Behavior: Causes and Diagnosis of Problems

What makes a pet misbehave?

Behavior problems can be due to medical or behavioral causes, or both. A clinical history, physical examination, and diagnostic testing will determine if there are underlying medical conditions contributing to the problem. Although there may be a single cause for a behavior problem it is often the combined effect of the environment and learning on the pet's mental and physical health that determines behavior.

For example, the pet that is fearful of children may begin to become more reactive, irritable, and aggressive as diseases such as dental problems or arthritis make it more uncomfortable, painful or less mobile.

Another example is the cat that had been exposed to other cats roaming across its territory, but only began to mark when it developed an overactive thyroid at 10 years of age. Correcting the thyroid problem as well as behavior modification techniques resolved this problem.

What are some behavioral causes of behavioral problems?

Any change in the environment may contribute to the emergence of behavior problems. For example, schedule changes, a new member of the household (baby, spouse), moving, loss of a family member or pet, or the addition of a new pet can have a dramatic impact on behavior. Any medical or degenerative changes associated with aging may cause the pet to be even more sensitive to these environmental changes.

Learning (e.g. reinforcement, punishment) also plays a role in most behavior problems. When a pet's actions result in unpleasant consequences (discomfort, lack of attention) i.e. punishment, the chances of repeating the behavior will decrease. If the behavior is followed by pleasant consequences such as obtaining food, attention, or affection (rewards), the behavior is likely to be repeated. These consequences could occur unintentionally as when the pet gets into the garbage and finds some appealing leftovers, or could be administered by the owners, as when a reward is given following a behavior. It can be difficult to determine what might be reinforcing a behavior, but reinforcement maintains behavior problems.

What tests can be done to determine a behavioral cause?

A good history is one of the most important means of determining the cause of a behavioral past including any training as well as the circumstances surrounding the problem itself. Daily interactions with the pet and any changes in schedule need to be explored. Often the event that precipitated the behavioral change may be different from that which maintains it.

Based on the behavioral problem, the pet's age, and a physical examination, the veterinarian first determines if there are any medical causes or contributing factors. Diagnosis of a behavioral cause can only be made after all medical factors have been ruled out.

What medical conditions can cause or contribute to behavior problems?

A decline in the pet's hearing, sight or other senses, organ dysfunction (e.g. liver or kidney disease), hormonal diseases, diseases affecting the nervous system, diseases of the urinary tract (infections, tumors, or stones), any disease or condition that might lead to pain or discomfort, and those that affect the pets mobility can all cause or contribute to behavior problems.

a) Any condition that leads to an increase in pain or discomfort can lead to increased irritability, increased anxiety or fear of being handled or approached, and ultimately an increased aggressiveness. If these aggressive displays are successful at removing the "threat" (and they usually are) the behavior is reinforced. Medical conditions that affect the ears, anal sacs, teeth and gums, bones, joints or back (disks) are some of the more common causes of pain and discomfort. If the pet's mobility is affected, it may become increasingly aggressive, choosing to threaten and bite, rather than retreat. A decrease in mobility could also affect urination and defecation by reducing the pet's desire or ability to utilize its elimination area.

b) Sensory dysfunction: Pets with diminished sight or hearing may have a decreased ability to detect or identify the stimuli, and might begin to respond differently to commands, sounds or sights. Sensory decline is more likely to be seen as pet's age.

c) Diseases of the internal organs, such as the kidneys or liver, can cause a number of behavior changes, primarily due to the toxic metabolites that accumulate in the bloodstream. Organ decline and dysfunction is more common in the older pet. Any medical conditions that cause an increased frequency of urination or decreased urine control, such as kidney disease, bladder infections, bladder atones, or neurological damage might lead to an increase in house-soiling. Similarly, those problems that affect the frequency of bowel movements or bowel control, such as colitis or constipation might lead to house-soiling with stools.

d) Diseases of the brain and spinal cord can lead to a number of behavior and personality changes. Conditions such as epilepsy, brain tumors, infections, immune and degenerative diseases can all directly affect a dog or cat's nervous system and therefore its behavior. In the older pet aging changes can have a direct effect on the brain, leading to cognitive dysfunction and senility.

e) The endocrine (hormone) system also plays a critical role in behavior. Over-activity or under-activity of any of the endocrine organs can lead to a number of behavior problems. The thyroid and parathyroid glands (in the neck), the pituitary gland (in the brain), and adrenal gland (by the kidneys), the pancreas, and the reproductive organs can all be affected by conditions or tumors that lead to an increase or decrease in hormone production. Endocrine disorders are more likely to arise as the pet ages.

f) The aging process is associated with progressive and irreversible changes of the body systems. Although these changes are often considered individually, the elderly pet is seldom afflicted with a single disease, but rather varying degrees of organ disease and dysfunction. Cognitive decline and senility have also been recognized in older dogs (and perhaps cats).

What tests need to be done to determine if my pet's behavior problem is due to a medical condition?

Clinical history and physical examination

The assessment begins with a clinical history and physical examination, Laboratory tests may be needed. A more comprehensive examination such as a neurological examination or sensory testing may be required. For some of these tests your pet may need to be referred to a specialist.

Medical, surgical, dietary, or pharmacologic treatment