As usual, I can only speak for the classical world, and (in this case) for dogs....

Arrian of Nicomedia, who wrote in the mid-century CE, is most famous for his account of Alexander's campaigns. He also composed, however, Cynegeticus, a treatise on hunting with dogs. In this work, he provides some interesting tidbits about Roman dog food. Good dogs, he assures his readers, will eat biscuits:

"Good dogs are not bad feeders, but fond of bread [probably a hard biscuit] or gruel. This kind of grain-based food is most strengthening to them, and there is no fear of their gorging themselves too much with it." (8)

This food, he continues, should be given to dogs dry, or slightly moistened if the animals seems to prefer it. Sick dogs require a more specialized diet:

"When a dog is sick, administer the broth of fat meat to him, or having roasted a bullock's liver over some hot coals, and rubbed it abroad, sprinkle it like flour into the broth. This is good also for puppies to strengthen their limbs, when they are first weaned from milk. But milk is the best food for the support of puppies till the ninth month, and even longer; and is serviceable to the sick and delicate as both food and drink." (8)

Later in his treatise, Arrian notes that feeding times and diet should be varied with the season:

"In the winter feed your dogs only once a day, a little before evening ; for the days are short...But in summer it is right to give them a little bread in addition, that they may not be exhausted by the length of the day; and if thirsty, they will drink with less detriment after having eaten. To thrust down a dog's throat a piece of salted fat is also found beneficial. But if the Weather be very hot, I would have you take an egg in your hand, open your dog's mouth, and push it down, that he may swallow it at one gulp. This will be nourishment enough for him, will cherish his wind, and quench his thirst." (12-13)

So far as we can tell, dogs fed this grain-based diet lived about as long as their modern counterparts. Aelian claims that dogs can live up to 14 years (On the Nature of Animals, IV.40), and Aristotle mentions that some breeds lived to 20 (History of Animals, VI.20).

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