If cats are lactose-intolerant, how did we come to believe that giving cats milk is good?

"Kittens produce this enzyme in smaller amounts as they develop, and by six months of age, most kittens have adult levels of lactase. These adult levels are insufficient to digest milk and their bodies can no longer tolerate it. Basically, like some humans, most cats become lactose intolerant." - Hastings Veterinary Hospital

"Kittens ingest digestible carbohydrates (i.e., lactose or milk sugar) before weaning. Adult cats must rely primarily on gluco-neogenesis from glucogenic amino acids (ketoacids), lactic acid and glycerol for maintenance of blood glucose concentration". - Introduction to feeding normal cats

The answer to the questions is this: kittens eagerly drink their mother's milk - colostrum. Observers would understand that adult cats also drink milk. But in the early days of cat domestication there was less knowledge and they didn't realise that at 6 months of age young cats do not have sufficient lactase (lactase deficiency) to digest lactose and become intolerant of it.

Nowadays, things have changed thanks to the huge amount of education provided by the internet on millions of cat websites!

But there are still people in developing countries and even developed countries where they believe that cats should be fed milk as a treat.

When they do this their cat enjoys drinking the milk because it is fatty. Cats like fatty foods. But it would seem that the adult cat does not understand that they are lactose intolerant.

But they don't need to realise it because they have inherited their wild cat ancestor's character and that wildcat never has the opportunity as an adult to drink milk.

It is only in the human environment as domesticated wildcats that they encounter a bowl of cow's milk containing lactose which they cannot digest but which tastes good normally. Not all domestic cats take to drinking it.

What is lactose?

Lactose, or milk sugar, is a disaccharide sugar composed of galactose and glucose subunits and has the molecular formula C₁₂H₂₂O₁₁.
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P.S. please forgive the occasional typo. These articles are written at breakneck speed using Dragon Dictate. I have to prepare them in around 20 mins.

Ginger tabby almost drowns himself in cow's milk. Diarrhea should follow.

Well, cats love cow's milk as it is fatty. And this little ginger tabby loves milk more than most cats as he almost drowns himself in it as he submerges his head in the stuff. He comes up for air with his head covered. I think he hasn't learned yet that cow's milk tastes nice but it isn't so nice for the digestive tract.

P.S. Maybe he is fishing around for something in the milk. I am unsure. I think this is about youthful exuberance in finding a food they love but not having experienced the downsides.

Back in the day, say around a hundred years ago and even more recent than that, hundreds of millions of cat owners thought that giving their domestic cat cow's milk was the thing to do. Not nowadays. These days we are more educated generally and in respect of the feline diet. Did I say that people are more educated nowadays than a hundred years ago? I am not sure that that is true but let's move on.

Certainly, the internet has educated hundreds of millions of people about cat welfare including their diet. We know that the large majority of domestic cats are lactose intolerant and therefore they are intolerant of cow's milk. This is because they lack the enzyme to break it down. It causes bloating and diarrhoea.

The same thing happens with people. Many humans are turning away from cow's milk which is the wise thing to do. I am one of those people. Cow's milk causes bloating for me. I use oat milk but there are many alternatives these days. You can buy specially prepared milk for cat but it is very expensive.

Other symptoms of lactose intolerance may include:

• tummy pain or discomfort.
• bloating.
• farting.
• diarrhoea or constipation.
• feeling sick or being sick.

The best solution is to give them water but ironically tap water sometimes doesn't taste very good for cats. That's why they tend to prefer rainwater in a paddle even if it is muddy compared to tap water in a bowl.

Tap water contains anti-viral, anti-bacterial and anti-parasite chemicals such as chloride. It cleans up the water but as domestic cats have very highly tuned senses including a great sense of smell, they don't like the smell of chlorine which they pick up but we don't.

Apparently if you leave it standing for a while it helps to allow the chlorine content to evaporate. I don't know if that is true but a good source told me that information.

Ginger tabby almost drowns himself in cow's milk. Diarrhea should follow. Screenshot.