Can a walking service be extended to an hour?

My dog has separation anxiety when he's left in my apartment alone. I'd love to take some yoga/pilates classes or go to the gym and not have my dog be an anxious ball of nerves. I was wondering if all the walks are limited to 30 minutes or if they can be extended so that I can go to a class and have someone look after him. I'd rather book a walking service instead of a house sitting service because I want my pup to expend some energy.

Thank you for any help! :)

-Sydney