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Every Animal is DifferentIndividual Differences AAFP Fall 2002 Meeting The study of individual differences is well recognized in human psychology, to the point that university courses on this topic are routinely offered. Among domestic animals, however, there is still very much a tendency to attempt to always conceptualize a given species as a whole, i.e. cats do this and dogs do that. To best address behavior problems, and to better understand cats, it is essential that we also get in the habit of thinking of our patients as unique individuals. A given cat that comes into your exam room will have a unique temperament. The term temperament is simply a shorthand term for the collective set of behaviors and behavioral tendencies exhibited by a given animal. The temperament is a consequence of many independent variables, including but not limited to gender, neuter status, size, health, age, genetics (breed, strain), experience (learning), relationship with other cats in the household, familiarity with other cats in the household, hair length, current environment and many other variables. These variables also interact, e.g. an intact male of Breed A responds to Learning experience 1 a given way, a neutered male of Breed A responds to Learning experience 1 another way, an intact male of Breed B responds to Learning experience 1 a third way while a neutered male of Breed B responds to Learning experience 1 yet a fourth way. Particularly given the variety of learning experiences possible as a cat interacts with the world, and the relevance of the specific age at which those experiences occur, it is obvious that a very large number of permutations are possible. Gender is an independent variable that is commonly assumed to be the basis for substantial differences in behavior, and in some cases, it is. Males are more likely to spray than are females. For example, of a set of 61 cats presented to the University of Georgia Behavior Service for urine marking only, 42 were neutered males and 16 were neutered females. In this case, the definition of urine marking included both cats that sprayed and a small number of cats that deposited small amounts or urine on the baseboards of walls or the bottom of curtains. Interestingly, two intact females and one intact male were presented. This is an example of the fact that just because some behaviors are more common in a given gender, it is not necessarily the case that they are absent in the other gender. This is a common misunderstanding, and I am still contacted by people who are surprised that their female cat sprays because they thought females did not spray at all. In contrast, of 85 cats that only had a problem of urinating large volumes of urine on horizontal surfaces outside the litter box, 51 were neutered females and 28 were neutered males. The differences in these two samples beg the question of why there is a differences. Do we have a sufficient understanding of the motivation for each behavior to adequately explain this difference? While we can make guesses, e.g. hormonal influence (proximate cause), strategies for scent marking (function), we do not really know. Aggression is another area in which there may or may not be differences. Lindell et al. (1997) found that, among pairs of cats presented for a chief complaint of fighting, males were the initiators more often than were females. However, Barry and Crowell-Davis (1997) found, among pairs of neutered cats sampled randomly from the population, that there was no difference in the level of aggression among male-male dyads, male-female dyads or female-female dyads. Nevertheless, male cats are uniquely presented for human-directed aggression with sexual components. In these cases, the male cat climbs on the arm or ankle, grasps the limb as he would the scruff of a female cat's neck, and initiates pelvic thrusting. While female cats have thick skin and dense hair on the dorsal neck to protect them from injury by the nape grasp, human forearms in particular have thin skin and no hair for protection, so injury is common. This behavior can occur in neutered as well as intact males, and is best addressed by identifying the behaviors that immediately precede mounting and disrupting them before the skin is grasped. Once the skin is grasped, attempts to dislodge the cat may result in further injury. Females may likewise interact with humans in the household in a sexual fashion, but the behavior is not perceived as a problem as it is with males. Specifically, petting a prone female may elicit upward thrusting of the hindquarters and deviation of the tail. Neuter status clearly has substantial effects on behavior. Reproductive behaviors are either substantially reduced in intensity and frequency, or are absent altogether. Neutering can also changes some behaviors indirectly related to sexual behavior, such as roaming (Hart and Barrett 1973). Age is another variable that can have an effect on behavior. When the phrase "developmental behavior" is used, people of think of kitten-hood, puppy-hood, childhood, or whatever phrase is relevant for the pre-adult stage in a given species. However, behavior changes throughout life, partially as a result of experience, but also as a result of physiological changes that occur in the body as it passes from "babyhood" through "childhood", "preadolescence", "adolescence", "adulthood", "middle age" and "old age". This is as true for cats as it is for people. Some behavior problems are