Determination of Blood Biochemistry Reference Intervals in Eastern Collared Lizards (Crotaphytus collaris)
Eastern collared lizards (Crotaphytus collaris) are growing in popularity as exotic pets in the United States and worldwide. However, clinical biochemistry reference data to support the interpretation of health and disease for this species are lacking. This study evaluated 87 apparently healthy eastern collared lizards (C. collaris). Blood samples were collected from the ventral coccygeal vein and assayed via an Abaxis VetScan VS2 analyzer and avian/reptile profile plus rotor. Although lizard weight and snout–vent length (SVL) were normally distributed, most biochemical analytes, except albumin and total protein, were not. Many analytes were affected, albeit slightly, by lizard age, SVL, body condition score, gravidity and/or recent oviposition, sex, health status, and color and locality. However, except for calcium, phosphorous, and albumin for gravid or immediately postoviposition females, biochemical values remained within the generated reference interval. Limitations of this study included that the VetScan VS2 avian/reptile profile plus rotor was unable to successfully provide values for bile acids for most of these apparently healthy lizards. When compared to biochemistry analyte values of lizards from the suborder Iguania from the western hemisphere, eastern collared lizard biochemistries were similar for some analytes, but a relatively increased plasma glucose and uric acid occurs in this species, which could affect the diagnosis of clinical disease or other health abnormalities.Abstract
Restraint method for ventral coccygeal venipuncture of eastern collared lizards (Crotaphytus collaris) sampled in this study.
Multiple venous blood biochemical analytes of eastern collared lizards (Crotaphytus collaris) change appreciably based on lizard length. Pearson’s correlations support the association of increasing glucose and phosphorous concentrations with decreased snout–vent length (SVL) in captive eastern collared lizards (a,b). For uric acid concentrations, Pearson’s correlation confirmed the association of increasing SVL and increasing uric acid (P = 0.0004). SVL was normally distributed (SWp, 0.7348).
Glucose concentrations were lower and uric acid concentrations were higher in adult (A) eastern collared lizards (Crotaphytus collaris) than those in juveniles (J) (Kruskal-Wallis P = 0.0057 and P = 0.0131 respectively). In this box-and-whisker plot, the median is shown as a thick black line, the mean is shown as a filled square, the box represents the 5%–95% quantiles of the median, and the whiskers represent the full range of the data, with each data point represented as a dot.
Uric acid concentrations were associated with changes in body condition score (BCS) of eastern collared lizards (Crotaphytus collaris) (Kruskal-Wallis ANOVA P = 0.0156) and post hoc testing (Tukey-Kramer multiple comparisons of the means) supported that uric acid of lizards with a BCS of 2 was increased compared to that of lizards with BCSs of 3 and 5, respectively (post hoc Tukey-Kramer P = 0.0208 and P = 0.0326). In this box-and-whisker plot, the median is shown as a thick black line, the mean is shown as a filled square, the box represents the 5%–95% quantiles of the median, and the whiskers represent the full range of the data, with each data point represented as a dot.
As lizard body condition score (BCS) increased, blood glucose also increased in eastern collared lizards (Crotaphytus collaris) (Kruskal-Wallis P = 0.0002). Post hoc testing supported that the mean glucose of lizards with a BCS of 5 was higher than that of lizards with a BCS of 2 or 3 (post hoc Tukey-Kramer P = 0.0001 and P = 0.0043, respectively). In this box-and-whisker plot, the median is shown as a thick black line, the mean is shown as a filled square, the box represents the 5%–95% quantiles of the median, and whiskers extend to the full range of the data, with each data point represented as a dot.
Differing uric acid concentrations of eastern collared lizards (Crotaphytus collaris) based on color and/or original locale. Plasma uric acid concentrations of AQFOK were significantly decreased compared to those lizards from Texas and New Mexico (post hoc Tukey-Kramer P < 0.0001, 0.0092, 0.0010, respectively). LBTX lizards also had significantly higher blood concentrations of uric acids than YNM lizards (TK P < 0.001). The median is represented by a thick black line, the mean is a filled square, the box represents the 5%–95% quantiles of the median, and the whiskers extend through the data range, with each data point represented as a dot.
Blood calcium concentrations of eastern Collared Lizards (Crotaphytus collaris) vary based on sex and reproductive status (Kruskal-Wallis ANOVA P =0.0459). Gravid (FG) and postoviposition (FO) female lizards have significantly higher blood calcium concentrations than male (M) lizards (post hoc Tukey-Kramer P = 0.0013 and P = 0.0149, respectively). However, reproductively quiescent females (F) do not have blood calcium concentrations that significantly differ from those of males. The median of the data is shown as a thick black line, the mean is shown as a filled square, the box represents 5%–95% quantiles of the median, and the whiskers extend to the full range of the data, with each data point represented as a dot.
