Some dogs (and other animals) are classed as “Working animals”, for example farm working dogs, gamekeepers’ spaniels, police dogs, or army bomb disposal dogs. If you own a working animal of any kind, the animal must be used primarily or exclusively for working purposes, such as drafting, herding, or guarding.
These working animals are treated in the business books as capital assets
that qualify for capital allowances, and feeding and caring for them would be tax-deductible expenses. So you could put food for these animals, veterinary fees and so forth into your business’s profit and loss account as business costs, and save tax.