The episode describes the silly behaviour of Mrs. Pumphrey. She was rich and lonely. She loves her dog and pampers him. She is emotionally attached to him.

Due to her pampering, the dog has become hugely fat and eventually falls ill. She was over protective but her indulgence was foolish. Mr. Herriot, the veterinary surgeon, had warned her and given her certain instructions but she did not pay any heed to them. This made Tricki fall ill and had to be treated. Yes, I think such people can cause harm to others as it is evident that her foolishness had put Tricki in trouble.