QimmeqHealth-thyroid status of Greenland sled dogs (Canis lupus familiaris borealis).

BACKGROUND: Greenland sled dogs (GSD) are a unique, genetically isolated population of dogs living under exceptional environmental conditions. Metabolism, and thereby thyroid hormones are affected by multiple factors. Among other activity, energy balance and environmental conditions are important. A breed-specific reference interval (RI) can be useful for diagnostics of potential thyroid-related pathologies. The aim of this study was to establish RIs of the thyroid hormones thyroxin (T4), free thyroxin (fT4), and thyroid stimulating hormone (TSH) in GSD. In addition to evaluate the effect of sex, age, season, management, and body condition score (BCS) in GSD. Physical exams and cephalic venous blood sampling were performed in the period of 2018-2019 from 265 GSD managed either privately or by the Danish navy. Serum biochemical analyses, including C-reactive protein, were performed and RIs were determined for TSH, T4 and fT4 in only healthy dogs. The RIs were determined using American Society for Veterinary Clinical Pathology guidelines and the effect of varying factors were evaluated by linear regression and further tested by Mann-Whitney test. RESULTS: 144 GSD were included in the reference group resulting in RIs: T4: 6.44-48.65 nmol/L; fT4: 3.91-18.51 pmol/L; and TSH: 0.04-0.55 ng/mL. Female GSD had significantly higher concentrations of T4 (P = 0.039) and fT4 (P = 0.015) compared to males; a positive correlation between TSH and aging was found; T4 concentrations were significantly higher (P = 0.003) during summer; and TSH concentrations were lower in GSD managed by the navy (P < 0.0001). BCS was higher (P < 0.0001) in Sirius GSD compared to civilian GSD, and BCS was positively correlated with T4 and negatively correlated with TSH. CONCLUSIONS: Reference intervals for T4, fT4 and TSH in GSD were established. The RI for T4 and fT4 was lower compared to other breeds. In addition, sex, age, season, management and BCS demonstrated variable effects on thyroid hormones. Our results can be used as a foundation for improving management and further research of GSD.

Challenges and standardization of microRNA profiling in serum and cerebrospinal fluid in dogs suffering from non-infectious inflammatory CNS disease.

Non-infectious inflammatory (NII) central nervous system (CNS) conditions are primarily diagnosed by the demonstration of inflammatory changes in the cerebrospinal fluid (CSF). However, less-invasive methods and peripheral biomarkers are desired. Changes in circulating microRNA (miRNA), which are short non-coding regulatory RNAs, may serve as biomarkers of disease. The aim of this pilot study was to investigate selected miRNAs in serum and CSF, hypothesizing that the levels of specific miRNAs in serum correlate with their presence in CSF, and that changes in serum miRNAs levels may reflect CNS disease. We profiled serum and CSF samples using quantitative real-time PCR (qPCR) searching for selected and previously profiled miRNAs in serum (let-7a, let-7c, miR-15b, miR-16, miR-21, miR-23a, miR-24, miR-26a, miR-146a, miR-155, miR-181c and miR-221-3p) and in CSF (let-7c, miR-16, miR-21, miR-24, miR-146a, miR-155, miR-181c and miR-221-3p) from 13 dogs with NII CNS disease and six control dogs. We demonstrated the presence of several miRNAs in CSF (let-7c and miR-21 dominating) and serum (miR-23a and miR-21 dominating). However, we generally failed to reproduce consistent results in CSF samples due to several reasons: unacceptable PCR efficiency, a wide variation between cDNA replicates and/or no-amplification in qPCR suggesting very low levels of the investigated miRNAs in canine CSF. Serum samples performed better, and 10 miRNAs qPCR assays were qualified for analysis. We were nevertheless unable to detect a difference in the expression of miRNA levels between cases and controls. Moreover, we could not confirm the results of recent miRNA investigations of canine CNS diseases. We believe that these disagreements highlight the significant effect of methodological/analytical variation, rather than the incapacity of circulating miRNAs as biomarkers of CNS disease. A secondary aim was therefore to communicate methodological challenges in our study and to suggest recommendations for circulating miRNA profiling, including pre-, post- and analytical methods based on our experience, in order to reach reproducible and comparable results in veterinary miRNA research.