Evaluation of point-of-care analysers for blood gas and clinical chemistry in Hermann's tortoises (Testudo hermanni)

Diagnostic Clinical Pathology of Tortoises

Clinicopathologic evaluation of terrestrial tortoises is useful for health assessment and monitoring. There are specific considerations when evaluating data from these species, including sex, age, time of year/season, reproductive status, diet, captive versus wild, geographic location, methodology, and anticoagulant. The authors describe sample collection, hematology, biochemistry, and urinalysis features of terrestrial tortoises and discuss clinical relevance.

Relationship, difference, and diagnostic discordance between blood ionized and total calcium concentrations in client-owned chelonians

OBJECTIVE

To determine (1) the relationship, (2) the difference, and (3) the diagnostic discordance between blood total calcium concentration (tCa) and ionized calcium concentration (iCa) in a population of client-owned chelonian patients.

ANIMALS

161 consecutively admitted client-owned chelonians.

PROCEDURES

Results for tCa, iCa, and other variables were extracted from records. Bound calcium concentration (tCa - iCa) was calculated. General linear models were developed to evaluate factors affecting tCa, iCa and bound calcium concentrations. Diagnostic discordance between tCa and iCa was assessed.

RESULTS

iCa decreased with increasing albumin concentration, it was not influenced by sex, and it was lower in chelonians with disorders of the reproductive tract than in those with disorders of the endocrine/hemopoietic and urinary systems. Total calcium and bound calcium concentrations increased with increasing albumin concentration; they were higher in females and in chelonians with disorders of the reproductive tract. Of the 161 chelonians, 93 (57.7%; 95% CI, 49.7% to 65.5%) would have had a different diagnosis of calcium status based on tCa and iCa results (ie, diagnostic discordance). A 2.2 mmol/L cutoff value for bound calcium could differentiate chelonians with and without disorders of the reproductive tract with a sensitivity (95% CI) of 81.8% (64.5% to 93.0%) and specificity of 76.4% (68.0% to 83.5%).

CLINICAL RELEVANCE

tCa and iCa were related and were associated with albumin concentrations in chelonians. Evaluation of tCa or iCa alone is likely to result in underdiagnosis of alterations of the calcium status. Calculation of bound calcium concentration could help identify chelonians with reproductive disorders.

Agreement between hematocrits measured with electrical conductivity on the i-STAT analyzer and manual packed cell volume measurements in 148 chelonian patients

BACKGROUND

Point-of-care (POC) analyzers are increasingly used for diagnostic testing in exotic animals. A few studies with small sample sizes, evaluating agreement between hematocrit (Hct) and packed cell volume (PCV) measurements in chelonians, showed conflicting results.

OBJECTIVE

We aimed to assess the agreement between Hct values measured with a POC analyzer and manual PCV measurements in venous samples from 148 chelonians.

METHODS

All chelonians that underwent bloodwork for clinical reasons had Hct measured with an analyzer employing electrical conductivity (i-STAT, Abbott), PCVs measured using centrifugation, and total solids (TS) measured with refractometry. Bland-Altman plots were built to assess agreement between the measurements. Generalized linear mixed models were used to determine the effect of different variables on the difference between Hct and PCV.

RESULTS

Of 192 chelonians sampled during this period, 148 had Hct, PCV, and TS results. Hct significantly underestimated PCV, with a mean difference between the techniques of -3.8% (95% CI: -4.5 to -3.2; LoA: -11.5 to 3.8). There was a negative correlation between the value of TS and the difference between the methods. Controlling for other factors, the magnitude of the disagreement was not affected by the sex of the chelonian but was smaller in red-eared sliders (Trachemys scripta elegans).

CONCLUSIONS

Hct values measured with electrical conductivity in chelonians significantly underestimated manual PCVs by about 4%. This difference should be considered whenever an Hct measured on a POC analyzer using electrical conductance is used in chelonian patient assessments.

Respiratory Disorders in Chelonians

"Respiratory tract disease in chelonians can be difficult to treat and as such proper diagnostics are paramount. Infectious agents that can affect the respiratory tract of chelonians include viral, bacterial, fungal, and parasitic organisms. Noninfectious diseases can also develop. Because chelonians lack a proper diaphragm, changes in size of celomic organs can cause compression of the respiratory system. These conditions result in clinical signs that could be attributed to the respiratory system, such as open-mouth breathing. In this article, anatomy, physiology, and current standards for diagnostics and treatments of major diseases of the respiratory tract in chelonians are discussed."

Prognostic value of packed cell volume and blood glucose concentration in 954 client-owned chelonians

OBJECTIVE

To evaluate the prognostic value of PCV and blood glucose concentration in chelonians presented for veterinary care and to develop risk categories on the basis of the interaction of these analytes.

ANIMALS

954 client-owned chelonians (34 genera).

PROCEDURES

Medical records of 1,059 client-owned chelonians presented to 2 veterinary institutions between 2014 and 2018 were reviewed. Logistic regression models were developed to evaluate factors associated with death, including PCV and blood glucose concentrations.

RESULTS

There were 954 chelonians (34 genera) for which the data required to be included in the analysis were available. Both PCV and blood glucose concentration were significant prognostic indicators of death. Odds of death for chelonians with severe anemia (PCV, < 10%) and moderate anemia (PCV, 11% to 20%) were 6.8 times (adjusted odds ratio [aOR], 6.8; 95% CI, 3.8 to 12.3) and 1.6 times (aOR, 1.6; 95% CI, 1.01 to 2.7), respectively, the odds of death for chelonians with PCV within reference range. Odds of death for chelonians with severe hypoglycemia (< 30 mg/dL), moderate hyperglycemia (91 to 150 mg/dL), and severe hyperglycemia (> 181 mg/dL) were 5.3 times (aOR, 5.3; 95% CI; 2.4 to 11.4), 3 times (aOR, 3.0;95% CI, 1.4 to 6.3), and 4.3 times (aOR, 4.3; 95% CI, 2.4 to 7.6), respectively, the odds of death for chelonians with blood glucose concentration within reference range. Five risk categories were identified on the basis of PCV and blood glucose concentration.

CONCLUSIONS AND CLINICAL RELEVANCE

Derangements in PCV and blood glucose concentration in client-owned chelonians were associated with increased odds of death. On the basis of these results, more aggressive diagnostic testing and treatments may be indicated in chelonians with similar alterations.

Advances in Exotic Animal Clinical Pathology

Over the last 10 years, exotic animal clinical pathology has been evolving, improving health assessment in avian, mammal, fish, reptile, and amphibian patients. These advances are reviewed in this article. Species-specific reference intervals for blood parameters are becoming more available (eg, for ionized calcium, endocrine panels, and vitamin D plasmatic concentrations). In addition, new technologies are being developed to facilitate targeted metabolite detection and result acquisition by veterinarians. Novel techniques, biomarkers, and clinical changes related to disease have been described in avian, mammal, fish, reptile and amphibian species. The use of mobile applications may also be helpful.