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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][3]
  • Activity anorexia; a condition where animals exercise excessively while simultaneously reducing their food intake.[4]
  • 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.[5]
    A dog chasing its tail
  • Barbering, or fur and whisker trimming; removing the whiskers or fur of another animal.[6]
  • Broodiness; sitting on a clutch of eggs to incubate them. (Broodiness is undesirable and considered abnormal in modern commercial egg-laying hens.)[7]
  • Cannibalism; eating the flesh or internal organs of another animal of the same species.[8]
  • Coprophagia; eating faeces.[9]
  • 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.[10]
  • Depression; behaviours associated with a state of low mood and aversion to activity.[11]
  • ; vocalising more frequently than expected.[12]
  • Excessive aggression; aggressive acts that are more frequent or of greater intensity than expected.[13]
  • Excessive/submissive urination (Polyuria); urinating more frequently than expected or under conditions where it would not be expected[14][15]
  • Excessive licking; excessive licking of the floor, wall or other environmental features.[16]
  • Fainting; a transient loss of consciousness and postural tone, characterized by rapid onset, short duration, and spontaneous recovery.[17]
  • Feather pecking; one bird repeatedly pecking or pulling at the feathers of another.[18]
  • Feather-plucking (Pterotillomania); birds chewing, biting or plucking their own feathers with their beak, resulting in damage to the feathers and occasionally the skin.[19]
  • Forced moulting; commercial egg-laying hens losing their feathers due to the deliberate removal of food and water for several days.[20]
  • Geophagia; eating soil or sand.[9]
  • Herbivory in carnivorous animals; eating plant material by an animal that is considered to usually be meat-eating.[21]
  • Infanticide; killing of young offspring by a mature animal of its own species.[22]
  • 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.[23]
  • Lignophagia; eating wood.[9]
  • Obsessive-compulsive disorder; a specific, unnecessary action or series of actions that is repeated more often than would normally be expected.[24]
  • Osteophagy; chewing or eating bones.[9]
  • Pica; eating materials other than normal food.[25]
  • Polydipsia; excessive drinking.[26]
  • Savaging; overt aggression directed to newborn offspring by a mother animal, often including cannibalistic infanticide.[27]
  • Self-cannibalism (Autophagy, Autosarcophagy); an animal eating itself.[28][29]
  • Self-injury; an animal injuring its own body tissues.[30]
  • Sham or "vacuum" dustbathing; dustbathing in the absence of appropriate substrate.[31]
  • Stable vices; stereotypies of equines, especially horses.[32]
  • Stereotypy (non-human); repeated, relatively invariant behaviours with no apparent purpose (multiple types).[33]
  • Stress/Anxiety; behaviours associated with being exposed to a stressor (e.g. loss of appetite, social withdrawal.[34]
  • ; chewing stones or rocks without swallowing them.[35]
  • Tail biting; biting or chewing the tail of another animal.[36]
  • Tail chasing; an animal chasing its own tail in circles[37]
  • Toe pecking; one bird pecking the toes of another.[38]
  • Trichotillomania; an animal pulling out its own fur, hair or wool, often followed by eating it.[39]
  • Urine drinking; drinking urine.[9]
  • Vacuum activity; innate, fixed action patterns of behaviour performed in the absence of the external stimuli that normally elicit them.[40]
  • Vent pecking; injurious pecking directed to the cloaca, the surrounding skin and underlying tissue.[41]
  • Weaving; repeatedly rocking backwards and forwards, or from side to side.[42]
  • 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.[43]


