There are many symptoms of parvovirus in dogs, such as:

1. Vomiting: Dogs will frequently vomit, sometimes even vomiting yellow liquid or blood.

2. Diarrhea: Dogs will have severe diarrhea, and their feces will be black or blood-streaked, sometimes watery or mucus-like.

3. Weight loss: Due to vomiting and diarrhea, the dog's body will become very weak and symptoms of weight loss will appear.

4. Refusal to eat: Dogs often have symptoms of loss of appetite and are unwilling to eat or only eat a little.

5. Fever: Dogs may have a high fever, and their body temperature may exceed 40°C.