Tonguez
A suffusion of yellow
Yeah which is why I ended with noting that in worlds where dogs are commonly ridden they would likely be bred for larger size and strength - crossbreeding with dire wolves might help too.The largest dog I have ever seen/touched was a 210 lbs mastif in good, not great, shape. The owner told me that is father as 220-230lbs, but it had to get down to 185lbs to bread. So just because we have dogs that 200-300lbs doesn't mean that they should or that it is a healthy weight.
But even a 180kg dog might cope with a halfling (though maybe not armour)