Chronic dysfunction syndrome among manageable behavioral problems

Published on September 01, 2005
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Geriatric behavioral problems are so common that Dr. William Fortney's convention presentation July 18 on managing them drew a spillover audience. The first question to ask, he said, is whether the patient's behavior is primary or the result of a medical condition. A detailed workup is in order.  

Behavioral changes commonly seen in aging pets include a need for more attention, less mental alertness, more jealousy and irritability, and altered sleep habits. The latter can be difficult for owners because 62 percent of pets sleep in the owner's bed or bedroom.

Sleep disturbances can result from painful conditions such as osteoarthritis, an altered biological clock, anxiety and fear of the dark, discomfort from pain or being cold, and less rapid-eye-movement sleep.

Management options for improving an older pet's sleep include providing a warm and comfortable bed, use of a night light, playing the radio softly, offering a bedtime snack or warm milk, or taking the pet for a brief walk before bedtime.

Administering hydroxyzine or melatonin or a two-week analgesic trial are other options. "One of my concerns is that we miss a lot of (signs of) pain in older pets because it's not so obvious," Dr. Fortney said.

Cognitive dysfunction syndrome can also account for sleep problems and other abnormal behaviors in aging dogs. "It is a disease that has behavioral manifestations," he said. "It is slowly progressing and difficult to diagnose, but a lot of management options are available."

Owners, however, tend to think that nothing can be done about it. A recent study revealed that only a tiny percentage of dog owners and even fewer cat owners who observed changes in behavior consistent with CDS reported them to their veterinarian.

The most common signs of CDS can be remembered by the acronym DISH: disorientation, less social interaction, altered sleep patterns, and house soiling. It's unusual to see all four signs in an animal, and the diagnosis can be made on the basis of only one sign.

In cats, common clinical signs include aggression against the owner, strangers, or housemates; inappropriate elimination; increased vocalization; disturbances in the sleep cycle; excessive grooming; and disorientation or confusion. Many causes of CDS exist for cats.

The diagnosis of canine cognitive dysfunction involves exclusion, so veterinarians should obtain a behavioral history and perform a physical examination, neurologic examination, laboratory evaluation, and evaluation of thyroid function. Veterinarians must rule out intracranial diseases, such as neoplasia and hydrocephalus, and extracranial diseases, such as hepatic encephalopathy, hypoglycemia, hypothyroidism, and hyperadrenocorticism.

"I'm convinced low thyroid (hormone concentration) causes a lot of disease," Dr. Fortney said.

Multiple causes of CDS have been identified, including neural infiltrations, chronic hypoxia, damage from free radicals, and alterations in CNS neurotransmitter concentrations.

One management strategy for dogs is to increase delivery of oxygen to the brain by increasing cerebral blood flow or improving compromised cardiac output. This can be accomplished through exercise or use of vasodilators (eg, gingko, nicergoline [available in Australia and Canada but not available in the United States], and propentofylline).

Antioxidant treatment is most successful for managing animals with CDS, Dr. Fortney said, when it is combined with an enrichment program, such as playing with toys or other animals. Animals with depleted dopamine concentrations can benefit from administration of a specific B monoamine oxidase inhibitor, such as selegiline.