List of abnormal behaviours in animals

Abnormal behaviour in animals can be defined in several ways. Statistically, abnormal is when the occurrence, frequency or intensity of a behaviour varies statistically significantly, either more or less, from the normal value. This means that theoretically, almost any behaviour could become abnormal in an individual. Less formally, 'abnormal' includes any activity judged to be outside the normal behaviour pattern for animals of that particular class or age.^[1] For example, infanticide may be a normal behaviour and regularly observed in one species, however, in another species it might be normal but becomes 'abnormal' if it reaches a high frequency, or in another species it is rarely observed and any incidence is considered 'abnormal'. This list does not include one-time behaviours performed by individual animals that might be considered abnormal for that individual, unless these are performed repeatedly by other individuals in the species and are recognised as part of the ethogram of that species.

Most abnormal behaviours can be categorised collectively (e.g., eliminative, ingestive, stereotypies), however, many abnormal behaviours fall debatedly into several of these categories and categorisation is therefore not attempted in this list. Some abnormal behaviours may be related to environmental conditions (e.g. captive housing) whereas others may be due to medical conditions. The list does not include behaviours in animals that are genetically modified to express abnormal behaviour (e.g. Reeling mice).

A polar bear performing stereotyped pacing.

An Asiatic elephant performing stereotyped rocking and trunk swinging.

• Abnormal sexual behaviour; various types.^[2]
• Activity anorexia; a condition where animals exercise excessively while simultaneously reducing their food intake.^[3]
• Adjunctive behaviour; an activity reliably accompanying another response that has been produced by a stimulus, especially when the stimulus is presented according to a temporally defined schedule.^[4]
• Barbering, or fur and whisker trimming; removing the whiskers or fur of another animal.^[5]

• Broodiness; sitting on a clutch of eggs to incubate them. (Broodiness is undesirable and considered abnormal in modern commercial egg-laying hens.^[6])
• Cannibalism; eating the flesh or internal organs of another animal of the same species.^[7]
• Coprophagia; eating faeces.^[8]
• Cribbing or crib-biting; grabbing a solid object such as a fence with the incisors, arching the neck, pulling against the object, and sucking in air.^[9]
• Depression; behaviours associated with a state of low mood and aversion to activity.^[10]
• Excessive vocalisation; vocalising more frequently than expected.^[11]
• Excessive aggression; aggressive acts that are more frequent or of greater intensity than expected.^[12]
• Excessive/submissive urination (Polyuria); urinating more frequently than expected or under conditions where it would not be expected^[13][14]
• Excessive licking; excessive licking of the floor, wall or other environmental features.^[15]
• Fainting; a transient loss of consciousness and postural tone, characterized by rapid onset, short duration, and spontaneous recovery.^[16]
• Feather pecking; one bird repeatedly pecking or pulling at the feathers of another.^[17]
• Feather-plucking (Pterotillomania); birds chewing, biting or plucking their own feathers with their beak, resulting in damage to the feathers and occasionally the skin.^[18]
• Forced moulting; commercial egg-laying hens losing their feathers due to the deliberate removal of food and water for several days.^[19]
• Geophagia; eating soil or sand.^[8]
• Herbivory in carnivorous animals; eating plant material by an animal that is considered to usually be meat-eating.^[20]
• Infanticide; killing of young offspring by a mature animal of its own species.^[21]
• Learned helplessness; failing to respond even though there are opportunities for the animal to help itself by avoiding unpleasant circumstances or by gaining positive rewards.^[22]
• Lignophagia; eating wood.^[8]
• Obsessive-compulsive disorder; a specific, unnecessary action or series of actions that is repeated more often than would normally be expected.^[23]
• Osteophagia; chewing or eating bones.^[8]
• Pica; eating materials other than normal food.^[24]
• Polydipsia; excessive drinking.^[25]
• Savaging; overt aggression directed to newborn offspring by a mother animal, often including cannibalistic infanticide.^[26]
• Self-cannibalism (Autophagy, Autosarcophagy); an animal eating itself.
• Self-injury; an animal injuring its own body tissues.^[27]
• Sham or "vacuum" dustbathing; dustbathing in the absence of appropriate substrate.^[28]
• Stable vices; stereotypies of equines, especially horses.^[29]
• Stereotypy (non-human); repeated, relatively invariant behaviours with no apparent purpose (multiple types).^[30]
• Stress/Anxiety; behaviours associated with being exposed to a stressor (e.g. loss of appetite, social withdrawal.^[31]
• Stone chewing; chewing stones or rocks without swallowing them.^[32]
• Tail biting; biting or chewing the tail of another animal.^[33]
• Tail chasing; an animal chasing its own tail in circles^[34]

