Managing common behavioral changes in older pets (Proceedings)

Definite personality changes and behavioral problems can be extremely challenging to the practitioner and extremely frustrating to the client. Some problems are mild and acceptable, while others are major concerns initiating euthanasia discussions. Referral resources for complex behavioral problems include American College of Veterinary Behaviorist 409/845-3195; Animal Behavior Society 781/891-4200; and American Society of Animal Behavior 630/983-7749.

General behavioral changes are elderly patient's desire more attention, are more jealous, are more irritable, are less mentally alert, and have altered sleep cycles. 60% of pets sleep in the owner's bed or in the bedroom according to a AAHA sponsored study. Altered sleep patterns are common geriatric "behavioral" dilemmas especially in those situations where both the patient and owner are affected. The owners report one or more of the following complaints; pacing at night, periods of panting, awaking the owners to go outside for no obvious reason, inability to get comfortable or constantly "fluffing" their bed. Various causes include an underling painful condition such as osteoarthritis, spondylosis or a chronic IVD; sleeping on a hard surface; an altered biological clock where they sleep all day then can't get to sleep at night; cold from poor circulation or a basal metabolic rate or a poor thermoregulation; or a phobia of the dark. This complaint can also be linked with Canine Cognitive Disorder. The author would advocate the following options; a warm soft bed, a night light, a radio playing softly, a brief walk before bedtime, hydroxyzine 1-3 mg/kg prior to bedtime, melatonin 1-3 mg, and/or a 2 week trial of a short term pain management program.

Cognitive Dysfunction Syndrome

Many of these common "old dog or old cat" behaviors are often grouped into a syndrome called Cognitive Dysfunction Syndrome (CDS). CDS is a progressive disease syndrome of older dogs and cats associated with some brain pathology that results in commonly recognized group of behavioral changes. The clinical signs in older patients are related to impaired mental function commonly referred to as "senility, dementia, or doggy Alzheimer's disease". Impairments in memory, learning, perception and/or awareness are common. CDS is a progressive disease of the brain in older dogs and cats associated with changes in behavior.

The pathogenesis of CDS is complex and is associated with four categories of pathology each resulting in altered behavior. Initially any one of the following agents will initiate varying degrees of neuronal dysfunction that can be reversible if treated early. Except with alterations in neurotransmitters levels, with time the damaged neurons will eventually die leading to permanent abnormal behavior. This explains why some treatments may be not be beneficial at all or become less effective with time.

One cause of CDS is the accumulation of metabolic waste products in the neurons. The primary offender in humans, dogs and cats is Beta amyloid that exhibits characteristic plaques when viewed on histopathology sections. Initially any behavioral changes associated with Beta amyloid can be attributed to neuronal dysfunction but eventually the affected cells will die. Another category of causative agent is hypoxia. Decreased oxygen to neurons will result in neuronal dysfunction and eventually neuron death. The hypoxia can result from decreased cardiac output, chronic pulmonary disease or vascular compromise from arterial constriction or sclerosis. Another area of current CDS research focuses on the age-related decreases in various CNS neuro-transmitter levels i.e. ACH, GABA, dopamine, nor-epinephrine, or serotonin. The confirmatory diagnosis of a specific neurotransmitter deficiency is based on the patient's behavioral response to any replacement therapy. The last category of a cause for CDS involves the deleterious affect of oxygen derived free radical on brain neuronal function. There has been considerable research into the effects of positive effects of anti-oxidants on brain function in patients with CDS. Antioxidant packages are becoming common place in most quality senior diets and are currently being investigated as possible preventatives for many age-related diseases.

The common clinical signs of Canine Cognitive Dysfunction fall into four distinct categories found in the acronym DISH. The D= disorientation / confusion: the I = decreased interactions with family or housemates; the S= Sleep cycle disturbances; and the H= house soiling. It is important to note that most cases of CDS have symptoms in only one or two of the four categories. In the feline, the common clinical signs of CDS include one or more of the following; aggression, inappropriate elimination, increased vocalization, sleep cycle disturbances, excessive grooming, and/or disorientation/ confusion.

Since certain metabolic diseases, endocrinopathy, sensory dysfunction, or brain tumors can also present with similar if not identical symptoms, the patient should undergo a complete work up prior to initiation of any therapy. The minimum data base for CCD should include a behavioral history, a complete physical examination, neurological examination, CBC, chemistry profile, UA, and thyroid evaluation. CSF tap, and brain imaging is also recommended to run out other causes of organic brain disease.

