Noninvasive pregnancy diagnosis in felids based on faecal prostaglandin F2α metabolites

Dehnhard M., Jewgenow, K.

Leibniz Institute for Zoo and Wildlife Research, Alfred-Kowalke-Str. 17, 10315 Berlin, Germany; e-mail: dehnhard@izw-berlin.de

In mammals, intrauterine tissues showed a high capacity to synthesize, metabolize and release various prostaglandins (PG) such as PGF2α, which is involved in luteolysis. In canine placenta, PGF2α synthesis is up-regulated after implantation and remained elevated through early and mid-gestation, whereas PGE2-synthases showed a gradual increase and a strong prepartal up-regulation. PGF2α and PGE2 are rapidly metabolised to their metabolites PGFM and PGEM. PGFM has been detected in urine and faeces and can be used for non-invasive pregnancy detection in felids allowing the differentiation from pseudo-pregnancy. The PGFM elevation during last pregnancy trimester has been proved to be valid in six of the eight cat lineages; in some cat species of the Panthera lineage and the domestic cat unclear hormone pattern were described.

By high-performance liquid chromatography (HPLC) immunograms of faecal extracts from different felids, authentic PGFM and several additional prostaglandin metabolites of distinct higher polarity were found to cross-react with our PGFM antibody. Additional LC-MS analyses clearly confirmed the presence of PGFM, but did not result in an identification of any other prostaglandin metabolites.

Several species differences in faecal PGFM metabolite composition were found. In the sand cat, PGFM represents the major faecal metabolite, whereas in lynx it was only a minor component. We also could show that faecal metabolite composition was changing throughout the time course of pregnancy in lynx, probably indicating for changing prostaglandin synthesis and metabolism. Screening faecal samples from lynx with PGF2α - and PGE2 antibodies, however, did not reveal courses of prognostic value.

The physiologic role of PGF2α in felids remains to be elucidated. In the cat, particularly large doses of PGF2α are needed to induce abortion. Therefore, we suggest that the lack of luteolytic capacity of PGF2α is related to other factors that have not been well identified.