A dog chasing its tail

• Toe pecking; one bird pecking the toes of another.^[35]
• Trichotillomania; an animal pulling out its own fur, hair or wool, often followed by eating it.^[36]
• Urine drinking; drinking urine.^[8]
• Vacuum activity; innate, fixed action patterns of behaviour performed in the absence of the external stimuli that normally elicit them.^[37]
• Vent pecking; injurious pecking directed to the cloaca, the surrounding skin and underlying tissue.^[38]
• Weaving; repeatedly rocking backwards and forwards, or from side to side.^[39]
• Wind sucking; similar to cribbing whereby the horse arches its neck and sucks air into the windpipe but without needing to grab a solid object.^[40]

References

1. "Abnormal behaviour". Retrieved April 6, 2013.
2. McDonnell, S.M., (1992). Normal and abnormal sexual vehaviour. Vet Clinics of North America: Equine Practice, 8: 71-89
3. Hampstead, B.M.; LaBounty, L.P.; Hurd, C. (2003). "Multiple exposures to activity anorexia in rats: Effects on eating, weight loss, and wheel running". Behavioural Processes 61 (3): 159–166. doi:10.1016/s0376-6357(02)00188-2. PMID 12642171.
4. Robert, S., Matte, J.J., Farmer, C., Girard, C.L. and Martineau, G.P., (1993). High-fibre diets for sows: Effects on stereotypies and adjunctive drinking. Applied Animal Behaviour Science, 37: 297–309
5. Garner, J.P., Weisker, S.M., Dufour, B. and Mench, J.A., (2004). Barbering (fur and whisker trimming) by laboratory mice as a model of human trichotillomania and obsessive-compulsive spectrum disorders Comparative Medicine, 54: 216-24
6. Burrows, W.H.; Byerly, T.C. (1938). "The effect of certain groups of environmental factors upon the expression of broodiness". Poultry Science 77: 324–330.
7. McGlone, J.J., Sells, J., Harris, S. and Hurst, R.J. Cannibalism in growing pigs: Effects of tail docking and housing system on behavior, performance and immune function.Texas Tech Univ. Agric. Sci. Tech. Rep. No. T-5-283
8. "Pica behavior in horses". Retrieved April 5, 2013.
9. Malamed, R.; Berger, J.; Bain, M. J.; Kass, P.; Spier, S.J. (2010). "Retrospective evaluation of crib-biting and windsucking behaviours and owner-perceived behavioural traits as risk factors for colic in horses". Equine Veterinary Journal 42 (8): 686–92. doi:10.1111/j.2042-3306.2010.00096.x. PMID 21039797.
10. Kalueff, A. V.; Tuohimaa, P. (2004). "Experimental modeling of anxiety and depression". Acta Neurobiology 64: 439–448.
11. Posage, J.M. and Marder, A. "Excessive barking". PetPlace.com. Retrieved April 5, 2013.
12. Reinhardt, V.; Reinhardt, A.; Eisele, S.; Houser, D.; Wolf, J. (1987). "Control of excessive aggressive disturbance in a heterogeneous troop of rhesus monkeys". Applied Animal Behaviour Science 18: 371–377. doi:10.1016/0168-1591(87)90231-0.
13. petMD. "Increased urination and thirst in cats". Retrieved April 5, 2013.
14. "Submissive urination in dogs". Retrieved April 5, 2013.
15. Blackshaw, J.K. "Behavioural profiles of domestic animals - horses". Retrieved March 5, 2013.
16. Sponenberg, D.P. "Why fainting goats do what they do". Retrieved March 2004.
17. Huber-Eicher, B.; Sebo, F. (2001). "The prevalence of feather pecking and development in commercial flocks of laying hens". Applied Animal Behaviour Science 74: 223–231. doi:10.1016/s0168-1591(01)00173-3.
18. Johannes, T.; Lumeij, J.T.; Hommers, C.J. (2008). "Foraging ‘enrichment’ as treatment for Pterotillomania" (PDF). Applied Animal Behaviour Science 111: 85–94. doi:10.1016/j.applanim.2007.05.015.
