Posted on Saturday, September 23, 2006 - 08:37 am:
My wife has a gelding that had one 'crypt' testicle that was (at least theoretically) entirely surgically removed before she bought the horse. The gelding has started exhibiting stallion behaviors this spring after arriving at our farm in mid winter.
We had the hormone challenge test done (actually described on in a recent post on the stallion page I believe) in which a baseline level is taken and then a stimulating hormone injected and testerone levels are measured again.
According to the surgery vet's interpretation our horse shows a noticeable elevation, more than would be expected for a gelding, but not to stallion levels and not necesarily indicative of testicularly based response.
first testosterone test early spring when first noticed the problem:
.25 n/mg
2nd test as baseline for hCG (human chorionic gonadotropin ?) challenge test performed mid summer. .15 n/mg
hour after challenge injection
.28 n/mg
The vets who did the surgery insist they remember the surgery and think they quite successfully removed all the testicular tissue. They suggest that exploratory surgery could reveal some 'stump' of testicular tissue but they are not highly confident of finding it, and don't seem to feel any accomodation on the costs on their part is in order.
It may well be that they performed with the highest quality of care and that these unusual conditions can result from stray testicular tissue or the substitute production of testosterone by other glands filling in for the missing equipment. This is a possibility disputed between the several vets we have consulted.
This was a modestly priced horse supplanting a 20 something horse my wife has had for most of its life but has become unrideably lame probably due to a past founder. (Gets around fine and still bosses other horses but corrective shoeing no longer makes him comfortable on the trail).
The new horse is a small young (just under 4) quarter horse. It may be possible to try to respond quickly to some of the staillion like behaviors to prevent their becoming ingrained, but we both are full time workers elsewhere and I don't know if management alone is practical.
The quote for the surgery around $2000 is more than the price of the horse.
The vets recommended as an alternative the use of 'feminizing' drug to counter the testosterone production. They recommended a generic verison of depoprovera called medroxyprogesterone.
The dosage recommended for our just sub 1000 lbs. horse appears to be an intiative course of three weekly injects of 1500 mg (10 ml injections of 150mg/ml. Then assuming satisfactory response, monthly maintenance with a similar injection once a month.
The vets offered us the first 30 ml for $250. I found it online at Heartland Vet supply for $269 for 100 ml.
The second possibility starts to work into a cost framework we might be able to live with.
Finally to the questions.
Has anyone had experience with the use of this particular drug for this purpose? The vets suggest it is relatively new approach and we haven't been able to find too much confirmation as to effective dosage or any ponters to veterinary journals or discussions of its efficacy.
How might this drug compare in theoretical approach, effect and cost with other possible compounds, e.g. regumate?
Given what we found, the Heartland Vet Supply seemed the most cost effective, but if anyone has recommendation for supplier who perhaps specializes in supplying these hormonal regulateors for veterinary use that might have even better prices?
Any other drug, laproscopic, or more invasive approaches or management hints obviously appreciated as well?
We've gotten various analysis of the testing from various vets. The vets who did the surgery insist that the test response was not that significant with a 5 to 10 fold increase is indicative of stallion status, e.g. significant retention of testicular tissue. Our local vet who is less focused on equine practice understood the literature to suggest that a two-fold increase, i.e. what was observed in our case, is signficant in pointing toward retained testicular tissue.
Last question would be, the debate over whether these levels of testosterone can possible be produced in substitute by the adrenal or pituitary glands. IS it possible? How unusual? Obviously we're dealing with a modestly unusual but not unheard of condition in a gelding exhibiting some stallion behavior and some stallion chemistry. In trying to figure out why this might be happening we're obviously trying to figure out the most likely culprit within this subset of horses.
Don't know the politenesses of this board. I noticed that some of these questions are also asked in the general stallion questions area. Would it be impolite to post over there or do most people glance at both anyway?
Posted on Saturday, September 23, 2006 - 07:33 pm:
There are several factors to consider in connection with this post.
Some geldings - who most decidedly do not have retained testicular tissue - will tease, gain an erection, mount and breed a mare. Their ejaculate however will not contain sperm. Again, this is in complete absence of testicular tissue.
Some stallions have more than 2 testicles - I had one that was castrated twice with 2 external (normally situated) testicles, and then 2 abdominally retained testicles.
