The Milk Mystery. Why Cats Can’t Resist Cream Despite Lactose Intolerance


For centuries, cats have been known for their love of milk. The iconic image of a cat lapping up a saucer of milk is familiar to pet owners and cat lovers worldwide. However, recent research has revealed that cats are actually lactose intolerant and unable to properly digest milk. This seems contrary to their well-documented affinity for the white stuff. So why do cats love milk so much if it gives them digestive trouble? This article will explore the science behind feline lactose intolerance, reasons why cats still find milk irresistible, and tips for safely giving milk treats.

Brief history of cats drinking milk

The idea that cats drink milk likely began centuries ago when cats lived in close proximity to humans keeping dairy cows. Before commercial cat food was invented, these cats had access to fresh milk in larger quantities than seen in the wild. According to sources, felines first developed a taste for milk when humans began domesticating cows around 6000 BC. As cats and humans began living together, especially on farms, cats were often fed milk fresh from the cows as a treat or supplement to hunted prey (Why can’t cats drink milk?). Over time, cats came to expect and enjoy milk provided by their human owners.

The saying “cats and milk” became widespread in popular culture in the 16th century with the phrase “care killed the cat,” meaning worry rather than milk killed cats. Later variations led to “curiosity killed the cat” (Origin of cats drinking milk). The myth solidified when cats were commonly portrayed in cartoons and TV lapping up a saucer of milk. So while milk may not be ideal nutrition for cats, the historical association persists.

Biology of lactose intolerance

Lactose is a sugar found in milk and dairy products. It requires the enzyme lactase to be properly digested. Kittens produce lactase to digest the lactose in their mother’s milk, but as they grow, most cats lose the ability to produce this enzyme. According to petMD, around 50-90% of adult cats are lactase deficient and unable to fully digest lactose.

When cats consume lactose without enough lactase to digest it, the undigested lactose travels to the large intestine where it ferments and causes gas, abdominal pain, and diarrhea – the signs of lactose intolerance. Dutch (2022) states that most cats begin losing the ability to digest lactose between 6-12 weeks as they are weaned off their mother’s milk.

Signs of lactose intolerance

Lactose intolerance in cats can cause a range of gastrointestinal symptoms. The most common signs of lactose intolerance after a cat drinks milk include:

Diarrhea – Drinking milk can cause loose, watery stool in lactose intolerant cats. Diarrhea may start within a few hours after ingesting milk and can last 1-2 days if untreated. If prolonged, diarrhea can lead to dehydration.

Vomiting – Some cats may vomit repeatedly after consuming milk products. Vomiting may be accompanied by lack of appetite, lethargy and discomfort.

Gas – Lactose intolerance can also lead to gas, abdominal distension and flatulence. The indigestible lactose in milk causes bacterial fermentation and gas production in the colon.

According to VCA Animal Hospitals, over 50% of cats experience diarrhea or vomiting after ingesting cow’s milk. The gastrointestinal upset is a result of insufficient lactase enzymes needed to properly digest lactose sugars in milk [1]. These symptoms may start shortly after drinking milk or could take up to 12 hours to develop.

Why cats love milk anyway

Even though most cats are lactose intolerant as adults, they still love to drink milk for a couple key reasons. First, the high fat content of milk products like cream appeals to cats’ instincts and tastes. Milk products contain more fat than cats’ normal prey diet, so they find it very appealing (Source). Fat helps give milk its creamy, rich texture that cats find irresistible.

Additionally, the instincts of kittens drive them to seek out milk from their mother in their early development. So the association of milk with kittenhood creates a strong imprint to seek out and enjoy milk, even into adulthood (Source). As they get older this imprint remains, even though their bodies lose the ability to properly digest lactose.

Risks of Giving Milk

Giving milk to cats, especially cow’s milk, comes with several risks. The main risk is digestive issues due to lactose intolerance. Lactose is a sugar found in milk that requires the enzyme lactase to digest it. Most cats’ digestive systems stop producing lactase after weaning, making them unable to properly digest lactose as adults (source).

When cats drink milk, the undigested lactose travels to the large intestine where it ferments and causes gas, abdominal pain, cramping, diarrhea, and even vomiting in some cases. The results can range from mild indigestion to severe diarrhea and dehydration if a cat consumes a large amount of milk (source).