unique to particular ages, or at least occur more commonly at particular ages. For example, play aggression is most common in juvenile and young adult cats. Play aggression directed at humans by healthy young adult cats can be particularly problematic. These cats may play extremely vigorously, chasing people and leaping on their calves with great energy, digging teeth and claws in and leaving clear wounds. While these cats are sometimes described as "vicious", their underlying motivation is play, specifically predatory play. They appear to consider the humans they are attacking to be good "playmates". Treatment involves redirecting the cats' normal behavior to acceptable objects of predatory play, while consistently punishing playing with human body parts. Owners who play with kittens with their hands or feet may facilitate the problem. Kittens do not have the strength for this to result in injury. However, they are learning in the process that human hands and feet are acceptable objects of play. Thus, owners must be instructed to never use their hands or feet for play, even with the very youngest kittens. At the other extreme, old cats may develop problems of senility and cognitive dysfunction. While cognitive dysfunction has not been studied in cats as extensively as it has been in dogs, it appears to be very similar to CCD and to human Alzheimer's disease. Declining cognitive abilities may manifest in a variety of ways, including loss of litter box use, excess vocalization in a cat that has not previously exhibited this problem, changes in social responses to humans and other pets in the house, and aimless wandering. Treatment at this time consists of logistical management of specific symptoms, coupled with treatment with selegiline hydrochloride (Anipryl®) (0.5 mg/kg PO daily). Size may be relevant for some behaviors. For example, in a free-ranging population, Liberg (1981) found that larger males tended to more dominant to smaller males. Coat length will strictly determine whether behavior problems that are a direct product of long coat occur. For example, some longhaired cats that do not use the litter box resume using the litter box if the long tufts of hair coming out from between their toes are trimmed. The exact mechanism for this is unknown. Perhaps grains of litter get caught between the hair tufts and the pads, making pawing in the litter painful. On the other hand, it may be that the tufts simply interfere with normal tactile sensory perception. Genetics, most readily measured via breed and coat color, no doubt has some effect on behavior. However, most studies to date focus on human opinion about various breeds, and thus are subject to substantial bias as introduced by prejudice, "urban legends", small sample size, assessment in novel situations rather than the home, atypical individuals making a large impression, effect of human expectation on behavior, and for other reasons (e.g. Fogle (1991), Hart & Hart (1984)). Thus, people may say a particular breed or coat-colored cat is "shyer" or "more aggressive" because they have been told that or read that, rather than because they have objectively evaluated a large number of cats. Urban legends abound. A friend was recently refused emergency treatment for her calico cat because that hospital didn't treat calicos due to their "aggressiveness". While a series of studies have supported the hypothesis that, at least in Europe, the orange allele is linked to aggressiveness (summarized in Mendl and Harcourt 2000), communication with a number of veterinarians in the southeastern United States has revealed that orange cats are popularly perceived as being the friendliest and most non-aggressive of cats in at least this region. Opinions may be based on having only actually known two or three cats of a given breed or color; hardly a sample size on which to evaluate an entire species. Even cat show judges, who assess a large number of cats, only have experience with many cats in a specific and limited context, the show. Also, having known a particularly aggressive/shy/fearful/any other temperament cat of a particular breed can leave an unobjective individual with the impression that that cat is representative of the breed. Finally, expectations of a given animal's behavior will modify human behavior, which in turn is likely to affect the animal's behavior. Thus, a veterinarian who puts substantial credence into ideas of coat color effects on temperament is likely to behave differently toward orange, calico and gray cats. The veterinarians' behavior may then elicit a self-fulfilling prophecy, e.g. they pin the calico cat down because they expect it to be aggressive, and the calico cat is aggressive in response to being pinned down. To the degree that coat color differences in behavior do exist, there are at least three possibilities to explain such an association. First, different pigmentation may directly affect sensory perception. Second, coat color pigments are the product of the same biochemical pathways as some chemicals that are active in the brain that affect behavior, e.g. dopamine. Third, genes controlling coat color may be positioned on chromosomes at locations close to some genes affecting neurochemical processes. Overall, a clear understanding of real differences in behavior between cats of different color requires further objective research on a large sampling from each breed and color. REFERENCES Sharon L. Crowell-Davis, DVM, PhD, DACVB |
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