Are Dogs Lactose Intolerant?

Dogs love nothing more than to sample whatever their parents are eating or drinking, even if it’s not good for them. And pet parents love to watch their dogs go wild for a yummy snack. While it’s not always ideal to give dogs a bunch of human food, most of us can’t resist sharing a little food with our pups when it’s safe.

Puppies thrive on their mother’s milk, but adult dogs may not handle milk quite as well. Does this mean that dogs are lactose intolerant?

Are all dogs lactose intolerant?

There’s a lot of back and forth on social media about the appropriateness of pup cups. Although Puppucinos at Starbucks are a popular treat for dogs on the go, many pet parents have heard or read that lactose intolerance in dogs is a thing, leading to questions like this: “Can dogs be lactose intolerant? I see people on TikTok getting pup cups for their dogs, but I thought dogs weren’t supposed to drink milk. I’m sure my dog would love a cup of whipped cream, but I want to make sure it’s safe.”

The question “Are dogs lactose intolerant?” actually doesn’t seem to have been researched super deeply. We know that the amount of lactase, the enzyme that breaks down lactose in dogs’ intestines, decreases significantly after puppyhood. The degree of decrease varies from dog to dog, so some dogs are able to tolerate more lactose than others.

There’s also a report that lactase is not an inducible enzyme in dogs. This means that feeding a dog dairy products regularly will not help them build a tolerance to lactose over time. They’re able to process a baseline amount of lactose, and that’s it.

This means that some dogs handle lactose better than others. Milk and dairy products should not make up a significant portion of an adult dog’s diet. Feeding too much dairy to dogs can result in some unpleasant side effects.

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Signs of lactose intolerance in dogs

So, what is lactose intolerance? It’s usually defined as an inability to fully break down lactose (milk sugar) in the diet. This can be measured in a matter of degrees, though: Anyone who drinks enough milk can overwhelm the enzymes that break down lactose and end up with the symptoms of lactose intolerance. Most dogs aren’t able to handle the same amount of lactose that humans can, likely because they didn’t evolve with a lot of milk in their diet. It’s very hard to milk a cow effectively without opposable thumbs and having a well-developed agricultural system.

How do you know if your dog is lactose intolerant? You give them milk, and then both you and your dog suffer through the side effects, which include:

• Gas: Awful farts are one of the first signs of problems in a lactose intolerant dog. The incompletely digested lactose is fermented by bacteria in the colon, resulting in copious gas production. Rumbly guts and frequent flatulence may portend further lactose intolerance symptoms.

• Diarrhea: Undigested lactose is a large molecule. Large molecules have a strong osmotic pull, meaning that they draw water to them. An overabundance of lactose in the colon will lead to loose or watery stools due to this effect.

• Abdominal pain: All this gas and diarrhea can lead to significant abdominal discomfort. Dogs with bad cramping and gas pain may pant, whine, or become restless. This should improve as the gas and diarrhea resolve.

Can dogs drink milk?

Milk contains a large amount of lactose, so it’s not the best treat for dogs. While milk isn’t toxic or poisonous to dogs, what happens if a dog drinks milk usually isn’t pleasant for anyone involved. Some dogs can handle a little milk without issue, but why risk gas, diarrhea, and abdominal pain for your pup if you don’t have to?

Cow’s milk is also a commonly implicated cause of cutaneous adverse food reactions in dogs. Even if your dog’s GI tract is able to process milk without significant disruption, the proteins in the milk may induce skin allergies that can result in itchiness, skin discoloration, and bald patches.  

Are pup cups safe for dogs?

Pup cups are made with whipped cream, not milk. Cream only contains about a tenth as much lactose as milk, so it’s much less likely to trigger lactose intolerance symptoms in dogs. Cream has very little lactose because it consists of the fattier part of cow’s milk, with relatively little protein. Feeding such a high-fat treat has its own issues though: pancreatitis in dogs is triggered by fatty meals. Some dogs can handle the fat content of whipped cream without issue, but others may develop significant problems because of it. Check with your veterinarian to see if your dog may be predisposed to pancreatitis before offering a pup cup.

Can dogs eat cheese?

If they can’t drink milk, can dogs eat milk products like cheese? Cheese contains less lactose than milk because the lactose is broken down during the aging process. This means that young cheeses like cottage and American cheese still contain a moderate amount of lactose, while aged cheeses like cheddar contain very little.

Will paying the cheese tax cause issues in a lactose intolerant dog? Probably not, as long as snacks are kept to a minimum. A little bit of cheese to hide a pill or a sprinkling of shredded cheese as a treat is unlikely to cause issues for most dogs.

As with any treat, it’s important to keep things in moderation with cheese. Most dogs would happily eat a whole block of cheddar, but that’s likely to cause significant stomach upset. Keep snacks to less than 10 percent of your dog’s caloric intake per day, and be sure to remember that calories add up fast for dogs because they’re (usually) smaller than us. What seems like a small snack here and there can lead to weight gain quickly for dogs.

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Bottom line

Much like Ron Burgundy, dog parents will generally end up thinking that milk was a bad choice. Milk isn’t a necessary part of the diet for adult dogs, and lactose intolerance is common enough that it’s not worth risking a night of smelly dog farts and extra trips outside to blast milky diarrhea everywhere.

Cheese can be used as an occasional treat for most dogs, but it should also be given in moderation to prevent stomach upset and weight gain. Always check with your veterinarian before starting new foods and treats to make sure that they’re appropriate for your dog.

References

• Coughlan, Michael P et. al. “On the inducibility of a pancreatic lactase.” Archives of Biochemistry and Biophysics. Vol. 131,1 (1969): 177-9. doi:10.1016/0003-9861(69)90118-0

• Gaschen, Frédéric P, and Sandra R Merchant. “Adverse food reactions in dogs and cats.” The Veterinary Clinics of North America. Small animal practice vol. 41,2 (2011): 361-79. doi:10.1016/j.cvsm.2011.02.005

• University of Virginia Health System. “Lactose Content of Common Dairy Foods.”

• Wills, J, and R Harvey. “Diagnosis and management of food allergy and intolerance in dogs and cats.” Australian Veterinary Journal vol. 71,10 (1994): 322-6. doi:10.1111/j.1751-0813.1994.tb00907.x

• Zentek, Jürgen et al. “Intestinal effects of mannanoligosaccharides, transgalactooligosaccharides, lactose and lactulose in dogs.” The Journal of Nutrition vol. 132,6 Suppl 2 (2002): 1682S-4S. doi:10.1093/jn/132.6.1682S