improving rat euthanasia

a while ago, we compared intraperitoneal pentobarbital as a euthanasia technique with carbon dioxide overdose in rats. we expected, naively, that this would serve as an appropriate gold standard but were disappointed to find considerable variety in its effects, including a fairly high misinjection rate. the misinjection rate has been documented before, in rats and mice e.g. Corey-Avila et al. 2007 Lab Anim 36:25-30.

we wondered if the variability in effect could be improved, if not the misinjection rate. so we compared a fairly standard dose of pentobarbital with a high dose and a larger volume of the standard dose. time to loss of consciousness was shorter with both high dose and high volume approaches and similar with each technique; however, the time to death was substantially faster in the high dose group (5 times faster than the standard dose and 3 times faster than the high volume group). thus, the higher dose shortens the time to death, limiting any period of suffering that might exist. additionally, because of the reduced variability, we were able to suggest guidelines for when a misinjection has occurred i.e. if loss of consciousness does not occur within 2.5 minutes of injection. these findings should improve both the speed and predictability of euthanasia in rats when using an intraperitoneal pentobarbital injection technique.

this project was the work of katie zatroch, who is now an anesthesiology resident. the resultant paper has been published in BMC Vet Research (DOI: 10.1186/s12917-017-0982-y).

2017-03-19 08.48.40 pm

paper early on line

Just had a notification that one of our papers is now available early on-line (pre-formatted version). There was a delay is this coming out as our specialty journal, veterinary anaesthesia and analgesia has recently migrated publishers, from Wiley to Elsevier. I have very mixed feelings about the change of publisher (our paper was submitted months before the change came in to effect) as Elsevier has received considerable criticism for its business model, where libraries have limited ability to subscribe to single journals titles but rather, must subscribe to large (expensive) packages of titles that include the title they are interested in. This is better and more completely explained here, here and here. I am not (yet) a signatory on The Cost of Knowledge Website as Vet Anaesth Analg remains the most efficient way to reach our target audience for most of our clinical research papers. This is a difficult position: support colleagues in other fields, notably mathematics, who are more directly affected by these business practices by publishing elsewhere and risk missing our target audience (or at least slowing the time for our papers to be “found”), or continue as usual to ensure the visibility of our research? I have little doubt that our recent move to publishing more frequently in open access journals has had a negative effect on who sees our work. I have tried to offset this by sending links to papers to colleagues who I think might be interested, though this form of self-promotion feels a little odd.

Of course, Elsevier is not alone in its practices. It just happened to be the first publisher to face a large scale, organized response from scientists.

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Back to the paper…we used a very nice demeanor (behaviour) assessment scale, published by Gareth Zeiler, to show that demeanor can interfere with pain assessment. Essentially, cats that are timid or aggressive tend to have inflated pain scores. This is not a justification to not administer analgesia (pain relief) but another indication that, sadly, pain assessment is more complicated than we’d like to believe.

congratulations Jesse!

many congratulations to Jesse on winning a poster presentation prize at the University of Calgary’s Undergraduate Research Symposium.

Veterinary students often struggle with selecting the appropriate endotracheal tube size for different sizes of dogs. Placing an endotracheal tube (breathing tube) in the trachea is a key skill as part of anaesthetic management as it facilitates breathing and protects the airway (and lungs) from accidentally inhaling foreign material. However, there are few guidelines available on how to select the correct tube size; large variations in body weight and race (think chihuahua, great dane and pug!) mean that this skill is largely gained through experience.

Jesse took a lot of anatomical measurements and tried to find if there were any that could be used to predict the correct endotracheal tube size. Though none were ideal, he did identify a  couple of options that serve as a good starting point, helping students to get within a few millimetres of the right size.

paper progressing through review

just received the notification that a paper, submitted to the journal of feline medicine and surgery, has come back from the reviewers with minor comments.

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always good to have positive reviews with constructive criticism; all the better for the swift turnaround, with a time from submission of only 17 days. this is a first paper for marika & tatum, and marika is on a roll with a second paper in review.

textbook citation

spotted by michelle in a the latest edition (2015) of lumb & jones, THE veterinary anaesthesia reference text. this references our work (#200) showing a small increase in intraocular pressure (approx 5 mmHg) following induction of general anaesthesia with the neurosteroid alfaxalone. Whether such a small increase is relevant is debatable, as it remained within the normal range of intraocular pressure for dogs with healthy eyes. However, this change could have adverse consequences where the intraocular pressure is already raised or where minimal changes in pressure are tolerated. this paper was mentioned in the very first post on this page, here.

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