Which animals have tail glands that them identify individual animals?

Fox, domestic dogs and cats, wolves have tail glands that help them identify individual animals.  

Explanation:

The violent gland or supracaudal tail gland is situated on the tail's upper surface. The tail gland consist of one hair per follicle which helps in recognizing the person from their own species. When you tend to compare the hair follicle in tail gland to numerous hair follicle it has only one hair follicle. The hair breaks off easily and it causes the area to become bald. The tail gland is developed more in the species which are solitary for example foxes.

because they are eaten by the frog and the frog getseaten by the snake and the snake by the eagle