Dewlaps and Dogs

The dewlap is defined as a flap of skin beneath the lower jaw. Fat is stored beneath the surface of the skin and if an animal has a fur coat, there will be fur covering the outside of the dewlap. A large variety of animals, including mammals, birds, reptiles and amphibians all have dewlaps. It is more prominent in some species, like the rabbit, and less prominent in others, such as the dog and cat. Naturally, you would assume that since so many animals across different species have dewlaps, it must serve some crucial function, right? Correct! The dewlap in different animals tends to look physically different, which is most likely a result of its wide range of functions.

In rabbits, the most obvious physical difference between males and females is that mature females have a large flap of skin under their neck. This extra flap of skin is none other than the aforementioned dewlap. But wait! Do not be hasty in calling your rabbit a girl just because it has a dewlap. Males can also have skin resembling a dewlap on their neck. In particular, obese males tend to develop a dewlap similar to that of females. In light of this ambiguity, it is unwise to sex your rabbit through its dewlap alone. Being aware of the hint the dewlap provides as to the gender of your pet, you are probably wondering, “What is its purpose?” The function of the dewlap is to provide extra surface area for the mother to pull hair from to build a nest for her young. In many animals, it is used as a portable nesting material reserve. Basically, when pregnant female animals are nearing birthing, they pluck out the fur from their dewlap to help line the nest she is making for her babies. You would be surprised by the amount of fur that can be pulled from this area – it is astoundingly impressive!

Additionally, if one day you happen to find your female pet with its dewlap fur pulled out but it is not pregnant, it may be experiencing what is called a pseudo-pregnancy (false pregnancy). Stress, hormonal imbalances and exposure to a male are a few possible scenarios that may cause this behaviour. In many animals that we keep as pets, the cause continues to be unknown. However, it does seem that spaying your female pet is usually a solution. If you are unsure and are worried that the dewlap is abnormal, it can gently be pulled away from the neck a short distance. Upon touch it should feel fleshy and soft with no swelling or hardness.

Though the dewlap is usually found in female rabbits, in other animals such as the anole lizard, the male has a larger dewlap than the female. Although these lizards have dewlaps, they are used for a completely different function than that of the rabbit dewlap. The anole male dewlap is large and brightly coloured. Male anoles use their dewlap as a beacon – to attract females during mating season, as well as a warning to potential rivals. These males like to show off their flashy dewlaps to draw attention to how ‘handsome’ they are; thus, bigger is better. Showoffs!

Though the function of the dewlap and similar structures in some animals is known, in others it remains a mystery. Perhaps in some cases we already know its function and are just trying to dig too deeply. For example, did you know that some humans have a dewlap as well? Overweight and elderly people have the all-too-familiar “double chin” or dewlap, which is just the storage of extra fat under their necks. So you see, the dewlap occurs in humans as well; just another thing we have in common with our animal friends!

By Laura Platt – Pets.ca writer