Veterinarians divide a dog's expected life span into six life stages based on developmental milestones. These age ranges are for a medium-sized dog; smaller dogs tend to live longer, while larger dogs tend to have shorter life expectancies.
Stage | Age (years) | Characteristics |
|---|---|---|
| Puppy | 0 - 0.5 | Birth to sexual maturity |
| Junior | 0.5 - 0.75 | Reproductively mature, still growing |
| Adult | 0.75 - 6.5 | Finished growing, sexually and structurally mature |
| Mature | 6.5 - 9.75 | From middle to last 25% of expected lifespan |
| Senior | 9.75 -13 | Last 25% of life expectancy |
| Geriatric | over 13 | Beyond life span expectation |
