While the points made regarding the changing demographics from predominantly men to women in the industry as well as the fact that many take some time off for children, what I found most upsetting was the huge difference in equine practices compared to other types of practice ownership. You're probably right in regards to the factors affecting female salaries and that things are changing. I just have a hard time reading about such a difference in one particular practice. ~$89 000/yr difference is quite far from the next biggest difference in food animal at ~$61 000/yr. We'll see a few years down the road how things pan out -- which will hopefully be for the better.
As an equine girl, I suppose I'm more sensitive to such numbers.
You need to dig deeper into things, as minnerbelle points out.
I definitely do not believe that these numbers were controlled properly.
Owning a practice is not the same as being an employee, there's so many more factors in the equation. There are far fewer equine-only practices than there are companion, and so smaller samples are more susceptible to error.
Also, given the changing demographic (which means that males have more experience on average than females), the female practice owners are more likely new owners of a practice..
From there, you reach multiple conclusions:
1) The female owner is on average less experienced and so therefore will not be as efficient of a worker as an (on average) older male, and will probably bring in less cash to the practice as the primary vet.
2) Females are more likely to own a new practice, and since practices are less profitable near their start (when growing their customer base), you'd expect the average to be so much less.
3) If females do not own a new practice, but rather bought an existing one, then it's less likely to be a very profitable practice. The more profitable practices are not for sale, the least profitable ones are (on average).
Also you can't ignore what previous posters mentioned: Males are less likely to be held back from work by a family. Therefore males would put on average more hours of work in.
Then, don't forget about the massive equine behemoth in the room: Thoroughbred Racing
The equine practices bringing in half million plus profits annually are based on the racehorse industry, centered around a racing hub like Kentucky. These practices are much more likely to be male-owned and have likely been around a long time (since the days of mostly male grads).
Not to mention that 'high-end racehorse owners' is an old boys club, and foolishly rich old males are more likely to be sexist.
These are mostly non-malicious and non-discriminatory variables, save the last one about rich old men being sexist
Don't forget that there are a ton of factors at play.
