Can Dogs Drink Milk?
It’s a common question among dog owners and the most frequent answer is “No, dog’s are lactose intolerant!”
But is that really the case?
So, today I want to talk about dogs, milk, and lactose intolerance. Is what you know really true or are you believing a lie?
Can Dogs Drink Milk? AKA Are Dogs Lactose Intolerant?
What is Lactose Intolerance?
Milk contains a type of sugar known as lactose. In order to digest milk efficiently, the body produces an enzyme called “lactase”. The only purpose of the lactase enzyme is to process lactose.
When someone is lactose intolerant, they do not produce enough lactase to efficiently digest milk sugars and as such, they experience a number of unpleasant side effects. These side effects include pain, bloating, and gastrointestinal discomfort and are the result of undigested milk sugars being fermented in the gut.
Like humans, adult dogs may or may not produce enough lactase enzymes to break down milk sugars.
What does that mean, can dogs drink milk or not?
It means that whether or not a dog is lactose intolerant depends on their ability to produce the lactase enzyme. It also means that lactose intolerance can vary in degrees of severity based on how much lactase the body can produce.
But don’t puppies drink milk?
Yes! Most puppies produce significant amounts of the lactase enzyme so that they can process their mother’s milk (which contains less lactose, more fat, and more protein than cow’s milk).
However, like the majority of mammals, as puppies wean from their mother’s milk, the production of lactase enzymes slows.
Why? Because lactose is not commonly found in the diet of weaned mammals.
This means that by virtue of evolution, weaned mammals are unable to efficiently process dairy products.
So why can some adult dogs…and humans digest dairy products?
The answer to this is multi-faceted.
Firstly, some dairy products contain lower levels of lactose and as such, they can be digested by dogs with lowered lactase production without the symptoms associated with lactose intolerance.
Secondly, for those dogs with no trouble digesting dairy at all, we have to look to something called “lactase persistence”.
What is Lactase Persistence?
As I mentioned above, the natural process for most mammals is to wean from their mother’s milk to solid foods that do not contain dairy. Neither herbivores, omnivores, or carnivores incorporate dairy into a “natural” diet.
This lack of need for the lactase enzyme caused lactase production to decrease by virtue of evolution.
However, over time, genetic mutations have developed that have resulted in the continued production of lactase in various mammals (read: humans and dogs). This is referred to as lactase persistence.
What causes this lactase persistence?
Researchers believe that lactase persistence is a result of human pastoral ways of life and natural selection.
In societies where dairy products are now consumed regularly, milk offers a source of nutrition and the ability to digest that source of nutrition is advantageous.
In societies where milk is less of a staple, lactase persistence is less common because it offers no advantage.
So essentially, it is our human way of life that has influenced our dog’s (and our own) ability to process dairy products.
Because of our pastoral way of life, our dogs are increasingly able to digest dairy where they once could not. However, like many genetic mutations, lactase persistence is present in only a portion of the population. Should we continue raising our dogs with increased exposure to the human way of life, however, it is likely that lactase persistence will become increasingly prevalent in our domesticated friends.
So…can dogs drink milk? There is no catch-all answer to that question.