A dog's nose, on the other hand, should be cool and damp to the touch. This is due to it being cooled by the surrounding air. A dry, warm nose is more likely to signify illness than a warm tongue. In addition to this, some dogs get hot ears when they have a fever.
If your dog has other symptoms of illness such as tiredness, runny eyes, diarrhoea, sickness or general difference in personality then keep an eye on it, make sure it has plenty of water and give it food in small quantities. If it doesn't seem to get better within a couple of days or starts getting worse, it is probably best to seek veterinary advice. With animals, it is often a change in personality noticed by the owner which is the first sign of illness. A generally depressed dog which refuses a walk is usually the best sign it is feeling under the weather.