From Cat
Non-pruritic telogen effluvium (telogen defluxion) in a 16-year-old Domestic shorthair cat persisting for some months. Routine testing for hyperthyroidism and Cushing's syndrome were negative. Courtesy Dr Jim Euclid
Feline endocrine alopecia; causes include overgrooming, Cushing's syndrome or hypothyroidism
Self-inflicted alopecia secondary to flea allergy
Generalised atrophic alopecia in a Domestic longhair cat with iatrogenic Cushing's syndrome
Paraneoplastic alopecia in a Siamese cat - note the shiny appearance and the generalised distribution of the alopecia

Alopecia, or 'hair loss' in cats is a common skin disorder of cats which occurs in all ages from newborn kittens (hormonal alopecia) to aged cats (hypothyroidism). The most common causes of alopecia in cats are atopy, fleas and food allergies.

  • Congenital/genetic
- Follicular dysplasia - seen in Devon rex kittens
- Pili torti (trichokinesis, corkscrew hair) - seen in American wirehair cat
- Telogen defluxion
  • Parasites
- Fleas - biting around flanks and tail. Fleas and flea dirt (brown spots) often seen when hair is parted.
- Demodectic, Cheyletiella, Notoedres and Sarcoptes mange - intense itching on flanks, with ulcers and bleeding. Usually seen in outdoor cats, infection from hunting rodents.
  • Allergies/Immune mediated
- Flea allergy dermatitis, Eosinophilic granuloma complex and miliary dermatitis, but also to certain types of food, flea collars, shampoos and bedding/carpets
- Alopecia areata (immune-mediated)
- Pseudopelade (immune-mediated)
  • Drug induced
- Reactions have been associated with vaccines, ivermectin, praziquantel, antibiotics and glucocorticoids. Lesions are present at sites where injections are given. Therapy is usually not required. Hair regrowth may take several months to a year. In some cases the alopecia is permanent.
- Trichorrhexis nodosa
  • Psychological (psychogenic) licking
- Overgrooming - constant licking of skin, especially insides of legs, with red lumps on skin
- Hyperesthesia syndrome
  • Neoplasia
- Squamous cell carcinoma - sores on tips of ears, nose and around the edges of eyelids. Most common in white cats.
- Pancreatic paraneoplastic alopecia
- Paraneoplastic alopecia seen in Bile duct carcinoma. Has been associated with crusting of the footpads and alopecia in cats.
- variants of Lymphosarcoma, including:
- Epitheliotrophic lymphoma, also known as pre-neoplastic 'Alopecia mucinosa' or 'Mycosis fungoides'[1]
- Sezary syndrome
- Pagetoid reticulosis
- Idiopathic lymphocytic mural folliculitis
  • Hormonal disease (Feline endocrine alopecia syndrome)
- Stud tail
- Hypothyroidism - hair loss around flanks and tail base, but not usually itchy
- Diabetic dermatosis
- Cushings syndrome - can manifest as hyperpigmentation, alopecia, seborrhea, calcinosis cutis, and secondary pyoderma. In cats, the skin becomes extremely friable. In diabetes mellitus, pruritus and secondary infection rarely occur.
- Thymoma
- Pinnal alopecia - hairloss over ears - no therapy required