Here's why:
* Dogs have an estimated 100-300 million olfactory receptors in their noses, while killer whales have only a few million. This means dogs can detect a far wider range of scents and at much lower concentrations.
* Dogs' olfactory bulbs, the part of the brain that processes smell, are much larger proportionally to their brain size than killer whales'. This allows for greater processing power and sensitivity to smells.
* Dogs have a specialized organ called the vomeronasal organ (Jacobson's organ), which helps them detect pheromones. Killer whales don't have this organ.
While killer whales have a good sense of smell, it's primarily used for detecting prey in the water. They rely more on echolocation for navigating and finding food.