While there can be several reasons for a horse’s behavior to change for the worse, one of the most common in mares is related to their breeding cycle.
A recent case in Florida highlights the issues that can beset mares. When amateur polo player and physician Dr Carl Gittens noticed his thoroughbred mare, Mintz, was acting unusually aggressive towards other horses, he knew there must be an underlying cause. Gittens, who has a string of horses at his farm in Stuart, Florida, bought six-year-old Mintz two years ago and, until recently, she had always been a gentle horse.
“She began mounting the other mares, and one day I brought two mares from Wellington back to my barn and she went crazy,” Gittens said.
“She was banging on the door, kicking, all kinds of things just like a stud would do and I really thought she was going to hurt herself. I finally decided that it had to be taken care of. She became very violent and it was a bad situation.”
Gittens said he’d had Mintz for 18 months when her behavior changed. “She is an excellent horse; she never had any problems. My groom rides her more than I do and he just loves her. When he found out what was happening, he said we had to do something because we could not afford to lose this horse.”
Gittens consulted his primary veterinarian, Dr Paul Bryant, who began investigating hormonal causes of the behavior change. He performed a rectal palpation and trans-rectal ultrasound examination for evaluation of her ovaries and uterus. Mintz had a severely enlarged left ovary on palpation with an abnormal “honeycombed” appearance on ultrasound. Bryant suspected an ovarian tumor and referred her to the team at Palm Beach Equine for evaluation and surgical removal of the left ovary.
The surgery was performed under the care of Dr Weston Davis with Mintz standing, using a minimally invasive key-hole surgical technique called laparoscopy. She was sedated for the procedure and pain management was performed with a combination of intravenous medications, an epidural, and local anesthesia of the skin, abdominal musculature, and ovary.
The enlarged left ovary was visualized laparoscopically and the vasculature ligated using electrocautery instruments. The ovary was then removed entirely through a small flank incision. The gross appearance of the enlarged and distorted ovary was consistent with the granulosa/thecal cell tumor type. Immediately after the procedure, Mintz was walked to her stall and soon allowed to resume her normal diet.
Davis explained that a granulosa/thecal cell tumor is a spontaneous occurrence that is relatively rare in horses. It is the most common type of ovarian tumor in mares, and almost always benign. Because of the variety of cell types involved and the hormone production that may ensue, these horses may have symptoms ranging from failure to cycle to nymphomania to stallion-like behavior.
Mintz was given a good prognosis and recovered nicely from the surgery. After a few days of antibiotics and several weeks of restricted activity (stall rest), she was cleared for light exercise and she had no further episodes of abnormal behavior.
With a busy work schedule, Gittens has not ridden her yet, but looks forward to getting back on the field soon. Mintz has been exercising with her groom, and Gittens plans to play her in Wellington this month.