Researchers believe they have solved the mystery surrounding dogs' noses and why they are so cold. Scientists in Sweden and Hungary found that when the ambient temperature was 30C, a dog's rhinarium - or the bare end point of the nose - was 5C cooler.
https://news.sky.com/story/secret-behind-dogs-cold-noses-revealed-by-scientists-11947742
https://news.sky.com/story/secret-behind-dogs-cold-noses-revealed-by-scientists-11947742