Aye. But we must never let on that we know, Lassie. It would break his poor heart.
10 seconds sound clip from the Lady and the Tramp (1955) movie soundboard.
You can hear this line at 00:12:33 in the Blu-ray version of the movie.
Quote context
[...]
- They were? But that was before...
- 'Tis time you knew the truth, Lassie.
- It shouldn't have happened to a dog. But, well... Trusty has lost his sense of smell.
- No!
- Aye. But we must never let on that we know, Lassie. It would break his poor heart.
- Uh... Uh... Which way did he go? Which way did he go?
- Yeah, big fella. About, uh, six-foot-two. No, uh, three. Wore a striped suit. No collar. Uh...
- Why, Miss Lady. You have a collar.
- Aye.
[...]