It is often debated among cat owners whether cats can tolerate milk. Indeed, there are cats who tolerate milk, while others can not.
The same problem is known in humans and here we know what the cause is. When the milk comes down in the small intestine, it decomposes to absorption into the body. For this to occur, milk is degraded by an enzyme called lactase.
If this enzyme is not present, the cat will not be able to absorb the milk and you will often see that the cat gets diarrhea in varying degrees. The reason for this type of diarrhea is that lactase deficiency leads to a acid reaction in the colon, causing the absorption of water to decrease.
What can I do?
If you offer your cat dairy products and diarrhea occurs, it may be because lack of lactase.
If you provide food free of lactase so food that does not containing milk or milk products, then the diarrhea will stop. If this happens, then it may be dairy products, which cause diarrhea, so you should avoid these.