While there are canines on Venus (dangerous varieties of jackals and hyenas, at a minimum) I'm considering using pigs as a replacement for dogs in most pet roles.
If we imagine the wild ancestors of Venusian pigs were smaller and less dangerous than Terran wild pigs, it's entirely plausible they, rather than canines, were the first animals to be domesticated by Venusian humans. Pigs thrive on the same food as humans, are smart, have a great sense of smell and can be trained to forage for humans, or help people in foraging. They're powerful and fearsome enough to be bred as guardians, and they can be bred in a variety of sizes (and colors) to fit into just as many roles, from huge boar-like war-pigs to cute, diminutive lap-pigs wealthy ladies carry around almost like fashion accessories.
Pigs dislike climbing stairs, which makes it extremely easy to keep them out certain areas in towns and cities. There would of course be a widespread taboo against eating pork - held to be gross and scary as a food, as it resembles human flesh way too much. But such an outlook wouldn't be universal amongst Venusian cultures: in areas where an abundance of other meats have long been available, the mere thought of eating pork would be disgusting, whereas some people from a number of agriculturally "backwards" areas of Venus would have local traditions of consuming pork, and generally think about it in more practical terms (and would be dubbed "pig-eating savages" by their neighbors).
I also think pigs (being more opportunistic feeders than aggressive predators) don't make for good hunting animals. Domesticated canines would thus exist on Venus too, specifically feral hunting-dogs descended from jackals or hyenas. These would be generally mistrusted animals non-specialists dislike to deal with. I can see one or more species of bats being bred for hunting as well.
Should I opt to take this route, horses would be horses - there's such a thing as "too much weirdness" indeed.