Signs of fatal diseases in dogs:

1. Rapid weight loss. If a dog suffers from a serious illness, it will cause a loss of appetite. The body can only consume the previous nutritional reserves, and the protein in the body will be lost rapidly, which will make the dog become more and more emaciated.

2. Difficulty breathing. If the dog's respiratory rate is significantly accelerated and the breathing depth is increased, it may indicate that the dog is suffering from respiratory diseases, such as tracheitis, bronchitis, pneumothorax, etc. This should not be taken lightly, as there is a risk of death at any time.

3. Bleeding in the stool. Under normal circumstances, a dog’s stool is solid. If a dog suffers from a serious disease, such as parvovirus, it will excrete watery stool with blood in the stool.

4. Fainting. Dogs are very lively animals. If they appear faint and drowsy, it means they are suffering from a serious disease and should receive treatment immediately.

5. Afraid of light and water. If your dog is afraid of light and water and likes to hide in dark places every day, this is a sign of rabies.