Sample Chapter The Mouse Doctor

One of the more enjoyable tasks on a farm is mowing hay! It's a pretty routine job and depending on the year, it was possible to get three crops in a single summer. The first cutting was the best. Finally it had stopped raining and that big tangled and unkempt looking field was about to have a haircut. It would soon be neat and tidy looking and the sweat smell of new mown hay would soon be permeating the air. We had a large disc mower that allowed the work to progress quickly and didn't have a tendency to plug up the way the old sickle bar type mower of my father's day did on tangled hay.

As soon as the local coyotes heard the noise of a large farm tractor mowing they would come in their two's and three's and trot dutifully behind the mower looking for the mice that have been uncovered by the mower. Overhead, the red tail hawks would circle waiting for mice that the coyotes had missed. Some of the mice are squashed by the tires of the tractor or the mower but the majority would still remain intact and they would try to run and hide as best they could in the clumps of mown hay. Some years we would run over a family of pheasants and there would be a free for all of commotion behind the mower, the red tails feeding dangerously close to the coyotes.

When Michael, our oldest son was ten years old, he ran behind the non human predators with a pair of over sized gloves and managed, after a while to collect an unwounded mouse. He brought it home for a pet. This mouse was a Townsend vole, a very common field mouse in our area. He wanted me to examine it because he said, "it had something wrong with it!" By this time he had it in a small bucket.

Indeed it had a huge lump on its side. When I examined it closely, I thought the lump moved. Initially, I thought it was some type of a tumour. But this thing seemed to move! That lump couldn't have moved, tumours don't move. So Mike and I watched very closely fascinated now by this lump and then it moved again and we both saw it so it wasn't just my imagination.

Of course Mike wanted me to fix it as this was now his pet and I suppose he had already bonded to it. How do you operate on a mouse and how much freezing do you use? I thought if you made a quick cut with a very sharp knife right over the tumour the mouse would only feel the pain for an instance and we could see what the problem was.

Accordingly, Mike held the mouse firmly in his glove and I made the incision. With the help of needle nose pliers, (I could have used forceps but they were over in the barn at the other end of the farm and needle nose pliers work pretty much the same way), I removed three lumps of tissue each about ¾ of an inch long and about 1/3 of an inch in diameter. When we got them out, sure enough, each of them showed a very small amount of movement. When we opened these masses up there was a fly larva inside! We estimated that the weight of these three lumps in this single mouse would represent about 40% of the entire weight of the mouse.

These things are Bot fly larva or warble fly larva and were very common in cattle during that time. With the advent of "Spot On" and other drugs the problem in cattle has been pretty much eliminated. However, it remains common in some wild animals and Canadian Caribou have them. The Inuit children like them and if an animal has these Bots they pop them into their mouths and I am told that they have somewhat of a peppermint flavour.

The Bot fly larva if left undisturbed will eventually erode through the skin leaving a scar on the hide and will fall to the ground. There it matures and a fully formed fly will emerge, dry its wings off and then fly off and find a mate and then it lands usually on the heels of a cow, drills a small hole in the animal and deposits a number of eggs that will turn into a minute larva that will eventually end up along the spine of the animal, form a cocoon, and mature in it. It will then erode through the skin and fall to the ground to begin the cycle all over again the following year.

Michael's pet survived his surgery and lived for two years. It eventually became very tame and we could handle it without fear of being bitten. In the wild, the usual life span of these creatures is about a year and a half. In captivity they can live longer. We have no idea how old he was when captured but he was likely a young mouse considering how long he lived afterwards. To put parasites this big in a small mouse might suggest that Mother Nature can be very cruel but we already knew this didn't we?