  1. ^ "Abnormal behaviour". Retrieved April 6, 2013.
  2. ^ Bill Wayne Pickett; E. L. Squires; James L. Voss (1981). Normal and abnormal sexual behavior of the equine male. Animal Reproduction Laboratory, Colorado State University, 1981.
  3. ^ McDonnell, S.M. (1992). "Normal and abnormal sexual vehaviour". Vet Clinics of North America: Equine Practice. 8 (1): 71–89. doi:10.1016/s0749-0739(17)30467-4. PMID 1576555.
  4. ^ 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.
  5. ^ Robert, S.; Matte, J.J.; Farmer, C.; Girard, C.L.; Martineau, G.P. (1993). "High-fibre diets for sows: Effects on stereotypies and adjunctive drinking". Applied Animal Behaviour Science. 37 (4): 297–309. doi:10.1016/0168-1591(93)90119-a.
  6. ^ Garner, J.P.; Weisker, S.M.; Dufour, B.; Mench, J.A. (2004). "Barbering (fur and whisker trimming) by laboratory mice as a model of human trichotillomania and obsessive-compulsive spectrum disorders" (PDF). Comparative Medicine. 54 (2): 216–24. PMID 15134369. Archived from the original (PDF) on 2013-12-03.
  7. ^ Burrows, W.H.; Byerly, T.C. (1938). "The effect of certain groups of environmental factors upon the expression of broodiness". Poultry Science. 17 (4): 324–330. doi:10.3382/ps.0170324.
  8. ^ 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 [1] Archived 2013-05-21 at the Wayback Machine
  9. ^ a b c d e "Pica behavior in horses". Archived from the original on May 3, 2013. Retrieved April 5, 2013.
  10. ^ 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.
  11. ^ Kalueff, A. V.; Tuohimaa, P. (2004). "Experimental modeling of anxiety and depression". Acta Neurobiology. 64: 439–448.
  12. ^ Posage, J.M. & Marder, A. "Excessive barking". Retrieved April 5, 2013.
  13. ^ 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 (3–4): 371–377. doi:10.1016/0168-1591(87)90231-0.
  14. ^ petMD. "Increased urination and thirst in cats". Retrieved April 5, 2013.
  15. ^ "Submissive urination in dogs". Archived from the original on April 16, 2013. Retrieved April 5, 2013.
  16. ^ Blackshaw, J.K. "Behavioural profiles of domestic animals - horses". Archived from the original on March 17, 2012. Retrieved March 5, 2013.
  17. ^ Sponenberg, D.P. "Why fainting goats do what they do".
  18. ^ Huber-Eicher, B.; Sebo, F. (2001). "The prevalence of feather pecking and development in commercial flocks of laying hens". Applied Animal Behaviour Science. 74 (3): 223–231. doi:10.1016/s0168-1591(01)00173-3.
  19. ^ Johannes, T.; Lumeij, J.T.; Hommers, C.J. (2008). "Foraging 'enrichment' as treatment for Pterotillomania" (PDF). Applied Animal Behaviour Science. 111 (1–2): 85–94. doi:10.1016/j.applanim.2007.05.015.
  20. ^ 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 (2): 109–113. doi:10.1590/s1516-635x2009000200006.
  21. ^ Cooper, M. "Herbivorous house cats". Archived from the original on September 3, 2012. Retrieved April 5, 2013.
  22. ^ Hausfater, G. and Hrdy, S.B., (1984). Infanticide: Comparative and evolutionary perspectives New York, Aldine. ISBN 0-202-02022-3
  23. ^ Seligman, M.E.P. (1972). "Learned helplessness". Annual Review of Medicine. 23 (1): 407–412. doi:10.1146/ PMID 4566487.
  24. ^ Korff, S.; Harvey, B.H. (2006). "Animal models of obsessive-compulsive disorder: rationale to understanding psychobiology and pharmacology". Psychiatr. Clin. North Am. 29 (2): 371–390. doi:10.1016/j.psc.2006.02.007. PMID 16650714.
  25. ^ Speilman, B. "Pica in dogs". Retrieved April 6, 2013.
  26. ^ Hamm, R.J.; Porter, J.H.; Kaempf, G.L. (1981). "Stimulus generalization of schedule-induced polydipsia". Journal of the Experimental Analysis of Behavior. 36 (1): 93–99. doi:10.1901/jeab.1981.36-93. PMC 1333055. PMID 16812235.
  27. ^ Harris, M.; Gonyou, H.; Bergeron, R. & Li, Y. (2001). "Savaging of piglets: A puzzle of maternal behaviour" (PDF). Retrieved April 5, 2013.
  28. ^ Libbon, Randi; Hamalian, Gareen; Yager, Joel (2015). "Self-Cannibalism (Autosarcophagy) in Psychosis". The Journal of Nervous and Mental Disease. 203 (2): 152–153. doi:10.1097/nmd.0000000000000252.
  29. ^ Joffre, Carine; Djavaheri-Mergny, Mojgan; Pattingre, Sophie; Giuriato, Sylvie (2017-03-01). "L'autophagie : le yin et le yang des cancers". Médecine/Sciences (in French). 33 (3): 328–334. doi:10.1051/medsci/20173303021. ISSN 0767-0974.
  30. ^ 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
  31. ^ 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.
  32. ^ Christie, J.C. (2008). "Horse behavior and stable vices". Regents of the University of Minnesota. Retrieved April 6, 2013. Cite journal requires |journal= (help)
  33. ^ Mason, G.J. (1991). "Stereotypies: A critical review". Animal Behaviour. 41 (6): 1015–1037. doi:10.1016/s0003-3472(05)80640-2. hdl:10214/4622.
  34. ^ Bradshaw, G.A.; Grow, G.; Capaldo, T. & Lindner, L. (2008). "Building an inner sanctuary: complex PTSD in chimpanzees" (PDF). Journal Trauma Dissociation. 9 (1): 9–34. doi:10.1080/15299730802073619. PMID 19042307.
  35. ^ Marchant-Forde, J. (2007). "Stone-chewing". USDA. Retrieved April 7, 2013.
  36. ^ Schrøder-Petersen, D.L.; Simonsen H.B. (2001). "Tail biting in pigs". Veterinary Journal. 162 (3): 196–210. doi:10.1053/tvjl.2001.0605. PMID 11681870.
  37. ^ "Tail chasing in dogs". Archived from the original on March 22, 2013. Retrieved April 5, 2013.
  38. ^ 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
  39. ^ Reinhardt, V (2005). "Hair pulling: A review" (PDF). Laboratory Animals. 39 (4): 361–369. doi:10.1258/002367705774286448. PMID 16197702.[permanent dead link]
  40. ^ Dewey, R.A. (2007). "Vacuum, displacement, and redirected activities". Retrieved April 5, 2013.
  41. ^ 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
  42. ^ Elzanowski, A.; Sergiel, A. (2006). "Stereotypic behavior of a female Asiatic elephant (Elephas maximus) in a zoo" (PDF). Journal of Applied Animal Welfare Science. 9 (3): 223–232. doi:10.1207/s15327604jaws0903_4. PMID 17112333. Archived from the original (PDF) on 2015-04-06. Retrieved 2013-04-09.
  43. ^ 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[1]
  • Abnormal Behavior in Animals. (1968). Edited by M.W. Fox. W. B. Saunders Company, Toronto.

External links

Media related to Animal behavior at Wikimedia Commons

  1. ^ "Archived copy". Archived from the original on 2015-02-22. Retrieved 2013-04-09.CS1 maint: archived copy as title (link)