While milk is not necessary to a cat's diet, it can be a treat if given from time to time. However, some pets cannot tolerate milk because they do not produce an enzyme called lactase. Lactase helps with the digestion of lactose, which is found in milk. After weaning, the level of lactase activity falls to about 10 per cent of its peak activity. In some animals, diarrhea will occur if more lactose (i.e. milk) is consumed than the pet can digest. This is called "lactose intolerance".
A further contributing factor is the fact that cow and goat milk contains 4.5% to 5% lactose, compared to 4.2% in cat's milk. The high level of lactose in cow's milk can overpower a cat's ability to digest it. This is why many kittens often get diarrhea from drinking cow's milk. This does not mean that milk is unhealthy for cats. On the contrary, in pets that are able to tolerate it, milk can be an excellent source of protein and calcium.
Pets with milk intolerance can still consume dairy products under certain circumstances. For example, dairy products such as cheese (including cottage cheese) and unpasteurized yogurt usually have the lactose removed or have it partially broken down through bacterial action. As a result, these products are often well tolerated by cats that would otherwise get diarrhea after drinking milk.
It should be stated that neither boiling milk nor the use of skim milk affects an animal's ability to tolerate milk, since the lactose content remains unchanged in either case. The same applies to pasteurized yogurt and cultured milk (e.g. buttermilk), neither of which is well tolerated by lactase-deficient pets.
Lactose Intolerance, a common digestive disorder, is caused by the inability to break down the sugar in milk. That undigested sugar forms the perfect environment for bacteria to form in the intestinal tract and attack the stomach. cat and cat owners should be aware of the symptoms so they can remove all dairy products immediately from their pet's diet if they think lactose intolerance is at work.
Symptoms of Lactose Intolerance
The most common and overt signs of lactose intolerance are vomiting and diarrhea, which isn't surprising because the digestive system isn't working properly. Sometimes a cat will drink excess amounts of water because lactose intolerance can also cause dehydration.
Since lactose intolerance is essentially an allergic reaction, owners should also look for the signs one might more often associate with allergies. For instance, if the cat or cat licks its paws or rubs its face on the floor, then its skin is clearly irritated and itchy, and this could be the result of lactose intolerance if dairy products are indeed a staple of the pet's diet. It's also possible that other allergic reactions like a mucus discharge from the eye or nose could occur, although this is less common.
Other dairy products can have a different effect. Cheese, for example, can cause constipation. This problem manifests itself in the cat and/or cat straining to have regular bowel movements and small, hard, and dry feces.
Even puppies and kittens, who can obviously tolerate their mother's milk, are not necessarily immune to this problem. Puppies and kittens are often allergic to cow's milk, but not their mother's milk. This can lead to diarrhea and the pet being unable to wait until it's outside to have a bowel movement. The best rule of thumb for a cat and/or cat owner is to severely limit or simply eliminate dairy products from their pet's diet.