Because accounting/bookkeeping is what I do, I was pleased to find this succinct summary of the ways that dog expenses could be a write off, reducing your taxes.
Is your dog tax deductible?
The costs of livestock guardian or farm dogs are generally considered a business/farm expense, of course; though this article goes into other cases, too, such as guard or rodent control dogs, service dogs, or dog expenses for breeders or dog show businesses.
I think it's interesting that the article says the IRS would require a guard dog to be certified. I wonder if there could be other ways to prove a dog is a guard dog for someone's business and/or business inventory.