How do I repair a damaged back door trim that a puppy chewed.

Fill with wood filler, sand, and sand some more. Prime and paint. I would be giving puppy some bones to knaw on. And paint the trim with some bitters or cayenne pepper to discourage this habit.

I had a puppy once that loved to chew on antique furniture legs. Once you repair the door trim, get a small spray bottle and fill it with hot sauce and the puppy shouldn't chew on it again after you spray it on the trim on both sides. You should renew it in case he goes back by habit, but should learn fairly quickly. Watch out for new spots the puppy may start chewing on and repeat the process as necessary until he learns you don't chew wood!

Fill and form with wood filler. Make the final shape while filler is still pliable. If the filler is sagging, put it on in thinner layers, building up to the final shape. It is extremely difficult to sand wood filler into shape on trim so get it as close as possible.

😊

Use wood putty and a sander/sandpaper. You'll probably need to repaint. Can be tricky to use wood putty so you might want to hire a profissionable.

sorry...professional.

Agree with wood filler, shape and paint. I wouldn't do sticky mess and stains of hot sauce, there are plenty of bitter sprays/gels from pet supply stores