Pergolide dosing compliance and factors affecting the laboratory control of equine pituitary pars intermedia dysfunction.

BACKGROUND Equine pituitary pars intermedia dysfunction (PPID) is treated with daily pergolide therapy. Owner compliance and its effect on PPID control have not been previously investigated. METHODS Clinical records were searched to identify the sample of animals with PPID treated with pergolide from 2016 to 2019. The signalment was noted and the dose of pergolide received calculated. Animals were classified as compliant (receiving ≥90% of the veterinarian recommended dose of pergolide) or non-compliant, and as controlled (follow-up basal adrenocorticotrophic hormone concentrations within the reference range) or not. RESULTS In total, 110 animals were included. The majority (85%) were ≥16 years (mean ± SD 19.8 ± 4.4 years); the most common breeds were Cob (18%), Thoroughbred (16%) and Welsh (15%); 37% were female and 63% male. Overall, 48% were compliant and 52% non-compliant. There was no significant effect of compliance on laboratory control. Of those that were compliant, 74% were controlled, while 67% of non-compliant animals were controlled. Univariable analysis revealed a significant (p < 0.001) effect of age and breed on compliance and control, and of sex on control. On multivariable analysis, only age (compliance) and breed (compliance and control) were retained in the final model. CONCLUSION Only half of animals received the recommended pergolide dose; however, this did not affect laboratory control of PPID.