Cat Facts: Cats Are Lactose Intolerant

brown tabby kitten drinking a bowl of milk

We know, of course, that kittens drink milk. But do adult cats still need milk as part of their diet? Can they even drink milk?

Many cats are lactose intolerant and cannot digest milk properly. While small amounts of lactose-free milk or dairy can be given as an occasional treat, they should not be a regular part of a cat’s diet. Cats require a diet that’s high in animal protein and fat to meet their nutritional needs. 

In this article, we will discuss the facts about cats and their digestion of dairy products. If you’re interested in learning more about how cats digest dairy, keep reading!

What Is Lactose Intolerance?

Lactose intolerance means that the body is unable to digest lactose, which is the primary sugar found in milk and other dairy products.

Normally, lactose is broken down into easily digestible bits by the enzyme lactase, which is produced by cells in the small intestine. Young mammals produce plenty of lactase, which is important because milk is their only source of nutrition during the first few weeks – or months – of life.

As mammals grow out of infancy, the amount of lactase produced by the body decreases. Most adult mammals have a reduced ability to digest lactose to varying degrees, from mild reduction to total inability to digest it.

Lactose intolerance is a well-known problem in humans, for example. Approximately two-thirds of adult humans have some level of lactose intolerance. This is a rather surprising fact, given that milk is a common food item for a large portion of the population.

Are Cats Lactose Intolerant?

Like most other mammals, as kittens mature and begin to eat solid food the amount of lactase produced by their intestines decreases. By the time they are adults, most cats produce little or no lactase which means they are unable to digest the lactose present in the milk.

So yes, cats are, for the most part, lactose intolerant. But just like people, some individuals continue to produce enough lactase throughout their entire lives to be able to comfortably digest lactose.

Should I Give My Cat Milk?

Because most cats are lactose intolerant, it is not recommended that they be fed milk. They may certainly enjoy it and lap it up enthusiastically but, like lactose intolerant people, cats may suffer from digestive problems if they consume dairy products.

But what about lactose-free milk, you ask? If lactose intolerant people can drink lactose-free milk, shouldn’t cats be able to as well?

The answer to this one is yes, you can give your cat lactose-free milk if you want to. However, we recommend it as an occasional treat only, rather than a regular part of their diet.

This is because if your cat is drinking a lot of milk, then it will be drinking less water. Also, cats may end up consuming more calories when they replace water with milk, which can lead to overweight or obesity in cats.

There are commercially available lactose-free or lactose-reduced milk formulated specifically for kittens and cats. These can usually be found on pet store shelves.

two cats drinking from a bowl of milk

What Happens To Lactose In The Absence Of Lactase

Without lactase, lactose cannot be digested. For lactose to be absorbed by the body, it must be broken down into simple sugars.

When lactose is consumed, it passes through the stomach into the small intestine. There, the lactase produced by cells inside the small intestine then breaks the lactose down into smaller parts, which are the simple sugars (monosaccharides) glucose and galactose.

The glucose and galactose monosaccharides are then absorbed across the intestinal wall and enter the bloodstream, where they can be transported to various tissues and organs for energy production.

In individuals who are lactose intolerant, the body does not produce enough lactase to fully digest the lactose in milk and other dairy products. As a result, the undigested lactose passes through the small intestine and into the large intestine, where it can be fermented by bacteria.

The process of fermentation process generates gases, such as hydrogen, carbon dioxide, and methane, which can cause bloating, flatulence, and abdominal discomfort. The undigested lactose can also increase the water content in the large intestine, leading to diarrhea.

This fermentation of lactose in the large intestine leads to the digestive upset typically seen in lactose-intolerant people. The severity of symptoms can vary depending on the degree of lactose intolerance and the amount of lactose ingested.

In some individuals, small amounts of lactose may be tolerated without symptoms, while others may experience severe symptoms after consuming even small amounts of lactose.

What Are The Symptoms Of Lactose Intolerance In Cats?

When lactose intolerant cats drink milk they suffer the same digestive upsets as people do.

The symptoms of lactose intolerance include the following:

  • Diarrhea: This is the most common symptom of lactose intolerance in cats. Diarrhea can range from mild to severe and may be accompanied by vomiting at times.
  • Abdominal pain: Cats with lactose intolerance may experience abdominal pain or discomfort. It can be difficult to detect signs of abdominal pain in cats. Things to look for include restlessness, vocalizing, or avoiding being touched.
  • Bloating: Lactose intolerance can cause gas to build up in the intestines, leading to bloating and pain.
  • Flatulence: Cats that are lactose intolerant may experience an increase in flatulence due to the production of gas from the lactose fermentation. Yes, your cat will fart noticeably!
  • Lethargy: Cats that are not feeling well tend to sleep more. Some cats may become lethargic or less active than usual due to the discomfort caused by lactose intolerance.

