Is there an acceptable term for 'male fox' other than 'dog'?
In the scientific arena, stick to male and female.

The word reynard can apparently describe a male fox or foxes in general (either gender).

It is presumably derived from the French word for fox, renard.

I don't know French, but a little research suggests that la renarde describes a female fox (vixen), while le renard can refer to a male fox, or it can describe foxes in general.

I did a little work with foxes in Alaska years ago and never heard them described with any terms other than fox, male and female.