Is milk bad for cats?

While milk can be healthy for humans, it is not a good source of nutrition for cats, since they cannot process the vitamins and minerals in the milk like we do. The best way to keep your cat healthy is to ensure they have access to plenty of clean drinking water and a varied, cat- friendly diet.

Domestic cats’ diets should replicate what they would eat if they were still in the wild. Cats are obligate carnivores, which means they must ingest certain amino acids to build protein. Cats achieve this by ingesting meat in their diet. Milk is not a natural source of protein for cats, and the notion that cats should drink milk is fundamentally a myth.

Kittens are born with the ability to digest lactose (the sugar found in milk) and they initially drink their mother’s milk for the first month after birth. Her milk contains the fat and other nutrients that a kitten needs to grow into a healthy, adult cat. When kittens are around four weeks old, their mother will start to push them away when they are trying to feed, to wean them off her milk.

After kittens are weaned onto solid foods, the enzymes in their digestive system change and they will become increasingly lactose intolerant. Adult cats have low levels of the enzyme lactase, which is the enzyme needed to digest lactose. As a result, cats can suffer gastrointestinal upsets if they consume milk.

Some cats can have an intense reaction to cows’ milk and become very ill after consuming it. Even cats with moderate lactose intolerance can experience discomfort due to colic after consuming milk.

If your cat is unable to digest the sugar present in milk, the lactose will pass through their intestinal tract undigested. There, it begins to ferment and it can produce gases. These gases can then lead to colic and cramps and occasionally excessive flatulence. Signs that your cat may be in pain with colic include lethargy as well as sometimes curling into a defensive posture to ‘guard’ their abdomen. You may also notice them having a bloated tummy when you pet them.

A cat with lactose intolerance may also develop diarrhoea. This is due to undigested sugars drawing water into the intestines.

With this in mind, it’s generally not recommended to give your cat milk, especially if you are unsure how they will react to it. There is no test to find out whether your cat is lactose intolerant; the only way to tell is when your cat ingests milk. Testing your cat by giving it milk is risky as a severely lactose-intolerant cat will quickly become very unwell and need urgent medical attention.

As with any other changes you might plan to make to your cat’s diet, it is best to consult your vet before giving milk to your cat.

You can buy special milk, called ‘cat milk’, from most supermarkets and pet shops. This cat milk is safe for cats and fully weaned kittens to drink. It is usually lactose-free but retains the higher fat content that cats enjoy.

As your cat gets older, treats such as cat milk should be reduced. When cats age, they become less active and too many treats can lead to them gaining weight.