Practical Approaches for Studying Sea Turtle Health and Disease
399
that depict dorsal, ventral, and side views of a turtle can be used for noting location
and relative size of specific external abnormalities and lesions. Pritchard and Mortimer
(1999) provide excellent line drawings of each sea turtle species. Photographs can
be valuable, but should not replace line drawings, because it is sometimes easier to
interpret line drawings. Film photography may be problematic because of the additional notes needed to link photos to field notes, and because the quality of the
photograph may not be readily apparent. Digital photography has made photography
relatively simple and inexpensive. Images can be circulated electronically to individuals who may be able to render an opinion when an abnormality is recognized or
when a question arises about an animal’s appearance. In addition to the basic descriptive and morphometric data collected, the following additional procedures can be
performed in the field and should be considered for incorporation in routine studies.
15.3.2.5 Blood Samples
Blood collection has not always been part of routine fieldwork, but because blood
samples are easily obtained and can provide much valuable information, we strongly
recommend that samples be collected. With the ability to determine the sex of
immature turtles using plasma steroid hormone assays (Owens, 1999; Wibbels, 1999)
and to perform genetic analysis on DNA derived from blood cells (FitzSimmons
et al., 1999), it has become more commonplace for blood to be collected and
archived. Additional health information can be obtained from this blood with a little
extra effort. For example, blood smears can be prepared by spreading a drop of
whole blood on a microscope slide. Blood smears provide a way to evaluate blood
cell morphology and relative cell abundance, and smears can also be examined for
blood-borne parasites. If adequately dried and fixed, the smears can be stored
indefinitely at room temperature and examined at a later date. Blood cell counts can
be performed on whole blood samples if they are transported on ice to the clinical
pathology laboratory within 12 h. Preservative solutions need to be developed that
maintain cell morphology and integrity for longer periods of time.
If blood is collected for any reason, an aliquot should be centrifuged to separate
blood cells from plasma. The pelleted blood cells are a source of DNA, and the
plasma can provide a resource for biochemistry and serology screening assays.
Plasma should be removed from whole blood immediately to prevent artifacts, such
as elevated potassium from cell leakage or decreased glucose because of cell metabolism, and either transported on ice for immediate analysis or archived at ultralow
temperatures.
When blood is separated, measurement of the packed cell volume (PCV) is a
simple-to-perform procedure that can provide additional health data (Herbst, 1999).
PCV is the proportion of cells by volume in blood. A clinical benchtop centrifuge
or microhematocrit centrifuge provides rapid separation of blood cells and plasma,
and PCV can be measured in straight-walled tubes using a ruler or calipers. PCV
is a robust indicator of health status, although the causes of low PCV may not be
apparent. Because PCV will decrease in chronic debilitating diseases such as neoplasia, severe parasitism (leeches), and prolonged anorexia, the finding of a series
of animals with low PCV could be reason to initiate a disease investigation.
1123 book.book Page 399 Monday, November 11, 2002 11:11 AM
399
that depict dorsal, ventral, and side views of a turtle can be used for noting location
and relative size of specific external abnormalities and lesions. Pritchard and Mortimer
(1999) provide excellent line drawings of each sea turtle species. Photographs can
be valuable, but should not replace line drawings, because it is sometimes easier to
interpret line drawings. Film photography may be problematic because of the additional notes needed to link photos to field notes, and because the quality of the
photograph may not be readily apparent. Digital photography has made photography
relatively simple and inexpensive. Images can be circulated electronically to individuals who may be able to render an opinion when an abnormality is recognized or
when a question arises about an animal’s appearance. In addition to the basic descriptive and morphometric data collected, the following additional procedures can be
performed in the field and should be considered for incorporation in routine studies.
15.3.2.5 Blood Samples
Blood collection has not always been part of routine fieldwork, but because blood
samples are easily obtained and can provide much valuable information, we strongly
recommend that samples be collected. With the ability to determine the sex of
immature turtles using plasma steroid hormone assays (Owens, 1999; Wibbels, 1999)
and to perform genetic analysis on DNA derived from blood cells (FitzSimmons
et al., 1999), it has become more commonplace for blood to be collected and
archived. Additional health information can be obtained from this blood with a little
extra effort. For example, blood smears can be prepared by spreading a drop of
whole blood on a microscope slide. Blood smears provide a way to evaluate blood
cell morphology and relative cell abundance, and smears can also be examined for
blood-borne parasites. If adequately dried and fixed, the smears can be stored
indefinitely at room temperature and examined at a later date. Blood cell counts can
be performed on whole blood samples if they are transported on ice to the clinical
pathology laboratory within 12 h. Preservative solutions need to be developed that
maintain cell morphology and integrity for longer periods of time.
If blood is collected for any reason, an aliquot should be centrifuged to separate
blood cells from plasma. The pelleted blood cells are a source of DNA, and the
plasma can provide a resource for biochemistry and serology screening assays.
Plasma should be removed from whole blood immediately to prevent artifacts, such
as elevated potassium from cell leakage or decreased glucose because of cell metabolism, and either transported on ice for immediate analysis or archived at ultralow
temperatures.
When blood is separated, measurement of the packed cell volume (PCV) is a
simple-to-perform procedure that can provide additional health data (Herbst, 1999).
PCV is the proportion of cells by volume in blood. A clinical benchtop centrifuge
or microhematocrit centrifuge provides rapid separation of blood cells and plasma,
and PCV can be measured in straight-walled tubes using a ruler or calipers. PCV
is a robust indicator of health status, although the causes of low PCV may not be
apparent. Because PCV will decrease in chronic debilitating diseases such as neoplasia, severe parasitism (leeches), and prolonged anorexia, the finding of a series
of animals with low PCV could be reason to initiate a disease investigation.
1123 book.book Page 399 Monday, November 11, 2002 11:11 AM