Adventures of a veterinary pathologist
This blog was written by SEA partner Dr Andrew Brownlow, veterinary pathologist with the Scottish Marine Animal Stranding Scheme (SMASS).
A wee tale about how, sometimes, it’s good to have a strong rope on a tail.
It’s often the case when, turning up on a beach with your post-mortem kit, a bizarre combination of laboratory-grade plastic, kitchenware and DIY tools accompanying a reassuringly solid bucket of very sharp knives, that you have no idea what you will find over the subsequent few hours of work. That’s what keeps this job interesting of course, and makes up for the occupational hazard of having your plans for an evening randomly supplanted by a mad dash for a ferry to a remote island. In this particular case the destination was the West coast of Lewis, a dramatic, beautiful place with an admirable tenacity for resisting both the winds of an Atlantic storm and those of cultural change. We had learnt of this case the previous day, a recently deceased Sowerby’s beaked whale, and, knowing the importance of this species and the capacity for our post-mortems to give us much needed information about the health and ecology of marine mammals, decided we needed to examine the animal. In many cases we are able to collect the carcase and take them to our facility in Inverness, however in this case the animal in question was over 4m long and stranded on a remote rocky beach with little option for recovery. A beach-post-mortem it would have to be.
A post-mortem, or necropsy examination can allow us to understand not just how an animal died, but also much about how it lived; what it ate, how old it was, if it had reproduced and what diseases, infections and threats it may have encountered. It also allows us to take samples for subsequent analysis that can tell us about the health of the wider ocean environment, such as the presence of toxins or pollutants and the possible effects they are having on the ecosystem. As mentioned, you never quite know what you’re going to find, however we do usually have a case to work on. It was with some dismay therefore that we discovered, having scrambled to the top of the wave-thrown shingle on Brue beach, that despite being firmly anchored by the tail the previous evening, the Atlantic swell had reclaimed the carcase and now our patient was nowhere to be seen. This was particularly frustrating, given the efforts Janet, one of our volunteers had gone to locate and secure the animal.
There followed a few hours of fruitless searching, scanning between surfers and seals enjoying the white-topped breakers for any evidence of a fin or fluke. I had all but given up and was returning to the car in a foul mood when Siobhan’s keen eyes, honed by years of spotting live cetaceans as a marine mammal observer- glimpsed the shadow of a fluke silhouetted against the blue-green curl of an incoming wave. We had found it. It was about 50m out in shallow water and heading the wrong way on the ebbing tide. Now in the battle against middle-aged spread, I had recently taken to open water swimming, and hence had just enough neoprene and stupidity with me to make wading out for this seem not a wholly ludicrous idea. As I stumbled my way out into waist deep surf, my feet slipping on the bowling-ball sized boulders of Lewisian gneiss- some of the oldest and most durable rock on the planet polished glass-smooth by the sea – I began to question how much of a good idea this was. The wellies were protecting my feet but not my balance and I had lost sight of the animal. Then, turning to avoid a breaking wave I literally tripped over it, just below the surface with the rope still attached to the tailstock. With the help of the surf, the carcase was reasonably easy enough to tow back into the shallows.
Figure 1: This is as far as we could tow it ashore
After all that, the actual post-mortem was a comparative piece of cake, and between us Mariel and I collected the measurement tissues and samples we sought. It wasn’t in great condition, hadn’t fed recently but, apart from the damage brought about by stranding, there wasn’t much in the body of the animal to indicate why it stranded. By this time however, the tide was on the turn and there was a ferry to catch, so, like some Victorian trophy hunter, I removed the head, balanced it on my shoulder and headed back to shore, to Stornoway and home.
Figure 2: It didn’t stay here once the tide came in.
The following day, in the wind and surf free environment of our laboratory in Inverness, we were able to examine the brain and found the reason for the stranding. In the middle of the brain sit the cerebral ventricles, normally small, spiralling reservoirs filled with the clear cerebrospinal fluid which nourishes and protects the central nervous system cord and balances the exquisitely complicated chemistry of a mammalian brain. When we sectioned through the skull and into the brain of this whale, it all looked very wrong indeed. Hugely dilated, the ventricles poured an alarming excess of murky, turbid and blood stained fluid. In addition, the meninges, usually translucent, delicate membranes surrounding the brain were rough and inflamed.
Figure 3 the thickened meninges of the brain
This animal had been very sick indeed with an apparent meningoencephalitis; a severe brain disease most likely due to infection with a virulent bacteria. This would likely have affected the whale’s ability to feed and navigate and was almost certainly a causal factor in its stranding. We’ve seen this before in this species, and it is possible that there was some underlying condition which made this animal susceptible to the infection. We are continuing to investigating this case as there is still much to learn, but it was certainly worth all that effort. Next time we get a stranding in those seas however, we’ll use a stronger piece of rope!