RESEARCH COMMUNICATIONS OF THE 28th ECVIM-CA CONGRESS

Pituitary radiotherapy (RT) is a treatment for macroadenoma induced neurological complications. A previous study reported concurrent pituitary dependent hyperadrenocorticism (PDH) did not affect outcome for dogs undergoing RT. However, as PDH is associated with multiple comorbidities, authors hypothesised dogs with PDH would have poorer survival than those without PDH. This retrospective study recruited dogs who underwent pituitary RT at a single centre between 01/01/2008 and 01/01/2018. Signalment, time to RT post‐diagnosis, tumour characteristics, RT protocol and PDH status were recorded. Thirty‐one dogs were enrolled: 16 males and 15 females. Median age was 9 years (IQR 4.7) and 14 dogs had PDH; twenty‐six underwent definitive RT. Median tumour size was 2.60 cm3 (S.D. 1.47) and median radiation dose was 48 Gy (IQR 4). Follow‐up intra‐cranial imaging was available for four dogs; all experienced tumour volume reduction (38,45,72 and 78%). Median survival times of patients with and without PDH were 750 (IQR 915) and 709 (IQR 761) days, respectively (Kaplan‐Meier log‐rank P=0.386). Variables with P<0.2 on univariate Cox regression analysis (gender and age at diagnosis) were included in multivariate analysis to assess patient characteristics associated with survival. Only gender remained significant (male HR 2.722, 95% CI 1.089‐6.804, P=0.032). Male and female survival times were 360 and 957 days, respectively (Kaplan‐Meier log‐rank P=0.074).