Screening and Management Considerations for the Geriatric Dog ...

associated with hypertension. Depending on the clinical condition of the patient and the results
of the aforementioned tests, further testing may be indicated. A more complete senior panel is
outlined in Table 2.
Senior pets are more likely to have a multitude of disease with the most common being;
neoplasia, chronic kidney disease, hyperthyroidism (cats), hypothyroidism (dogs), dental
disease, diabetes mellitus, and arthritis. In addition, some deterioration in cognitive function and
sensory perception is often observed.
Virtually every organ system is affected by aging and it is important to differentiate true
pathology from expected, age related changes. When abnormalities are detected on screening
tests, they must be interpreted in conjunction with the clinical condition of the patient. When
assessing the results of any biochemical evaluation, it is important to define the “normal” range
in order to understand and appreciate the significance of reference values assigned to all
laboratory tests. Laboratory references ranges are typically established by measuring
biochemical parameters on a group of patients that have been declared “normal”. If an
adequate number of samples are obtained, the results should follow a bell-curve or normal
distribution. The references range is defined as the range of values that falls within two standard
deviations above or below the mean value. Therefore, by design, approximately 2.5% of the
“normal” population will have laboratory values that fall outside the upper and lower limits of
normal. When the minimum database is performed on a given patient, approximately 40
biochemical parameters will be assessed. Statistically, it is highly likely that at least one
parameter will fall outside of the normal range. It is incumbent on the clinician to assess the
magnitude of the abnormality. Assessment of the variance of a value outside the normal range
will differ among individual laboratory parameters. For example, a creatinine value of 1.5 x the
upper limit of the reference range definitely warrants further investigation, while an ALT of 1.5x
the upper limit may not.
The purpose of the above discussion was to stress the importance considering all aspects of the
clinical evaluation when dealing with senior patients. The remainder of the lecture will be
focused on the significance of some of the more commonly detected biochemical abnormalities
and the diagnostic plan once they have been discovered. Although problems with the
cardiovascular and gastrointestinal system are fairly common in senior pets, disorders of these
systems are more readily identified on physical exam and clinical history. Changes in
biochemical parameters are not consistent or typical and will not be discussed here.
Selected biochemical abnormalities of senior pets
Elevated liver values
One of the more commonly reported biochemical abnormalities of senior pets are isolated
elevations in alanine transaminase (ALT) and/or alkaline phosphatase (ALP). Assessment of
tests of liver injury should be approached in a stepwise and cost-effective methodological
manner, particularly if they are discovered in an otherwise normal patient. Normal ALT and ALP
values vary depending upon other factors such as age, weight, time of day, and level of
exercise. Unfortunately many tests of liver injury are neither highly sensitive nor specific. Thus, it
is imperative that the clinician confirms the result of an abnormal test by either repeating it
and/or ordering a more specific one. Initial evaluation of all patients with persistent ALT /ALP
elevations should include a thorough and accurate history and physical examination. The history
must include questions about previous diseases, prescription and non-prescription medications
or supplements, diet, environment, etc.
In asymptomatic patients with mild elevations of transaminases (less than two times the upper