Page 217 - The Veterinary Care of the Horse

Clinical signs and diagnosis

If the foreign body is still in place then the diagnosis is straightforward. In other cases, it can
VetBooks.ir be difficult to establish the extent of the injury without further investigations. There may be

no obvious signs shortly after the accident occurs. Penetrations of the frog are particularly
difficult to locate as the elastic nature of the horn means that the puncture hole seals leaving
very little trace of the injury. Sometimes increased warmth of the foot and an obvious digital

pulse are detected. Lameness is variable to start with but quickly becomes severe if vital
structures are damaged and become infected. The degree of lower limb swelling is variable

depending on which structures are damaged.

As with superficial penetrations, the site of entry may be found with the aid of hoof
testers and scraping away the superficial layers of horn.

RADIOGRAPHIC EXAMINATION

Special radiographic techniques are often used to help with the diagnosis. Once the entry
hole has been found, a sterile metal probe (Figures 6.18 and 6.19) or a fluid which shows up

on the X-rays (contrast medium) may be introduced into the hole before the X-rays are taken.
These assist the vet in determining the extent and potential seriousness of the injury.
However, both of these techniques incur the risk of introducing infection and there is a risk of

accidental penetration of synovial structures with a probe. Another diagnostic technique is to
inject the coffin joint, navicular bursa or digital sheath with a contrast medium using a sterile

technique and then X-ray it to see if the contrast agent leaks out into the penetrating tract
(Figure 6.20).