Lecture 10: Common Disorders of the Equine Hind Limb

What are the common etiologies of cervical spine OA and how is it diagnosed?

etiology: trauma, unnatural head carriage, OC
diagnosed: stiff neck, ± lame or neurologic, rads

How is cervical spine OA treated and what is the prognosis?

tx: inject facets with corticosteroid, acupuncture, mesotherapy

prognosis: fair, will require life long maintenance, may progress and cause neurologic signs

What is kissing spines?

impinging dorsal spinous process caused by trauma or poor fitting saddle

What is this and how is it diagnosed?

impinging dorsal spinous processes aka kissing spines

diagnosis:

• pain on palpation

• reduced performance (behavior change)

• rads

How is kissing spines treated and what is the prognosis?

tx: check saddle fit, inject area with corticosteroids, surgical resection

prognosis: depends on severity

What are the possible etiologies of general back muscle pain and how is it diagnosed?

etiology: underlying hind limb lameness, poor saddle fit, poor riding, trauma

diagnosis: pain on palpation and reduced performance

How is general back muscle pain treated and what is the prognosis?

tx: check saddle fit, inject area with corticosteroids (mesotherapy), acupuncture, rest

prognosis: good once address underlying cause

What is this and what is it caused by ?

SI disease (arthritis or subluxation of SI joint = hunters bump) caused by trauma or inappropriate use

How is SI disease diagnosed?

• clinical signs

• acute: lame, can feel crepitus by rectal palpation

How is SI disease treated and what is the prognosis?

tx: rest, inject SI joint with corticosteroids

prognosis: good, may require ongoing maintenance

What structures commonly cause hind limb lameness in the horse from most to least common?

1. hock

2. below hock

3. stifle

4. above stifle

What commonly causes metatarsal 2 & 4 fractures (splint bones) and how are they diagnosed?

etiology: kick injury - if wound, sequestration likely

diagnosis: rads, observe wound - often non-healing

How are metatarsal 2 & 4 fractures treated and what is the prognosis?

tx: ostectomy

prognosis: excellent

What are the gait characteristics of hock lameness?

• drag toes

• fails to “track up” on lame leg

• lame leg adducts most

• rider feels difference in their connection

How is hock lameness diagnosed?

• joint palpation: often none, bone spavin = hard swelling, bog spavin = effusion

• flexion tests

• blocks

• rads, nuclear scintigraphy, CT

What is the most common cause of hind end lameness diagnosed in performance horses?

hock OA (distal intertarsal and tarsometatarsal joint)

What are the common etiologies of hock OA and how is it diagnosed?

etiology: athletic use, genetic - juvenile spavin

diagnosis: + upper limb flexion, BLOCKS to distal hock joints, rads (do NOT correlate well with clinical lameness)

How is hock OA treated and what is the prognosis?

tx: intra-articular corticosteroids, shoeing (squared toe), facilitated ankyloses or arthrodesis

prognosis: good, will require ongoing maintenance during career

What are the common etiologies of tibiotarsal effusion (bog spavin)?

• OCD

• synovitis - poor conformation, hard work

• OA - rare

• blood = hemarthrosis (associated with collateral ligament injury)

• infection = septic arthritis

How is tibiotarsal effusion (bog spavin) diagnosed?

• effusion in TT joint

• radiographs

• ultrasound?

• diagnostic arthroscopy

What are the most to least common locations of hock OC?

