Reference Intervals and Physiologic Alterations in Hematologic and Biochemical Values of Free-Ranging Desert Tortoises in the Mojave Desert

Abstract

Desert tortoise (Gopherus agassizii) populations have experienced precipitous declines resulting from the cumulative impact of habitat loss, and human and disease-related mortality. Evaluation of hematologic and biochemical responses of desert tortoises to physiologic and environmental factors can facilitate the assessment of stress and disease in tortoises and contribute to management decisions and population recovery. The goal of this study was to obtain and analyze clinical laboratory data from free-ranging desert tortoises at three sites in the Mojave Desert (California, USA) between October 1990 and October 1995, to establish reference intervals, and to develop guidelines for the interpretation of laboratory data under a variety of environmental and physiologic conditions. Body weight, carapace length, and venous blood samples for a complete blood count and clinical chemistry profile were obtained from 98 clinically healthy adult desert tortoises of both sexes at the Desert Tortoise Research Natural area (western Mojave), Goffs (eastern Mojave) and Ivanpah Valley (northeastern Mojave). Samples were obtained four times per year, in winter (February/March), spring (May/June), summer (July/August), and fall (October). Years of near-, above-and below-average rainfall were represented in the 5 yr period. Minimum, maximum and median values, and central 95 percentiles were used as reference intervals and measures of central tendency for tortoises at each site and/or season. Data were analyzed using repeated measures analysis of variance for significant (P Ͻ 0.01) variation on the basis of sex, site, season, and interactions between these variables. Significant sex differences were observed for packed cell volume, hemoglobin concentration, aspartate transaminase activity, and cholesterol, triglyceride, calcium, and phosphorus concentrations. Marked seasonal variation was observed in most parameters in conjunction with reproductive cycle, hibernation, or seasonal rainfall. Year-to-year differences and long-term alterations primarily reflected winter rainfall amounts. Site differences were minimal, and largely reflected geographic differences in precipitation patterns, such that results from these studies can be applied to other tortoise populations in environments with known rainfall and forage availability patterns.

Comparative Health Assessment of Western Pacific Leatherback Turtles (Dermochelys Coriacea) Foraging Off the Coast of California, 2005–2007

“…Malnourished sea turtles in negative energy balance might exhibit anemia, hypoproteinemia, and hypoglycemia, and can have a concave plastron, sunken eyes, muscular atrophy, and decreased body weight (George, 1997), some of which were observed in nesting females in this study. Although elevated AST, LDH, and potassium in foraging leatherbacks could indicate cellular muscle damage or increased metabolic activity, they were more likely associated with gross hemolysis during blood collection (Christopher et al, 1999). Creatine kinase also may be elevated in cases of difficult sampling (Campbell, 2006), but differences could not be detected here due to the wide range of values for both groups and large degree of variability associated with the measurements.…”

Guidelines for the Field Evaluation of Desert Tortoise Health and Disease

“…Health assessments of wild animals are becoming more common, and often include blood sampling, complete blood counts and biochemical profiles, as well as analyses for vitamins, minerals, and organochemical compounds (e.g., Calle et al, 1994;Dunlap, 1995;Christopher et al, 1999). We recommend that the health assessments described herein become required and standard guidelines for prescreening any animal to be used in a research project, whether the research project is conducted by veterinarians, herpetologists, ecologists, or zoologists.…”

“…Photographs also have proven to be a valid and reliable approach for grading trachoma in humans (West and Taylor, 1990). Close-up views of eyes and shells of the tortoises were especially critical for interpretation and grading of diseases and trauma (e.g., Jacobson et al, 1994;Brown et al, 1999;Christopher et al, 1999) and proved more reliable and consistent than the field evaluations.…”

“…Techniques for recording journal notes and information about live tortoises were developed, tested, and revised between 1971 and 1998 at 27 study plots in the California deserts (e.g., Berry and Medica 1995;Berry 1997b) with Ͼ20,000 captures of wild tortoises. Most techniques for assessing health and disease were developed and tested between 1988 and 1998 at 36 sites in California with Ͼ5,000 captures of tortoises (e.g., Berry, 1997b;Henen et al, 1998;Homer et al, 1998;Brown et al 1999;Christopher et al, 1999). These standardized field methods represent a productive collaboration between wildlife biologists, veterinarians and pathologists, and are applicable to other chelonians and reptiles.…”

Factors Affecting Hematology and Plasma Biochemistry in the Southwest Carpet Python (Morelia Spilota Imbricata)

“…Evaluating hematologic and biochemical responses can facilitate the diagnosis of stress and disease states in reptile species (Christopher et al, 1999). Blood analysis can be used to detect conditions such as anemia, inflammatory disease, parasitemia, hematopoietic disorders, and hemostatic alterations by comparing individual samples with a clinically normal sample population (Campbell and Ellis, 2007).…”