The image is a cartoon and comedy favorite all around the world – if there’s a fire hydrant, there's sure to be a dog lifting his leg on it. But why do fire hydrants (and other vertical surfaces) prompt this behavior?
The short answer – dogs are marking their territory, and the higher up the spray, the harder it will be for another dog to come along and overwrite the information. Think of the fire hydrant, or lamp post, or car tire as a chat room for all the local dogs – that fragrant mix of messages is announcing who has more testosterone, who is in heat, and who is new to the neighborhood.
It’s not just male dogs who lift their legs to pee. Many years ago, I had an adorable female beagle on my dog walking route who would use one of her hind legs to ratchet herself halfway to a headstand so that she could pee three feet above the ground. (I loved her for many reasons, but that particular acrobatic feat was the clincher for me.)
And it’s not just female dogs who squat to pee – many male dogs never get in the habit of lifting their legs, and the jury is still out on whether or not this is a learned behavior or an instinctive one, or more common in unaltered vs neutered dogs. So if your male dog never hoists a leg, don’t worry about it; that's just who he is. But, if he has been raising his leg his entire life and all of a sudden starts squatting, it may be a sign of a UTI or even a hip injury, and you should take him to the vet to get it checked out.