Cryptorchid... from mare or sire???

[Rhyadawn]

In talking to some breeder friends it has come to my attention that this is a bone of contention among many breeders. Could someone explain it, or give references.

It seems like mare owners want to blame stallions, and stallion owners say it comes from the mare line.

[columbus]

I knew a few horses who were all cryptorchids and they shared a damline. PatO

[exvet]

I knew several offspring by the same stallion who were cryptorchids; however, that being said I did not know the pedigree of the dams (except 1) and knowing the breed (and what the farm was breeding for) there is a high possibility that they were all closely linebred. The majority of foals put on the ground by this stallion in the few years I was "around" were colts and there were several that weren't cryptorchids as well. I know in cattle that they have the inheritance (well genetics and physical attributes in general) better mapped out but in horses I have yet to read (though it might be available/evidence) a definitive inheritance pattern. Just my worthless 2 cents.

[whbar158]

I would think that it could come from either since the foal gets 50/50 from each, but maybe it can hide better in the dam line?

[Equine Reproduction]

Ah, the million dollar question. In most species, cryptorchidism is well documented and researched as being a heritable condition. Not so the equine. Lots of anecdotal information out there both for and against the theory, but no hard facts proving or disproving that it is indeed a heritable condition. With that said, there is now some indication that the condition is passed on through the damline, but again, not sufficient to give a definitive answer on the heritability of cryptorchidism.

Would I breed to a cryptorchid stallion? Nope. Not until there is a bit more information proving one way or the other that it is or isn't heritable.

Hope that helps!

Kathy St.Martin
Equine Reproduction Short Courses
http://www.equine-reproduction.com

[FriesianX]

Kathy, I'm curious - if a stallion is cryptorchid, wouldn't there be semen problems anyway? Semen from the "inside" testicle would probably be dead, wouldn't it (overheated)? I've never actually SEEN a crypto stallion, although I've had worries before about some of the studdy geldings I've seen - could they be cryptorchids that weren't fully gelded...

[Equine Reproduction]

Kathy, I'm curious - if a stallion is cryptorchid, wouldn't there be semen problems anyway?

Not necessarily. The external testicle can and will continue to produce normal spermatozoa. The internal testicle may not be producing any sperm. You "may" see a reduction in sperm numbers inasmuch as you'll only have 1/2 the sperm numbers, but some stallions will still produce a good number of sperm cells despite that.

Semen from the "inside" testicle would probably be dead, wouldn't it (overheated)?

The internal testicle, more than likely, won't be producing sperm cells. Often the internal testicle is small.

I've never actually SEEN a crypto stallion, although I've had worries before about some of the studdy geldings I've seen - could they be cryptorchids that weren't fully gelded...

The AVMA discourages veterinarians from doing a unilateral gelding because of the possibility of a cryptorchid being sold as a gelding when he is not. Unfortunately, there is no way of knowing by visual examination if the "gelding" has a retained testicle or not, so in the interest of ethics, removing a single testicle is discouraged. Obviously, testing can be done to determine if the gelding is producing testosterone, but it does involve more work and costs. Be aware that some stallions that are gelded late in live will continue to have stallion like behaviors that may never completely stop.

Additionally, it can take up to 6 years for some stallions to drop <sigh>. And, one can attempt using hCG to get a testicle that is retained in the inguinal canal to drop although my last experience with that didn't work.

Hope that helps!

Kathy St.Martin
Equine Reproduction Short Courses
http://www.equine-reproduction.com

[Linny]

One of the most expensive stallions on Earth, A P Indy is a ridgeling. His sireline is famous for it. To the best of my knowledge his fertility is good, he's getting on in years so a decline wouldn't shock me.

I don't know if it's a mare or stallion issue but sone sirelines seem to be known fo rit.

[K~2]

One of the most expensive stallions on Earth, A P Indy is a ridgeling. His sireline is famous for it. To the best of my knowledge his fertility is good, he's getting on in years so a decline wouldn't shock me.

I don't know if it's a mare or stallion issue but sone sirelines seem to be known fo rit.

Ah.. but AP Indy's dam threw a couple other ridglings (one a full brother, and one by a completely different stallion). There are unconfirmed reports that all but one of her sons were ridglings.

So is him being a crypt coming through his sireline or his damline? (Which doesn't help answer the OP question at all! :lol:)

[secretariat]

The testosterone test isn't always accurate, either. We gelded a yearling pony that I KNOW had two descended. He retained studdish behavior and tested positive for elevated testosterone 6 months after gelding by a reputable vet.

[Rhyadawn]

Ah.. but AP Indy's dam threw a couple other ridglings (one a full brother, and one by a completely different stallion). There are unconfirmed reports that all but one of her sons were ridglings.

So is him being a crypt coming through his sireline or his damline? (Which doesn't help answer the OP question at all! :lol:)

This is the type of thing that we keep on finding. Its confusing, and it seems like no one really has an answer.

[eqrider1234]

im clueless....whats a cryptorchid?

[camohn]

Well I suppose it is just easier to ID the stallion as having the problem since it is physically obvious. If a mareline carries it she will have probably had a few foals by the time any trends are discovered...so it is probably easier to blame the stallion.

[camohn]

im clueless....whats a cryptorchid?

Only one testicle descended in a colt...a one nut wonder!

[grayarabpony]

You learn something new every day -- I did not know that AP Indy is a cryptorchid. I wonder how many of his offspring are too.

[Tnavas]

My boy was recently gelded at almost 2yrs and it nearly turned into a very expensive op as initially the vet could only find one testicle.

She usually checks for two before dropping the horse but we were chatting and she didn't check him. So there she was on the ground outside my paddock arm buried deep inside my boy rumaging around for the lost boy bit.

Eventually it was found and it was really small - I think my dog had bigger ones! The other was a normal healthy size.