Trademark Infringement question

Trademark law allows companies that sell in unrelated markets to use the same trademarks. As an example, Delta Faucets are sold by a company unrelated to Delta Airlines. They both own the DELTA trademark for their markets and they do not infringe each other.  The Trademark Office will consider the relationship of the markets.  If a company tried to register an athletic apparel trademark and the Trademark Office saw that the trademark was registered for sporting goods, but not apparel, by another company, the athletic apparel mark would likely be rejected. Trademarks in sporting goods and athletic apparel tend to flow into each other's markets. I am not aware of a relationship between the pet supply market and rust prevention market. A relationship could be inferred if you marketed the product specifically for pet cages, for instance.