Q. I have a female Collie mix who, for some reason, keeps biting and tearing out her fur. I want to know if maybe she has a skin irritation, because the only part of her body she bites is her leg. The reason I am asking for grooming advice is because now her fur is so tangled that I can't brush it.
A. There are a few reasons she may be chewing and biting her leg. She may have had an insect bite or a flea infestation, and started this obsessive behavior to relieve the itch. She may have some sort of underlying injury and be doing it to relieve pain. She may have an allergy from food, flea saliva, pollen, or a substance in her environment, indoors or out. It also could be a behavioral problem due to a change in your family situation, separation anxiety, lengthy confinement, or just plain boredom.
A checkup with her vet would be a good idea. A thorough examination and a skin test should help determine if it is an allergy problem, an underlying injury, or if flea control is needed. Sometimes the vet will prescribe antihistamines to relieve the itching as well as topical treatment with hydrocortisone ointment. If the vet suspects some ingredient in her current food could be causing an allergic reaction, a dietary change may be in order and it may take some experimentation to come up with the right food for your girl.
At this point, with her fur so tangled, you might also have your groomer spot-shave the area first, so you can see if she has a hot spot underneath. If her fur is sticky and you detect an odor, this may be the case. These painful, oozing sores can develop from allergies, insect bites, or a lack of grooming. If undercoat builds up in a thick-coated dog like the Collie, the skin underneath can’t breathe and such sores can develop, especially in warm weather or if her fur stays wet after swimming or a bath. Usually, applying a topical antibiotic for a couple of weeks will help a hot spot heal, but your dog may have to wear an Elizabethan collar to keep her from chewing at the area.
You are right to be concerned because whatever the cause, if your pet keeps up this behavior, she could end up with a lick granuloma, evidenced by hair loss and thickening of the skin, sometimes resulting in permanent damage.