The interplay between medicine and behavior (Proceedings)


Most medical conditions lead to changes in behavior. Veterinary visits are scheduled when pets are "not acting right". Behaviors of concern might include limping, coughing, and vomiting.

Most medical conditions lead to changes in behavior. Veterinary visits are scheduled when pets are "not acting right". Behaviors of concern might include limping, coughing, and vomiting.

These clinical signs, or behaviors, will be considered as the diagnostic plan is systematically formulated. The work-up will include history-taking, physical examination, and possibly some laboratory testing or diagnostic imaging. Once the diagnosis is established, then treatment of the underlying disease will result in resolution of the behavior change. The fractured femur is pinned, and the lameness resolves.

If reasonable diagnostic testing does not identify an organic condition, then the problem may be psychogenic. Certain clinical signs fit textbook descriptions of primary behavior problems. The patient profile may even support the diagnosis. But without an appropriate physical evaluation, easily treatable organic conditions may be overlooked.

For example, a diagnosis of psychogenic alopecia should not be assigned until the patient has been tested for common dermatological conditions such as atopy, dietary hypersensitivity, and external parasites. Psychogenic PUPD is always a diagnosis of exclusion. And management of housesoiling will be challenging without concurrent treatment of UTI, FLUDT, or IBD in affected patients.

Should you suspect an underlying medical condition?

Medical problems and behavioral problems routinely overlap. A purely behavioral diagnosis assumes a healthy patient. Medical problems may function to cause, exacerbate, or maintain behavior problems. Infection, inflammation, neoplasia, toxin, cardiovascular disease, metabolic disease and developmental disease may all cause behavioral abnormalities including aggression and anxiety. In many cases, even though the medical condition has been cured or controlled, behavior changes persist.

In addition, drugs used to treat medical conditions can result in adverse behavioral side effects. Aggression or anxiety have been reported with such commonly prescribed medications as phenylpropalolamine, acepromazine, diazepam and thyroxine.

Partial or psychomotor seizures may be responsible for a wide range of behavioral signs including aggression, ritualized behavior, and paroxysmal behavior. EEG and / or response to antiepileptic drugs are used to support a diagnosis.

Is this a primary behavioral problem?

A detailed behavioral history will identify and characterize patterns of behavioral abnormalities. There may be evidence that the presently problematic behavior had been exhibited previously, perhaps with reduced intensity such that it did not concern the owner.

Age of onset affects the index of suspicion for a primary behavioral problem. Aggressive behavior, for example, often surfaces as pets mature socially.

Diagnostic tips

1. A sudden behavior change with no change in the physical or social environment should increase the index of suspicion for organic disease.

2. A medical cause is less likely in a young, healthy patient exhibiting a gradual change in behavior.

Initial diagnostic testing may be less rigorous for a young patient, particularly if the onset of the behavior change has been gradual. Confirming normal physical, chemical and endocrine parameters is still indicated.

3. Therapeutic trials may sometimes be used to support a diagnosis.

Medical conditions improve more rapidly than primary behavioral problems. A primary medical problem will not resolve with behavior modification alone.

Treatment strategies

The patient must be treated in entirety. Behavioral and medical conditions all need to be addressed, as does as the interaction between them. Although the primary diagnosis may be behavioral, underlying medical conditions will affect the intensity and frequency of the problematic behavior. For example, identification and management of pain can reduce the incidence of anxiety or aggression.

Sometimes, patients exhibit anxiety in response to their primary medical condition. Behavior modification and anxiety-reducing medication can improve their tolerance. For example, patients sometimes exhibit anxiety in response to immobility; they may be conditioned to relax on cue. Reward-based training using audible cues and scents may reduce anxiety secondary to blindness.

Psychotropic medication may be prescribed even in the face of organic disease. It is important to remember that drug interactions are not always predictable. The bioavailability of commonly used medications can be affected and the dosages may need to be adjusted.

Prognostic considerations

The greater the number of diagnoses, be they medical or behavioral, the less favorable the prognosis. Client compliance decreases as the number of treatment steps increases. Since medicating pets can be a challenge for many clients, the need to administer multiple drugs translates into reduced compliance.

The client's ability to maintain a safe environment will affect the prognosis for an aggressive patient, even if there is a medical basis for the aggression.

A very favorable prognosis may be offered if an easily managed or curable underlying medical condition is responsible for the behavior changes.

Clients seem more likely to empathize with a physically "sick" pet than with a pet that is simply not behaving appropriately. It is very important to assure clients that the patient is not acting out or acting badly, and that even in the absence of physical disease, behavior problems can be successfully treated with a systematic protocol.


In conclusion, medical and behavioral problems are not mutually exclusive. Behavioral history, behavioral observations, physical findings, and laboratory findings are used to determine whether a behavioral complaint is secondary to organic disease or whether it represents a primary behavior problem.

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