Non-Invasive Measurement of Thyroid Hormones in Domestic Rabbits

Abstract

Thyroid hormones are essential for metabolism, energy homeostasis and reproduction. Hormones can be measured in various biological source materials: blood, feces, urine, saliva and others. The aim of our study was to verify usefulness of thyroid hormone analysis in the urine and feces of the domestic rabbit (Oryctolagus cuniculus f. domesticus), comparing them with the serum analyses. Samples were collected from 27 does in the age of 12–14 weeks. Total thyroxine (tT4), total triiodothyronine (tT3), free thyroxine (fT4) and free triiodothyronine (fT3) were tested using the radioimmunological method in serum, feces and urine. The highest concentration of tT4 was found in feces (104.72 ± 59.52 nmol/mg) and the lowest in urine (3.03 ± 3.11 nmol/mL). The highest tT3 concentration was found in blood serum (3.19 ± 0.64 nmol/L) and the lowest in urine (0.31 ± 0.43 nmol/L). The highest concentration of fT4 was observed in feces (43.71 ± 4.79 pmol/mg) and the lowest in blood serum (14.97 ± 3.42 pmol/L). The statistically highest concentration of fT3 (28.56 ± 20.79 pmol/L) was found in urine, whereas the lowest concentration of this hormone was found in feces (3.27 ± 1.33 pmol/mg). There was a positive and statistically significant correlation between serum and urine fT3 (r = 0.76) and a high positive correlation between serum and feces fT3 concentration (r = 0.62). Correlations between concentrations of other thyroid hormones between serum, urine and feces were found to be insignificant. The results suggest that fT3 can be accurately and reliably measured in the feces and urine of the domestic rabbit.

Non-invasive Assay for Measurement of Fecal Triiodothyronine (T3) Metabolite Levels in European Mouflon (Ovis aries musimon)

“…In recent years, the use of non-invasive techniques for the analysis of endocrinological parameters in animals and humans has been intensified ( 12 , 13 ). This aspect is essential especially for wild animals since it eliminates the stressful events associated with capture, handling and the need to acquire ethical approval.…”

“…Traditionally, THs have been determined from blood or urine samples. However, the urine and blood collection requires the capture and restraint of wild animals without considering the stress that would result for them ( 6 , 13 ). In birds and mammals, THs are excreted in the bile and this create the conditions for their determination in feces where T3 represents the major metabolite, as confirmed by Wasser et al in dogs ( 6 ).…”

The Impact of Transportation on the Cortisol Level of Dwarf Rabbits Bred to Animal-Assisted Interventions

“…The plasma’s glucocorticoid level is increased by the activation of the HPA axis, consequently, analyzing the blood’s stress hormone levels is possible [ 48 , 49 ]. The most common method for assessing hormone levels is a blood test, but this method has many limitations, especially in the diagnostic process of non-domestic animals [ 50 ]. The procedure of sampling the animals needs to be undertaken by capturing, clamping and venipuncture, which is a highly stressful situation for them and thus increases stress hormone levels [ 48 , 51 ].…”

“…An alternative method for blood sampling is measuring glucocorticoid levels in feces, urine, saliva, or hair in various animals in order to quantify stress [ 48 , 50 ]. Samples collected in a non-invasive way are stress-free methods and, therefore, are highly considerable to fulfill animal welfare criteria [ 48 , 50 ].…”

“…An alternative method for blood sampling is measuring glucocorticoid levels in feces, urine, saliva, or hair in various animals in order to quantify stress [ 48 , 50 ]. Samples collected in a non-invasive way are stress-free methods and, therefore, are highly considerable to fulfill animal welfare criteria [ 48 , 50 ]. Metabolites of glucocorticoids (GCMs) appear in feces, reflect the accumulation of glucocorticoids over several hours and can be collected without disturbing the animal.…”