QotW: Why don't dogs get hairballs?

Sally Le Page spoke to three animal aficionados: Nick Sutton, Science Communications Advisor at The Kennel Club; Justine Shotton, Junior Vice President at the British Veterinary Association; and Ann Hohenhaus, Staff Doctor at NYC’s Animal Medical Center

Nick - Contrary to popular belief dogs do sometimes get hairballs, as can rabbits, ferrets, cows and even humans. When animals groom themselves, any hair they swallow usually passes through their digestive tract and is excreted in their faeces. If too much hair is swallowed, or if it wraps around any food items, it can form a clump that’s too big to pass out of their stomach. As more hair is swallowed it clings to this mass and begins to grow in size. Once it’s big enough to cause discomfort the affected animal will usually vomit it up (so long as they have a vomit reflex, unlike cows and other ruminants).

Sally - You know, I had never thought about whether cows can vomit until now. Of course, cats famously get hairballs, so why is Beth’s dog hairball free when her feline friends aren’t?

Justine - Hairballs are a lot less common in dogs than cats, and this is for a number of reasons. First of all, dogs do lick themselves, particularly their paws for example, but don’t groom their whole bodies in the same way that cats do. Cats have tongues with small backwards pointing spines which help them to groom their entire bodies, picking up a lot of fur in the process, particularly if they are long-haired.  Dogs’ tongues are much softer as will know if one of your canine friends has ever given you an affectionate lick!

Sally - And it’s not just that cats swallow more fur than dogs, but they also struggle to digest it more, as Ann explains:

Ann - Cats are obligate carnivores, meaning they are designed to eat meat. Carnivores have a shorter digestive tract than omnivores because it is easier to digest a meat diet than a vegetarian or omnivorous diet. Dogs are omnivores and thus have a longer digestive tract which may digest hair more efficiently.

Sally - And finally, it’s still worth keeping watch if your dog does get hairballs:

Nick - Although it’s unusual for dogs to get hairballs, they may be more prone to them if they have longer hair or lick themselves more often. If your dog does get a hairball it could be a sign that they are licking themselves to relieve stress or anxiety, or to soothe any areas that are painful, uncomfortable or itchy.

Justine - If you notice your dog vomiting up hairballs or passing a lot of hair in its poo... always speak to your vet for advice.

Sally - Our next question of the week is this short but puzzling question from Henk:

Henk - Is lava wet?