Ahmed Tibary
Washington State University
Factors Affecting Measurement of Serum Progesterone Levels in Alpacas
9/01/05 - 2/28/07
Total funding - $6,993.58
Alpaca breeders rely on progesterone concentration level
in blood samples for pregnancy diagnosis. Progesterone concentration of 2
nanograms per milliliter (ng/ml) is considered indicative of normal pregnancy.
However, some laboratoies use a cutoff concentration of 1.5 ng/ml making
interpretation of values below 2 ng/ml often problematic. This is critical as
many veterinarians and breeders may be inclined to consider alpacas with serum
concentrations of less than 2 ng/ml as suffering from progesterone deficiency
and treat them with progesterone throughout pregnancy to prevent abortion. Our
hypothesis is that progesterone levels reported in many cases may be erroneous
because of problems in sample handling or may be affected by individual alpaca
variation. Errors in progesterone determination may be due to assay techique
but should not be a problem if the laboratory used has a good reputation. The
objectives of our study are 1) to determine if there is a correlation between
progesterone concentration and other indicators of blood volume such as weight,
body condition and the amount of cells in the blood (packed cell volume); 2) to
determine if the time the sample is taken in relation to feeding has any impact
on progesterone concentration, and 3) to compare the effect of commonly used
blood sample handling methods on variation in results of progesterone
determination. The results from this study will offer recommendations on how to
handle blood samples and determine if the size (generally larger in