They can but it isn't as common as environmental allergies. Despite what people may cling to, or swear is happening, the reality is that while food allergies are rare, when they happen they are only to the protein sources in the food, such as the chicken and beef. This has been scientifically proven. Allergies to every thing under the sun are unfounded, such as grains, glutens etc, however this doesn't stop food companies from advertising the hell out of it, and thus convincing the public that their animals have allergies to things that have not been proven, in order to convince people to feed their dog extremely expensive and pointless food . In fact, on that topic, there is going to be a paper coming out soon that links grain free diets to dilated cardiomyopathy, a life threatening heart condition, which is very frustrating as there is no researched based reason to feed grain free. Additionally, if you are actually honing in on a food allergy, all of these over the counter diets that are devoid in one particular ingredient is relatively deceptive, as most of these foods are all produced in the same factories, thus if a food is "grain free", there is still a good chance that at some point at that same plant, foods with grains were processed there.

Yes dogs can’t have chocolate and cats can’t eat certain things either

Yes they can

My mom has two dogs.. One would eat regular dog food till he burst if you allowed him to.

The other would starve himself to death. Only eats chicken and rice.

Oh yes my dog can’t eat gluten. It makes her belly swell like a balloon 🎈 poor thing

yep, my cat is allergic to corn.

I’m sure they can.

Yes

yes.