If the Doctor didn't know any better he'd say that the Master was plotting with the cat.

The more he thought about it the more certain he was that that was the case. After all, the Master had been partly feline for a while, possibly still was, if his tendency to purr ever so softly when he was sleeping deeply was any indication.

The Doctor had decided that some companionship (other than him) would be good for the Master. Since humans were out, a pet would have to do. Finding an animal that the Master wouldn't despise and wasn't dangerous proved difficult. In the end the cat proved the ideal choice, too ideal perhaps.

Clearly the Master was using the cat in some sort of nefarious or sex-driven plot.

The cat's motives however, were unclear.

The Doctor decided he needed to find a way to communicate with the cat and make it see the light, so to speak.

It did not go well. The situation reminded him of an Eddie Izzard sketch he and the Master had watched once.

Deciding to reason with the Master instead (bound to go well) he cornered him in the kitchen.

The Master wrinkled his nose at the burnt smell that was emanating from the Doctor's suit.

"What happened you?" he chuckled.

The Doctor, in no mood for the Master's games, ignored him.

He pulls himself up to his full height, "If you don't stop it I'm getting rid of the cat."

Then he storms out, leaving a thoroughly confused Master in the kitchen.

He has nothing to do with the cat's schemes.