Weakness, increased appetite, constant hunger and weight loss: If your dog has worms, the worms are stealing your dogs nutrition. Your dog may be weak or constantly hungry, and in severe cases, may be losing weight. These signs could indicate another health issue, therefore its important to consult with your vet for a diagnosis and treatment. Diarrhoea: Particularly with blood in it. Again, diarrhoea can also be indicative of other serious conditions, and your vet should be contacted ...