Monitoring and assessing behavioral signs is a critical component of every veterinary visit. Virtually any medical condition
can present with behavioral signs and behavioral signs may be the first indicators of disease (e.g. irritability, anxiety,
aggression, anorexia, depression, decreased response to stimuli, housesoiling, night waking, etc). Behavioral signs can also
be used to monitor improvement or response to therapy. Therefore to insure early diagnosis and intervention, owners should
be asked about behavior problems at each visit and pet owners should be encouraged to seek guidance as soon as signs arise.
Rather than directly initiating the signs, medical factors may play a contributory role in how a pet might behave in certain
situations or respond to specific stimuli which may vary with genetics, previous experience, environment, the stimulus, etc.
Signalment is also an important consideration since, for example, the onset of behavior problems in older pets may increase
the suspicion of a medical cause.
Stress and its effects on health and behavior
While it is common to consider the effects of disease on behavior, both acute and chronic stress can have an impact on health
as well as behavior, through its effects on the HPA axis and activation of the noradrenergic system. Stress is an altered
stated of homeostasis which can be caused by physical or emotional factors. Stress triggers psychological, behavioral, endocrine
and immune effects that are designed to handle stress. The first component is the HPA axis, in which the hypothalamus releases
corticocotropic releasing hormone (CRH), which stimulates the release of ACTH. The second component is the sympathetic-adrenal-medullary
system which releases noradrenaline and adrenaline. Noradrenaline is associated with sensitization and fear conditioning.
If stress is persistent or chronic there is continued stimulation of the HPA axis and an increase in cortisol with a depression
of the catecholamine system, leading to alterations in the immune system and the possible development of stress related diseases.
In humans there may be a correlation between stress and poor health, poor immune function, cardiovascular disease, and cellular
aging. In pets, stress has been shown to be a contributing factor to some forms of feline interstitial cystitis (FIC), gastrointestinal
diseases, dermatologic conditions and behavioral disorders.
Cats with FIC have altered bladder permeability during stress when compared to cats in an enriched environment. An increase
in plasma norepinephrine has been demonstrated in cats with interstitial cystitis. Cats receiving MEMO (multimodal environmental
modification) had a significant reduction in FIC, respiratory disease, fearfulness, and nervousness and less inflammatory
bowel disease and aggression. In a placebo controlled study there were less bouts of FIC when a Feliway diffuser was installed.
Stress and anxiety can alter bacterial flora, inhibit gastric emptying, increase colonic activity, and increase intestinal
permeability leading to irritable bowel syndrome, gastrointestinal reflux, stress induced hypersensitivity, and heartburn.
In pets, acute fear and anxiety can lead to a decrease in appetite or anorexia such as what might be observed in a pet with
separation anxiety that does not eat until the owner returns home. A more chronic form of anxiety may arise with the introduction
of a new pet or moving (especially in cats) while the loss of a human or pet in family can cause a "grief" response in some
dogs and cats that can affect appetite and health. Stress and anxiety can also lead to diarrhea, vomiting, colitis, picas,
polyphagia and polydypsia and may aggravate underlying disease states such as atopic pruritus.
In humans, anxiety might contribute to pruritus in humans, since stress can lead to an increase in cytokines, release of opioids,
serotonin and other vasoactive peptides, and a reduction in cortisol especially in atopic individuals. A link has also been
found between stress and increased epidermal permeability.10 If this were also the case in dogs, lead a genetically predisposed individual to develop atopic disease. Opioid peptides
released during stress may further potentiate pruritus.
Chronic anxiety, stress, conflict and frustration, may lead to behavioral disorders in humans including panic disorders, separation
anxiety, social and other phobias, obsessive-compulsive disorders, generalized anxiety disorders, post-traumatic stress disorders,
impulse control disorders, and sleep disorders which likely have similar animal correlates. A recent study in dogs identified
higher prolactin levels with chronic stress and high anxiety, that was associated with stereotypic and displacement behaviors,
fear aggression and autonomic signs. Lower levels of prolactin were associated with fear and phobias. Therefore identifying
whether a self-traumatic disorder is behavior, medical or a combination of both is essential for successful control or resolution.