There are various factors that can cause bald spots to crop up on a dog's legs, including acral lick dermatitis, also known as a dog hot spot. These spots are localised infections that are generally caused by staphylococcus intermedius, which is a bacterium. The spots can be the result of allergies, mites, fleas, bacteria or irritants. A hot spot appears because of the itch-scratch cycle. The spots get worse because of self trauma that the dog inflicts as she is scratching, licking, rubbing and biting because of lice, mites, fleas, fungi, allergies, ticks, infections or topical irritants, explains Petwave.com. Sometimes a case of severe essential fatty acid deficit can contribute to the problem.
When a dog has mange, which is referred to as canine scabies, this can cause hair loss and bald spots on the dog's front legs. He may also get bald spots in his armpits and elbows. Mange causes terrible itching because the mites get into the dog's skin. Mange also causes crusty, dry skin lesions. The mites burrow under the dog's skin and this prompts skin inflammation and hair loss as well as dry spots. Demodectic mange is common and generally doesn't result in major problems because the dog and the mites seem to coexist without any problems. However, sarcoptic mange, also known as scabies, causes hair loss and extreme itching. The dog needs to take oral medicine as well as be dipped.
If the hair loss is in a circular patch this may be the result of a fungus called ringworm, which exists in the hair, nails and dead skin tissues of the dog. The leg is the area that is most frequently targeted by ringworm. Ringworm is a fungus and not a worm, despite its name. The fungus resides in hair follicles and is spread by contact with an infected plant or animal. Ringworm generally shows up on the dog's front paws, ears, head and tail. It can be spread to humans, so be careful when handling the dog. This is a resistant fungus and it definitely produces hairless spots on the dog.
When a canine is infested with fleas this creates allergic dermatitis, itching and the dog will lose her hair, mostly on the backs of her legs. The parasites make a meal of your dog's blood. Some dogs are allergic to fleas. If the dog is bitten even once, this can cause a severe allergic flare. When a dog suffers from this allergy you will see hair loss and red bumps as well as flaky, dry spots on her skin. The allergic symptoms manifest on the legs, belly, base of the tail and on the dog's groin.
When a dog gets a hot spot this is the result of allergies, fur that is damp all the time or nervous licking. The hot spot is an open wound and it usually appears on the dog's legs. A bald patch will appear. The infected area become hairless as the result of incessant licking and gnawing.
Allergic to Food
If your dog is allergic to his commercial dog food, this may result in an allergic reaction, which manifests in scratching. This leads to bald spots on the dog's legs as well as elsewhere. Such an allergic reaction may also be the direct cause of hair loss.