Non-canine ResearchA case-control study of compulsive wool-sucking in Siamese and Birman cats (n = 204)
Introduction
Obsessive-compulsive disorder in humans and compulsive behavior in animals are characterized by repetitive, ritualistic behaviors, which interfere with normal activities and functioning (Overall and Dunham, 2002). Specifically, in domestic animals, compulsive behaviors such as wool-sucking are exaggerations of natural behaviors such as grooming, eating, or suckling (Dodman et al., 2010). Wool-sucking is a stereotypic, oral compulsion that manifests in cats as the chewing, sucking, or ingesting of nonfood items such as wool or plastic. (Dodman, 1998, Overall and Dunham, 2002). In its most severe manifestation, the ingestion of foreign material may result in the obstruction of the gastrointestinal tract, which can be potentially life-threatening to the cat (Hayes, 2009).
There is a lack of consistency in the definition of fabric sucking, chewing, and ingestion behavior in the literature. It is variously referred to as wool-sucking (Dodman, 1998, Overall and Dunham, 2002) and pica (Bradshaw et al., 1997). In this study, the term wool-sucking was used to describe the sucking, chewing, and ingestion of nonfood items consisting of fabric, paper, plastic, and metal. A recent paper by Tynes and Sinn (2014) raises the question of whether it is valid to consider pica a form of wool-sucking as ingestion of foreign material has been shown to be associated with certain feline medical conditions (Tynes and Sinn, 2014). The question is whether medical conditions contribute to the onset of wool-sucking behavior. Additional research would be needed to assess whether fabric ingestion belongs in a category of its own.
Bradshaw et al. (1997) reported an early age of onset of wool-sucking (typically 18 months or less), implying that genetic or early life influences are involved (Bradshaw et al., 1997). Oriental breeds, such as Siamese and Birman cats, are more prone to wool-sucking behavior than domestic shorthair or domestic longhair cats which again suggest a genetic susceptibility (Overall and Dunham, 2002). Similarly, psychogenic alopecia, a compulsive behavior in which a cat excessively grooms and licks its own hair coat and skin, seems to be more prevalent in Oriental breeds of domestic cat, as suggested by Sawyer et al. (1999). The behavior may also be influenced by environmental factors early in the animal's life, as the condition commonly manifests before 6 months of age (Dodman, 1998). There are several hypotheses regarding the possible triggers of the behavior. For one, it is fairly common for the onset of the behavior to occur within 2 months of rehoming a cat, suggesting that the stress of separation from littermates and placement in a new environment may be a factor (Bradshaw et al., 1997). It has also been hypothesized that wool-sucking derives from factors in the infantile environment such as early weaning (Bradshaw et al., 1997, Dodman, 1998).
There is a paucity of scientific evidence as to the causes of “wool-sucking” in cats. To date, no studies have examined potential risk factors associated with feline wool-sucking behavior using a control group for comparison. The purpose of our study was to distinguish environmental and physical differences between affected and control cats and to determine whether these differences facilitate (increase the risk of) the compulsive behavior of wool-sucking.
Section snippets
Study participants
Convenience sampling was used to collect our sample. Siamese and Birman cat owners were recruited from various sources including the case load of Tufts Cummings School of Veterinary Medicine, advertising via the Cat Fancy Association newsletter, posting ads in breed-specific online chat groups including SIAMESE, BiColourOrientalSiamese, and Cats-healthandbehavior on Yahoo.com. Advertisements were also posted on “Cat Health and Care,” “Behavior,” and “Cat Breed” discussions forums at //ConnectedbyPets.com
Age of weaning
In the Siamese group, no differences were noted in the percentage of affected versus control cats weaned before the normal weaning age of 7 weeks (Martin, 1986, Bateson, 2000). There was also no significant differences seen between the mean weaning ages of affected and control Siamese cats (9.5 weeks vs. 10.3 weeks, P = 0.39). However, affected Birmans were more likely to have been weaned before 7 weeks (10 (35.7%) vs. 4 (11.8%), P = 0.02). Also, the mean weaning age of affected Birman cats was
Discussion
This study represents the first attempt to investigate compulsive sucking, chewing and ingesting of fabric, and other substrates in Oriental cats by comparing affected and control populations of 2 different Oriental breeds.
Our data show that the onset of wool-sucking behavior in Birman cats was associated with early weaning whereas the onset of wool-sucking in Siamese cats was independent of weaning age. Weaning is normal developmental phase that is usually completely at about 7 weeks (Martin,
Conclusion
Our data supported our hypothesis that early weaning was associated with an increased risk of wool-sucking in Birmans cats, whereas the age of weaning did not have a significant effect on the development of wool-sucking in Siamese cats. Siamese cats with a history of medical problems had an increased risk of wool-sucking. Intense appetite was associated with wool-sucking in both Siamese and Birman cats.
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