19. Molino, A.B.; Garcia, E.A.; Berto, D.A.; Pelícia, K.; Silva, A.P.; Vercese, F. (2009). "The effects of alternative forced-molting methods on the performance and egg quality of commercial layers". Brazilian Journal of Poultry Science 11: 109–113. doi:10.1590/s1516-635x2009000200006.
20. Cooper, M. "Herbivorous house cats". Retrieved April 5, 2013.
21. Hausfater, G. and Hrdy, S.B., (1984). Infanticide: Comparative and evolutionary perspectives New York, Aldine. ISBN 0-202-02022-3
22. Seligman, M.E.P. (1972). "Learned helplessness". Annual Review of Medicine 23 (1): 407–412. doi:10.1146/annurev.me.23.020172.002203.
23. Korff, S.; Harvey, B.H. (2006). "Animal models of obsessive-compulsive disorder: rationale to understanding psychobiology and pharmacology". Psychiatr. Clin. North Am. 29: 371–390. doi:10.1016/j.psc.2006.02.007.
24. Speilman, B. "Pica in dogs". PetPlace.com. Retrieved April 6, 2013.
25. Hamm, R.J., Porter, J.H. and Kaempf, G.L. (1981). Stimulus generalization of schedule-induced polydipsia. Journal of Experimental Analysis of Behaviour, 36: 93–99
26. Harris, M., Bergeron, R., Li, Y. and Gonyou, H. (2001). "Savaging of piglets: A puzzle of maternal behaviour." (PDF). Retrieved April 5, 2013.
27. Baker, K., Bloomsmith, M., Griffis, C. and Gierhart, M., (2003). Self injurious behavior and response to human interaction as enrichment in rhesus macaques" American Journal of Primatology 60 (Suppl. 1): 94-95. ISSN 0275-2565
28. Olsson, I.A.S.; Keeling, L.J.; Duncan, I.J.H. (2002). "Why do hens sham dustbathe when they have litter?". Applied Animal Behaviour Science 76: 53–64. doi:10.1016/s0168-1591(01)00181-2.
29. Christie, J.C. (2008). "Horse behavior and stable vices". Regents of the University of Minnesota. Retrieved April 6, 2013.
30. Mason, G.J. (1991). "Stereotypies: A critical review". Animal Behaviour 41: 1015–1037. doi:10.1016/s0003-3472(05)80640-2.
31. Bradshaw, G.A., Capaldo, T., Lindner, L. and Grow, G. (2008). "Building an inner sanctuary: complex PTSD in chimpanzees" (PDF). Journal Trauma Dissociation 9 (1): 9–34. doi:10.1080/15299730802073619. PMID 19042307.
32. Marchant-Forde, J. (2007). "Stone-chewing". USDA. Retrieved April 7, 2013.
33. Schrøder-Petersen, D.L. and Simonsen H.B., (2001). Tail biting in pigs. Veterinary Journal, 162: 196-210
34. "Tail chasing in dogs". Retrieved April 5, 2013.
35. Krause E.T., Petow, S. and Kjaer J.B., (2011). A note on the physiological and behavioural consequences of cannibalistic toe pecking in laying hens (Gallus gallus domesticus). Archiv für Geflugelkunde, 75: 140-143
36. Reinhardt, V., (2005). Hair pulling: A review. Laboratory Animals, 39: 361-369
37. Dewey, R.A. (2007). "Vacuum, displacement, and redirected activities.". Retrieved April 5, 2013.
38. Sherwin, C.M., (2010). The welfare and ethical assessment of housing for egg production. In The Welfare of Domestic Fowl and Other Captive Birds, I.J.H. Duncan and P. Hawkins (eds), Springer, pp. 237-258
39. Elzanowski, A. and Sergiel, A., (2006). Stereotypic behavior of a female Asiatic elephant (Elephas maximus) in a zoo. Journal of Applied Animal Welfare Science, 9(3): 223–232
40. Malamed, R.; Berger, J.; Bain, M.J.; Kass, P; Spier, S.J (November 2010). "Retrospective evaluation of crib-biting and windsucking behaviours and owner-perceived behavioural traits as risk factors for colic in horses". Equine Veterinary Journal 42 (8): 686–92. doi:10.1111/j.2042-3306.2010.00096.x. PMID 21039797.

Further reading

Behavior Consultation

Abnormal Behavior in Animals. (1968). Edited by M.W. Fox. W. B. Saunders Company, Toronto.