Legal Question in Real Estate Law in California

This isn't a real estate question. Pets and domestic animals are personal property.

The issue here will be whether this breach of your contract entitles you to return of the dog or only money damages. Money damages are the usual remedy for breach of contract. However, the Civil Code recognizes that the ownership of personal property can be absolute or conditional, and failure of a condition may cause a reversion of ownership.

This is much more common in real-estate deals, where a deed may convey land to a grantee upon an express condition, e.g. "so long as the building is never used for a liquor bar," and upon failure of the condition subsequent (when someone uses the building for a bar), title reverts. However, the statutes do not seem to limit the principle of ownership subject to reversion to real property. There are in fact some old cases (1850s) that seem to apply the concept of reversionary title to personal property.

In modern commerce, goods are frequently "sold" on conditional sales contracts, where title does not pass until a condition (i.e., payment in full) is met. Your dog deal does not sound like a conditional sale, however. Title passed upon your giving the dog away, but what you gave was ownership subject to a condition.

See Civil Code sections 655 (things subject to ownership); 678 and 680 (qualified ownership) and 707 and 708 (conditions of ownership).

The idea that you are going to control what someone does with the dog you gave him, short of him selling it for some inhumane purpose such as dogfighting or medical experiments, is completely ridiculous. Aside from that, to have a valid contract there has to be something called "consideration" which merely means that he would have to have given you something of value in exchange for the dog. If you had sold it to him for $10 instead of giving it away you might have a better claim to enforce your contract.