How I approach… Overgrooming in cats

What is overgrooming?

Overgrooming is the most common cause of feline symmetrical alopecia (FSA), one of the four major cutaneous reaction patterns expressed by cats. The other reaction patterns are head and neck pruritus, lesions of the eosinophilic granuloma complex and miliary dermatitis, and all four patterns occur in response to a wide variety of underlying diseases 3 (Table 1). Although previously named “feline endocrine alopecia”, it is now known that the majority of FSA cases are caused by overgrooming in response to pruritus 4.

Is overgrooming present?

When presented with a case of feline symmetrical alopecia, it is essential to employ a thorough and systematic approach in order firstly to establish whether it is due to overgrooming or, more rarely, spontaneous hair loss. This requires a detailed history, a thorough dermatological and general clinical examination, and some basic diagnostic tests. 

This article will consider in detail the author’s approach to cases of overgrooming, but the reader is referred to the standard dermatology texts for further details on the conditions causing spontaneous hair loss, which often require histopathology and appropriate laboratory tests for diagnosis. 

History and signalment

A thorough history is an important first step in approaching the overgrooming cat. Unfortunately, cats are secretive animals and owners may not see them overgrooming or may not recognize the level of grooming observed as abnormal. However, a history reporting hair in the feces, vomiting of hairballs or finding hair in the house would be highly suggestive of self-inflicted hair loss. 

Other areas that should be covered in the history include:
• Details of the cat’s lifestyle and potential for contagion.
­ Does the owner have other pets and do they have skin problems?
­ Does the cat go outside? Is there direct or indirect contact with other cats, dogs, hedgehogs or rabbits?
­ Does the cat visit other homes or catteries? Do other pets visit the owner’s home?
• Details of ectoparasite control employed.
­ Is an effective product applied at the correct frequency to all in-contact animals?
­ Is environmental control used correctly?
• Details of past or concurrent skin problems and response to previous treatment. Does the cat appear pruritic?
• Details of the cat’s systemic health.
• Are there any other behavioral signs of stress such as inappropriate urination or defecation?
• Are there any obvious potential causes of stress – a multi-cat household, changes at home (e.g., new pet in the home or neighborhood, new baby)?

Information may also be obtained from the signalment. For example, hypersensitivity disorders usually develop in young adulthood, although food allergies can develop at any age. Neoplasia and systemic disease are more common in older individuals. Persian cats are predisposed to dermatophytosis, and Oriental cats to psychogenic alopecia 6.

Clinical examination

A full general clinical examination should be carried out, looking for evidence of systemic disease, which may underlie spontaneous hair loss particularly. 

Hair in affected areas that feels stubbly and broken off is consistent with overgrooming. Additionally, the presence of other lesions linked with pruritic, allergic or ectoparasitic disorders (such as excoriations, miliary dermatitis or eosinophilic granuloma complex lesions) would support the notion of overgrooming (Figure 3), as would the presence of visible ectoparasites such as fleas, lice or harvest mites. However, hair loss from areas that cannot be reached by the tongue, and hair that is easily epilated (i.e., pulled out to reveal a patch of alopecia) would be suggestive of spontaneous hair loss. 

Further evidence can be obtained by performing a trichogram, which can also prove useful to convince owners that hair loss is due to overgrooming, rather than spontaneous loss. Hairs are plucked from the area of loss using forceps and placed, aligned with each other, in liquid paraffin (mineral oil). They are then examined under a coverslip at low and high magnification. Angular and ragged distal tips to the hairs are consistent with overgrooming (Figure 4) whereas the tip of hairs in cases of spontaneous loss will be pointed. Information can also be obtained by examination of the hair bulbs.The normal cat will have 10-20% anagen (actively growing) bulbs and 80-90% telogen (resting) bulbs (Figure 5 and 6), but if multiple samples show the presence of 100% telogen hairs this may suggest spontaneous hair loss and an underlying etiology such as an endocrinopathy, telogen effluvium or systemic disease. 

How should overgrooming be investigated?

Once the presence of overgrooming has been confirmed, it is important to establish the cause so that appropriate treatment can be undertaken. 

