Constructing An Emergency Slide Warmer
By Jos Mottershead
Sometimes lab equipment may not be available, so one has to become inventive. An emergency slide warmer is one such piece of equipment! Easily constructed – in a variety of ways – one can be up and running to do a basic sperm motility evaluation on warmed cooled or frozen semen in no time!
I regularly hear stories of people complaining that cooled transported or frozen semen had poor motility at the time of insemination. When asked if the semen was warmed prior to analysis, the typical reply is “no, the veterinarian only had his microscope with him, not a slide warmer”. Sometimes I even hear that the vet didn’t have a microscope with him, but carried a semen sample back to the clinic to evaluate (we’ve heard of it being transported in the ‘fridge on the truck, a shirt pocket or even on the dashboard of the truck!!). The semen is subsequently evaluated and found to be, shall we say “less than stellar” in its performance, and the blame is rapidly placed on the stallion or his manager. To say that it is likely that this blame is unfairly placed is perhaps an understatement…
If the sample is not to be evaluated at the breeding location – although hopefully it will be – it is important that it be maintained at a suitable temperature prior to undergoing analysis. Wherever the evaluation is to be performed, it is equally essential that the analysis be performed on semen in a warmed state in order to get a clear picture of the progressive motility. While many AI technicians and some general practice veterinarians do carry a microscope with them on farm calls, most don’t go to the extreme of carrying an incubator or slide warmer with them for this purpose, which is understandable. What is neither understandable, nor acceptable, is the subsequent pronouncement of “poor motility” upon evaluation without warming. More often than not, this is wrong, and simply upsets the mare owner, annoys the stallion owner and frustrates all concerned.
To avoid this eventuality, and in order to be able to provide a better service, it is desirable that a few minutes be spent constructing an emergency slide warmer. This can be very simple in design and cheap to produce. Indeed with a little ingenuity there can even be a variation in designs!
One simple and easily constructed emergency slide warmer consists of a sealed Zip-Loc® freezer bag filled with warm (body-temperature) water. Having a thermometer to ensure the unit is at body temperature is nice, but not essential. As a rough guide to obtaining the correct water temperature, place the back of your hand or forearm on the bag once filled. If it feels neither hot nor cold, then it is at approximately body temperature. Any air must be excluded from the bag to avoid insulating bubbles, and the surface of the apparatus wiped dry.
A simpler warmer that should be readily constructible by your attending veterinarian or AI technician is to take a rectal palpation (insemination) sleeve, tie a knot in the “hand” to close off the fingers, fill it with suitably warm water, and then again exclude the air and knot off the open end.
Another even simpler emergency slide warmer requires once again warm (body temperature) water, a desert bowl, and a piece of “cling film” such as is used in the kitchen. Fill the bowl with the warm water. Next take the cling film, place it over the bowl, and allow the film to sag in the center to come into contact with the surface of the water. Ensure that the cling film seals the bowl around the edges, and no water escapes onto the outer surface of the cling film – it should be carefully wiped dry prior to use to prevent any possible water contamination of the semen sample.
This is not rocket science! You now have an emergency slide warmer!!
Take the microscope slide and cover slips and place them on the top of your slide warmer. Allow them to warm for 5 minutes, and then put the drop of semen to be evaluated onto the slide. Allow it to warm a few minutes, place one of the pre-warmed cover slips over the sample, and evaluate the motility under your microscope. You will be amazed at the increase in motility over the semen sample when still cool!
Note that it is also advisable to turn on the microscope light source at the same time as commencing constructing the “slide warmer” if that equipment does not have a heated stage. This will warm up the microscope stage somewhat, assisting in preventing accidental re-cooling of the sample during analysis. Alternatively, the microscope stage can be warmed with a (warm) hand or the water-in-the-bag warmer prior to placement of the slide. Note that if the microscope does have a heated stage, then clearly that should be used to warm the slide and its contents!
These slide warmers of course are not accurate scientific instruments, but I bet if they were used more, there would be more “good motility” cooled and frozen semen shipments seen – and more happier mare and stallion owners!
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