Estimation of the intraoperative blood loss in dogs undergoing enucleation

To quantify the surgical blood loss during canine enucleation and to investigate the relationship between this and any patient, surgical, and anesthetic factors.

A prospective observational analysis was conducted on 121 client-owned dogs (130 eyes) undergoing enucleation at a referral ophthalmology clinic. Blood loss was estimated by the gravimetric method (weight difference between dry and blood-containing surgical materials) to provide absolute blood loss (ABL) in milliliters, expressed as a percentage of circulating blood volume, to establish relative blood loss (RBL).

Median ABL was 12 ml (1.6-116 ml), and median RBL was 1.3% (0.1%-6.7%). A higher RBL was associated with the following: use of a bupivacaine splash block versus retrobulbar nerve block (1.9 vs. 1%; p < .001), transpalpebral versus subconjunctival approach (2.2 vs. 1.3%; p = .003), and small versus large breed dogs (1.7% vs. 1.1%; p = .001). Both ABL and RBL differed significantly between surgeons. There was no significant difference in hemorrhage associated with the presence of ocular hypertension, systemic illness, surgical time, administration of meloxicam or choice of pre-medicant (acepromazine vs medetomidine). No dog required supportive intervention in response to surgical hemorrhage.

This study has established a surgical blood loss estimate for dogs undergoing enucleation at an ophthalmology referral centre. Subconjunctival enucleation may be preferred for patients at greater risk of haemodynamic complications.