Available on DVD: “Quill: The Life of a Guide Dog”

The opening shot of Quill illustrates just how willing the director Yoichi Sai is to exploit his film’s protagonist: it’s an irresistible close-up of a sleeping Labrador retriever puppy. Therein lies the essence of this simple, bluntly effective movie. Its principal selling point — the supreme watchability of dogs, especially working dogs — is undeniably powerful.

Quill (named after a birdlike birthmark on his side) is born in Tokyo and initially raised by a loving young couple who recognize his potential as a companion to the blind. He is taken to an obedience school where a firm but compassionate trainer, Satoru Tawada (Kippei Shiina), notes that Quill, unlike the rest of the dogs he is training with, responds thoughtfully to commands, not impetuously — an ideal quality for a seeing-eye dog. (The training segments are the movie’s most fascinating.)

Tawada finds a potential owner for him: the cantankerous Mitsuru Watanabe (Kaoru Kobayashi, overacting), an advocate for the disabled who has long resisted having a guide dog. Quill gradually wins Watanabe over, of course, and moves in with his family. And here the story, which thus far has underplayed its sentiment, overreaches: Watanabe’s wife is cool toward Quill, and he is consigned to an outdoor pen, in pelting rain and baking heat. At least Watanabe’s son plays with him.

Watanabe ages and grows ill, and so eventually does the title character. Quill lives only 12 years, but when you consider the devotion, responsibility and affection a dog can demonstrate in that time, you appreciate just how full their lives can be.