Background <p>Recent advances in preventive veterinary healthcare, nutritional management, and owner engagement have extended the longevity of domestic dogs. However, this increased lifespan has led to a higher prevalence of age-associated physiological and functional decline. Equine placental extract contains a variety of bioactive constituents, with reported antioxidative and anti-inflammatory properties. Although the use of equine placental extract in veterinary practice is expanding, empirical evidence supporting its effects on ageing-related clinical outcomes in dogs remains limited. In this study, we aimed to evaluate the effects of 28 days of oral equine placental extract supplementation on ageing status, vitality, appetite, and safety in geriatric dogs using a single-group pre–post design. Accordingly, 20 client-owned geriatric dogs aged &gt; 11 years received daily oral equine placental extract supplementation; and longitudinal changes in clinical ageing scores, owner-assessed vitality and appetite, haematological and biochemical parameters, and safety outcomes were evaluated.</p> Results <p>Daily equine placental extract supplementation significantly reduced ageing-level assessment scores, with the median (interquartile range) values decreasing from 24.0 (15.0–29.0) at Day 0 to 21.5 (12.0–23.0) at Day 14 and 18.0 (10.5–21.5) at Day 28. Vitality and appetite, assessed using a 10-point visual analogue scale, increased from 5.0 ± 1.2 to 6.7 ± 1.5 and 7.5 ± 2.0, and from 5.3 ± 1.5 to 7.1 ± 1.3 and 8.4 ± 1.7, respectively, across the same timepoints. No significant changes were observed in body weight, rectal temperature, or haematological and biochemical parameters. Two adverse events occurred—one episode of haematuria occurring prior to the intervention and one fatality suspected to be attributable to rodenticide ingestion. Neither was considered related to the intervention. Exploratory physical activity monitoring was conducted; however, no statistical analysis was performed due to the small sample size.</p> Conclusions <p>Oral equine placental extract supplementation for 28 days was associated with improvements in ageing-related clinical scores, vitality, and appetite in geriatric dogs. These findings should be interpreted as preliminary and hypothesis-generating, and do not establish efficacy. Equine placental extract may have potential as a supportive intervention for age-associated decline; however, further controlled studies are required. Adequately powered, controlled trials are required to confirm its efficacy and clarify underlying mechanisms.</p>