A common enemy in Silent Hill 4: The Room, the Sniffer Dogs are dog-type creatures that have long, prehensile tongues that they use to drain the blood of their prey. They serve the same function as Groaners and Double Heads from previous installments.
They have dirty, leathery skin which appears to be decaying and, strangely, make snarling sounds which resemble that of a large feline or even a frightened rat. Their gums are prominent and hold large, dagger-like canines.
The male variety has visible eyes, ears and green tinted fur and flesh. Females are missing eyes and ears and are purple-tinted, with longer, sharper claws. The gender and rank of the Sniffer Dog is betrayed by their coloration. Green-tinged Sniffer Dogs, considered to be males, are weaker and less threatening than the purple-tinged variety, considered to be females.
The male Sniffer Dogs have green-yellow tinges to their skin and attack by charging and lunging at Henry Townshend's torso. Female Sniffer Dogs, which have a purple-pink appearance, are much more intelligent and tend to detect Henry's presence more quickly. The females are capable of grabbing onto Henry's leg and pinning him down while their companions attack him. The Sniffer Dogs often appear in groups and are usually witnessed feeding on monster carcasses, something they do via literally stabbing their tongues into the dead and fiercely sucking out internal fluids, suggested by the violent quivering of their heads while feasting.
Their canine form is a reference to young Walter Sullivan's fear of dogs after he visited a pet shop during his childhood and was nearly bitten by one. Additionally, their tongues bear a close resemblance to an umbilical cord, echoing Walter's longing for his mother. The numerous animal noises the Sniffer Dog makes may also be a nod to the pets Walter killed in Garland's Pet Shop.
- It is possible that the Sniffer Dog's behavior is modeled after the "Hounds of Tindalos" created by Frank Belknap Long. The Hounds of Tindalos were said to be creatures with long, hollow tongues, or proboscis, to drain victims' bodily fluids, and supposedly inhabit the foul angles of time. The Sniffer Dogs similarly are unique to Walter's foul Otherworld while Henry and Eileen Galvin are of, in Joseph Schreiber's words, "the Lord's world".