Investigations into ectoparasites and infections

It is essential to carry out this initial step thoroughly, particularly as flea hypersensitivity is the most common cause for feline pruritus 7. 

Ectoparasites: The coat should be combed and brushed over a large sheet of white paper to look for evidence of fleas, flea feces and lice. Coat combings and skin scrapings should also be examined in liquid paraffin for evidence of Cheyletiella, Otodectes, Demodex and, rarely, Notoedres or Sarcoptes species. Trichograms may also show eggs on the hair shafts in infestations with lice and Cheyletiella (Figure 7). 

Demodex gatoi, a Demodex mite with a broad blunted abdomen (Figure 8), occurs in some geographical regions and may cause overgrooming in cats. Unlike D. cati, it inhabits the superficial layers of the skin and so may be found on tapestrips as well as superficial skin scrapings. Due to its small size and translucency, samples should be examined with the x10 objective, with the light source reduced in intensity to avoid overlooking the parasite. However, as false negative results may occur due to removal of the mites by overgrooming, it is also useful to scrape apparently unaffected areas that are out of the cat’s reach. Additionally, as it is contagious, testing of asymptomatic in-contact cats may aid diagnosis. Mites may also be found on fecal examination following ingestion while grooming. If D. gatoi is suspected but mites cannot be found, a therapeutic trial can be undertaken, ideally using a 2% lime sulphur dip, applied weekly on three occasions to all in-contact cats. If this is unavailable, oral ivermectin (0.2-0.3 mg/kg Q24-48h) has been reported, but is unlicensed in this species and carries a risk of neurotoxicity 8  9  10.

Prior to embarking on these investigations, it is helpful to explain to the owner the possibility of false negative results. Therefore, even if no parasites are found, an ectoparasite treatment trial carried out for at least 12 weeks, should be undertaken to eliminate fleas and non-demodectic mites. Spot-on preparations such as selamectin or imidacloprid/moxidectin, applied to all in-contact cats and dogs, are likely to be effective, although these drugs are typically unlicensed for mites in cats. 

Concurrent environmental treatment with a spray containing an adulticide and an insect growth regulator is essential, but frequently overlooked. Areas outside the house in which the animal spends time such as the car, outbuildings, and cat carriers should be included. The treatment should be repeated in 4-8 weeks, dependent on the duration of action of the adulticide used. As the pupae may take up to three months to hatch but will be unaffected by the treatment, replenishment of the adulticide will ensure that emergent fleas continue to be killed before biting. It is important to recognize that if the cat continues to go outside, reinfestation, particularly by fleas, may be impossible to prevent, especially if the cat has access to untreated animals or homes. However, this has to be balanced against the practicalities and potential stress of keeping the cat indoors. 

If an improvement occurs, regular flea control must be maintained; systemic products are to be preferred, as overgrooming does not deplete their levels. Treatment reminders can be sent to owners by emails or text messages to optimize compliance 11.

Infections: Examination of the coat for dermatophytosis with an ultraviolet lamp should be carried out, allowing five minutes for the lamp to warm up before use. However, as false negative results are common, a sample should be submitted for culture if dermatophytosis is suspected. This is best performed by sending a sterile toothbrush that has been used to brush the affected animal to the laboratory, along with hairs plucked (using sterile forceps) from the periphery of the lesion. 

Cytology of the skin surface may also be carried out, particularly if bacterial or Malassezia infections are suspected, using stained impression smears or acetate tapestrips. Any infections identified are likely to be secondary to an underlying cause, but should be treated appropriately. 

Note that if there is no evidence of infection or demodicosis, and the pruritus is unacceptable, glucocorticoids may be given in the initial stages of the ectoparasite trial, ideally using oral prednisolone (1-2 mg/kg Q24h). The dose can be tapered to the lowest effective alternate day dose and withdrawn at the end of the trial to observe the effect of the ectoparasite treatment alone.

Drug reactions

Potential drug-induced causes should be identified from the history, and the suspected drug withdrawn if possible, alongside the above measures. 

