Puncture wounds at the coronary band or in the sole are not uncommon in horses. Although the site of the injury may be obvious, it is often less clear whether any foreign material remains buried in the wound.
Researchers with the Philip Leverhulme Equine Hospital at the University of Liverpool conducted a study to compare the value of different imaging techniques for identifying foreign bodies in horses’ feet.
Nadine Ogden and colleagues assessed the ability of three equine veterinarians, experienced in advanced imaging interpretation, to identify foreign bodies buried in the cadaver specimens of horses’ feet. They used five different materials: slate, glass, dry wood, soaked wood and plastic. Each foot had two different foreign bodies implanted, at the coronary band and in the sole.
Computed tomography (CT), magnetic resonance imaging (MRI) and digital radiography (DR) were used to obtain images, which were then examined by the clinicians.
Digital radiography (DR) uses x-ray sensitive plates to capture data during object examination, which is immediately transferred to a computer without the use of an intermediate cassette.
“Computed tomography” (CT) uses a narrow beam of x-rays quickly rotated around the body, producing signals that generate cross-sectional images.
Magnetic resonance imaging (MRI) scanners use strong magnetic fields, magnetic field gradients, and radio waves to generate images.
The researchers found little variation between the clinicians studying the images. CT was the most useful imaging modality, having a higher visibility score, sensitivity/specificity, and interrater agreement for detection of all materials; particularly slate, glass, and dry wood, compared to the other imaging modalities.
They found that foreign bodies were often visible on MRI, although the images were generally not clear enough to determine the type of material involved. They also found that even relatively large foreign bodies consisting of plastic or wood were not detectable on DR.
The authors of the study, published in Veterinary Radiology and Ultrasound, said that although it is not usually necessary to identify the specific material involved, it is important to select an appropriate imaging technique to detect the suspected foreign body.
They suggest that in cases with negative findings on MRI and DR, where there is a suspected foreign body within the hoof, particularly in cases where plastic or wood fencing or glass materials have been found at the scene of the injury, CT examination should be considered.
CT more accurately detects foreign bodies within the equine foot than MRI or digital radiography. Nadine K E Ogden, Peter I Milner, John D Stack, Alison M Talbot. Vet Radiol Ultrasound (2020). doi: 10.1111/vru.12944