If there is an abdominally retained testicle that is not removed, then there is an increased risk for subsequent testicular cancer.
There is no research associated with the use of Medroxyprogesterone acetate (which is the drug that is marketed under the brand name of Depo-provera) in the stallion that I am aware of. there has been research into the use of Regumate, although there were mixed results on behaviour that were greatly influenced by the age of the animal involved. Once the stallion had developed certain learned behaviours, the addition of Regumate had a lesser effect in "down grading" such behaviour.
Medroxyprogesterone acetate use in mares has been researched, and found not to support pregnancy in mare whose endogenous progestin source has been removed. Regumate on the other hand did support the pregnancy.
Freeman D. E. in a paper presented at the Italian Association of Equine Practitioners conference in 2003 made the following observation relative to testosterone levels following an hCG challenge test:
To perform an HCG challenge test, a 0 time blood sample is drawn and the horse is given 10,000 IU of HCG, IV. Additional blood samples are drawn at 30, 60, and 120 minutes. A normal horse with 1 or 2 testes will show testosterone levels from 100 to 1,500 pgm/ml with a peak at around 35 minutes. A gelding should have testosterone levels below 30 pgm/ml.
This does give me cause to suggest that you confirm the levels that were identified in this gelding and make absolutely sure that the units of measurement were ng/ml and not pg/ml! Based on the readings you offer above, the gelding certainly evidences stallion-like levels - as long as the units of measurement are ng/ml. If it turns out that they are in fact pg/ml, then he is well within normal gelding limits. If they are in some other entirely different measurement, then you will have to perform conversions to make any sense of the above!
If you do confirm that the levels are indicative of testicular tissue presence, I would go ahead with surgery if it were my horse, as a result of (a) the annoyance of the unwanted behaviour; and (b) the increased risk of testicular cancer. Laparoscopic surgery is one option and would be less traumatic for the horse.
Thanks for your informed response. I clicked post a new thread but I must have been in another thread when I did that so it posts a new title under an existing one. That is why I could not find our post on the board.
Your posts are thorough, and I expect if I had read through the entire history of this board I could have gleaned approximately the same information from your having generously shared it before.
Thanks for taking the time to do it again.
We will confirm the levels. We appear to be one order of magnitude off in regards to your analysis and that of the various vets we have talked to.
Our vet who drew the blood for the test and is wonderful and friendly but is not solely equine focused gave us the results as I related them to you and where we had found a non challenged range of .15-.25 ng/ml and a doubling after the challenge she understood that 1.0 was the base for a stallion.
To convert this to the units of measure you cited we understood her to say that the horse exhibited unchallenged response in two tests of 150 - 250 picograms. I suppose it is possible that my wife did not write down correctly that the results were .015 and .025 but she thought she payed very specific attention and had the results carefully read and written since she initially communicated them between the vet who did the tests and her prepurchase vet and the vet who did the original operation to remove the retained testicle.
Disagreement continues between vets as to the significance of the change following the hCG challenge. Our local vet thought the doubling was significant indicator of testicular tissue even though the numbers were below her understanding of stallion range (her understanding of the stallion range would put the threshold at 1000 pg/mg.)
The surgical castration vet said that a five to tenfold increase after the hCG challenge test was more indicative of testicular tissue than the actual numbers in what you suggest is the lower stallion range.
We also had Esterone Sulfate levels taken which apparently are another indicator of crypt condition. Again our local vet who drew the blood gave us the following analytical framework.
<5 ng/ml is gelding
>10 ng/ml indicates crypt
the test result for our horse was 17.32 ng/ml leading her to suggest that this indicated a horse that had not had the retained testicle removed. The surgical vet insisted that these results are difficult to interpret and suggested they be reviewed in context of the testosterone tests, behaviors, and knowledge of previous surgery by University of California at Davis.
We're going to try regumate right away to see if we can enhance our management efforts to prevent behaviors from becoming ingrained while we wade through this.
The surgery, especially laproscopic is probably more than we can afford unless the vets make some kind of accomodation based on not having looked for anamolous additional testicles to begin with.
The prepurchase vet insisted once this problem arose that there is no such thing as stallions having more than 2 testicles. I think to order our thoughts before visiting the surgery option we will need to read the medical literature and inform ourselves in order to discuss this on a more equal plane with the vets.