The therapy depends on the underlying pathological cause. One of the management strategies of CDS involves increasing the oxygen to the brain by increasing cerebral blood flow. A product approved for use in Europe called propentofylline (Vivitonin) increases the blood flow to the brain and therefore the oxygen supply without increasing the brain's glucose demand. Another European product Nicergolin (Fitergol) is a competitive antagonist to norepinephrin at the alpha-adrenergic receptors. This drug effectively increases the cerebral blood flow via decreasing the vasoconstriction associated with excessive norepinephrin production.

Numerous other products are advocated as effective neuroprotectants agents (those nutritional supplements that protect the neurons from the effects of oxygen derived free radicals) including nutritional supplements vitamins E, C and zinc; other antioxidant compounds; anabolic steroids; and selegilline. Specific agents such as selegilline, Nicergolin, Cholodin® & Dynaload® alter specific neurotransmitter levels often associated with CDS.

Until the advent of selegilline, the management of CDS was extremely frustrating. Dr. Sheffy advocated mild exercise in older dogs in1985. He reported that mild forced exercise was conducive to increased alertness, plus improved the dog's spirit and enthusiasm in response to human socialization. Dr. Mosier reported positive clinical cognitive benefits in dogs using oxygen therapy on a weekly schedule. In addition The lay press was filled with testimonials of the benefits of nutritional supplements (vitamins, antioxidants, and Cholodin).

Selegilline also known as L deprenyl is a specific B monoamine oxidase inhibitor (MOA-B). The animal form of Selegilline is marketed as Anipryl by Pfizer Animal Health. In some dogs and cats with signs of CDS, prolonged Selegilline therapy resulted in significant clinical improvements in greeting behavior, client / patient interactions, inappropriate urination and defecation, activity levels, confusion/disorientation, and/or sleep cycle disturbances. These positive behavioral effects are usually attributed to restoration of depleted Dopamine levels via MOA activity and/or the facilitation of Dopaminergic transmission by some other related mechanism. However, another suggested mechanism of action includes the CNS stimulatory action of two of the metabolites, L-amphetamine and L-methamphetamine. Selegilline has some neuro-protecting properties against amyloid deposition and oxygen derived free radicals.

Regardless of the exact mechanism(s) of action, Selegilline can be beneficial in managing certain age-related behavioral problems in dogs. The initial dosage of Anipryl for use in Cognitive Dysfunction Syndrome is 1.0 mg/kg PO SID each morning for at least a 60-day trial. Adverse reactions including restlessness, vomiting, diarrhea, diminished hearing, pruritis, shivering/shaking/trembling and disorientation can occur at the lower dosage but are much more commonly reported at the 2.0 mg/kg PO SID range or when given at bedtime. The contraindications of Anipryl therapy include concurrent use with meperidine (and other Apodes), tramadol, or use in combination with other MOA inhibitors. Expense will become a major issue with the life long administration.

Recently the use of dietary "anti-oxidants" and essential fatty acids (hills b/d) has been shown to be effective in the managing some clinical aspects of CDS especially when used in combination with environmental enrichment activities.

Geriatric anxiety is defined as a fear that is out of proportion to the stimulus. These exaggerate fear or phobias are often called panic attacks in people. Signs include trembling, salivation, pacing, vocalization, destructive behavior, eliminations, and escapism. Fear of load noises i.e. fireworks or thunderstorms can be very distressful for both the pet and owner. Unfortunately, many owners reinforce the fears with their comforting behavior toward the pet. Instead a program of counter conditioning and desensitization can be successful. The desensitization attempts to increase the threshold of abnormal behavior plus associating the positive reinforcement during the distraction period. The stimulatory levels are gradually increased. Often pharmacological intervention is also needed. Diazepam 1.25 - 5.0 mg. PO / IM / PR , Buspirone 1.0 mg/kg PO bid, or Amitriptyline 1.0 - 3.0 mg/kg PO tid. are recommend options. Separation anxiety is another example of a fear or phobia out of control. The dog will manifest various degrees of distress, escapism, destructive behavior, and inappropriate eliminations. 14% of canines will demonstrate one or more of these signs. Many reports suggest the case is decreasing cerebral levels of serotonin and/or nor epinephrine CNS neurotransmitters. Clinical response to tricyclic antidepressants Amitriptyline, Clomipramine, and doxepin HCL has been very rewarding especially when used with behavioral modification strategies. These agents are cholinergic and therefore emesis, diarrhea, and lethargy are common adverse reactions. BID usage has less side effects that SID. These agents should not be used in combination with other TCA's or MOA's or in animals with known seizure histories. Fluoxetine (Reconcile) has been used successfully in separation anxiety.