There is a trend in veterinary medicine where the ovariohysterectomy is
switched out for the ovariectomy.
There are advantages to performing an ovariectomy because it is a much faster procedure and the incision can be better positioned over the ovaries to easily access both ovaries. But are there any disadvantages? There are not many studies that have looked at this, I found 2 in the literature, and they were not very strong regarding being able to make significant conclusions.
However, in some European countries, they have doing ovariectomies for many years and have not reported many issues at all with leaving the uterus behind.
Logic would state that with the ovaries removed, there should be no risk of developing a pyometra.