What causes hair loss in cats?Abnormal hair loss, medically known as alopecia, is a common dermatological problem in cats. The extent of hair loss varies depending on the cause and severity of the condition. Some conditions cause complete and generalized hair loss while others result in localized and partial alopecia. Depending on the underlying cause, the skin affected can appear normal or may become inflamed, infected, or change in color. Continue reading to learn about the common causes of hair loss in cats and how you can help!FirstVet is the #1 online video veterinary service.FirstVet offers video calls with experienced veterinarians for just $35. You can get a consultation within minutes by downloading the FirstVet app for free from the Apple App Store or Google Play Store. Over 500,000 users trust FirstVet to care for their animals. Rating: 4.9 - more than 1600 reviewsRating: 4.9 - more than 1300 reviewsRating: 4.9 - more than 1600 reviews Download app There are different causes of alopecia in cats, and treatment ultimately depends on proper diagnosis. Often, alopecia in cats comes with other clinical signs such as excessive scratching or generalized discomfort.Congenital vs. Acquired Hair Loss in CatsThough there are numerous possible causes of hair loss in cats, they can be classified into 2 general types: congenital and acquired. Congenital hair loss in cats is a type of alopecia that is usually present at birth or appears shortly after being born. It’s caused by a genetic defect leading to a lack of hair follicle development.Affected cats are often born hairless or initially have a normal coat but eventually, get localized hair loss which then progresses into generalized alopecia. This condition is usually hereditary but it’s possible for cats affected with the disease to not pass it on to their offspring. Sphynx, a breed of cat known for not having fur, is known to carry the gene responsible for congenital alopecia.Acquired alopecia, on the other hand, is a type of hair loss that develops secondary to an underlying cause. It may be complete or partial alopecia depending on the cat’s health or the skin problem causing it. Most acquired alopecia can be treated, but a definitive diagnosis of the underlying condition is needed.External ParasitesWhen a cat shows signs of hair loss, the first condition that needs to be ruled out is external parasite infections. The presence of fleas, ticks, or lice can cause severe inflammation of the skin leading to extreme discomfort and pruritus (itchiness) in cats. Microscopic parasites such as mites burrow under the skin and live in the hair follicle, causing inflammation and destruction of the hair follicle and all tissues surrounding it.The destruction of the hair follicle paired with excessive scratching causes hair loss in cats infested with external parasites. It often starts as local alopecia, but if left untreated, it can easily spread and progress into a generalized hair loss.Most cases of alopecia secondary to external parasites respond well to treatment. Commercially available anti-parasitic medications can kill and protect cats against external parasites for a certain amount of time. Once external parasite infestation is eliminated, inflammation and itchiness are controlled, and fur will start to grow back.Bacterial and Fungal Skin InfectionsCats can get skin infections from either bacterial or fungal microorganisms. Skin infections in cats occur as either uncomplicated infections or secondary to a possible inflammatory or allergic skin problem. Infection-induced alopecia occurs when a bacterial or fungal microorganism penetrates the skin’s protective barriers and grows within the superficial layer of the skin. This destroys hair follicles, leading to hair loss.Severe bacterial skin infections often result in moist dermatitis with skin inflammation. Fungal infections tend to cause severe dryness coupled with inflamed skin. Uncomplicated infections are easily treated with systemic or topical antibacterials and antifungals. For secondary infections, the underlying condition needs to be addressed as well for the treatment to work.Allergic DermatitisAnother common cause of hair loss in cats is allergic dermatitis. Many allergic reactions in cats are due to food allergies, but environmental causes are also common. Allergic reactions happen when a certain allergen, food ingredient, or otherwise, is recognized by the cat’s body as something foreign and the immune system mounts a response against it.This results in inflammatory processes inside the cat’s body, most of the time manifested in the skin. This leads to severe itchiness and compromises the skin’s integrity, making it prone to secondary infections. This cascade of changes along the skin eventually leads to hair loss, often starting as patchy baldness but progresses to a complete hair loss if not addressed accordingly.Treatment for allergy-induced alopecia can be tricky. Allergic and inflammatory processes can be controlled with medications like antihistamines or corticosteroids, while secondary infections can be treated with anti-bacterial and/or anti-fungal medications. These treatments, however, only control the symptoms associated with the condition. Determining the exact allergen triggering the reaction is important for the long-term management of the condition.Hormonal ImbalancesCertain hormones like thyroid or cortisol affect a wide range of cells in a cat’s body. Any imbalance in these hormones causes a multitude of symptoms affecting different organ systems, often including hair loss. Alopecia associated with hormonal imbalance is often symmetrical and generalized. Most cases don’t have inflamed skin unless secondary infections have started.Treatment would rely on resolving the underlying hormonal condition. Abnormal cortisol levels like Cushing’s or Addison’s disease can be managed medically. Hypothyroidism, though rare in cats, can be managed by providing an exogenous source of thyroid hormone. Hyperthyroidism, a relatively common hormonal condition in older cats, can also be managed with oral medications but some cases would require surgery.Resolution of clinical signs, particularly alopecia, often come a few weeks after the hormone levels have been controlled. Any secondary infection can be treated with topical or oral antibiotics.Anxiety and Stress-Induced Hair Loss in Cats Cats are very sensitive creatures and they get stressed easily. Even the slightest change in their environment can cause stress in cats that can lead to physical changes. If cats are exposed to a certain stressor for a prolonged period, they can develop certain compulsive habits that often affect their health condition.Psychogenic alopecia, a well-documented condition in cats, is a hair loss condition due to excessive grooming. This usually happens when a cat is stressed or very anxious, causing them to obsessively lick different parts of their body resulting in eventual hair loss. In these cases, hair loss is localized and confined only in regions where the cat can reach with its tongue.Secondary inflammation and infection may occur due to the constant friction brought about by the continuous licking. Treatment and management require proper identification of the stressor triggering the cat’s anxiety.Read more:Miliary Dermatitis in CatsRingworm in Cats and DogsCheyletiella Mites in Cats and DogsHave more questions about hair loss in cats?Schedule a video consult to speak with one of our vets.