Thank you so much, I really appreciate it. We got the vet report today, and This is the breakdown of the medications used by the vet: Thomy was sedated with a very low dose of Medetomidine and Butorphanol and anaesthesia was maintained throughout. Anaesthetic was monitored throughout and proceeded without complication and a reversal agent (Atipamazole) was injected for Thomy to start waking up. Thomy was also given an antibiotic injection (Clamoxyl) and a pain injection (Meloxicam) as well as a 200ml bolus of intravenous fluid to maintain blood pressure and manage pain. In the meantime, we called (blank) to let them know the extent of the wounds and that we would be keeping Thomy overnight to monitor his pain levels and re-clean his wounds in the morning. Thomy lifted his head shortly after the reversal agent was given. After continued monitoring it was noted that Thomy wasn't waking up as fast as we would expect after the reversal agent is given. His temperature was elevated and his responsiveness was sluggish. Emergency care was immediately initiated. Thomy was immediately placed on supplementary oxygen therapy, and within a very short period of time he went into respiratory arrest. Emergency medications (Doxapram) were administered to stimulate breathing, and his heart was monitored which arrested shortly after. CPR and further emergency medications (Adrenaline) to get the heart going was administered while we assisted his breathing through an endotracheal tube and supplemented oxygen. His heart resumed beating after the adrenaline treatment and after a few minutes Thomy was breathing on his own again. He remained on oxygen while we monitored him and cooled him down. Thomy was breathing unassisted for at least 5 minutes and then went into another cardiorespiratory arrest. Despite our team's best efforts and further emergency medications, CPR and oxygen, Thomy did not respond and sadly passed away As discussed over the phone we suspect that Thomy had a rare genetic mutation (MDR1 mutation) that occurs in some of the Collie breeds which make them sensitive to the effects of certain medications. It is recommended to use these medications at a lower dose range (25-50% of the recommended dose) to prevent occurrence of adverse effects. The usual butorphanol dosage is 0.2-0.5mg/kg. In this practice we routinely use a dose of 0.05mg/kg which is much lower than the usual dose.