Front Matter

Chapter 14 Disorders of the Pelvic Limb: Diagnosis and Treatment 381

Achilles tendon injuries

Anatomy

The Achilles tendon is made up of three compo­
nents: the gastrocnemius tendon, the common
calcaneal tendon (the combined tendons of the
biceps femoris, gracilis, and semitendinosus),
and the superficial digital flexor tendon (Dyce
et al., 1996). The blood flow to the common cal­
caneal tendon arises predominantly from the
caudal saphenous artery. The midbody of the
tendon has the poorest blood supply, while the
calcaneal insertion has the most vascularity
(Gilbert et al., 2010); however, there are five
avascular fibrocartilaginous zones located in
the distal tendon (Jopp & Reese, 2009). These
fibrocartilaginous zones are thought to be an
adaptation to pressure and are not considered
pathological (Tillmann & Koch, 1995; Benjamin
& Ralphs, 1998).

Pathophysiology

Achilles tendon rupture is a common tendon
injury in veterinary medicine. Laceration of the
Achilles may occur, and in some cases, a skin
lesion may not be evident. More often, avulsion
of the gastrocnemius tendon is seen after heavy
activity in mature sporting and working breeds.
Labrador Retrievers and Doberman Pinschers
appear to be overrepresented (Corr et al., 2010).
An underlying degenerative process is sus­
pected; however, the definitive cause is not

known. Both human and canine Achilles ten­

don ruptures tend to occur in the area of the

fibrocartilaginous zones, which are thought to

be areas of increased stress loading (Tillmann

& Koch, 1995; Benjamin & Ralphs, 1998). Some

drugs and disease processes such as diabetes,

endogenous or exogenous steroids (Hossain

et al., 2008), and fluoroquinolones (Lim et al.,

2008) have been implicated.

Clinical presentation

Patients with acute gastrocnemius avulsion

present non‐weight‐bearing to toe‐touching

lame with swelling at the calcaneus. Chronic

injuries may present with a weight‐bearing

plantigrade stance. There may be digital flexion

present due to increased stress on the intact

superficial digital flexor tendon (Figure 14.34).

Palpation may identify a fibrous thickening at

the site of injury.

Diagnostics

Radiography may demonstrate soft tissue

swelling at the level of the injury with possible

avulsion of bone fragments and/or mineraliza­

tion of the tendon (Figure 14.35). Diagnostic

ultrasound can identify partial tears, and be

used to monitor healing (Kramer et al., 2001).

MRI, commonly used in human Achilles ten­

don injuries (Schweitzer & Karasick, 2000), is

gaining use in veterinary medicine.

then sit‐to‐stand repetitions on flat ground with brief

tugging. Walking times increase with start of gentle

hills in week 6.

Week 8‐12: External fixator removed; Therapaw®

(nonthermoplast) support brace in place when

not  confined or resting. Manual therapies pro­

gress to complete ROM for gentle passive

flexor  tendon  stretching. Hill walking increased,

with  gradually incorporated side hill, circles,

and  backwards walking. Balance disc work

added, increasing repetitions and difficulty. Brace

is somewhat cumbersome so exercises are modi­

fied.  Hydrotherapy introduced at 8 weeks, and

client can remove brace for massage and stretching

at home.

Week 12‐16: Brace is downgraded to remove support

straps, and used during lengthy walks or when excit­

able. Hydrotherapy continues; 45–60‐minute walks and

hiking in brace, shorter walks without brace, and light

trotting and loping allowed for short durations.

Therapeutic exercises performed without brace.

Week 16: Transition to off‐leash work over next

2 weeks while in brace.

Week 20: Transition to full activity without brace.