Can Dogs Drink Milk?

By Caitlin Ultimo

When you picture a pet drinking milk, most will imagine a cat happily lapping up some out of her bowl. So many, might be surprised to hear that cats really shouldn’t ever be poured a bowl of milk. But, when it comes to their four-legged counterparts, is there a similar answer to the question: Can dogs drink milk? There may not be a simple yes or no response, but there are a few guidelines to keep in mind. “Most dogs can drink cow's milk or goat's milk, however some dogs may be allergic or lactose intolerant,” cautions Dr. Stephanie Liff, DVM and owner of Pure Paws Veterinary Care of Clinton Hill Brooklyn, N.Y. And further, while most dogs will readily drink milk, “It's the consequence of that milk drinking that we worry about,” says Dr. Heather Brausa, staff doctor at NYC’s Animal Medical Center. 

When Can Dogs Drink Milk?

You may be thinking: “Don’t puppies drink their mother’s milk?” And, the answer to that question is: Yes. “Milk contains a sugar called lactose that requires an enzyme called lactase for digestion,” explains Brausa. “Puppies generally have the enzyme in abundance as it is used to breakdown their mother's milk while nursing.” While puppies thrive on their mother’s milk, they may not tolerate the cow’s or goat’s milk that you find in your fridge later on in their lives.

Can Dogs Become Lactose Intolerant?

Once puppies have been weaned they’ll produce less lactase and this is when most dogs can, in fact, become lactose intolerant. A dog that is lactose intolerant can experience the same kinds of symptoms as people with the condition. “Dogs have varying degrees of lactose intolerance, so some dogs who drink milk may just experience mild GI distress, or none at all, while others will have severe clinical signs,” shares Brausa. Further, milk and dairy products are common triggers for food allergies in dogs. “A food allergy to milk or dairy can appear as irritation of the skin, redness, itching and GI upset such as vomiting and diarrhea,” says Liff.

What Will Happen If Your Dog Drinks Milk?

Without the abundance of the enzyme lactase that breaks down sugars in milk, adult dogs can have a more difficult time digesting it. The lactose found in milk will pass through their GI tracts and into their colons undigested, and this undigested sugar will draw water into the colon causing diarrhea, and the fermentation of bacteria in their colon may result in flatulence and discomfort. “Due to the deficient levels of lactase, milk ingestion can lead to GI upset including diarrhea and vomiting,” says Liff. “Additionally, whole fat milk or other dairy products may contain too much fat and can also lead to diarrhea and vomiting too.” Dogs may also develop a potentially serious disease called pancreatitis if they eat dairy products—particularly high fat dairy products—that are unfamiliar to them.

What to Do if Your Dog Drinks Milk

While the occasional lick of your ice cream cone or lap from your mug should not be a big deal—unless your dog is allergic—you should avoid allowing your pet to indulge in large amounts of milk and other dairy products. “GI upset will generally occur within 12 hours or so of consuming milk,” says Brausa. So if your pet accidentally gets his paws on a larger helping than you had planned for, monitor for any abdominal distress or discomfort including vomiting and/or diarrhea for that amount of time.

Image: Proxima13 via Shutterstock

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