Giving CT scans the 'seal' of approval

Have you ever seen a seal at a vet’s office? No, us neither. But, seals, like many animals, do sometimes need medical attention. At A-Seal, a rescue centre in Stellendam, the Netherlands, the care and rehabilitation of sick or injured seals is, sadly, commonplace. The organisation rescues the animals from the Dutch coastline, many of which are pups that have been separated from their mothers. They are then nursed back to health by an expert team before being released back into the wild, where they belong.

Veterinarians, however, face a number of challenges when examining wild seals. As you might imagine, they are usually not the most cooperative patients! But there are other issues which make examination difficult. Not only do they have a thick and stocky build, but a layer of blubber often makes the evaluation of the spine, limbs or joints tricky. And diagnosing ear problems can be impeded by their very narrow auditory canal. Sometimes, rehabilitation centres use X-rays to investigate bones and organs, such as the lungs, but for some seals a CT scan is a quick and non-invasive means of obtaining more detailed information.

Preparing seals for CT

Take, for example, the cases of Vincent and Elvis. These fantastically named seals were rescued and, on closer examination, presented two very different problems. So, veterinarians Dr Machteld Geut, Dr Gert ter Haar and Dr Susanne A.E.B. Boroffka concluded that using their Canon Medical CT Scanner was the way forward for their particular evaluations. This, of course, would require Vincent and Elvis to be anaesthetised for the duration, but this in itself is not without complexity. Seals have a remarkable physiological adaptation called ‘dive response’, which is how they survive long and deep dives. It also helps their bodies to conserve oxygen, regulate blood flow and tolerate the extreme pressures of the deep sea by slowing down their heart rate, constricting their blood vessels and reducing their lung volume. However, under anaesthetic or during treatment, their already low oxygen levels can lead to hypoxemia – decreased oxygen in the blood – or even cardiac arrest.

Marine mammal veterinarian, Geraldine Lacave, developed a special kind of anaesthesia for these circumstances, which was used on both Vincent and Elvis for their examination. They were then intubated and connected to a mechanical ventilator before being taken to the CT room and laid prone on the CT table for scanning. Both seals were scanned three times, with a contrast agent used during the second scan, which gives the veterinarians a clearer image of the seal’s bodies.

A nasty ear infection

Of course, seals don’t have ears like ours – just a small opening that closes underwater – but Vincent’s ‘ear’ was producing chronic discharge. So, it was important to examine every aspect of his auditory canal, middle and inner ear. A comprehensive CT scan confirmed that he was indeed suffering from an ear infection, but several rounds of treatment didn’t solve the problem. The vets discussed the next course of action, and it was decided that he would require surgery. Thankfully, Vincent recovered well and was returned to A-Seal, where he was kept on dry land for a few days before being released into a pool of salt water.

Seeking out the source

Elvis was moving unusually, which gave rise to the suspicion that he might be experiencing pelvic pain. In this instance, it was important to rule out any fractures or dislocations, perhaps in the spine or pelvis. However, after anaesthesia and CT scanning, no signs of fracture or dislocations could be seen, which helped the veterinarians to rule out certain conditions in the pursuit of a diagnosis.