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Diagnosing and managing common age-related problems in older dogs and cats (Proceedings)

May 01, 2011

Aging in dogs and cats is associated with gradual and progressive deterioration in the delicate body systems that eventually results in anatomical changes and decreased physiological functions. At some stage in the progressive decline, a "tipping point" is reached, where all of the physiological reserves are exhausted resulting in altered biochemical parameters; overt changes in diagnostic screening tests; and/or the onset of clinical symptoms of age-related disease occurs. These measurable points are referred to as "benchmarks" of aging. Usually these slowly progressive organ system changes are subtle; undetected by the owner or miss-interpreted by the owner, until the patient is stressed by an unrelated illness, boarding, medications or general anesthesia. Increasingly, those benchmark changes are being routinely identified on senior wellness screening tests, further validating the value of such standardized testing protocols.

Decisions regarding specific drug therapies, anesthetic protocols, pain management strategies, and quality of life issues hinge on the variety of declining physiological "benchmarks." A knowledge and clear understanding of the level of physiological decline of each organ system dictates how an individual patient is best managed. In addition to a complete history and age-related physical examination, the assessment of the level of physiological decline in each organ system requires diagnostic evaluations. Accurate interpretation of a patient's urinalysis, hematology and biochemistry

panels results in data used to aid in the diagnosis, prognosis and treatment of various conditions. Combined with appropriate imaging techniques and other advanced diagnostics presumably will facilitate early identification of both physiological decline and various pathological states. Three gerontology reference books one should consider for their library include J. Hoskins, Geriatrics and Gerontology of the Dog and Cat, 2 nd ed.; the Veterinary Clinics of North America, 2005 Geriatrics Ed; and U. Mohr; W.W. Carlton; D. L. Dungworth, Pathobiology of the Aging Dog (vol. 1 & 2).

The generalized changes associated with aging include dryness of all tissues, progressive degeneration of organ function, tissue hypoxia, cellular membrane alterations, decreased enzyme systems, decreased immune competence, and definite personality alterations.

The TEN most common causes of death in older dogs, based on a study funded by the Morris Animal Foundation for Animals, are cancer, cardiovascular disease, renal failure, epilepsy, hepatic diseases, bloat, diabetes, stroke, Cushing's disease, and immune mediated disease. The ten most common causes of death in older cats are cancer, cardiovascular disease, renal failure, diabetes mellitus, FIP, FIV, FeLV, hyperthyroidism, liver and infections. Knowledge of the early warning signs of the 10 most common life threatening diseases in the elderly pets alerts the owner and staff of impending health threats in a timely manner. In addition the list is helpful in determining what specific tests should be included in your "Senior Care" health screening program.

Thermoregulation alterations

Effective thermoregulation (heating and cooling) is deceased in the aging dog. Their decreased ability to pant, decreased cardiac output, combined with ineffective vasodilatation make older pets more prone to heat stroke. Conversely, older patients are also more susceptible to cold ambient temperatures. This age-related cold intolerance is attributed to a decreased basal metabolic rate, decreased cardiac output, decreases in peripheral vaso-constriction, plus less subcutaneous fat in many cases. Cold intolerance can also be a predominant sign of hypothyroidism long before skin and hair coat changes. The resulting response to "cool ambient temperatures" may manifest as behavioral issues including reclusiveness, trembling, and reluctance to go outside for eliminations, and/or sleep cycle disturbances. In addition to suggested environmental changes and thyroid evaluation, warm bedding and outdoor garments may help alleviate some of the abnormal behavior while increasing the animals well being.