What is Polled Intersex Syndrome (PIS)?
In goats, PIS is the sex reversal of a female to male at puberty. Affected animals are usually sterile, display male traits like shaggy coats and behaviors such as rutting but also experience estrus.
Is PIS the same as hermaphroditism or freemartinism?
No, PIS is caused by a mutation in the animal’s DNA whereas hermaphrodites and freemartins are caused by a combination of environmental and genetic factors.
How is PIS caused?
PIS is strongly associated with polledness (an absence of horns). Breeding two polled animals together is highly likely to produce kids with PIS.
Is it possible to separate the gene for polledness and the gene for PIS?
Although both polledness (dominant) and PIS (recessive) follow a simple inheritance pattern, they are not actually alleles of different genes but mutations which affect how other genes work. This means it is much more difficult to separate the two traits using traditional breeding techniques and it may not actually be possible at all. Active research is ongoing in this area, which you can participate in here.