Chewing, both environmental and self-directed, may be normal behavior; a displacement behavior arising out of conflict, frustration and stress; or an abnormal repetitive behavior which may be a result of an underlying medical condition or a compulsive disorder. Stress may also contribute to both gastrointestinal and dermatologic disorders. The diagnosis is further complicated, as the medical problem could be either the cause or an effect of the behavior. For example, self-trauma can lead to pain, inflammation, and infection, while pica can lead to gastrointestinal signs and foreign body obstructions. Compulsive behaviors arise from normal behaviors that become exaggerated, repetitive, out of context, and fixated on a goal. They may be sufficiently intense or sustained that they cannot be easily interrupted or directed into alternate outlets. In addition, there may be a lack of control in terminating or initiating the behavior. The behaviors may initially be seen in response to situations of conflict (competing motivations or uncertainty), frustration (motivation to a achieve a goal that is behaviorally or physically prevented) or in environments that do not adequately meet the pet’s behavioral needs. With repeated stress, the behavior may become compulsive, with altered neurochemical responses, especially in individuals that are genetically predisposed. Abnormal serotonin transmission has been identified as a primary mechanism by which compulsive disorders are induced, and drugs that inhibit serotonin reuptake can be effective, e.g. clomipramine, fluoxetine.^1,2 However, multiple neurotransmitters might be implicated, including alterations in dopaminergic and glutamatergic pathways or opioid receptors.³

Environmental Chewing

Environmental licking, chewing and picas may begin as normal behaviors arising from play and exploration, or because of taste, texture or odor appeal. However, the behaviors become compulsive when they are repetitive, excessive and fixated on a goal, including wool or fabric sucking, chewing or pica. In one study focused on Siamese and Burmese cats, wool was most commonly chewed, followed by cotton, synthetic fabrics, rubber, and plastic.² In Siamese, Burmese and Birman cats, there appears to be a genetic predisposition, which may be triggered by social or physical stressors in the environment.^2,4-6

In another study of 91 cats with pica, most of which were domestic shorthair, the most common targets were shoelaces, thread, plastic and fabric.⁷ No association was found between pica and a suboptimal environment or early weaning.⁷ Significantly more cats in the pica group were likely to self-suck, indicating that there may be common contributing factors.⁷

Compulsive disorders are diagnosed by first ruling out medical conditions that might cause or contribute to the signs, including anemia, FIP, hyperthyroidism, diabetes mellitus, cancers, and gastrointestinal disease.^7,8 In a recent case series of cats with fabric sucking and ingestion, seven of eight had mild to moderate gastroenteritis. However, only three improved with gastrointestinal treatment.⁸ Compared to a control group, cats with pica vomited more frequently and cats in the control group were more likely to be fed ad lib.

Self-Trauma

In cats, self-grooming and scratching increase in response to conflict and with repeated stress, and might progress to self-traumatic disorders.^3,9 In addition, stress might contribute to increased inflammation and pruritus.

Medical differentials include adverse food reactions, atopy, parasitic hypersensitivity, parasites, fungal infections, pain or discomfort at the site of licking and the dermatologic manifestations of systemic diseases, e.g. hyperthyroidism and hepatocutaneous syndrome. Drug reactions, including to treatment with methimazole, can also cause pruritus. In a clinical trial of 21 cats referred for psychogenic alopecia, each cat was examined, anal sacs expressed and a trichogram, CBC, biochemical profile, T4, FeLV and FIV testing, urinalysis, fungal culture, skin scraping and biopsy performed. If there were no abnormal findings, a parasiticide (Revolution®) and an eight-week trial of hydrolyzed protein diet (Hills prescription diet Z/D) were dispensed. If the cat improved significantly, it was challenged with its own food. If there was no improvement, the cat was treated with two injections of methylprednisolone acetate three weeks apart, to rule out pruritus. Using this protocol, 16 cats were diagnosed with a medical etiology, two were psychogenic, and three had both. A combination of atopy and adverse food reaction was most common (12 cats). Out of 20 cats biopsied, 14 had inflammatory skin lesions. All cats with histological evidence of inflammation had an underlying medical condition. However, of six cats with no histological abnormalities, four had atopy, an adverse food reaction or both.¹⁰

Treatment

As stress is an underlying factor in initiating and maintaining the behavior and may be a contributing factor to gastrointestinal and dermatologic disorders, stress assessment and management (both social and environmental) is an integral part of both diagnosis and treatment. However, a combination of both behavioral management and drug therapy will generally be required for successful improvement of most compulsive disorders.

