Dogs and cats both have anal glands, small sacs on either side of the anus, that fill with a scent that is uniquely their own (which is why dogs like to sniff at each others’ rear ends – it’s like a badge that says, “Hi, My name is Fido!”).
Anal glands are supposed to empty on their own when a pet defecates, but if that fails to happen, the material in the glands becomes impacted and makes the pet uncomfortable. Your pet may try and scoot his rear along the ground, lick excessively, or chase his tail to empty the glands. (Cats, by the way, will chase their tails whether their anal glands are full or not! Licking and scooting are better indicators of anal gland troubles in cats.)
Although you can empty the sacs yourself at home, most people prefer to let us do it for them! It’s, well, smelly…
If your pet has frequent trouble with her anal glands, switching to a high quality diet with plenty of fiber will help bulk up the stool and cause the anal glands to empty on their own more often.