Abstract

AGGRESSIVE behaviour by dogs is the most frequent behaviour
problem reported to veterinary behaviour clinics (Bamberger and
Houpt 2006, Fatjo and others 2007). The behaviour is a serious
problem for the victims (Weiss and others 1998) and for the
animals themselves, since it often reflects a negative underlying
emotional state, especially if associated with pain (Bamberger
and Houpt 2006, Hsu and Sun 2010). Pain may lower the dog’s
general threshold for aggressive behaviour, while also encouraging
specific aggressive displays as part of a protective/defensive
response (Rutherford 2002, Muir and others 2004, Landsberg
and others 2013). Beaver (1983) has suggested that more than a
quarter (28.2 per cent) of dogs exhibiting aggression do so
because of a medical condition, including pain, but pain-related
aggression has been considered to account for only a small per
cent of the total caseload in behaviour clinics, that is, 2–3.3 per
cent (Beaver 1983, Borchelt 1983). However, when pain is identi-
fied, the data from Beaver (1983) suggest the prognosis is excellent,
with all cases in her case review reported to have a
successful treatment outcome. A recent small case series of
aggressive dogs with a pain focus indicated that musculoskeletal
pain from hip dysplasia and osteoarthritis of the elbow was the
main cause of pain, occurring in 75 per cent (nine of 12 cases) of
these cases (Camps and others 2012).