Evaluation of the use of dry blood spots for progesterone determination in ewes

The use of dried blood spots on filter paper has been shown to be a practical alternative in several studies with humans and animals, enabling a simple means of storing and transporting viable blood samples for various laboratory analyses. However, its applicability in the measurement of progesterone in animals is scarce. Thus, the objective of this study was to evaluate the feasibility of using dried blood spots for the measurement of progesterone in sheep. In total, 38 blood samples from 6 sheep were dripped onto filter paper, and the remainder of each sample was separated into serum. The progesterone levels in the serum samples and in the dry drops were measured by enzyme immunoassay and subsequently correlated. The levels of progesterone in the serum and dry spots showed a high correlation between the matrices (R2 = 0.9694). In conclusion, this study demonstrated the feasibility of using samples of dried sheep blood spots for the measurement of progesterone, and the storage and transport technique can be applied in the field.