If you use something like Avon's Skin so Soft, citrenella or another one of the natural repellants it is. I've used Skin So Soft on my dogs. Ones that contain DEET--like OFF or Muskol--aren't safe for animals. They can ingest the chemicals.

I use a horse repellant on my dogs. I have a spray one and one that looks like a roll-on deodorant. I just put it on their noses and faces. Be careful to avoid their eyes no matter what you use.