Hair Loss in cats can happen for a variety of reasons. The major reasons for hair loss in cats are grouped into 3 categories: hair loss due to over grooming/self trauma, hair loss due to systemic illness, and hair loss due to infectious causes. Hair loss caused by itch and over grooming is the most common cause of balding in cats.
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Hair loss due to itch or self trauma in cats:
Many times cats are brought to the veterinarian to evaluate the cause of diffuse over-grooming on their bellies, inner thighs and sometimes along their flanks.
Although it’s not readily apparent, the majority of cats studied with over grooming behavior are doing so because of underlying itch. In a study of these cats, 76% had a medical underlying cause. only a small number of cats (10%) were due to behavioral causes. Fourteen percent were due to a combination of both.
Major medical causes that drive these cats to over groom are: flea allergy, environmental hypersensitivity, adverse food reactions, or a combination.
Diagnosing a medical cause for over grooming or barbering in cats:
Cats are diagnosed with an allergic cause for their over grooming if they respond to treatments designed to treat itch. All cats that over groom should be placed on a monthly flea preventative like Revolution. A strict diet trial with a hydrolyzed diet like feline Hills Z/D or Purina HA is recommended. Excess grooming behavior that does not respond to a diet trial can be given a steroid trial to address possible underlying itch. Steroids act to stop itch related to environmental allergy or flea allergy. Food-allergy related over grooming has no response to steroid therapy.
Of all the causes of over grooming behavior in cats, only 10% were attributed to psychological reasons alone.
Regardless of the initial medical trigger for self induced alopecia, this can progress to a compulsive over grooming behavior in some cats.
Food allergy in cats causing hair loss
Adverse food reactions “food allergy” often causes over grooming on the ventral abdomen and inner thighs. It is non seasonal and diagnosis involves a food elimination diet for 8 to 12 weeks. A hydrolyzed protein diet like Hills Z/D or Royal Canin HP has proteins that are small, only 1-12000 Daltons. Most proteins that trigger a reaction are recognized because their size is over 14,000 Daltons. Choosing a prescription hydrolyzed diet for a food trial is recommended. Your veterinarian must prescribe the diet.
Hair loss in cats due to seasonal or environmental allergy
Seasonal or environmental allergy also manifests as over grooming on the belly, the chest thighs and forelegs. Miliary dermatitis (punctate small scabs) can accompany the hair loss signs in cats with seasonal allergy. It can be seasonal or non-seasonal and intradermal skin testing can determine which allergens your cat is reacting to and hyposensitization therapy with injections or sublingual drops can be crafted. Many cats are managed with immune modifying drugs like steroids or cyclosporine to mitigate their allergy signs.
Hair loss in cats due to infectious causes
Hair loss due to infectious causes commonly include: flea allergy reactions, ringworm infections and mite infections.
Flea allergy reactions are treated by providing routing flea preventative and giving steroids to reduce itch and inflammation.
Ringworm is a fungal skin infection of the hair shaft and is transmissible to people as well. It is typically not itchy and causes patchy hair loss. Ringworm is treated with weekly lime sulfur dips and oral antifungal medication for several weeks. Always be sure to follow instructions regarding proper dilution of lime sulfur and do not get the product near the eyes. A solitary, small area can sometimes be managed with twice daily application of an antifungal cream like terbenafine (Lamisil).
Demodecosis gatoi is a feline mite that lives in the top layer of skin in cat. It causes marked itch that drives cats to over groom and create symmetrical alopecia of ventral abdomen and flanks Demodex gatoi is also best treated with 5-6 treatments of weekly lime sulfur dips.
Of all the possible causes of itch in cats, a study in a veterinary dermatology journal identified flea allergy as the number one cause of itch in cats. Nearly 40% of studied cases were identified as flea allergy. A non allergy cause of itch was present in 25% of cats and 20% were due to environmental allergy. Food allergy was the least common cause of itch at 12%.
Hair loss due to systemic or metabolic illness in cats
Hyperthyroidism as a cause of balding in cats
Overactive thyroid function is a common endocrine disorder in cats and has increased frequency in cats over the age of seven. Cats that are hyperthyroid are generally overactive and this hyper excitable behavior may manifest as excess grooming.
Feline cushings as a cause of balding in cats.
Cushing’s disease in cats is exceedingly rare. Cushing’s disease is over activity of the adrenal glands which produces an abundance of a natural steroid in the body. This leads to symmetrical hair loss over the trunk and hairs that easily fall out with brushing. Feline Cushing’s is also characterized by marked skin fragility.
Lower urinary tract infections as a cause of hair loss in cats
:Some cats with urinary tract problems like urinary tract infections or bladder stones may over groom on their lower abdomens
Impacted anal glands causing hair loss in cats
Discomfort from full anal glands may also lead cats to lick the fur around their anus and perineal region.
Cancer as a cuase for balding in cats
Hair loss secondary hair loss secondary to cancer is most often seen with pancreatic cancers in cats . Pancreatic cancer in cats can cause diffuse hair loss over the belly, chest and the insides of the legs. The skin often looks smooth and shiny. This cancer can be detected with imaging of the abdomen with an ultrasound evaluation.
Psychological over grooming in cats
Psychological over grooming is best addressed with modifications around the home to reduce stress: providing vertical space for cats to relax (cat towers, access to tall furniture ), unobstructed access to litter boxes and food, and the use of calming feline pheromones such as feliway diffusers. Sometimes psychotropic medications are needed such as amitryptiline or fluoxetine.
Hair loss patterns in cats
Patchy hair loss
Patchy hair loss is seen with dermatophytosis. Dermatophytosis is also called ringworm and it is generally not itchy. It causes patches of hair loss and scales. There may be a history of other pets or humans in the house with skin lesions. Some of the varieties of ringworm fluoresce under a special woods lamp. The infection is classically identified by collection of hair for fungal culture or fungal PCR.
Mosquito bite hypersensitivity happens seasonally and presents as patchy hair loss over the ears and on the nose most frequently. The reaction is typically very inflamed and causes scabs and itch. This reaction responds well to treatment with steroids.
Thinning hair over the cat’s rump
Hair loss over the rump area is often a sign of flea allergy. Most cats don’t have an active flea infestation, but may have a profound allergy response to a single flea bite. This triggers intense itch primarily over their rump.
Over grooming the belly, chest and inner thighs
Hair loss over the ventrum, sometimes chest and inner thighs can be caused by food allergy, environmental allergy and by psychological over grooming.
Tiny scabs and hair loss between the eyes and ears
Miliary or punctate scabs that erupt in the pre-aural area between the eyes and ears, the neck and around the face can be seen with food allergy. Sometimes thinning of hair is observed around the eyes as well.
Normal hair thining in cats
Thinning of fur between the ears and eyes can be a normal area for thinning hair in cats. This is called the pre-aural area.
If your cat is losing fur in patches or larger areas on the body, it’s best to have your veterinarian direct a plan to evaluate the underlying cause and provide treatment recommendations.