The Immulite 2000xpi, a chemiluminescent immunoassay (CLIA)-based analyzer, is currently recommended for measuring thyroid hormones (TH) concentrations in equids. However, scarce data are available on TH measurements in donkeys using this technique. Similarly, the effects of factors such as age and gender on TH concentrations have not been assessed with this analyzer. Serum free and total T4 and T3 concentrations were measured in 40 healthy donkeys (6.1 ± 0.8 years old; 8 intact jacks and 32 jennies) and 41 horses (10.7 ± 0.5 years old; 15 stallions and 26 geldings) using the Immulite 2000xpi. A Mann–Whitney test was used to compare two groups, and a Kruskal–Wallis test followed by Dunn’s post hoc test was used for comparisons among more than two groups. This analyzer had lower intra-assay variability and fewer measurements under the detection limit for tT4 and fT4 than for tT3 and fT3 determinations. The canine TSH kit for thyroid-stimulating hormone (TSH) showed high imprecision. Donkeys had higher serum TH concentrations than horses. No differences were observed among gender or age groups. This is the first study to report TH concentrations in donkeys using a CLIA-based analyzer and to evaluate the effects of several factors on TH concentrations. The canine TSH kit is not valid for measuring TSH in equids.

Endotoxemia is commonly observed in donkeys, secondary to colic, pleuropneumonia, or diarrhea among other disorders. Hematologic ratios are new biomarkers widely used in the diagnosis and prognosis of multiple conditions in human medicine, including sepsis. While the utility of these ratios has been proved in septic foals, no data are available on donkeys. Moreover, reference intervals (RIs) have not been studied in this species. In this study, RIs of the most commonly reported hematologic ratios were determined in 73 healthy adult donkeys. In addition, variations in these ratios in response to LPS infusion were also evaluated in six healthy adult donkeys. Most of the ratios evaluated showed significant variations after induced endotoxemia, with most of them showing values outside of the established RIs. Similarly to septic foals, the neutrophil to lymphocyte ratio was significantly reduced after LPS infusion. No significant changes were observed in the red cell distribution width to platelet ratio, contrary to reports on septic foals. Previously reported cut-off values for both of these ratios should not be extrapolated to donkeys. Future studies evaluating these ratios in natural endotoxemia or other diseases in donkeys, as well as establishing species-specific cut-off values, are necessary.

There are no capillary zone electrophoresis (CZE) comparative studies between horses and donkeys. Our objectives were to compare CZE results between both species, establish reference intervals (Ris), study age- and sex-related changes, determine the prevalence of bisalbuminemia, and correlate spectrophotometric albumin results with those calculated based on two different CZE methods. We performed CZE in 50 healthy horses and 49 healthy donkeys. There were significant differences (p < 0.03) in every protein fraction percentage and concentration (except for the β-globulins percentage) between both species, underlining the necessity of species-specific RIs. Considering the correlation to spectrophotometric results, the cathodal shoulder of the albumin should be kept in this fraction when performing CZE. Age- and sex-related differences in globulin fractions were noted in horses, but not in donkeys. Bisalbuminemia was a common finding in horses (36% of the animals), but was seldom observed in donkeys (4%). Further studies are warranted to investigate the clinical implications of these findings.