First, ensure that all of the cat’s behavioral needs are sufficiently and appropriately being met for bedding, perching, climbing, hiding, scratching, elimination, food and water, and object and social play as well as sufficient resources to avoid conflicts with cats, dogs, and family members. Desirable behaviors should be rewarded and sources of stress identified and prevented or resolved. Evaluate for owner responses that inadvertently reinforce the behavior or further add to the pet’s anxiety. Unpleasant interactions and fear-evoking stimuli must be identified and avoided, e.g. handling, visitors, children, or other cats. Train with rewards to reinforce what is desirable, including one or more cues to train alternate behaviors (mat, come/touch). Punishment must be avoided, since even if it suppresses the undesirable behavior, it will cause fear, conflict, and avoidance and negatively impact the human animal bond.

Provide constructive activities to maximize enrichment, including working for food (food-filled toys); multiple small meals; outlets to explore, chew and chase; positive social interactions, including play and reward training; and resting places and bedding that are elevated and secure. An E-collar might prevent self-trauma and provide temporary relief, while separation or cat-proofing will prevent access to objects that might be chewed or ingested; however, unless positively conditioned to wearing collars or to confinement, this will add to further anxiety.

If observed in the act, cue, lure or reorient the pet into a desirable behavior or ignore the pet until it settles. A leash might be left attached (to a body harness) to prevent undesirable behavior and prompt the pet into an acceptable outcome. For stimuli or situations that lead to fear and anxiety, avoid exposure or desensitize and countercondition to change the response.

Together with behavior management and modifications, drugs or supplements may be indicated to reduce fear, anxiety, stress, impulsivity and reactivity. These might include natural products such as pheromones, L-theanine, alpha-casozepine or combinations of ingredients; benzodiazepines, buspirone, gabapentin, clomipramine or selective serotonin reuptake inhibitors. For situational or as-needed use, gabapentin, trazodone, and benzodiazepines such as alprazolam, lorazepam or clonazepam might be considered.

For compulsive disorders, treatment with a selective serotonin reuptake inhibitor (fluoxetine or paroxetine) or with clomipramine should provide some measurable improvement within four to six weeks. If there is insufficient response, a higher dose, drug combination or change in medication will be required.

References

1.  Seksel K, Lindeman MJ. Use of clomipramine in the treatment of anxiety-related and obsessive-compulsive disorders in cats. Aust Vet J. 1998;76(5):317–321.

2.  Overall KL, Dunham AE. Clinical features and outcome in dogs and cats with obsessive-compulsive disorder: 126 cases (1989–2000). J Am Vet Med Assoc. 2002;221(10):1445–1452.

3.  Willemse T, Mudde M, Josephy M, Sprujit BM. The effect of haloperidol and naloxone on excessive grooming behavior of cats. Eur Neuropsychopharmacol. 1994;4(1):39–45.

4.  Bradshaw JWS, Neville PF, Sawyer D. Factors affecting pica in the domestic cat. Appl Anim Behav Sci. 1997;52(3–4):373–379.

5.  Borns-Weil S, Emmanuel C, Longo J, et al. A case-control study of compulsive wool-sucking in Siamese and Birman cats. J Vet Behav. 2015;10(6):541–548.

6.  Sawyer LS, Moon-Fanelli AA, Dodman NH. Psychogenic alopecia in cats: 11 cases (1993–1996). J Am Vet Med Assoc. 1999;214(1):71–74.

7.  Demontigny-Bédard I, Beauchamp G, Bélanger MC, et al. Characterization of pica and chewing behaviors in privately owned cats: a case-control study. J Feline Med Surg. 2016;18(8):652–657.

8.  Demontigny-Bédard I, Beauchamp G, Bélanger MC, et al. Gastrointestinal evaluation of cats presented with pica. In: VBS Proceedings; 2016; San Antonio, TX. 40–44.

9.  Van den Bos R. Post-conflict stress-response in confined group-living cats (Felis silvestris catus). Appl Anim Behav Sci. 1998;59(4):323–330.

10.  Waisglass SE, Landsberg GM, Yager JA, Hall JA. Underlying medical conditions in cats with presumptive psychogenic alopecia. J Am Vet Med Assoc. 2006;228(11);1705–1709.