1 00:00:02,040 --> 00:00:07,040 Speaker 1: Welcome to brain Stuff from how Stuff Works, Hey, brain Stuff, 2 00:00:07,080 --> 00:00:09,719 Speaker 1: Lauren vog Obam here. If you've ever shared a home 3 00:00:09,720 --> 00:00:12,840 Speaker 1: with a dog, you've probably had the startling experience of, 4 00:00:12,920 --> 00:00:16,280 Speaker 1: while minding your own business, having a cold, wet nose 5 00:00:16,400 --> 00:00:19,640 Speaker 1: thrust into your skin like a friendly ice cube. It's 6 00:00:19,680 --> 00:00:22,560 Speaker 1: your pup's way of getting your attention, and it's an 7 00:00:22,560 --> 00:00:24,680 Speaker 1: old wives tale that's such a wet nose is a 8 00:00:24,720 --> 00:00:27,240 Speaker 1: good thing because it supposedly means your dog is in 9 00:00:27,280 --> 00:00:30,280 Speaker 1: good health. But this idea has no basis. In fact, 10 00:00:30,560 --> 00:00:32,400 Speaker 1: whether a dog has a wet nose is not a 11 00:00:32,440 --> 00:00:36,159 Speaker 1: signal one way or another of health. But why are 12 00:00:36,200 --> 00:00:39,760 Speaker 1: dogs noses sometimes dry and sometimes wet. The short answer 13 00:00:39,880 --> 00:00:42,640 Speaker 1: is that dogs sometimes lick their noses, But the catch 14 00:00:42,720 --> 00:00:44,919 Speaker 1: is that no one knows for sure why they do that. 15 00:00:45,760 --> 00:00:48,880 Speaker 1: One theory suggests that because dogs are always licking their noses, 16 00:00:49,000 --> 00:00:52,240 Speaker 1: their saliva helps paint their schnas with the mucus produced 17 00:00:52,240 --> 00:00:55,440 Speaker 1: in the nostrils. As a result, all that mucus looking 18 00:00:55,520 --> 00:00:58,920 Speaker 1: improves a dog's ability to smell things. Let's break down 19 00:00:58,960 --> 00:01:01,720 Speaker 1: how that works. When dogs sniff the air, and they 20 00:01:01,760 --> 00:01:06,000 Speaker 1: are always sniffing the air, they inhale tiny suspended particles. 21 00:01:06,040 --> 00:01:08,880 Speaker 1: These particles get trapped in their nasal mucus, which helps 22 00:01:08,880 --> 00:01:11,720 Speaker 1: the dog figure out what they're smelling. As a dog 23 00:01:11,800 --> 00:01:13,800 Speaker 1: licks its nose, it picks up some of these scent 24 00:01:13,920 --> 00:01:17,520 Speaker 1: Latin goop. The tongue then brushes against an olfactory gland 25 00:01:17,560 --> 00:01:19,679 Speaker 1: on the roof of the mouth, which helps our four 26 00:01:19,760 --> 00:01:24,200 Speaker 1: legged companions figure out exactly what they're smelling. Another reason 27 00:01:24,319 --> 00:01:26,920 Speaker 1: some have suggested could be that a wet nose helps 28 00:01:27,000 --> 00:01:30,720 Speaker 1: keep a dog cool in warm weather. When we humans sweat, 29 00:01:30,920 --> 00:01:34,039 Speaker 1: the perspiration are sweat glands produce evaporates off of our skin, 30 00:01:34,360 --> 00:01:38,280 Speaker 1: cooling us down. Dogs, however, do not sweat. That's because 31 00:01:38,280 --> 00:01:40,800 Speaker 1: they have no sweat glands except from the bottom of 32 00:01:40,840 --> 00:01:45,160 Speaker 1: their pop haads. Instead, they pant to cool off. However, 33 00:01:45,240 --> 00:01:47,720 Speaker 1: a dog's nose, unlike the rest of its body, is 34 00:01:47,720 --> 00:01:51,080 Speaker 1: not covered in fur. It also brims with blood vessels. 35 00:01:51,520 --> 00:01:54,200 Speaker 1: When a dog licks its nose, the theory suggests it's 36 00:01:54,240 --> 00:01:57,920 Speaker 1: cooling itself down as it's saliva like human sweat, evaporates 37 00:01:58,360 --> 00:02:01,080 Speaker 1: that leaves the surface area of the no cool along 38 00:02:01,080 --> 00:02:05,000 Speaker 1: with the blood circulating in and around Fido's snout. Consequently, 39 00:02:05,200 --> 00:02:08,280 Speaker 1: cooler blood flows the dog's head and body, keeping our 40 00:02:08,360 --> 00:02:11,720 Speaker 1: best friends a little bit cooler. But then, why are 41 00:02:11,800 --> 00:02:15,080 Speaker 1: dogs noses often dry? A few factors can lead to 42 00:02:15,320 --> 00:02:18,440 Speaker 1: less licking. Touch your dog's nose in the morning, chances 43 00:02:18,480 --> 00:02:21,320 Speaker 1: are it'll be dries the sahara. That's because as a 44 00:02:21,360 --> 00:02:24,959 Speaker 1: dog sleeps, it rarely licks its nose, and certain breeds 45 00:02:24,960 --> 00:02:27,680 Speaker 1: like bulldogs and pugs, have noses that are mostly dry. 46 00:02:28,200 --> 00:02:31,480 Speaker 1: Age also tends to make a dog nose dryer. The 47 00:02:31,480 --> 00:02:33,480 Speaker 1: bottom line is that if your dog has a dry nose, 48 00:02:33,760 --> 00:02:36,560 Speaker 1: chill out. The dog isn't sick. Wait a few hours 49 00:02:36,600 --> 00:02:39,600 Speaker 1: and it will be wet again. Oh and a bonus 50 00:02:39,639 --> 00:02:42,519 Speaker 1: pup nose fact. Have you noticed that your dog has 51 00:02:42,560 --> 00:02:45,359 Speaker 1: slits on the sides of its nose. There's a reason 52 00:02:45,760 --> 00:02:48,600 Speaker 1: when dogs exhale, they do so out of those slits. 53 00:02:48,960 --> 00:02:51,320 Speaker 1: That's so that the exhaled air does not mix with 54 00:02:51,400 --> 00:03:00,480 Speaker 1: the scented inhaled air, which flows into the nostrils. Today's 55 00:03:00,520 --> 00:03:03,480 Speaker 1: episode was written by John Paritano and produced by Tyler Clang. 56 00:03:03,800 --> 00:03:06,040 Speaker 1: For more in this and lots of other startling topics, 57 00:03:06,160 --> 00:03:19,679 Speaker 1: visit our home planet, how Stuff Works dot Com.