Investigations into hypersensitivities

If overgrooming persists after elimination of ectoparasitic and infectious causes, investigations can be undertaken into hypersensitivities to dietary and environmental allergens. Although a history detailing gastrointestinal problems may suggest dietary hypersensitivity, this is not always present, and the clinical presentations of the two conditions may be indistinguishable. 

Dietary hypersensitivity: As in vitro tests to diagnose dietary allergies are of questionable accuracy 12, a strict elimination diet trial should be carried out for a minimum of 6-8 weeks. Traditionally, a home-cooked recipe using novel protein and carbohydrate has been used, but nowadays proprietary diets containing totally novel ingredients are increasingly fed, due to their convenience and balanced nutritional content. However, care must be taken that all ingredients are declared and are genuinely novel, which is not the case for many so-called “hypo-allergenic” diets, particularly over-the-counter options 13. Hydrolyzed protein diets are also available. However, concerns that individuals known to be reactive to the native protein may relapse when fed these diets have lead to the suggestion that a hydrolyzed diet based on the most novel proteins should be used if possible 14 15 .

Performing an elimination diet trial in a cat can be difficult and may require some level of compromise. If the individual refuses a single diet, the author may suggest more than one appropriate diet is fed to improve variety. Additionally, as many cats ”graze” throughout the day, it may be necessary to feed the diet to all cats in a multi-cat household. As with ectoparasite control, it is optimal if the cat is kept indoors to prevent hunting or eating elsewhere. However, if this is impossible for reasons of stress or practicality, measures can be taken to mitigate the effects as far as possible (e.g., providing neighbors who feed the cat with the appropriate diet) but the limitations of the trial must then be accepted. 

If pruritus has resolved after 6-8 weeks, it is useful to continue the exclusion diet for at least a month, while maintaining strict ectoparasite control, to ensure that this improvement is sustained. However, if this occurs, the previous diet should be reintroduced and a recurrence of the overgrooming demonstrated before a diagnosis of dietary hypersensitivity is made. The cat should then be returned to the exclusion diet until the overgrooming resolves and a diet selected which can be fed long term. This may be the exclusion diet itself, if nutritionally balanced, or a proprietary diet containing ingredients as close as possible to the exclusion diet. Alternatively, the offending allergens may be identified by the systematic reintroduction of individual ingredients, one every 7-14 days, and a diet avoiding these allergens identified. 

It should be appreciated that if relapse does not occur after reintroduction of the previous diet, the pruritus may have been due to an allergen to which the cat is no longer exposed by the end of the trial. This may occur particularly with seasonal allergens, which may not be apparent until re-exposure the following year.

As with the ectoparasiticidal trial, glucocorticoids may be required to control overgrooming in the initial stages of the diet trial, but should be withdrawn towards its end to assess the effect of the diet alone. If an improvement is not seen after the diet trial, the cat is likely to be suffering from environmental hypersensitivity.

Environmental hypersensitivity (atopy): This is the second most common cause of pruritus in the cat 7, and a sound diagnosis can only be made by working through the steps above, i.e., it is a clinical diagnosis. As in the dog, intradermal allergy testing and IgE serology cannot be used simply to diagnose whether an individual suffers from environmental hypersensitivities, due to potential false positive and false negative results 16 17 18. Additionally, intradermal allergy testing in cats may be difficult to read, and in vitro testing for IgE, though easier to perform, is not as well validated as for the dog 19 20.

Once a diagnosis of environmental hypersensitivity has been made, several treatment options are available, and the choice will depend on the severity of the clinical signs, owner preference and the disposition of the patient. Allergen-specific immunotherapy can be used in this species, but is less well evidenced than for the dog 18 21. The choice of allergens for inclusion is based on intradermal allergy testing or IgE serology, albeit with the limitations discussed above. Treatment is otherwise symptomatic and based on control of pruritus and the flare factors (e.g., fleas and secondary microbial infections). Allergen avoidance can also be attempted but is frequently not possible. 

What are the anti-pruritic options?

Pruritus may be controlled by glucocorticoids, ciclosporin or, possibly, antihistamines. Historically, other drugs such as megestrol acetate have been used but are nowadays best avoided in the presence of safer alternatives 22.

