Peri-anaesthetic mortality and nonfatal gastrointestinal complications in pet rabbits a retrospective study on 210 cases
Lee HW, Machin H, Adami C, Veterinary Anaesthesia and Analgesia (2018), https://doi.org/10.1016/j.vaa....
What did the research find?
The aim of this study was to determine the incidence and the associated risk factors of peri-anaesthetic mortality and gastrointestinal complications in pet rabbits.
The study found:
- Mortality rate of 4.8% (9 out of 185 cases).
- 6 rabbits died during sedation or general anaesthesia (intraoperative deaths).
- 4 (one of which euthanized) rabbits died during the first 72 postoperative hours.
- Of those whose outcome was not intraoperative death, 38% developed peri-anaesthetic gastrointestinal complications.
- Species-specific risk factors could not be identified, however, the odds for post-anaesthetic gastrointestinal complications increased significantly with body weight.
How was it conducted?
185 pet rabbits admitted to the Exotic Referral Service of Beaumont Sainsbury’s Animal Hospital over the period 2009-2016 where included in this retrospective cohort study. 25 underwent two anaesthetic events; therefore, data from 210 cases was used.
Three possible outcomes were considered to evaluate the incidence of peri-anaesthetic mortality: alive, dead or euthanized within the 72 hours following the anaesthetic event.
Food intake and stool production during the first 72 hours following the anaesthetic event were evaluated to investigate the occurrence of gastrointestinal complications. Risk factors such as administration of alpha-2 agonists, body weight, ASA classification and endotracheal intubation were tested against peri-anaesthetic mortality and gastrointestinal complications.
Why is it important?
Rabbits are becoming an increasingly popular pet in the UK which means there is greater demand for rabbit anaesthesia. Rabbits carry a greater risk of anaesthesia-related death and gastrointestinal complications than other domestic species. Some of the factors thought to contribute towards peri-anaesthetic complications are:
- the anatomy of the oropharynx and the common development of laryngeal spasm make intubation difficult,
- underestimation of anaesthetic risk as being prey animals means they don´t tend to show signs of disease,
- the use of certain drug classes, such as the alpha-2 agonists (Grint & Murison 2008).
Although the use of historical records posed some limitations in this trial, this study identifies several important findings of specific clinical relevance for the general practitioner involved in rabbit anaesthesia:
- Although it is thought that the relatively small body size and the predisposition to develop laryngeal spasm could represent a risk factor for pet rabbits, this study found that endotracheal intubation is safe if performed carefully and by experienced personnel.
- The study failed to confirm if alpha-2 agonists contribute towards peri-anaesthetic complications, but it is worth pointing out that 70% of the rabbits that died had an alpha-2 agonist as part of the anaesthetic protocol. It is, however, worth considering that besides alpha-2 agonists, the combination of medetomidine and ketamine, or possibly even ketamine alone, might have contributed to the negative outcome of these subjects.
- Rabbits undergoing abdominal surgeries did not have a higher risk of developing post-anaesthetic gastrointestinal complications. Interestingly, 14.5% of the rabbits that did experience gastrointestinal complications had undergone two anaesthetic events, and in 80% of them gastrointestinal impairment was detected both times.
- The incidence of nonfatal peri-anaesthetic gastrointestinal complications was also very high in the study population despite the use of metoclopramide or ranitidine.
Undertaking preventive measures such as using opioids consciously, encouraging eating soon after recovery and syringe feeding in cases of inappetence, especially when dealing with overweight rabbits, is recommended by the authors.
Link to the full article:
Originally published: Thursday, 14th June 2018
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