“Anton Bruckner had a chubby, fat pug dog named Mops,” Fritz Kreisler, a former pupil of Bruckner’s once recalled. “He would leave us with Mops munching our sandwiches while he himself hastened off to luncheon. We decided we’d play a joke on our teacher which would flatter him. So while the Meister was away, we’d play a motif by Wagner, and as we did so, would slap Mops and chase him. Next we’d start Bruckner’s Te Deum, and while this music was in progress, would give Mops something to eat. He soon showed a convincing preference for the Te Deum! When we thought we had trained him sufficiently so that he would automatically run away when Wagner was played and joyfully approach us at the sound of a Bruckner strain, we deemed the moment appropriate for our prank.
“‘Meister Bruckner,’ we said one day as he returned from lunch, ‘we know that you are devoted to Wagner, but to our way of thinking he cannot compare with you. Why, even a dog would know that you are a greater composer than Wagner.’
“Our guileless teacher blushed. He thought we were serious. He reproved us, paid tribute to Wagner as unquestionably the greatest contemporary, but was nevertheless filled with enough curiosity to ask what we meant by claiming even a dog could tell the difference. “This was the moment we had waited for. We played a Wagner motif. A howling, scared Mops stole out of the room. We started in on Bruckner’s Te Deum. A happy canine returned, wagging his tail and pawing expectantly at our sleeves. Bruckner was touched.”
Sources: Louis P. Lochner, Fritz Kreisler; Watson, Bruckner. Cited at: anecdotage.com