The short answer for plain pasta
A puppy can manage plain pasta when it is fully cooked, completely plain, and served in a bite-sized quantity. Boiled spaghetti, penne, or macaroni without anything on it is not toxic to dogs, and the soft starch is fairly easy for most puppies to chew and swallow once it has cooled. The important word in the question is plain. The moment pasta arrives under a tomato sauce seasoned with garlic and onion, under a creamy cheese coating, or tossed in oily butter, it stops being the simple food you asked about and becomes something that can upset a young stomach or, in the case of garlic and onion, harm a dog. Served clean and small, pasta is best understood as an occasional novelty, not a meaningful part of what a puppy eats.
Why pasta adds so little for a growing puppy
Puppies are building muscle, bone, brain, and coat at a pace an adult dog never matches, and that construction work runs on protein, fat, calcium, and a long list of vitamins in proportions a complete puppy food is formulated to deliver. Cooked pasta is almost entirely starch and water. It provides quick energy and a feeling of fullness, which is exactly the trade-off to watch: a puppy who fills up on noodles has less room and less appetite for the food that actually supports growth. A few pieces as a training surprise or mixed through a meal is a very different picture from a bowl of pasta standing in for dinner, and only the first of those belongs in a puppy's routine.
How to serve pasta safely the first time
Cook the pasta in plain water until it is softer than you would serve it to yourself, skip any salt or oil in the water, and let it cool completely so it cannot scald an eager mouth. Cut long strands into short lengths and halve tube shapes, because a puppy who gulps can struggle with a long, slippery piece. Start with two or three small pieces and wait until the next day before offering more, watching the stool and energy for any sign the starch did not sit well. Keep the total to a garnish, not a layer, and never use pasta to coax a puppy who has refused a full day of normal food, since a sudden loss of appetite is information a vet should hear about rather than a problem noodles should cover up.
When pasta should stay off the menu
Skip pasta entirely if your puppy has already had loose stools that day, is on a vet-directed diet, or tends to gain weight quickly, because extra starch helps none of those situations. Puppies who bolt their food need the pieces cut especially small and fed one at a time from your hand rather than scattered in a bowl where gulping is rewarded. Contact your veterinarian if a pasta trial is followed by repeated vomiting, watery stool that does not settle, a swollen-looking belly, or a puppy who seems uncomfortable and will not settle, and mention exactly what was eaten and how much. Those details are hard to reconstruct from memory a day later, which is why writing them down at the time matters.
Keeping the pasta rule consistent at home
Everyone who feeds a puppy tends to remember the yes and forget the small-print, so the serving size and the no-sauce rule need to live somewhere the whole household can see. In KinsLe, Care Teams let you record pasta as an occasional, plain-only treat with its portion written beside the duty, and each feeder marks the task complete with a timestamp so a second helping never happens by accident.