Abstract. Thyroxine (T4), free T4 (FT4), and thyrotropin (TSH) concentrations were measured in serum from 693 healthy representatives from 7 dog breeds (Alaskan Malamute, Collie, English Setter, Golden Retriever, Keeshond, Samoyed, or Siberian Husky) to determine whether breed-specific reference intervals (RIs) are warranted. Veterinarians reviewed the health history, performed a physical examination, and approved laboratory data for the enrolled dogs. Many purebred dogs had T4 and FT4 concentrations that were at, or below, the lower limits previously determined for non-breed-specific RIs. Median TSH values ranged from 6.10 mIU/L (0.07 ng/mL; Alaskan Malamute and Golden Retriever) to 17.6 mIU/L (0.26 ng/mL; Collie). Mean T4 and FT4 concentrations were higher in females. Increasing age was associated with decreasing T4 and FT4, and increasing TSH concentration. The substantial ranges across breeds of measures of central tendency (mean, median) for all hormones indicate that breed-specific RIs are warranted. RIs encompassing the central 95% of reference values for all breeds combined, and for individual breeds, were calculated using nonparametric (TSH) and robust (T4, FT4) methods. Use of breed-specific RIs in combination with careful attention to the potential for preanalytical and analytical variability in test results will improve thyroid function assessment in these breeds.

Porcine C-peptide concentration can be reliably measured in porcine serum samples with either assay (ELISA or RIA). However, the C-peptide results generated by these two assays are not equivalent. Therefore, assay bias must be considered before directly comparing pre-clinical studies that used either of these assays. We determined that harmonization between the assays is appropriate in a specific concentration range. Outside of that range, we do not know whether a linear correction function can be more broadly applied. The variation between the two assays may be related to calibration or reagent factors. To determine which assay is truly more accurate and to effectively compare interlaboratory results, we will need a traceable reference standard.

Porcine C-peptide can be reliably measured in NHP serum using the Mercodia ELISA, making this assay interchangeable with the Millipore RIA. Inherent differences in antibody affinity and calibration factors may explain the lower ELISA values as compared to the RIA; however without access to a traceable reference standard, it is not possible to determine which assay is most accurate. Regression modeling resulted in a correction factor appropriate for conversion of ELISA data to RIA-equivalent data facilitating comparison of assay results longitudinally and between groups.

Cytokine profiling is a valuable tool for monitoring immune responses associated with disease and treatment. This study assessed the impact of sex and sedation on serum cytokines in healthy nonhuman primates (NHPs). Twenty-three cytokines were measured from serum using a bead-based multiplex assay. Assay validation for precision, sensitivity, recovery, linearity, and stability was performed. Samples from male and female cynomolgus and rhesus macaques either cooperating or sedated were compared. All cytokines except TNFα demonstrated acceptable sensitivity and precision, with variable recovery and linearity. IFNγ, IL-2, IL-5, IL-6, IL-8, IL-12/23 (p40), IL-13, IL-15, MCP-1, TGFα, VEGF met acceptance criteria; G-CSF, IL-4, IL-10, MIP1α, sCD40L were marginal. Higher cytokine levels were observed in females and cytokine levels were blunted in sedated NHPs when compared to awake cooperating NHPs. Significant differences observed in cytokines related to sex, species, or imposed by handling highlight the importance of model design on translational relevance for clinical settings.

People with calcium oxalate (CaOx) urolithiasis and idiopathic hypercalciuria (IH) often have evidence of increased bone resorption, but bone turnover has not previously been investigated in dogs with these conditions. The aim of this study was to determine whether a marker of bone resorption, β-crosslaps, differs between dogs with CaOx urolithiasis and IH compared to controls. This retrospective, cross-sectional study used a canine specific ELISA to measure β-crosslaps concentrations in stored frozen serum samples from 20 dogs with CaOx urolithiasis and IH and 20 breed-, sex-, and age-matched stone-free controls (18 Miniature Schnauzers, 14 Bichons Frise, and 8 Shih Tzus). Dogs with CaOx urolithiasis and IH had lower β-crosslaps concentrations relative to controls (P = 0.0043), and β-crosslaps had a moderate negative correlation with urinary calciumto-creatinine ratios (r = −0.44, P = 0.0044). Miniature Schnauzers had lower β-crosslaps concentrations than the other two breeds (P = 0.0035). The ELISA had acceptable intra-assay precision, but concentrations decreased when samples were repeatedly assayed over time. Assay recovery rates were also below acceptance criteria. In conclusion, Miniature Schnauzers, Bichons Frise, and Shih Tzus with CaOx urolithiasis and IH have evidence of decreased bone resorption compared to stone-free controls. This suggests that other causes of IH, such as intestinal hyperabsorption of calcium, underlie risk for CaOx urolithiasis in these breeds. Results should be confirmed in larger populations and with other β-crosslaps assays and additional biomarkers of bone turnover. The stability of canine serum β-crosslaps after freeze-thaw cycles and storage at various temperatures requires investigation.