A healthy miniature schnauzer tends to enjoy 12 to 14 years in his life. Typically standing around a foot tall at the shoulder and maxing out at about 20 pounds, he's considered a small dog. Small dogs tend to reach maturity faster than large-breed dogs, which for a miniature schnauzer means by his first birthday.
Different Kinds of Maturity
No matter how cute a puppy is, you can't be blamed for wondering how much longer the little guy is going to chew up your shoes. Dogs go through different benchmarks of maturity, dictated by size, breed, health and nutrition. A miniature schnauzer finishes most of his physical growing by the time he's a year old, but he may still gain weight and fill out well into his second year. If he's a she, she'll become sexually mature at around 6 months old; boy schnauzers take a little longer to reach sexual maturity, usually by 12 months. As for his puppy-like behavior, miniature schnauzers are frisky fellows and often keep their playful dispositions well into middle age. This is a highly intelligent dog who responds well to training, so his normal exuberance combined with good manners gives you an engaging, fun companion.