Granulosa Ovarian Tumor

Hi Everyone,

Long time lurker first time poster here. I’m looking to see if anyone has experienced this before and what the result was (good or bad). I have a mare with a Granulosa Tumor on one ovary. Here is the kicker… she is 4 months pregnant. We are working with a great team of vets who are working to come up with an action plan for her but the ovary will need to come out. Tumor was not present at the time of breeding and was detected due to the mare’s odd change in behaviour. Has anyone performed this surgery during pregnancy? If so who did the surgery and what was the result for both the mare and foal?

We are also monitoring its growth to see if leaving it in until after foaling might be an option but right now the consensus is leaning towards that not being an option.

Any experiences would be greatly appreciated :slight_smile:


No personal experience but wanted to bump this to wish you all well

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My mare was sent to be bred but not pregnant at the time. The tumour grew very quickly while she was cycling and was too large to operate standing (~25yrs ago).
The testosterone levels were the problem --effectively behaved as a stud almost overnight–mounting another mare & fighting with stud that was to breed her… With the one ovary removed late fall–hospitalized for 2 weeks, another 2-3 weeks stall rest before TO with a gelding initially --however, she was fine the following spring (about 5 months later) when a paddock-mate delivered an earlier-than expected foal—concern had been over her behaviour but she would have stolen the foal if given a chance (over-protective not miserable with it).
Best of luck–hope you are able to maintain the pregnancy successfully.

I had a mare that had surgery for a granulosa tumor, but she was not in foal at the time. Original diagnosis was for it to come out ventrally, with a 1 mo. recuperation. I took her to VA Tech and they were able to do the surgery laterally with only a 2 week recovery period. They did a great job. Best of luck!!

I figured I would give everyone a quick update!

So first off everything is going well with the mare so far knocks on wood. She is rounding the corner on 7 months pregnant. Our vets in consultation with UC Davis opted to not do surgery during the pregnancy. UC Davis advised that these tumours tend to be oddly compatible with pregnancies and her hormones and behaviour should level out around 5-7 months. So far it looks like that is exactly what is happening. Her behaviour is back to normal. She is also getting monthly bloodwork and imaging of it to monitor it and at her last check the tumour had actually shrunk a bit as the hormones had levelled out. Right now the plan is to keep monitoring and remove the ovary after foaling!

Keep your fingers and toes crossed for us​:crossed_fingers::crossed_fingers::crossed_fingers: