The seeds are safe — preparation decides
When a squash gets carved or roasted, the scoop of seeds in the middle usually heads for the trash, but it does not have to. Squash seeds — pumpkin seeds most famously, and those from butternut, acorn, and similar winter squashes — are not toxic to dogs, and they carry genuinely useful nutrition: healthy fats, protein, fiber, zinc, and magnesium in a tiny package. The gap between a good snack and a careless one is preparation. A seed served the way it comes out of the squash, or roasted the way it comes out of a snack bag, is a different proposition from one cleaned, cooked plainly, and portioned for a dog.
Raw from the squash versus roasted plain
Seeds scooped fresh from a raw squash are not poisonous, but they are the least desirable form: fibrous hulls that pass through a dog largely undigested, moisture that invites mold if the seeds sit around, and whatever was on the squash's skin riding along. Roasting fixes all of that. Rinse the seeds clean of pulp, spread them on a tray, and roast them plain until dry and crisp — no oil needed, and absolutely no salt, garlic powder, chili, or the sweet coatings that flavor snack seeds for people. Store-bought pumpkin seeds sold as human snacks are usually salted heavily and sometimes seasoned, so the bag in the pantry is not automatically dog-safe just because the seed itself is. Homemade and plain is the standard.
Whole, chopped, or ground
How the seed is served changes how much good it does. A whole roasted seed often travels through a dog intact, hull and all, delivering its nutrition to the yard instead of the dog. Grinding roasted seeds into a coarse meal, or chopping them finely, opens the seed up so the fats and minerals are actually absorbed — a sprinkle of ground seed over regular food is the most useful serving style. There is also a choking footnote: whole seeds are small, but a small dog inhaling a mouthful of them dry can cough and gag, and mixing ground seed into food sidesteps that entirely. The hulls of larger, older squash seeds can be tough; seeds from younger squash are thinner-shelled and kinder.
Portions: rich food in a small package
Seeds are calorie-dense for their size because of their fat, so portions stay small: a pinch of ground seed for a small dog, up to a spoonful for a large one, a few times a week rather than a daily mountain. Too much, especially introduced suddenly, announces itself as soft stool or a gurgly stomach — the fat again, not any toxicity. That same richness is why dogs on low-fat diets, dogs with pancreatitis histories, and dogs working on weight loss should meet squash seeds only within their vet's feeding plan. Introduce them like any new food: a little, a day of watching the stool, then the regular small portion if all is calm.
When seeds need a vet's attention
Call your veterinarian if seed eating is followed by vomiting, diarrhea that persists past a day, or signs of belly pain, and mention if the seeds were salted snack-bag seeds, since heavy salt adds its own concern, particularly for small dogs. A dog who ate seeds from a moldy, long-kept squash or pumpkin deserves a call as well — mold, not the seed, is the worry there. As a routine matter, jotting 'squash seeds: roasted plain, ground, small sprinkle only' into your dog's extras in KinsLe through Care Teams carries the preparation rule to anyone else who cooks for him, so carving-night enthusiasm does not turn the whole seed tray into his serving.