridism.
These are a good source of calcium, phosphorus, and copper. Chewing on bones helps to maintain healthy gums and removes plaque and tartar from the teeth. The risk with bones is that they may become caught in the teeth or throat or may cause a blockage of the intestine if swallowed.
Green vegetables such as lettuce, cauliflower, and cabbage are not of much value to the pet because of high water fiber content and poor palatability. Other veggies such as potatoes, carrots, and turnips fed raw are not very palatable and are poorly digested. Cooking will improve their palatability and digestibility. When cooked they are a good source of vitamin A and energy.
If the pet is on a complete diet, that is, one which covers all of the nutritional requirements, the addition of a mineral- vitamin supplement may be harmful. This applies particularly to an excess of vitamin A and D, phosphorus, and calcium. If not harmful the addition may be of no benefit to the animal. The supplement should only be fed to the pet if the diet is deficient in those areas or if it has some kind of metabolic problem or disease. Always seek the advise of your veterinarian. Only your veterinarian can evaluate the need and quantity of a supplement.