While this armor for cats and mice is contemporary art (Itcy and Scratchy inspired, perhaps?), this suit of dog armor is authentic and 200 years old. Historians estimate that the armor was built in Japan between 1800 and 1850 (possibly before) and belonged to a high-ranking samurai. It's the only known suit of its kind and was quite expensive for the original owner — its materials include chanfron armor, doeskin leather, silk brocade, a hand-carved wooden mask and gold leaf.
The armor was recently auctioned to a British museum, but if you study the pictures closely enough you might be able to make a good enough replica at home to arm Fido so he can join you on the battlefield. Or so that he can defend himself from your jousting cat.