SCINTIGRAPHY is not so much about seeing structure, it’s more about how well something is working. Vets inject radioactive substances and then use a camera (linked to a computer) to track the movement of said substance around the body. A series of images is collected that tell us whether body tissue is functioning normally or not. For bone scanning of horses, we use a radioactively labelled bone-seeking agent. We want to know:

  • Is that bone chip we see on x-ray ‘silent’ or does it ‘light up’ on the screen?
  • If nerve blocks localised pain to a particular part, what structure(s) in the region showed up ‘red hot’?
  • Is the blood supply to a region okay or abnormally ‘cold’ on the screen?

    • Along with ultrasound, scintigraphy has proved particularly valuable in detecting cracks (fissure fractures) in inaccessible places like the pelvis. In the early 90s, it was wonderful to see a steady fall in the number of young thoroughbreds fracturing on the gallops at Newmarket: scintigraphy units there and at Cambridge Vet School allowed vets to detect bone disease in youngsters, early; and trainers to back off on their training regime before a catastrophe inevitably occurred.

    X-ray, CT and scintigraphy involve the use of radiation and thus comes the need for care. Care for the health and welfare of both horses and humans, exposing neither to unnecessary radiation hazard. A collective effort is needed by all to:

  • use these techniques wisely
  • employ lead shields, gowns and gloves
  • rotate personnel
  • keep exposure times to a minimum
  • be particularly vigilant around young and pregnant persons
  • monitor the radiation being received

    • I expect that in future, vets will even more have to justify the use of radiation to screen for disease in young horses not showing clinical disease - in equines expected to be ‘normal’. Indeed FEEVA (Federation of European Equine Veterinary Associations) has been working on a joint statement with the relevant radiation protection authorities. The three principles at the core are:

    1. Consider if the benefits (of taking x-rays) exceed the risk?

    2. When taking x-rays, minimise unnecessary exposure – to human and horse.

    3. Monitor and remain below the radiation limits allowed for people.

    And finally, MRI: Cambridge Vet School in the early 90s were pioneers in developing this technique for equines, mapping the magnetic resonance imaging (MRI) appearance of their limbs. Excuse the lack of sensitivities here; but the parts came from ponies, procured post-mortem – we were working with a physicist whose lab (a chaos of cages, cables and computers) couldn’t accommodate a live horse!

    The early images we collected of normal structures were stunning; others have since gone on to build a proper library illustrating disease conditions. Nowadays this exciting technology, as with CT, allows vets to construct 3-D images of live horse parts, viewing tissue damage in exquisite detail and tracking the progress of tissue repair.

    Diagnostic imaging permits us to see structure and link this to function; it enables us to understand equine disease better; and then help horses to heal – which is what it’s all about when all is said and done.