Cat Litterbox Odor from Milk Products

My mother's house reeked. There was no other word for it. The smell was overpowering and it was not caused by the usual dead-mouse-in-the-closet we normally found when a smelly problem developed.

It was easy to find the source of the smell, but understanding the reason behind it took a little bit of research. The culprit of the smell was the litter box. My mom had two half-grown kittens that were very conscientious about using the litter box. My mother changed the litter daily, but still the horrible odor remained and grew steadily worse.

Exasperated, she called me one day and said, "I think I'm going to have to get rid of my cats. I just can't take the smell anymore."

This puzzled me because I have always had indoor cats, litter boxes and never had a problem with the odor from the litter boxes. I made a special trip to her house to check out what could be causing the problem. It was easy enough to detect once I stepped through the door.

The smell of sour milk filled the house. "Mom, are you giving the cats milk?"

She smiled, "Oh, yes. I have been pampering them."

The culprit had been found. I explained to my mom that cats lose the ability to digest milk as they get older. Kittens have an abundance of the enzyme lactase. Lactase is used in the digestive track to break down some of the naturally occurring sugars in the milk. As cats mature, they lose the natural ability to digest milk, thus, the sour smell came from undigested milk in the litter box.

It took just the simple change in diet and a few days for their systems to clean out and the smell vanished. Mom was heart-broke that she had caused the problem herself and did not want the cats to feel like they were being punished for her mistake. She asked, "Is there a safe treat I can give them?"

A cat's diet should be made up of a high percentage of animal protein. Commercial cat food is the best source most people can obtain easily. Be sure to check that some type of meat is the first ingredient listed when buying cat food at the store.

You can find several brands of cat treats at the store. These are generally small pieces of prepared cat food that is soft, but not wet, so they are safe to give to the cat without worrying about having to clean up a mess.

By changing the cats' diet, my mom was able to enjoy her pets once again. The cats returned the favor by eliminating her annual mouse problem and by keeping her company. They had a great relationship where the cats would bring her the mice they caught and she would trade the dead mouse for one of the cat's special treats.

Cornell University: Feeding Cats

Cornell University: Giving Milk to Cats