Cross Breeds

Why do dogs get "snow nose" in the winter?

My White German Shepherds always get "snow nose" in the winter. But my Black German Shepherd does not. I know it is natural. And I know her nose will blacken come spring. But why does the nose change color in the first place? What biological purpose does the changing color serve. Or maybe there is no purpose for it, but rather an environmental cause. For those who do not know what "snow nose" is, here are a few images for examples: http://www1.istockphoto.com/file_thumbview_approve/181629/2/istockphoto_181629_snow_nose.jpg http://content.answers.com/main/content/wp/en-commons/thumb/5/5f/180px-Siberian_Husky_copper_bi-eye.jpg http://img267.imageshack.us/img267/7123/cimg2862il5my8.jpg http://huskyzone.zahoryzontem.org/wzorzec/65_nose_do_not_penalize_a_snow_nose.jpg http://www.mahkahtala-utonagan.co.uk/Snow%20nose%20-%20huge%20ears%20Sulin%20Shanaska%203.JPG

Public Comments

1. I don't have an answer.. but I did learn something new today.. Thank you!
2. they are cold and they are so cute.
3. If it's fresh snow that your dog stuck its nose in, it will turn white.
4. It's from lack of sunshine, that's why it comes back in the summer. I don't think there is a biological purpose for it, as I don't think wolves and coyotes have that problem.
5. Because dogs keep on wetting their noses
6. A term called snow nose is applied to dogs that lose the pigmentation of their nose during the winter months, but it darkens again in the spring and summer months. Something that has not been proven to work but may help is vitamin E and it is completely safe to try the dog on it. The condition itself is thought to be caused by the lack of sunlight, which is why the color returns in the spring and summer months. One thing to keep in mind is that complete depigmentation does not occur in this condition. So, if your dog does suffer from complete depigmentation, it is not snow nose and you should consult your local veterinarian to get a true diagnosis.
7. There is an enzyme that helps produce the black color that is dependent on temperature. It does not work well in lower temperatures -- hence it doesn't work in winter. Not all dogs are effected by this -- as you have seen in your two dogs. There are number of genes that modify how nose color is expressed. It's not just one gene that says what the color of the nose will be. Your dog that gets snow nose has the gene for it, the dog whose nose stays black does not have that gene.
8. I'm not positive as to any biological reasons. It is highly breed specific. However, it can also be caused by chemicals the dog comes in contact with. Some say that eating out of plastic bowls can cause it. It's not technically snow nose though, if it's not associated with the season. My Husky has a lightened stripe going down the middle of her nose. It's there all the time though- it started as a small dot when she was a puppy and has gotten bigger throughout the years.