No! It is not from nutrition.
Yes! It can be very inheritable. About 15 or 20 years ago, I went to a ranch production sale. All were high percentage Hancocks and most were blue roans.
Very early into the sale it became evident that almost all of the foals and yearlings from one of the ranch's stallions had umbilical hernias. Oddly enough (well, maybe not so oddly) that particular stallion was consigned to a big sale and was sold for a lot of money just before this sale and the word would be out on all of the foals with hernias.
The vet and geneticist I talked to after that (which was long before any genetic testing was available) thought it was a recessive gene and that particular stallion, being from a strong inbreeding / linebreeding program, could have been bred to several mares that also carried the same gene. I have not heard anything definitive since gene testing has become commonplace.
I would be interested to know if this breeding program was such that this stallion was related to many of the mares that produced this problem.
There are certainly bloodlines and individual stallions that produce a very high number of crypt-orchids and mon-orchids. Again, this is very inheritable. I was told (again before genetic testing days) that this was carried by the females and may also be a recessive that requires both parents to pass it on in the demonstrated form. I would be interested in learning more about both.
Last edited by Cherie; 12-17-2012 at 04:46 PM.