Mare... either ovarian tumor or she's a pseudohermaphrodite

I purchased a 4 year old mare a few months back and was told she has a granulosis tumor on her ovary. She had always acted a bit stallion-like, cycled very hard, acted "bi-polar", and mounted other horses both male and female (but that could have been just her playing). She had been diagnosed a year ago with the tumor due to her inhibin level. I spoke to 2 clinics in NJ, Dr Karlin at Mid Atlantic and Dr Smith at NJ Equine. We finally reached out and spoke to the vets at New Bolton in PA. They mentioned how they don't feel it is definitely a tumor on the ovary. She has had attitude issues since about 8 months of age. They feel there is a good chance she may be a pseudohermaphrodite. I was also told that her inhibin level could be indicative of either or. We won't know for sure what condition she has until I have an ultrasound done on her which will be done the day of surgery. Regardless, she is going in next week to have whatever issue she has resolved via lapro surgery. I'm not very familiar with the pseudohermaphrodite condition. I examined her genitalia and everything is normal. The vet tells me she could still possibly have a testicle in her abdomen. I am trying to grasp the idea of having to geld my mare?

The point of this thread is, I am wondering if there is anyone on here who has experienced either condition with their horses. If so could you explain any changes your horses had temperment-wise post surgery?

No personal experience, but everything I have read on pseudohermaphroditism involved a horse with an abnormal vulva that, on closer inspection, could be identified as a tiny penis. Does she have secondary male sexual characteristics, with heavy jowel muscling and such?

There's nothing heavy on her. Her face, nose, jowls are all very dainty and petite. If you were to look at her without looking under her you'd know she was a mare. I studied her vulva and there's NO sign of any abnormality. I checked many pictures online and they actually creeped me out. I don't think she's a pseudohermaphrodite. In fact I hope not since that's the more expensive surgery. I'm just hoping the severity of her mood quiets down a bit.

What does she show on a rectal palpation?

I, too, have always seen pseudohermaphrodites with a lower and elongated vulva.

Her previous owner never ran further diagnostics on her. She checked her inhibin and testosterone level. I have her set up for ultrasound and a "breeding exam" Monday so we can see what is exactly going on.

A pseudohermaphrodite is an animal that has the gonads of one sex and the external genitalia of the of the other sex. If your mare is a pseudohermaphrodite, she looks like a mare on the outside, but she is actually a stallion. Whatever her problem is (pseudohermaphrodite, ovarian tumor, or ovarian cyst) I bet that she will be a different and much better horse after having surgery to remove her gonads (ovaries or testicles). I would be very interested in updates.

Here's a question I've never gotten a satisfactory answer to: would a pseudohermaphrodite have udders, or would it depend on the individual?

All horses have teats. If the gonads were female, it would probably have some mammary development. This horse may have male gonads, so she most likely would not develop an udder. It would depend on the individual, because a pseudohermaphrodite has crazy hormones anyway. A true hermaphrodite has complete male and female reproductive tracts. These are extremely rare in mammals. I have never read about one or seen one. I did see a pseudohermaphite dog. He/she had the external appearance of a male (but with an empty scrotum). When I opened him up for surgery, there was a complete uterus and two ovaries. I spayed him. :)

Earth worms are all true hermaphodites and quite fertile. (Not that anyone cares about that except extreme geeks........ )

Fascinating subject. I look forward to updates. :)

Had a pug like that at my clinic. Was named Sam, had testicles and a penis and sheath, however the sheath/penis was located back from a normal males sheath location closer to the scrotum. Neutered him, then opened him up and sure enough, he/she had overies and uterous.... Was really interesting to assist in the surgery.