The variety of cat coats range from very dense thick fur to nearly hairless; therefore, noticing hair loss may not be apparent at first. Many conditions exist that cause sudden hair loss, so when hair loss is noticed, a vet should see your cat to properly diagnose the issue.
Sudden large bald spots often occur from licking. According to Dr. Wendy C. Brooks Educational Director at VeterinaryPartner.com, cats often lick bald spots on the back area or belly. Generally itching, not psychological problems, creates the licking behaviour, according to Brooks. Brooks notes that cats often lick in privacy preventing the owner from observing the actual licking. Sudden hair loss may follow exposure to chemicals, including cleaners, lawn treatments and carpet deodorisers. According to PetEducation.com, other causes include metals, rubber, poison ivy and topically applied antibiotics.
Ringworm, a fungus, creates patchy hair loss and sometimes loss of whiskers, according to Vetinfo.com. Demodectic mange symptoms include patches of hair loss or larger areas with the generalised form. According to PetEducation.com, hair loss at an injection site may occur due to a reaction. Fleabite reactions can result in hair loss, according to Vetinfo.com.
Infection and Medication
Allergic skin inflammation may result from items including food, pollen, mould and mites, according to Texas A&M University. Secondary infections increase the itching and hair loss. According to PetEducation.com, reactions to medications, including penicillin and cephalosporin, may result in symptoms including hair loss, redness and swelling.
According to PetEducation.com, a symptom of cancer can include hair loss. Stress responses can cause sudden hair loss as well. Excessive shedding may occur with hormone changes, including pregnancy, nursing and heat cycles. Feline hyperthyroidism symptoms include hair loss or poor coat condition, according to University of Georgia.