We’re not so sure about the claim that dogs can’t cry due to emotion. The dogs we have as pets are human creations and are very intelligent, social animals. Research shows that dogs can understand the emotions of others and show empathy and sympathy. Other research suggests that some nonhuman animals like monkeys, rats and dogs can laugh as an expression of joy, or that elephants and other animals cry as part of an emotional response. These highly social animals have shown that they experience emotions like humans do and probably express them in a similar manner; it wouldn’t be surprising if one day, it is proven that dogs and other animals can also cry when they’re sad. So while you should have your dog checked out by a vet if you see tears to make sure it isn’t an illness, we don’t rule out the possibility that maybe, the dog is just sad.
“If your dog has fluid coming out of its eyes, you might assume that the animal is crying. However, it’s important for pet owners to note that dogs cannot cry in the way that humans do. If a dog’s eyes are discharging liquid, it is because something is wrong, not because the animal is overcome with emotion.”