There was once a rich man who owned an old toothless dog and a cat. They were intelligent creatures, who could carry out almost any task that the rich man would give them. And they worshipped their master, and feared him, so great was his majesty.

The rich man had a daughter studying in a convent far away from his home. Every week, he would send her little gifts by carriage. But once, he had something very valuable to give her, and he could trust no one with its keeping save for his faithful cat and dog.

He turned to the cat first. "Keep this ring," he commanded. "It is magic. You are cunning as well as careful, and I trust you will not lose it." Then he turned to the dog. "Guard the cat and the magic ring well," he instructed. "You are strong and swift. Be watchful." This being said, he sent the creatures away.

Now it so happened that a swift-flowing stream barred the way of the cat and the old dog. The two servants had no alternative but to swim across it. The dog agreed to have the cat stay on his back while he would swim to the opposite bank. It was then that the dog urged the cat to entrust the ring to him.

"You are not a very good swimmer. I am," said the dog. "And the ring must get to the master’s daughter. Even if you fall off my back as I swim, the ring will be safe with me."

The cat protested. "But the master had said that I should keep the ring, not you."

The dog was angered by the cat’s stubbornness, and he threatened to kill the cat if he would not give him the ring. The cat surrendered, and gave the ring to the dog.

But the dog was toothless and the ring had nothing to cling on to in his jaws. It got swept away by the current as the dog and the cat were in the middle of the stream.

"Look at what happened!" the cat snapped. "Now we shall have to return to the master and tell him we had lost the ring."

The dog swam back to the bank they had left, and deposited the cat on solid ground. Just then the cat noticed that the dog looked very frightened. "Go on ahead to the master," the dog said to the cat. "I am too ashamed and afraid to face him." The dog swam to the opposite bank alone, and ran off. The cat tried to come after him by swimming across, but the water was too swift for him, and if he had not been able to swim back to shore he would have drowned. The cat started his long, lonely trek back to the house of his wealthy master. He was the one who had to explain the sad situation. The master became angry with the dog, and he sent scouts all over the world to hunt for an old, toothless dog and to cut off his tail once he was found. The scouts looked and looked, but they could find no such dog.

To this day, when one dog meets another, he asks "Are you the toothless cur who had lost a magic ring? If you are, then your tail must be cut off." And the interrogated dog would bare his teeth to show that he had them, and wag his tail to say no, I had lost no magic ring.
To this day, also, dogs and cats fight, or at the very least mistrust each other. And, after one of them having almost drowned, cats could not stand the touch of water.