Puppy feeding and growth
What age do puppy growth plates close?
Last updated 23 September 2026 · How we write and check this
Short answer
Growth plates typically close somewhere between 8 and 12 months for small breeds and can remain open until 18 to 24 months in large and giant breeds, generally closing later in the larger bones the bigger a dog's eventual adult size is expected to be.
What growth plates actually are
Growth plates are areas of developing cartilage near the ends of long bones where new bone growth happens. They gradually harden into solid bone as a dog matures, and once fully closed, that particular bone has stopped lengthening, though the dog may still fill out in other ways.
Why timing varies so much by breed size
Larger breeds have more overall bone growth to complete, so their growth plates generally stay open longer to allow for it, closing progressively later the bigger the breed's typical adult size, which lines up with the broader pattern of large and giant breeds taking longer to finish growing overall.
Why this timing matters for feeding and activity
Both nutrition, particularly avoiding excess calcium during this window, and activity level, avoiding repeated high impact stress on joints, are commonly discussed alongside growth plate closure, since bone at this developing stage is generally considered more vulnerable to injury than fully matured bone.
Key takeaways
- Growth plates close around 8 to 12 months in small breeds and 18 to 24 months in large and giant breeds.
- Larger breeds have more bone growth to complete, so their plates stay open longer.
- Once closed, that specific bone has stopped lengthening, though muscle filling can continue.
- Appropriate nutrition and moderated high impact activity are often discussed around this window.