Sniffer

Sniffers are a species of subterranean beast employed by some dwarves as working animals. They resemble a large, furless mole or rat, with wrinkly and translucent skin. They have no tails, and they only have rudimentary eyes which they use to detect the presence of light. They navigate the dark cave systems of the Underdark primarily by their keen sense of smell, for which they are named. They are also sometimes called nakies for their furless, naked appearance.

Biology

Sniffers have whiskers which are very sensitive to vibrations, and they are able to sense tremors over far distances, which allows them to anticipate cave-ins. Because of this, they are frequently employed by miners to warn them in the early seconds of an incoming tunnel collapse.
They are known to be highly resistant to the venom of several species of cave spider. They are natural predators of these arachnids, and are known to strike aggressively when they sense one nearby. Sniffers have a naturally diminished sense of pain, and when driven to fight, they tend to fight to exhaustion or until they or their adversary is dead. Gruesome scarring is a common sight on the territorial sniffer males.
In the wild, they live in colonies of 20-120 individuals. They dig out extensive tunnel systems, which form the colony's nest. A colony is highly protective of their broodmother, a highly fertile female with a role similar to that of an ant queen. For this reason, nests in the wild are usually left alone by dwarves and other peoples of the Underdark, as taking on an entire hive is a dangerous task.

Sniffers and dwarves

Sniffers are a popular companion and guard animal on cave expeditions, where dangerous populations of cave spiders are expected. However, great care has to be taken so that they do not devastate the population of dometicated spiders, which naturally produce the strands of web which are refined and turned into Dwarven Silk.
The sniffers employed by dwarves come from a domesticated colony, which over generations has integrated itself with a particular dwarven settlement. Moving sniffers between settlements is generally considered a very bad idea, as they are very territorial and known to blindly attack individuals of a different colony.
The Mound is known for fostering the questionable practice of sniffer fights, which is a gambling scene that abuses the natural aggression of sniffers. In these fights, dwarves from various settlements around the region bring their animals into the fighting pits and have them fight to the death for a chance to win money and fame.