I don't have the exact dialogue, but I was playing a pacifist run and called Papyrus outside Alphys's lab. Pap calls it a 'strange science house' to which Sans corrects him and says it's a 'laboratory'. "Labrador-y?" questions Pap. "There might be a few in there." replies Sans. Sans knows about the Amalga-dogs confirmed. Additionally, when calling Pap again he says "Strange dog's house..."