392
The Biology of Sea Turtles, Vol. II
15.3 SYSTEMATIC APPROACHES
15.3.1 H EALTH A SSESSMENT
An individual and population health assessment program can provide very useful
information, if it is conducted in a systematic manner. As stated above, the purpose
of health assessment is to describe the condition of an organism or group of organisms at a specific time. Obviously, by definition any health assessment program
should identify individuals that are exhibiting clinical illness or injury. However,
although turtles with overt disease may be easy to recognize, those with low-grade
and subclinical disease processes are often a challenge to identify. What other
observations, measurements, and tests can be included in health assessment, and
how are the data and results interpreted? Condition indices have been attempted and
promoted for use in assessing health of chelonians, but these can be used as only
one method in an array of diagnostics routinely employed in health assessment
(Jacobson et al., 1993).
15.3.1.1 Goals and Limitations
There is always a desire to make a health assessment program as comprehensive as
possible, but this is rarely feasible; it is important to develop a rationale for including
certain types of evaluation and excluding others. It is important to recognize up front
that it will not be possible to evaluate all body systems, both functionally (physiology) and structurally (anatomy). It is generally more valuable to do few things well
than to try to do too many things, all poorly. At the outset, the purpose and goals
of the health assessment program should be defined. Knowing why things are being
done helps to guide selection of methods and tests.
The following major goals should be considered when designing a health assessment program.
1. Establish normative reference ranges for the species or population for any
of the anatomic and physiologic parameters and analytes of interest. These
values will show both interspecific and intraspecific variation. Intraspecific
variation may occur with age, sex, season, and diet, and reference ranges
may need to be established for each subpopulation.
2. Establish a pathologic database (including serology and toxicology) for
the species or population being studied. This will allow an estimation of
the background prevalence of specific disease conditions, toxin levels, and
infections in the population at a given time. This provides a reference for
recognizing the most significant lesions in dead or stranded turtles and
for recognizing changes over time.
3. Establish a surveillance program to monitor the population through time,
including trends and spikes in prevalence (epizootics) or the introduction
of new pathologic agents to a population.
4. Evaluate the relationships between various environmental and demographic
factors and specific health parameters and pathologic conditions. Testing
hypotheses about the association of specific abnormalities, diseases, and
1123 book.book Page 392 Monday, November 11, 2002 11:11 AM
The Biology of Sea Turtles, Vol. II
15.3 SYSTEMATIC APPROACHES
15.3.1 H EALTH A SSESSMENT
An individual and population health assessment program can provide very useful
information, if it is conducted in a systematic manner. As stated above, the purpose
of health assessment is to describe the condition of an organism or group of organisms at a specific time. Obviously, by definition any health assessment program
should identify individuals that are exhibiting clinical illness or injury. However,
although turtles with overt disease may be easy to recognize, those with low-grade
and subclinical disease processes are often a challenge to identify. What other
observations, measurements, and tests can be included in health assessment, and
how are the data and results interpreted? Condition indices have been attempted and
promoted for use in assessing health of chelonians, but these can be used as only
one method in an array of diagnostics routinely employed in health assessment
(Jacobson et al., 1993).
15.3.1.1 Goals and Limitations
There is always a desire to make a health assessment program as comprehensive as
possible, but this is rarely feasible; it is important to develop a rationale for including
certain types of evaluation and excluding others. It is important to recognize up front
that it will not be possible to evaluate all body systems, both functionally (physiology) and structurally (anatomy). It is generally more valuable to do few things well
than to try to do too many things, all poorly. At the outset, the purpose and goals
of the health assessment program should be defined. Knowing why things are being
done helps to guide selection of methods and tests.
The following major goals should be considered when designing a health assessment program.
1. Establish normative reference ranges for the species or population for any
of the anatomic and physiologic parameters and analytes of interest. These
values will show both interspecific and intraspecific variation. Intraspecific
variation may occur with age, sex, season, and diet, and reference ranges
may need to be established for each subpopulation.
2. Establish a pathologic database (including serology and toxicology) for
the species or population being studied. This will allow an estimation of
the background prevalence of specific disease conditions, toxin levels, and
infections in the population at a given time. This provides a reference for
recognizing the most significant lesions in dead or stranded turtles and
for recognizing changes over time.
3. Establish a surveillance program to monitor the population through time,
including trends and spikes in prevalence (epizootics) or the introduction
of new pathologic agents to a population.
4. Evaluate the relationships between various environmental and demographic
factors and specific health parameters and pathologic conditions. Testing
hypotheses about the association of specific abnormalities, diseases, and
1123 book.book Page 392 Monday, November 11, 2002 11:11 AM