Dear Matthew: My 7-year-old boxer, Lucy, is aggressive toward other dogs her size or bigger. I have had her all of her life. She used to play with a large Doberman and others in dog-run parks. When she was a year old, a German Shepherd went after her. She was not injured, but I think she was traumatized by the attack.

After that, she became aloof around the other dogs. It was like she didn't even know they were there. When she was 5 years old, she snapped and attacked another dog.She heels well, but if we see another dog on our walk, it becomes a tug of war. Is there a way that I can resocialize Lucy that is safe for her and other dogs? -- Julie in Astoria, N.Y.

Dear Julie: It is entirely possible that a traumatic incident when your dog was a puppy helped cause her present state. Combined that with a lack of adequate socialization since then, and you could have a problem -- one that will take work and patience to overcome. And this is assuming your dog is neutered. If not, you should take him to the vet soon to have this safe, necessary procedure done.

It is possible to train your dog to behave well around fellow canines even at this late date, although you're never going to be able to be 100 percent certain that, given the wrong circumstances, an incident may occur.

The key to resocializing your dog is to have a friend who has a dog and is willing to help you. On neutral ground, in a controlled situation, introduce the two dogs. Either have your dog on a leash or in a crate, so he can't get at your friend's pet. Let them spend some time together and get used to one another. Your dog will probably go nuts at first, but eventually she'll wear herself out and start adjusting. Do this once every day or so until your dog starts getting used to see this other animal. The next step is to try letting them interact freely, sniffing each other and playing together. Separate them at the first sign of trouble, but by now -- with any luck -- your dog should be used to her new friend.

From there, try introducing your dog to other animals. Once again, be prepared to take control when there's trouble, but keep at it, and your dog should calm down.

Of course, this solution won't be of much help if you don't have any friends with dogs. In that case, I'd suggest you consult with a local dog-trainer, who will be able to provide other dogs for your pet to train with. Good luck!

Dear Matthew: We are going on vacation this year to Martha's Vineyard, and we want to bring our 3-year-old Newfoundland with us. She has never been to any beach but a lake's before, but she is very well trained.

Are there are precautions we should take in the ocean with her? Also, does salt water ruin coats? She isn't a show dog, so it wouldn't matter, but we want her to enjoy this vacation as much as we will. -- Neil in Baltimore

Dear Neil: I wouldn't worry too much about having your dog on the beach with you. I'm sure she'll have a blast running around in the water and breathing the fresh sea air. There are some steps you can take, however, that will ensure that your dog remains healthy and happy.

While salt water shouldn't damage your dog's coat, it could irritate her skin, so it's a good idea to wash off your pet with fresh water after a day at the beach. This is also a good idea, since it'll help keep your furry friend from bringing piles of sand into your room at night.

Also, I recommend you inspect your dog's paws at the end of each day, as beaches sometimes have shards of glass or other dangerous bits of trash that could hurt her feet. While chances are things will be fine, it's always a good idea to err on the side of caution. Have a safe and fun trip!

Matthew Margolis is the host of "Woof! It's a Dog's Life," a dog-instruction series airing every Saturday on your local PBS station.Read all of Matthew Margolis' columns at the Creators Syndicate Web site (www.creators.com). Write him at 5777 W. Century Blvd., Suite 700, Los Angeles, CA 90045. (C) Creators Syndicate Inc.