It is normal for cats to spend a great deal of time grooming. If the grooming is more than usual and you notice skin sores, patches of hair loss or redness, the cat may be suffering from:
Stress/Anxiety/Obsessive-Compulsive Disorder
Over grooming in cats may be caused by stress, anxiety or by an obsessive-compulsive disorder. It is similar to people biting their nails when they are nervous or obsessive hand washing. Cats can get stressed from a move, boredom, loud noises, previous abuse, dirty litter box, confinement, strangers in the home, or from the adoption of another pet.
Parasites
Fleas and mites can cause a great deal of irritation to the cat’s skin. Many animals are actually allergic to the flea’s saliva. The allergic reaction to the flea bite causes itchiness and swollen skin. The constant licking and scratching cause open sores and scabs on the cat’s skin. The sores can result in a secondary bacterial infection.
Food Allergies
Food allergies have been identified as over 50% of the cause of itching and scratching in cats. In cats, the most common food allergies are to beef, lamb, seafood, corn, soy, wheat and dairy products.
Wound Abscess
A wound abscess often occurs from an animal bite which gets infected. The abscess is filled with pus, bacteria and damaged tissue. Bite wounds can become easily infected due to the bacteria found in an animal’s mouth. The wound may cause the cat to excessively groom the abscess area.
Cystitis
Inflammation of the bladder is a painful condition, which may become life-threatening if not treated. Along with excessive genital licking, there may also be bloody urine, straining when urinating, accidents in the house and the cat may cry out in pain.