Another risk with milk is nutritional imbalance. Milk contains high amounts of fat, calories, and minerals like calcium and phosphorus. Consuming too much can lead to obesity, diabetes, and mineral toxicity in cats. It can also displace balanced cat foods in their diet leading to nutritional deficiencies (source).

Better milk alternatives

There are several milk alternatives that are safer for cats than regular cow’s milk:

Lactose-free milk formulated for cats contains the enzyme lactase, which helps cats digest the lactose. Brands like CatSip are designed to be easier on cats’ digestive systems.

Broths made from chicken, vegetable, or beef provide hydration and nutrients without lactose. Low-sodium and unseasoned broths are best.

Kitten formula is designed for young cats who need milk. While not ideal for adult cats, small amounts can provide nutrition without digestive upset.

Plant-based milks like almond, coconut, soy, oat, and rice milk are lactose-free options. However, they tend to be lower in fat and calories compared to cow’s milk so shouldn’t fully replace it.

No matter the alternative, moderation is key. Too much can lead to obesity or other health issues. Check with your vet on the best options for your cat.

Other treats cats enjoy

In addition to milk, there are plenty of other tasty treats that cats love. Three common favorites are meat, fish, and catnip:

Meat treats like chicken, beef, or turkey make an excellent choice. As obligate carnivores, cats thrive on a high-protein meat-based diet. Lean cooked meat is safe for cats and provides nutrients they crave (1). Just be sure to avoid seasoned or fatty meats which may cause stomach upset.

Fish can also make a healthy, irresistible treat for cats. Salmon, tuna, or tilapia are good options that provide protein and omega-3 fatty acids. However, fish treats should be given sparingly, as too much fish can lead to mercury exposure (2).

Finally, catnip is famous for sending cats into a euphoric frenzy. The herb contains a chemical called nepetalactone which binds to cat’s olfactory receptors. This triggers a pleasurable neurologic reaction and can make cats playful and affectionate. Catnip is completely safe and non-addictive when given occasionally (1).

Providing a variety of meat, fish, and catnip treats along with the occasional taste of milk can satisfy a cat’s cravings while avoiding overindulgence in any one treat. Moderation is key for maintaining health and happiness.

Moderating milk treats

Most experts advise against giving cats milk regularly or in large quantities. However, an occasional small treat of milk, such as a spoonful or two, is usually not harmful according to some sources. The key is moderation. A small amount of milk given only on rare occasions allows cats to enjoy the taste while minimizing adverse effects.

Cats typically do not need milk for nutrition, so it should be viewed as a special treat rather than a dietary staple. Pet owners can monitor their cat’s reaction after a small milk treat, watching for any signs of stomach upset or diarrhea. If the cat tolerates it well, then an occasional lick of milk is likely fine. But cats with lactose intolerance should not have milk regularly.

When in doubt, it may be best to avoid milk altogether. There are many other ways to provide cats with enjoyment and variety. But for those times when a feline family member begs for a taste of milk, a teaspoon or two will satisfy the craving. As long as milk is given in extreme moderation, most cats can indulge in this creamy treat.


In summary, most cats love milk and will eagerly lap it up even though they are lactose intolerant. Their enjoyment of milk likely stems from their ancestral history, when wild cats would drink milk in early development. However, today the lactose in regular milk can cause digestive upset and discomfort in cats. While it’s fine to give cats small amounts of milk occasionally as a treat, it’s best to opt for lactose-free varieties or cat-safe milk alternatives. There are also many other tasty treats cats love, from meat to fish flavors, that can satisfy their cravings without adverse effects. Moderation is key for milk, which should be an occasional treat rather than a dietary staple.

The key takeaways are:

  • Cats are lactose intolerant but many still love milk due to ancestral instincts
  • Signs of lactose intolerance include diarrhea, vomiting, gas
  • Giving regular milk routinely can cause stomach upset
  • Lactose-free or cat milk varieties are safer options
  • Treat milk in moderation, not as a regular part of diet
  • Other tasty treats can satisfy cats without stomach issues

By understanding cats’ complicated relationship with milk, cat owners can still safely provide milk as an occasional treat in moderation.

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