Abnormal Behavior Associated With Common Medical Disorders
Almost every illness affecting animals causes a change in normal behavior patterns. In fact, many diseases go unnoticed until an animal shows behavior changes. Loss of appetite, decreased activity, decreased grooming, withdrawal from social interaction and hiding are common signs of illness in pets. Changes in feeding behavior, including increased or decreased appetite and a change in food preference, should prompt veterinary attention. While a behavioral change may be the only obvious sign of an underlying illness, not every behavioral disorder is associated with a medical problem. It is often necessary to investigate the possibility of a hidden physical disorder before a behavioral problem can be clearly diagnosed and treated. Irritable aggression may be the first indication of an underlying medical disorder or may accompany a recognized illness. A sudden change in a pet's temperament should be reported to your veterinarian. If your dog or cat suddenly resents having its ears touched, for example, the discomfort may be caused by an ear infection. A gradual temperament change should also be brought to your veterinarian's attention, particularly if this is accompanied by physical changes. For example, in cats, progressive agitation and irritability combined with weight loss despite an increased appetite may indicate an overly active thyroid gland (hyperthyroidism). An aging dog may become uncomfortable and irritable during damp, cold weather because of arthritis pain. Some of the more common medical disorders that can cause behavioral changes are discussed below. This list is by no means complete, nor is it intended to be used for at-home diagnosis. Many diseases have the same signs and cause similar behavioral changes that must be distinguished by a veterinarian or a veterinary behavior consultant.
Itchiness and Hair Loss
Skin inflammation can cause itchiness and irritation. External
parasites (fleas, ticks or mites) and internal parasites (roundworms
or tapeworms) can cause skin eruptions. Allergies to pollen and
dust, certain types of food or direct contact with an irritant
can result in skin discomfort. Metabolic diseases, such as hypothyroidism
or Cushing's disease, can result in hair loss and skin problems.
Dermatitis can also be caused or complicated by infection from
bacterial, viral or fungal agents. Excessive scratching and self-grooming
may stem from anxiety or frustration. A pet may lick or chew at
itself, damaging hair and irritating the skin. It may even pull
out its hair, creating baldness. This behavior leads to skin inflammation,
which causes the pet to scratch, sometimes long after the initial
emotional upheaval has been resolved. Self-mutilation can recur
in times of emotional or physical stress.
Anal Sac Infection
The anal sacs are 2 small scent-producing pouches on either side
of the anus. These are normally emptied with every bowel movement,
but they can become inflamed and infected. "Scooting,"
or dragging the anal area against the ground, can be a sign of
anal sac infection. In addition to scooting, your pet may exhibit
tail-chasing, excessive grooming and self-mutilation of body parts
near the hindquarters.
Dental or Oral Disease
Pain and discomfort associated with problems in the mouth, including
the teeth, gums and tongue, may be signalled by behavioral changes.
Abnormal tongue, chewing or swallowing movements and salivation
may indicate oral disease. The pet may develop a sudden change
in food preference. A pet may begin to refuse dry food or chunk-style
meals, preferring moist food of a smoother consistency.
Excessive Thirst
Excessive thirst, or polydipsia, often accompanies disease of
the kidneys, urinary tract or digestive system and hormonal imbalances.
Excessive drinking may also be stimulated by emotional stress.
Hyperthyroidism
Abnormally high production of thyroid hormones is a relatively
common problem, especially in cats. Confirmed by blood test, it
often causes restlessness, vocalization, agitation and weight
loss despite excessive appetite. Some affected cats can become
aggressive.
Seizures
Seizures may originate in the brain itself or may be associated
with diseases elsewhere in the body, such as the heart, kidneys
and liver. Hypoglycemia (low blood sugar) and hyperglycemia (high
blood sugar), as seen in diabetes, can lead to seizures. Seizures
may be very subtle, almost imperceptible, such as an eye twitch
or a leg jerk, and may go unnoticed. Seizure activity can also
result in unusual behavior. For example, a pet may suddenly begin
"shadow chasing" and "fly catching." Jaw snapping,
tongue rolling or a simple momentary blank stare may indicate
minor seizures. Aggressive behavior may be triggered by a seizure.
The animal may show uninhibited rage or only growling or barking,
sometimes with a dazed appearance. Aggressive seizures can result
in self-mutilation, as seen in some tail-chasing dogs. Not every
episode of unexplained or bizarre behavior is provoked by seizures.
Physical examination and a complete behavioral history are necessary
for your veterinarian to make an accurate diagnosis. Behavioral
(or physical) abnormalities related to seizures may respond to
medical treatment.
Ear Infections
Head-shaking may be a sign of an ear infection. A pet may display
its discomfort by suddenly shying away from you or by growling
when you pet its head or touch the painful ear. (This is also
seen in dominant dogs without an ear infection.) Infections of
the inner ear and neurologic disturbances, such as vestibular
disease in old animals, may cause circling and incoordination.
Inappropriate Urination or Defecation
Inappropriate elimination may be a sign of a medical or behavioral
problem. When abnormal stools are voided in undesirable locations,
an almost endless list of infectious or inflammatory bowel disease
may require investigation. Inappropriate urination may be a sign
of a urinary tract infection or hormonal imbalance. Neuromuscular
diseases can affect the control of anal or bladder sphincters.
Seizure activity can also be accompanied by involuntary voiding
of urine and stool. This should not be confused with other forms
of inappropriate elimination. Inappropriate elimination can also
be an expression of territorial anxiety, inadequate exercise,
a regression in house-training, and attention-seeking behavior.