The Truth About Cats and Milk. Why Milk Isn’t Good for Kitties

Milk Is Not Natural for Cats

Cats are obligate carnivores meaning their bodies are designed to get nutrition primarily from meat sources (1). While kittens can tolerate milk from their mother in the early stages of life, cow’s milk and other dairy products are not a natural part of a cat’s diet once they are weaned.

Cats’ bodies produce only limited amounts of the enzyme lactase which is needed to properly digest lactose, the sugar found in milk. Lactose is not found naturally in the wild cat diet, so cats have not adapted the ability to digest it efficiently. Their gastrointestinal systems lack the proper bacteria and enzymes to break down and utilize the nutrients in cow’s milk (2).

Since cats are obligate carnivores designed to get nutrition from animal flesh, feeding them cow’s milk goes against their biology and can lead to digestive issues.



Lactose Intolerance

Most cats are lactose intolerant to some degree after weaning, according to experts (source). Lactose is a sugar found in milk and dairy products. Cats lose the ability to digest lactose after they are weaned off their mother’s milk as kittens. Unlike humans, cats stop producing the enzyme lactase which is needed to properly digest lactose. When cats consume dairy, the undigested lactose travels through the intestinal tract, drawing water into the intestines by osmosis. This leads to diarrhea and digestive upset.

Digestive Upset

Milk can cause digestive upset like diarrhea, vomiting, gas and stomach upset in cats. This is because most cats are lactose intolerant and lack the enzyme lactase needed to properly digest lactose, the sugar found in milk (Purina, 2023). When cats drink milk, the undigested lactose in their intestines pulls in fluid, leading to diarrhea. The lactose also ferments in the intestines, producing gas that can cause uncomfortable bloating and flatulence. Vomiting is another common symptom, as the lactose irritates the digestive tract. According to PetMD, signs of digestive upset from milk can show up within 12 hours of a cat consuming milk or milk products (PetMD, 2023). To avoid gastrointestinal upset in cats, it’s best to avoid giving them cow’s milk or products made with cow’s milk.


Some cats may be allergic to the proteins in milk. The symptoms of a milk allergy in cats can include chronic itching and skin inflammation, diarrhea, vomiting, gas, lack of appetite, and weight loss.

Cats with a milk allergy may experience a reaction every time they ingest milk. This is because their immune system sees the proteins in milk as foreign invaders and mounts an immune response. Allergies often develop after repeated exposure over time.

Treatment involves removing all milk and dairy products from the cat’s diet. Veterinarians may prescribe hypoallergenic diets or novel protein diets made with ingredients the cat has never eaten before. Anti-itch medication can provide relief from itching and skin issues.

If your cat shows signs of an adverse reaction to milk such as vomiting or skin irritation, discontinue milk and talk to your vet. They can help diagnose a milk allergy and recommend the best treatment options.

Obesity Risk

Milk is high in calories and fat, which can contribute to obesity if cats drink it regularly. According to Hill’s Pet Nutrition, milk and dairy products contain more calories per serving compared to meat-based cat foods [1]. They explain that “these products are actually quite fattening and if offered regularly to your cat, their solid food diet should be adjusted to compensate for the calories in the milk to avoid obesity.”

PetMD also warns that cow’s milk contains a significant amount of fat that can lead to obesity in cats if consumed regularly [2]. Allowing cats to drink milk on a regular basis without adjusting their main diet puts them at risk for becoming overweight or obese.

Safer Treats

While milk may seem like a tasty treat for cats, there are much healthier and safer options you can give your cat instead. Here are some vet-recommended alternatives to milk that your cat is sure to love:

Fish: Cats love fish, which is high in protein and omega-3 fatty acids. Salmon or tuna make great treats. Just make sure to get fish packed in water, not oil, and avoid raw fish due to bacteria risks (source).

Meat: Lean deli meats like turkey and chicken can satisfy your cat’s carnivorous cravings. Opt for low-sodium varieties. Canned fish like tuna is another protein-packed option (source).

Veggies: Surprisingly, cats enjoy veggies too. Try pieces of steamed broccoli, carrots, green beans or peas. Just don’t overdo it, as cats require more protein than plant-based foods (source).

Commercial treats: Look for all-natural, limited ingredient treats made with quality ingredients like chicken, salmon or tuna. Avoid milk, wheat, corn and soy. Prioritize treats made in the USA to ensure quality standards.

Treats specifically formulated for cats can provide a nutritious choice over milk. Focus on high-protein options free of fillers, artificial flavors and preservatives.

Kittens Can Have Milk

Mother’s milk provides essential nutrients for newborn kittens in the first weeks of life. Kittens rely entirely on their mother’s milk for sustenance during this early developmental stage. Mother’s milk contains the ideal balance of proteins, fats, carbohydrates, vitamins and minerals to promote healthy growth.1

While mother’s milk is perfectly suited to kittens’ needs, they do not stay entirely dependent on it for long. Kittens will begin sampling solid foods around 3-4 weeks of age as their teeth start to come in. By 8-12 weeks old, kittens should be completely weaned off their mother’s milk.23 Kittens this age are developmentally ready to transition to eating solid foods and no longer require the nutrition provided by mother’s milk.

Therefore, while mother’s milk is perfectly appropriate for young kittens, they should be fully weaned by around 12 weeks old. Once weaned, kittens will receive the nutrition they need from quality commercial or homemade cat foods rather than continuing to nurse from their mother.

Rare Exceptions

While most cats are lactose intolerant and should avoid consuming cow’s milk, a few individual cats may tolerate small amounts of milk. According to PetMD (, some cats continue to produce the enzyme lactase into adulthood, allowing them to break down lactose. Hastings Veterinary Center also notes that ( some adult cats may be able to consume small amounts of milk without issue. However, even cats that seem to tolerate milk should only have it in moderation, as overconsumption can still lead to digestive upset and other problems. It’s generally safest to avoid giving milk to cats, though the rare exception may do fine with an occasional small treat.

The Bottom Line

In summary, the majority of cats lack the ability to properly digest milk due to lactose intolerance. Consuming milk often leads to digestive upset in cats, causing diarrhea, vomiting, gas, and bloating. Some cats may even have milk allergies. Since milk provides a lot of calories and fat without adequate nutrition for cats, it can cause weight gain and obesity over time. While kittens can have milk before weaning, most felines should not drink milk after that point. Even though a small number of cats may tolerate milk without issues, it is not worth the potential risks for most cats. There are many other safe, healthy treats cat owners can offer instead. Unless recommended by a veterinarian for a specific cat, milk should be avoided for feline health and wellbeing.

Consult a Vet

If you’re still unsure about whether your cat can handle milk, it’s best to check with your veterinarian. They know your cat’s medical history and any sensitivities they may have. Your vet can make an informed recommendation on whether small amounts of milk are okay for your specific cat.

In general, kittens under 6 months old may tolerate small amounts of milk better than adult cats. But each cat is different, so don’t make assumptions. Check with your vet first before introducing milk.

For cats with gastrointestinal issues, allergies, obesity, or other health conditions, milk is usually not recommended at all. These cats are at higher risk for adverse reactions. Your vet can suggest healthier treat alternatives your cat can safely enjoy.

Your veterinarian wants what’s best for your cat. Don’t hesitate to ask them any questions you may have about milk and other foods. They can provide tailored advice based on your cat’s needs and history.

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