In other words, we have to know more about it than they do in order to be taken seriously. At first blush - but based largely on their own representations and our limited understanding - it appears that the prepurchase vet and the surgical castration vet performed within the range of acceptable care but that has to be a consideration that we examine from a more knowledgable standpoint.
If these conditions we're experiencing are extremely rare, perhaps it is not normal procedure or thought to be in the best health interests of the horse to search in abdominal tissue or other possible locations for a testicle beyond a two count.
On the other hand, if the horse is anesthesized and opened for surgery for a crypt testicle, perhaps there is an association between presenting crypt in the first place and the possibility that there would be more than two testicles, thus manual/visual exploration for another testicle might be indicated.
You mentioned a case of a horse with two descended testicles that then presented with two retained, so clearly there are many possible ways for this problem to rear its ugly head (sorry about that, the horse ain't that bad looking).
Would it be standard practice once aware of crypt condition to test a horse following the surgery, for instance in the same way we are now testing to understand behavior? Should a pre-purchase vet be well advised to test at least basic testosterone or esterone sulfate levels if not perform an hCG challenge test as part of pre purchase exam if knowing the horse had presented with a retained testicle?
I'm not trying to hang anyone out to dry here and we may be just unlucky owners of a stallion when we wanted a gelding. But the value of the horse is probably low to nil in our market with this problem (might be OK as a working horse on a 100,000 acre spread with a few geldings and cows and sheep and no female mustangs) but not practical to travel in the milieu of mares and geldings in popular trail riding spots or exhibtion circles. Thus, if we can't afford the surgery or the horse doesn't exhibit marked effect from the Regumate, we could be looking at glue here, at least metaphorically speaking.
On the other hand, one reason we didn't even seriously consider whether we could borrow enough money to cover the surgey is the vets didn't even discuss the possibility of an additional testicle and talked instead about the possibility of some small retained portion of the already removed testicle that would be very hard to find and thus we might spend $1500 or $2000 and accomplish nothing except cutting the horse open.
These are the same vets who analyze the test results as anamolous, i.e. falling in the range between stallion and gelding, although I agree with you that if the numbers are correctly reported this horse falls clearly in the stallion range at least according to that citation from the Italian Equine practioners which I have seen posted elsewhere now that I am searching this issue.
The surgical vet also said it was possible that the pituitary or adrenal glands were substituing somewhat for the lack of testicular function. Other vets have told us that is not possible.
My wife subscribes to "thehorse.com" and has a fairly extensive 2004 article that descibes all the possible locations for retained testicles. One oddity she has noted is that this horse stops to urinate on the trail which she has never experienced before making her wonder if there is an additional testicle could it lodged near or adhered to the bladder. This is one possibility among many presented in the article I mentioned.
I couldn't expect you to answer all these questions beyond what is professionally interesting to you to discuss and the utility of these circumstances to increase your own knowledge of the range of conditions in these behavior rather than reproductively focused fertility discussions.
Appreciate any thoughts this novel brings to mind as well as any citations to popular literature or veterinary journals. I think we are going to be needing to read the fine print to figure out our next step.
Brian - it sounds to me that you have already done extensive research on this subject and have found that there are lots of variables in this subject. By no means am I vet a vet, but 40+ years of horses has lead me to the belief that ANYTHING can and will happen when it comes to horses!!! Murphy's Law is the only law when it comes to horses!! LOL Good luck with your horse and I hope you get some answers to your questions. Keep us posted on the Regumate results. Cindy Moore www.crippledcatranch.com}
The presence of more than 2 testicles - abdominally/inguinally retained or otherwise - is extremely rare. Certainly it would not be a matter of routine for it to be considered a likelihood to the point of testing hormonal levels or doing a further intra-abdominal examination at the time of either sale/purchase or castration (respectively or collectively). I have only run across it once (or twice if you will... ).
You might want to contact either Texas A&M University or Colorado State University to discuss the whole situation with one of the veterinarians there (who specialise in equine reproduction), and you may also want to contact BET Labs and ask to speak with Dr. Douglas - they have performed reproductive endocrinology evaluations for years and are experts in the field.
What are the side effects of Medroxyprogesterone in mares
According to the latest research none. Including suppression of estrus, follicular development, and LH secretion. At least at the levels used in the study (follow the link for the abstract).
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