1. distal intermediate ridge of tibia (DIRT)

2. trochlear ridge (lateral > medial)

3. medial malleolus

What is the treatment and prognosis of tibiotarsal effusion (bog spavin)?

tx: drain joint and inject corticosteroids, arthroscopy

prognosis: good, usually cosmetic problem if underlying issue addressed

What is the etiology of plantar ligament desmitis (curb) and how is it diagnosed?

etiology: strain on plantar aspect of hock, sickle hocked horse, standardbreds

diagnosis: characteristic swelling, mild to moderate lameness, blocks, ultrasound

What is the treatment for plantar ligament desmitis (curb) and what is the prognosis?

tx: as for other ligament injuries, usually just need rest

prognosis: good, will always have a “curb” swelling

What is this and how is it diagnosed?

calcaneal bursitis (capped hock) caused by repeated trauma (stall kicker) and diagnosed by characteristic swelling and not being lame (usually)

What is the treatment and prognosis for calcaneal bursitis?

tx: drain and inject corticosteroids - cosmetic fix

prognosis: excellent for function, poor for cosmesis

How is septic calcaneal bursitis diagnosed?

• VERY lame

• pressurize bursa

• contrast radiographs

• ultrasound

How is septic calcaneal bursitis treated and what is the prognosis?

tx: flush bursa (tenoscopy best), regional limb perfusion, may require opening bursa and resecting part of calcaneus

prognosis: guarded

What is this and how is it diagnosed?

tarsal sheath tenosynovitis (thoroughpin) caused by wear and tear or conformation (straight hocks) and diagnosed by characteristic swelling and not being lame (usually)

What is the treatment and prognosis for tarsal sheath tenosynovitis?

tx: inject corticosteroids?, none, bandaging not effective

prognosis: excellent for athletic use, guarded for cosmesis

What are the common etiologies of a ruptured peroneus tertius and how is it diagnosed?

etiology: trauma (usually foals), full limb hind limb casts

diagnosis: ability to extend the hock with a flexed stifle, lameness and swelling initially, tarsus extends more than usual at the trot

What is the treatment and prognosis for ruptured peroneus tertius?

tx: avulsions near stifle → arthroscopy, stall rest

prognosis: good, but poor if involving stifle joint

What is the treatment and prognosis for SDF or gastrocnemius muscle/tendon rupture?

tx: long term splinting and rest - challenging

prognosis: fair to poor, good if heals

How is fibrotic myopathy due to trauma diagnosed?

• characteristic movement - most evident at walk

• palpable hardening in semitendinosus mm. (possible ossification)

What is the treatment and prognosis of fibrotic myopathy?

tx: semitendinosus ± semimembranosus tenotomy - may not result in complete resolution of clinical signs

prognosis: fair for success of tx, horse will likely have altered gait

What are the gait characteristics and clinical signs of stifle lameness?

gait characteristics:

• jumps off lame leg in weight bearing phase - quicker, short step

• drags toe because leaves leg out behind

• increased lameness when lib is on outside of circle?

clinical sings:

• joint effusion - femoropatellar pouch easily palpable

• hind end muscle atrophy with chronic problem

How is stifle lameness diagnosed?

• flexion test: upper limb and caudal extension

• blocks

• rads, ultrasound

• arthroscopy

• nuclear scintigraphy

What are the most common lesions of stifle OC?

medial femoral cysts and trochlear ridge OCD

What is the treatment and prognosis of stifle OC?

tx: sx (wait until 1 yr) - debride and treat cysts

prognosis: depends on severity and success of surgery, leads to OA

What are the common etiologies of stifle OA and how is it diagnosed?

etiology: underlying OC, trauma, athletic use

diagnosis: blocks to stifle

What is the treatment and prognosis for stifle OA?

tx: intra-articular corticosteroids

prognosis: fair - high motion, complicated joint

What causes upward fixation of the patella?

weak quadriceps or conformation (straight legs) causes the inability to release the stay apparatus - patella does not disengage from the medial trochlea of the femur

How is upward fixation of the patella diagnosed?

presentation

• severe → stifle is locked in extension

• mild → horse catches their stifle

How is upward fixation of the patella treated?

• immediate: back the horse up

• exercise strengthen quadriceps (works for most cases): hills, Cavaletti

• surgery: medial patellar ligament splitting or blistering, medial patella ligament desmotomy (last resort)