Dog possession was a very common feature for European courts for much of its history. Note that I say "possession," because in many cases historical dog ownership does not conform to contemporary notions in which a pet straddles the line between family and possession. If one can broadly generalize, two types of dogs typified the European court: small toy/lapdog breeds and hunting dogs. The smaller breeds were often a status symbol, especially for the women at court. One of the first English-language books on dogs in 1570 complains that small dogs are generally status objects for the amusement of women and serve no real useful purpose. The famous (and adorable) King Charles Spaniel were brought over from France by Charles II's beloved sister Henrietta of Orleans, you can see her holding one in her portrait here: http://upload.wikimedia.org/wikipedia/commons/thumb/f/fc/Henrietta_Anne%2C_Duchess_of_Orleans_by_Pierre_Mignard.jpg/640px-Henrietta_Anne%2C_Duchess_of_Orleans_by_Pierre_Mignard.jpg

Although it's unclear when the toy breeds became popular, there are accounts of Roman women walking small dogs, the large hunting breeds have a pedigree that dates to before antiquity. The strength and loyalty of these dogs has penetrated into folklore and mythology. In the Odyssey, Odysseus's dog Argos was the only one to recognize the fact that Ithaca's ruler had returned. Another sad dog tale is that of Gelert, the wolfhound of the 12th century Welsh king Llywelyn the Great. The story goes that Llwelyn slew Gelert when he found him with a bloody muzzle and his son's crib turned over (the baby had taken to teasing the dog), only to discover that Gelert had slain a wolf that had tried to eat the baby. This story is a folklore and its veracity is hard to determine, but Gelert's gravestone still exists http://en.wikipedia.org/wiki/Gelert#mediaviewer/File:Gelert%27s_Grave.jpg

The symbolic meaning of hunting dogs or other large breeds dovetails with the monarch's own pretensions of power. These dogs are large and fierce, but also loyal. Whereas artistic presentations of toy breeds tend to show them as passive adornments, the larger breeds are either more active (hunting with its master) or fawning at his feet. See this etching of Frederick the Great and his greyhounds: http://3.bp.blogspot.com/-brTlSKXD3a0/UUivYO2_obI/AAAAAAAAAUQ/jZurxwm8nx0/s1600/M137520.jpg

Of course Frederick was quite fond of his dogs and his grave is next to his favorite hounds. Other monarchs were fond o their dogs, a Louis XIV's son became so enamored with the Great Pyrenees named Patou that many in the court emulated the royal family and acquired Pyrs of their own. Dogs themselves were able to insinuate themselves into the daily lives of their royal owners. When Frederick the Great's beloved Biche died, he wrote:

I have had a domestic loss which has completely upset my philosophy. I confide all my frailties in you: I have lost Biche, and her death has reawoken in me the loss of all my friends, particularly of him who gave her to me. I was ashamed that a dog could so deeply affect my soul; but the sedentary life I lead and the faithfulness of this poor creature had so strongly attached me to her, her suffering so moved me, that I confess, I am sad and afflicted. Does one have to be hard? Must one be insensitive? I believe that anyone capable of indifference towards a faithful animal is unable to be grateful towards an equal, and that, if one must choose, it is best to be too sensitive than too hard.

Sources

Ritvo, Harriet. The Animal Estate: The English and Other Creatures in the Victorian Age. Cambridge, Mass: Harvard University Press, 1987.

Skabelund, Aaron Herald. Empire of Dogs: Canines, Japan, and the Making of the Modern Imperial World. Ithaca: Cornell University Press, 2011.

Wyett, Jodi L. "The Lap of Luxury: Lapdogs, Literature, and Social Meaning in the “long”; Eighteenth Century". Lit: Literature Interpretation Theory. 10, no. 4: 275-301.