It is important to note that these symptoms can also be caused by other digestive disorders, so it is always best to consult a veterinarian to determine the underlying cause of your cat’s symptoms.

orange tabby drinking from a bowl of milk

Diagnosing Lactose Intolerance In Cats

If you give your cat milk and you notice that your cat is not feeling and is showing some of the symptoms described above then your cat may very well be lactose intolerant.

However, none of the described symptoms are unique to lactose intolerance, and a sick kitty should always get checked by the vet to make sure the situation is under control.

Unlike in people where lactose tolerance testing is easily done, diagnosing lactose intolerance in cats typically means ruling out all other possible causes of gastrointestinal distress. If all other causes are ruled out, then lactose intolerance may be suspected.

The veterinarian may need to conduct a set of tests to distinguish lactose intolerance from other illnesses like inflammatory bowel disease (IBD), bacterial infection, and gastrointestinal cancer.

One of the first steps is to collect a fecal sample for testing for intestinal parasites or abnormalities that could be causing the symptoms. This helps to rule out any infections or other underlying issues.

In addition, blood tests will be done to evaluate the cat’s overall health. A complete blood count can provide information on the cat’s red and white blood cells, and a biochemical profile can reveal information about organ function and nutrient levels in the body.

If the cat’s symptoms persist, an abdominal x-ray may be done to confirm the absence of any abnormalities in the gastrointestinal tract. The x-ray can help identify if there are any obstructions or masses that could be the cause of the cat’s symptoms.

If all other causes of your cat’s distress are ruled out, the next step your veterinarian will recommend is a dietary trial. This is where you modify your cat’s diet to exclude all dairy products for a period of time. If your cat’s symptoms improve during this time, it may be an indication of lactose intolerance.

It’s important to remember that lactose intolerance is just one potential cause of digestive issues in cats, and other conditions may have similar symptoms.

If you suspect that your cat may be lactose intolerant, it’s best to consult with your veterinarian to determine the underlying cause of their symptoms and develop an appropriate treatment plan.

Foods To Avoid Giving To Cats

In general, feeding cats foods that are high in lactose can lead to digestive upset. While some cats can tolerate small amounts of dairy without issue, other cats may react to even very small amounts of lactose. For this reason we recommend avoiding it altogether.

Here are some foods to avoid giving to cats due to lactose intolerance:

  1. Milk and Dairy Products: Milk and dairy products like cheese, yogurt, and ice cream are high in lactose and can cause digestive problems in cats.
  2. Cream: Heavy cream and other cream-based products are also high in lactose and should be avoided.
  3. Butter: While butter is not high in lactose, it is high in fat and can lead to gastrointestinal problems in cats.
  4. Whey Protein: Whey protein is a byproduct of cheese production and is found in many protein powders and supplements.
  5. Baked Goods: Many baked goods contain milk or cream, so it’s best to avoid giving cats any type of baked goods, including cakes, cookies, and pastries.
white kitten drinking milk from a bottle

Safe Dairy Alternatives For Cats

As mentioned above, there are commercial kitten and cat milk products that are a safe option if you want to give your cat a dairy treat. But what above other milk substitutes such as soy, almond or coconut milk?

While soy, almond, and coconut milk are all safe for cats to consume in small amounts, some individuals with food sensitivities may not be able to tolerate even very small amounts.

Also, cats are obligate carnivores, which means that they require a diet that’s high in animal protein and fat to meet their nutritional needs. Plant-based milk alternatives like soy, almond, and coconut milk do not provide the same level of nutrition as animal-based proteins.

Therefore, it is not advisable to include plant-based milk substitutes in your cat’s regular diet.

Final Thoughts About Lactose Intolerant Cats

Although cats may love the taste of milk and dairy products, most cats are not equipped to digest lactose properly.

Feeding cats milk or dairy products can cause digestive problems, including vomiting and diarrhea. Therefore, it’s important to avoid giving them any foods high in lactose, including milk, cheese, and ice cream.

If you’re looking for an alternative to dairy, there are safe options available, such as lactose-free milk or specially formulated kitten milk replacer.

However, it’s always a good idea to consult with your veterinarian before making any changes to your cat’s diet to ensure that they are getting the nutrition they need to stay healthy and happy.

Disclaimer: This article is intended for information purposes only, and does not constitute medical advice. Always consult your veterinarian if you have specific concerns about your pet’s health.

ginger orange cat and kitten


  • Dr. Wendy Wilkins, DVM, PhD

    Dr. Wendy Wilkins is an experienced veterinarian and epidemiologist with over 20 years of expertise. She holds a Doctor of Veterinary Medicine (DVM) degree and a Doctorate in Epidemiology from the University of Saskatchewan. Throughout her career, Dr. Wilkins has excelled in clinical practice, academia, research, and regulatory veterinary medicine. She is a respected voice in knowledge dissemination, delivering factual information in a readable and understandable manner through articles, books, and public engagements.

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