Glucocorticoids

If glucocorticoids are used, oral administration is preferable so that the drug can be tapered to the lowest effective dose and frequency for long-term use (Table 2). Prednisolone is to be preferred to prednisone in cats as the latter is ineffectively metabolized. Depot glucocorticoids (e.g., methylprednisolone acetate) may be required for cats in which oral medication is not possible, although owners should be warned about the risks of iatrogenic side effects with prolonged use.

Ciclosporin

Ciclosporin is licensed in many countries for allergic dermatitis in cats, following initial evaluation of FeLV, FIV and toxoplasmosis status. A starting dose of 7 mg/kg Q24h can be reduced after 4-6 weeks to alternate day dosing in many cases, with subsequent reduction to twice weekly dosing being possible in some individuals (Figure 9 and 10).

Antihistamines

Antihistamines, possibly with concurrent oral essential fatty acid supplements, may be helpful in mild cases, though their use is poorly validated. They may also have a steroid-sparing effect when combined with prednisolone; although unlicensed in cats, reported side effects are generally infrequent and mild. Chlorpheniramine (chlorphenamine) at 2-4 mg/cat Q12h PO is usually considered the most effective 3. 

Oclacitinib 

Oclacitinib is unlicensed in cats, though an uncontrolled pilot study has reported its use in 12 cats with various presentations of feline environmental hypersensitivity, with a good response seen in 5 cases 23. Although it may represent an alternative treatment in the future, if used within the prescribing laws of the reader’s country, further evidence is required to establish the optimal dose regime and its long-term safety profile in cats.

What else can cause overgrooming?

Other causes are rare but should not be overlooked when investigating the overgrooming patient. 

Psychogenic alopecia: In rare cases, excessive self-grooming occurs in the absence of an organic cause, or may persist after an organic cause has resolved. It may be a displacement behavior triggered by a variety of environmental or social stressors. Most cases occur in cats that live indoors and with other cats 24, and Oriental breeds are predisposed. A thorough history may reveal potential stressors or other signs suggestive of a behavioral element such as inappropriate elimination 25. The lack of response to anti-inflammatory doses of glucocorticoids has also been suggested as supportive of a diagnosis of psychogenic alopecia 26, but it is important to rule out medical causes for overgrooming to avoid misdiagnosis: In one study, 16 of 21 cats referred for psychogenic alopecia were found to have an underlying medical condition 27. If psychogenic alopecia is diagnosed, it is important to try to identify the cause so that environmental and/or behavioral modification can be undertaken 25. This may involve enlisting the expertise of a veterinary behaviorist and observing the cat in the home environment. Pheromone diffusers may be helpful, but pharmacological intervention may also be required. Clomipramine has been reported as the most effective agent (0.5 mg/kg Q24h PO for 4-6 weeks; increase to 1 mg/kg Q24h if required). However, other tricyclic antidepressants, selective serotonin reuptake inhibitors, and benzodiazepines have also been used. These include fluoxetine (0.5-1 mg/kg Q24h), amitriptyline (0.5-1 mg/kg Q12-24h), and diazepam (0.2-0.4 mg/kg Q12-24h). Note these drugs are usually not licensed for use in cats, but further details can be found in the literature 26 28 29.

Feline hyperesthesia: Feline hyperesthesia may involve licking or chewing at the skin, particularly of the flank, lumbar, tail or anal regions. However, it is accompanied by other clinical signs such as rippling of the skin, muscle spasms, running, jumping, and vocalization. As with feline psychogenic alopecia, it has been associated with social or environmental stress 28.

Pain, neurodermatitis, neuralgia: Although rare, overgrooming may occur in response to pain or discomfort from an underlying organ, neuritis or neuralgia. In particular, the possibility of feline lower urinary tract disease should be considered in cats that lick the caudoventral abdomen 2.

Summary

Overgrooming in cats is a common presentation in feline practice with many potential underlying causes. A systematic approach to identifying its cause will optimize the likelihood of a successful outcome for both patient and clinician.