Abstract

Arousal and distress are considered important factors when dogs show problematic
behaviours and the crucial role of hormones and neurotransmitters involved in stress
responses is widely recognized.
Corticosteroids are important players in stress responses and, along with other hormones
and neurotransmitters, contribute to the onset of both physiological and behavioural
changes that can be either normal and adaptive or excessive and maladaptive
depending on several factors. A literature review revealed that exogenous corticosteroids
have been reported to change behaviour in human beings and laboratory animals
but no data were available as far as similar e�ffects in dogs.
The aim of this research was to identify possible behavioural changes in dogs treated
with corticosteroids. In the fi�rst study, the perception of behavioural changes in dogs
during corticosteroid therapy was investigated through semi-structured open interviews
of the owners of 31 dogs of di�fferent breeds, genders, and ages. All dogs had
received corticosteroid therapies in the past six months. Owners were asked to describe
their dog's behaviours both on and o� corticosteroid therapy.
Eleven owners reported behavioural changes in their dogs; nine dogs were reported
to show more than one behavioural change. Six dogs reportedly showed nervousness
and/or restlessness, three showed an increase in startle responses, three showed food
guarding, two showed a decrease in their activity level, three showed an increase in
avoidance responses, four showed irritable aggression, and two dogs increased barking.
Semi-structured interviews can be useful preliminary tools for the identifi�cation
of areas of future investigation, and the outcomes of the interviews were then used
to investigate more rigorously the possible relationship between these signs and corticosteroid
use in dogs.
In the second study 99 dog owners were asked to complete a 12 item questionnaire,
developed following the results of the previous survey. Owners were asked to evaluate their dogs' behaviour on and off� therapy, using a seven point scale. A sample
of owners whose dogs were receiving treatment for dermatological, orthopaedic or
other conditions completed the survey. The survey was completed by 44 dog owners
with animals receiving treatment with a range of corticosteroid preparations (mainly
prednisolone and methylprednisolone) and 54 dog owners with dogs receiving treatment
with other drugs, mainly antibiotics and non-steroidal anti-infl�ammatory drugs.
Dogs under corticosteroid treatment were reported to be signifi�cantly less playful,
more nervous/restless, more fearful/less confi�dent, more aggressive in the presence of
food, more prone to barking, more prone to startle, more prone to reacting aggressively
when disturbed, and more prone to avoiding people or unusual situations. The
last part of this study involved behavioural tests of dogs.
Eleven �treatment� dogs were then tested twice: before and during corticosteroid
treatment with either methyl-prednisolone or prednisolone to assess their sensitivity
to a potentially aversive stimulus. Eleven control dogs, not receiving corticosteroid
therapy, were also tested at the same time intervals in the same environment. Dogs
were exposed to a brief dog growl while they explored some bowls containing food
and their behaviour was video recorded. Treatment dogs investigated the area for
signi�ficantly less time and ate signi�cantly less food in the second test trial when on
corticosteroid compared to control dogs.
In �final study, exploring relationships between corticosteroid therapy and dogs with
behaviour problems, a review of the caseload of the author of 345 dogs reported for
behaviour and management problems was analyzed. It was found that 16 % of them
had a history of previous treatments with corticosteroids.
Previous treatment with corticosteroid was found to be signi�ficantly associated with
negative aff�ective states.
These results support earlier preliminary �findings concerning possible adverse behavioural
side e�ffects following the use of corticosteroids in dogs, and the possible need
for concomitant behavioural advice when these drugs are used in general veterinary
practice.