Page 210 - Adams and Stashak's Lameness in Horses, 7th Edition

176 Chapter 2

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Common or
long digital
extensor tendon

First
phalanx

Extensor
process
Dorsal branch of
Coronary band suspensory ligament
Second Collateral ligament
phalanx
of pastern joint

Third phalanx

Figure 2.172. Dorsal view of the injection site for the dorsal approach to the fetlock joint in the standing horse.

recess in the pastern superficial to the DDFT are diffi­ can be performed in the distended and non‐distended
cult to penetrate without sheath effusion. However, they DFTS. Both approaches are best performed with the
can often be the easiest approaches to perform if effu­ limb held with the fetlock slightly flexed. The axial sesa­
sion is present. The site for injection of the proximal moidean approach is performed 3 mm axial to the pal­
pouch of the DFTS is 1 cm proximal to the palmar/plan­ pable border of the midbody of the lateral proximal
tar annular ligament and 1 cm palmar/plantar to the lat­ sesamoid bone using a 1–1.5‐inch (2.5–3.8‐cm), 20‐
eral branch of the suspensory ligament (Figure 2.173; gauge needle (Figure 2.175; Video 2.29). The needle is
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Video 2.27). A 1‐ to 1.5‐inch, 20‐gauge needle is directed directed at a 45° angle to the sagittal plane to a depth of
slightly distally until the sheath is penetrated. approximately 1.5–2 cm. Ten to 15 mL of anesthetic is
The distal outpouching of the DFTS in the pastern recommended for diagnostic purposes for the DFTS.
region is often palpable as a distinct “bubble” when Improvement of lameness in horses after intrasynovial
effusion is present. It is located between the proximal analgesia of the DFTS is usually due to attenuation of
and distal digital annular ligaments and between the pain within the structures contained in the DFTS.
diverging branches of the SDFT where the DDFT lies Analgesia of the DFTS has little effect on lameness
close to the skin. A 20‐gauge, 1‐inch needle is directed caused by pain originating in the sole, DIP joint, or the
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in a lateral to medial direction just beneath the skin so navicular bone. 30
as not to penetrate the DDFT (Figure 2.174; distal nee­
dle; Video 28). Alternatively, the needle can be inserted
into the outpouching of the DFTS abaxial and distal to Carpal Joints
the sesamoid bones between the annular and proximal Arthrocentesis of the radiocarpal and middle carpal
digital annular ligaments. The needle is inserted in a dis­ joints can be performed using either a dorsal or palmar
tal to proximal direction at approximately a 45° angle approach. The dorsal approach is performed with the
to the sagittal plane (Figure 2.174; proximal needle). carpus flexed, and the palmar approach is performed in
This approach is referred to as the basilar sesamoidean the weight‐bearing limb and can be somewhat difficult
approach and can be performed in the standing horse. It in the non‐distended joint. Approximately 10 mL of
has been reported to be more reliable to obtain synovial anesthetic is recommended. Because the carpometacar­
fluid than the axial sesamoidean approach. 55 pal joint and the middle carpal joint communicate,
The axial sesamoidean approach at the level of the anesthetics injected into the middle carpal joint also
fetlock and the medial or lateral approach between the desensitize the carpometacarpal joint. Additionally, the
annular ligament and proximal digital annular ligament carpometacarpal joint has palmar pouches that extend