Pain scoring systems in hospitalized horses with ocular disease

Pain recognition in hospitalized horses is challenging, and the utility of pain scoring systems in horses with ocular disease has not been well-described.

Evaluate the horse grimace scale (HGS) and behavior pain score (BPS) in hospitalized horses with ocular disease. We hypothesized that HGS and BPS would be associated with different clinical progressions.

Privately owned horses hospitalized for ocular disease between September 2018 and September 2020.

Retrospective observational study. The HGS and BPS were recorded daily throughout hospitalization. Clinical progressions were categorized as: (a) discharge from hospital after medical treatment, (b) ophthalmic surgery (eg, keratectomy, conjunctival flap, amniotic membrane transplantation, corneal transplant), or (c) enucleation. Temporal trends in HGS and BPS were assessed using linear regression. Correlations among slope, intercept, and progression were determined using the Kruskal-Wallis test.

Of 65 horses that met inclusion criteria, 29 (45%) were discharged after exclusively medical management, 28 (43%) underwent ophthalmic surgery, and 8 (12%) underwent enucleation. Two horses (3%) had 2 ophthalmic surgeries performed. The BPS scores at admission were higher in horses that were managed medically than in those that underwent enucleation (P = .01). Horses requiring enucleation had higher increases in HGS (P = .02) and BPS (P = .01) during hospitalization than horses that were medically managed and a higher increase in BPS (P = .04) than horses that required ophthalmic surgery.

Pain scoring may represent a useful tool for monitoring progression and response to treatment in hospitalized horses with ocular disease.