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How a change in behaviour could indicate health problems

It is important to locate and rectify the cause of any behavioural change and to prevent any worsening of the condition and the eventual development of health issues

Behavioural normality can be an excellent signal that a pet or companion animal is doing well and is thriving and healthy. Even domestic species retain lots of “wild-type” behaviours (ie behaviours similar or the same as those of their ancestor) whose performance provides us with knowledge of their health and well-being. Maintenance behaviours are routines that animals will perform daily to keep themselves in good condition (Figure 1). Maintenance activities can include grooming and preening, washing and bathing, drinking and feeding; behaviours that allow an animal to keep homeostasis functioning normally.

FIGURE (1) Close companionship and playfulness can be the normal behavioural traits associated with a companion or domestic animal. Clean and well-groomed pelage, bright eyes and an interested appearance are indicative of an individual performing important maintenance behaviours, as evident in this pet domestic cat

Because these behaviours are so important to an individual’s overall condition as well as to its physical and psychological health, one of the first signs that an animal is not feeling well and may be in need of some veterinary attention is a change in its overall behaviour or demeanour, and thus a reduction in time spent on maintenance behaviour. One key pointer of health in most of the common domestic or companion species is a change in their social disposition: whether they become withdrawn or subdued and take themselves away from the new social environment and social character that is associated with that individual animal. Conversely, another friendly or peaceful individual could begin to show atypical and unexpected aggressive behaviour. Therefore, sudden changes to temperament can be linked to underlying heath conditions and are worthy of further investigation.

FIGURE (2) Space, furnishings and social grouping will influence aggression between individuals in an aquarium. Problem behaviours can occur if overly dominant or aggressive inhabitants start to bully or harass other members of the tank

Behavioural disorders can occur if animals are not provided with the correct diet, housing, social environment or abilities to keep themselves clean and well-groomed. These types of problem can be seen across all forms of domestic pet, be they familiar mammals (dogs and cats), to companion birds (budgies and parakeets) and even in aquarium fish that have found themselves living in an inappropriate “community tank” species mix. Owners of tropical aquaria may report dominance or bullying of other tank mates by individuals of territorial or highly aggressive species that find themselves constantly trying to defend a territory because the tank size is inadequate for the behavioural needs of all species of fish kept (Figure 2). Likewise, sensitive and highly specialised species that require specific water conditions, substrates and lighting may not thrive and not eat if aquarium conditions are too general. Consequently, regardless of the type of “pet”, it’s always important to pinpoint the cause of any change in behaviour and rectify the management of the animal to prevent any worsening of the condition and the eventual development of health issues.

It is important for owners with animals displaying potential “problem behaviours” to remember that the behaviour is not the animal’s fault and that the problem is related to the context in which the behaviour is performed.

For example, if it is inappropriate to the situation or it is negatively impacting on the owner’s quality of life with their pet, or if it is causing the owner to change how they interact with others (humans and animals) when their pet is around. A parrot that continues to squawk when an owner is out of contact and is overly aggressive to other members of the household will cause unwanted pressure on one caregiver and affect how the bird can be managed (Figure 3). A hyper-aggressive horse or pony that attempts to attack certain people when they approach or try to handle it may have past trauma or a history of abuse that is causing the dangerous bouts of aggression later in life. Inappropriate elimination behaviour in a pet cat can be suggestive of an animal that is trying to mark a territory, or it could be a stress response because the cat is unhappy or worried about using a litter tray, or it could indicate a urinary tract complication. Consequently, the multifactorial nature of “problem behaviours” needs to be considered and all potential causes assessed before any treatment plan is decided upon.

FIGURE (3) Parrots show strong social bonds and will form a close attachment to an owner if no other bird is present. The strength of this attachment can become overly exaggerated if a bird’s attention seeking is constantly reinforced by one owner (eg through stroking or petting) and consequently aggressive behaviours (such as screaming, biting or lunging at the cage front) can be directed at other members of the household

Individual cases of problem behaviours across a wide range of animal species can be referred by the owner’s veterinary surgeon to a qualified pet behaviour counsellor, such as those registered with the Association of Pet Behaviour Counsellors (APBC). APBC members have the experience and expertise for investigating the causation of the behavioural issue and can help implement a practical treatment plan to remedy the problem. The APBC also runs seminars and workshops for its members, as well as for veterinary surgeons to develop knowledge of and skills around the subject of pet behaviour therapy.

It’s important to realise that change to a pet’s behaviour can occur by using enrichment. Just in the same way that providing environmental enrichment to zoo animals is beneficial (Carlstead and Shepherdson, 2000), and can improve behaviour patterns and reduce the chances of seeing abnormal repetitive behaviours (“stereotypy”), so domestic pets benefit in the same way (Wells, 2004; van Zeeland et al., 2013; Vitale Shreve et al., 2017). And that’s not just the dogs, cats and parrots; research also shows that aquarium fish can benefit from behavioural enrichment (Näslund and Johnsson, 2016) with some species reducing performance of unwanted aggression to tankmates when provided with an enriched environment (Kadry and Barreto, 2010). Consequently, re-directing behavioural performance and changing stimuli to elicit more positive outcomes benefits the individual animal as well as the animal’s caregivers.


Carlstead, K. and Shepherdson, D.


Alleviating stress in zoo animals with environmental enrichment. In: Moberg, G. P. and Mench, J. A. (eds), The Biology of Animal Stress: Basic Principles and Implications for Animal Welfare, CABI Pub, Wallingford, UK. pp. 337-355

Kadry, V. O. and Barreto, R. E.


Environmental enrichment reduces aggression of pearl cichlid, Geophagus brasiliensis, during resident-intruder interactions. Neotropical Ichthyology, 8, 329-332

Näslund, J. and Johnsson, J. I.


Environmental enrichment for fish in captive environments: effects of physical structures and substrates. Fish and Fisheries, 17, 1-30

van Zeeland, Y. R. A., Schoemaker, N. J., Ravesteijn, M. M., Mol, M. and Lumeij, J. T.


Efficacy of foraging enrichments to increase foraging time in grey parrots (Psittacus erithacus erithacus). Applied Animal Behaviour Science, 149, 87-102

Vitale Shreve, K. R., Mehrkam, L. R. and Udell, M. A. R.


Social interaction, food, scent or toys? A formal assessment of domestic pet and shelter cat (Felis silvestris catus) preferences. Behavioural Processes, 141, 322-328

Wells, D. L.


A review of environmental enrichment for kennelled dogs, Canis familiaris. Applied Animal Behaviour Science, 85, 307-317

Paul Rose

Animal behaviour lecturer at University of Exeter

Paul Rose, PhD, completed his PhD on the use of social network analysis to assess behaviour and welfare in captive animal populations. Paul is Co-Chair of the IUCN Species Survival Commission Flamingo Specialist Group and Vice-Chair of the BIAZA Research Committee.

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