Overgrooming (or psychogenic alopecia) is a displacement disorder that causes significant hair-loss (alopecia) over the back regions, medial aspects of the hind-legs and lower abdomen. There are physical (diseases), psychological (obsessive compulsive disorders e.g. HsHa) and territorial conflicts which induce this stereotypy. Cognitively, the psychological parameters of stress-alleviation are similar to stress-related nail biting or cigarette smoking in humans. The cat liberates tension through mechanical activity.
The majority of cases in cats relate to or are triggered by changes in territoriality. This includes rehoming, introduction of new cats or kittens into the household, death or departure of primary caregiver, physical or psychological intimidation by other cats, etc. Physical diseases can exacerbate psychological stressors and magnify clinical symptoms. These include flea allergy, dietary allergy, hyperthyroidism, chronic renal disease, and more rare causes such as neoplasia and autoimmune diseases (e.g. pemphigus).
Overgrooming can be compared to obsessive-compulsive disorders in humans. In the majority of cases of overgrooming in cats, psychological factors such as stress play a predominant role in trigger this stereotypy where other methods of stress reduction such as territorial confrontation are unavailable to the cat. There seems to be little correlation between the degree of overgrooming and the temperament of the cat. Garfield-type cats are equally prone to displacement disorders as are highly strung Oriental cats (e.g. Siamese, Balinese, Tonkinese).
Diagnosis of overgrooming is an exclusion process, i.e. eliminating underlying psychological diseases (territoriality, separation anxiety, etc) and physical diseases (such as hyperthyroidism, chronic renal disease).
A full clinical examination, skin scrapings of alopecic skin, and full blood tests, including measurement of T4.
An exhaustive list of differential causes is usually investigated only when the condition worsens to the state where skin damage, secondary dermatitis and self-mutilation are manifest. At this point, the primary care-giver is distraught enough to propel the veterinarian into further clinical investigations. Underlying causes of overgrooming include:
- Allergies/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
- - Squamous cell carcinoma - sores on tips of ears, nose and around the edges of eyelids. Most common in white cats.
- - Paraneoplastic alopecia seen in Bile duct carcinoma and Pancreatic carcinoma. Has been associated with crusting of the footpads and alopecia in cats.
- - variants of Lymphosarcoma, including:
- 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
Psychogenic alopecia due to stress is probably a number one cause of this problem. That's not to say your cat is highly-strung. Often cats who over-groom are normally quite sedate. In a lot of cases, a contributing factor is a past or recent trigger, such as moving house, a stray cat hanging around outside the house, moving house, introducing a baby into the household. These little things can be highly stressful to some cats, and although they may not show signs of being stressed (such as aggression, aloofness or hiding), they can express their anger at a situation inward and take it out on themselves by licking constantly. This disease can be compared to obsessive compulsive disorder in humans, where people constantly wash their hands, stay up at night to clean the house, etc. It is usually a result of not being able to deal with a stress.
In psychogenic alopecia, working out the cause of the anxiety can be difficult, but often it is fairly obvious. Increasing environmental stimulation (play centres, chew toys, food or catnip packed toys, kitty videos, increased interactive play) can all be tried, particularly if the behaviour tends to occur in the owner’s absence. Toys should be kept out of the cat’s reach until put out daily by the owner. Then the toys should be rotated every 1 - 3 days to provide different play items. When home the owner should provide periods of interactive play and perhaps even a short training session to keep the cat occupied and focused. Attention should never be given to the cat when the behaviour is exhibited. In fact, inattention or some form of remote punishment device, may be the best way to ensure that no rewards are given. Remote devices such as a water rifle, a can of compressed air, or an ultrasonic or audible alarm may also serve to interrupt or deter the undesirable behaviour without causing fear of the owner. As soon as the undesirable behaviour ceases, the owner should immediately engage the cat in some alternative acceptable behaviour (e.g. play, chew toys). The owner should also try to identify environmental or social changes that may be contributing to anxiety and the behaviour.
The most commonly used drugs for treating overgrooming in cats include:
- prednisolone 5mg PO each evening for 7-10 days then reduced. Depomedrol (a depocortisone injection is an alternative in fractious or difficult to medicate cats)
- phenobarbital (0.5-2.2 mg/kg, b.i.d., or 15 mg/cat, twice weekly)
- diazepam (1-2 mg/kg, b.i.d.)
- Tricyclic antidepressants, such as amitriptyline (Clomicalm - 1 mg/kg, b.i.d.), are potent H1 blockers in addition to inhibiting uptake of serotonin and norepinephrine. These drugs can induce cardiac arrhythmias and lower the seizure threshold. Other side effects include dry mouth, hypersalivation, vomiting, constipation, urinary retention, ataxia, disorientation, depression, and anorexia. Tricyclic antidepressants should not be used concurrently with monoamine oxidase inhibitors, including amitraz dips for demodicosis. Dosages should be tapered slowly when discontinued.
- Prozac (Fluoxetine -1 mg/kg, s.i.d.), a selective serotonin-reuptake inhibitor, may be effective in treating pruritus or chronic licking in some dogs and cats. A single dose of the endorphin blocker naloxone (1 mg/kg, SC) may be effective in cats with psychogenic alopecia. A change in grooming habits lasts for a variable period of time (1 wk to 6 mo).
- Naltrexone (2.2 mg/kg, s.i.d.) has been used in dogs with some success.
- August, JR (2006) Consultations in feline internal medicine. Vol 5. Elsevier Saunders, USA