Someone asked me recently what my clothing of choice was for working around dogs, horses and other animals.
1) For footwear, I opt for waterproof work boots. Another good choice is the Muck Boots Muckster Pet Lovers shoe. You can hose them down if needed, and the materials are resistant to pet contaminates, such as bacteria from manure. These are short, clog like shoes that grip well against the ankle. Unlike taller boots, you can run in them if you have to. Riding boots used to be my boot of choice, but I would ruin them.
2) For outerwear, noting beats canvas work jackets. Leather is protective in the case of a biting horse or a fall, but heavy canvas can be worn at multiple times during the year. Heavy cotton canvas, such as that in a Carhartt jacket does protect you from some of the severity of a horse or dog bite, is easily washable at home and has lots of pockets. Just be careful with snoopy dogs and horses with your hidden pockets if they smell you have treats! Watch the material around the cuffs. If they start looking frayed, the jacket is for barn use only, not to double for dinner.
3) For summer, I wear layers starting with a T shirt and a button down shirt that acts as a sun shield. I keep a light cotton canvas or denim jacket handy to protect my arms when dealing with a scared pr excited horse or dog, again, to provide a little of a barrier for scratches and bites.
4) For horses, always have a riding helmet handy when working in close quarters. It is a habit I picked up as a child, drilled into my head because of my age, but its equally valid now.