He bites everything and even us at home. With lots and lots of energy. But the biting is troublesome

It sounds like you've got a very lively little guy on your hands! The good news is that what you're describing — constant biting and boundless energy — is completely normal puppy behavior, especially in a 3-month-old. At this age, puppies are in the thick of teething and are also learning how to interact with the world around them. Biting is one of their main tools for exploring. That said, it's really important to start shaping this behavior now, while he's young and learning fast.

Here are some things that tend to help:

• Redirect, don't just say no. When he bites your hand, calmly remove it and immediately offer a chew toy instead. You're teaching him what is okay to bite, not just that biting is bad.
• Yelp or go still. Puppies learn bite pressure from their littermates — a sharp "ouch!" or going completely limp and boring can signal to him that he's gone too far. Some pups respond well to this; others get more excited, so watch his reaction.
• Short time-outs. If biting continues, calmly step away or place him briefly in a safe, calm space (like a playpen). This teaches him that biting ends the fun.
• Burn that energy. A tired puppy bites less. Short play sessions, gentle fetch, and age-appropriate puzzle toys can help take the edge off. Keep sessions brief — his joints are still developing.
• Chew toys, chew toys, chew toys. Have them everywhere. Cold or frozen chew toys can also soothe teething gums.
• Consistency is everything. Everyone in the household needs to respond the same way. Mixed signals slow progress significantly.

Miniature Schnauzers are smart, spirited dogs — that energy is part of what makes them so fun. But that intelligence also means they pick up on training quickly when it's consistent and positive.

One thing worth knowing: at 3 months, he should be in the middle of his puppy vaccination series. Many areas offer puppy socialization classes that start around this age (sometimes even before the full vaccine series is complete, in controlled settings). These classes are fantastic for teaching bite inhibition in a structured way.

When to see your vet: If the biting seems unusually aggressive (growling, snapping with intent, stiff body posture), if he seems in pain or is biting at himself, or if you notice any swelling around his mouth or gums, bring it up at your next vet visit — or sooner if it seems urgent. Otherwise, mention the behavior at his next scheduled puppy checkup and ask about local puppy training classes. Your vet can also confirm he's on track with teething and development.