Evaluation of the role of clinical and histological variables on the predictability of rectal ectasia resolution and recurrence after surgical correction of perineal hernia in dogs

Perineal hernia (PH) is a common disease in intact male dogs amenable of surgical treatment1. Recurrence is associated to persistence of tenesmus and previous hernia repair2. Persisting Rectal ectasia (RE) represents a frequent complication of surgical reduction and may maintain persisting tenesmus. Aims of this study have been: to compare the histological features of the rectal wall in patients affected by PH with those from healthy dogs; to explore the possible correlation of RE and histological features with post-surgical RE persistence and PH recurrence. A total of 15 male dogs with right or bilateral naïve PH were enrolled over a 2-years period (P group). RE was scored according to Brissot3 (+1, +2, +3) at the first consultation (T0), immediately after surgery (T1) and after 60 days (T2). All patients underwent surgical repair by internal obturator muscle transposition. Full thickness rectal biopsy was performed through the surgical access for PH repair at the site of maximum RE. The outcome was defined as “positive” when were recorded: complete resolution of clinical signs (tenesmus, dysuria) and RE; no signs of PH recurrence. Ten fresh canine cadavers, free from gastrointestinal pathologies and abnormalities at rectal exam, underwent a full thickness rectal biopsy (C group). Histological features reported as scores were: inflammation, fibrosis, elastic fiber appearance and orientation, number of ganglions and positivity to immunoperoxidase. The two groups (P vs. C) were compared for histological scores with the median test. RE and histopathological variables were tested for predictability on outcome and recurrence with nominal logistic regression. Significance was set at p<0.05. The two groups were homogenous for age and bodyweight; they differed in inflammation (p=0.01) and fibrosis (p=0.04) scores. RE scores were: +2 in 3 and +3 in 12 at T0; +1 in 4, +2 in 8 and +3 in 3 at T1; +1 in 3, +2 in 7 and +3 in 5 at T2. Seven dogs had a negative outcome and 3 had recurrence within 12 months. +3 RE at T1 (p=0.008) and T2 (p=0.002) was predictive of negative outcome. Degree of fibrosis (p=0.048) and +3 RE at T1 (p=0.0005) and T2 (p=0.02) were predictive of PH recurrence. In conclusion, the present study corroborates the use of full thickness rectal biopsy results to help the clinician in communicating with the owner on the probability of recurrence or uncomplete resolution of clinical signs, based on clinical and histological features of the rectal wall.