Lameness – Part 2:
Specific Diseases
INAG 120 – Equine Health
Management
November 2, 2011
Common Lameness Disorders
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FRONT LIMB
 Shoulder
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HIND LIMB
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Stifle
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Hock
Knee
Fetlock
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Fetlock
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Pastern
Pastern
Navicular
Front Limb - Shoulder
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Signs of shoulder lameness:
Head lifts when limb moves forward
 Little flexion of limb (low foot arc)
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Swinging out of limb to avoid flexion
Failure to reach out (shortened cranial phase)
Fixation of shoulder joint  inability to move
 Hard or soft ground often has same effect if
level (may be slightly worse on soft ground)
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Lameness in the Shoulder
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Arthritis –
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Usually caused by trauma
Persistent lameness
In foals, other joints also
involved
Tx: injections with
steroid (usually cortisone)
followed by
hyaluronic acid
Lameness in the Shoulder
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Sweeny –
Atrophy of muscles around shoulder
 Paralysis of suprascapular nerve
 “Popping” of the
shoulder when horse
walked toward
examiner
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Sweeny
Front Limb - Knee
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Site of many developmental orthopedic
diseases
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Signs:
Stand with knee flexed
 Failure to reach out in stride
 Lower foot arc
 Stiff-legged paddling gait
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Carpal flexion test, joint blocks good tools for
diagnosis
Front Limb - Knee
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Fractures
Common in race horses, jumpers, hunters
 Factors = speed, immaturity,
long limb length, position of
rider, distances run, firm surface
 Most common is chip fracture
(also slab or fragmented
fractures – less common)
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Involves only one joint surface
© Clark Equine Clinic
Lameness in the Knee
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Anatomy of the knee:
Two stacked rows of cuboidal bones (6)
 Three joint spaces
 All held together by intercarpal ligaments
 Radius above, cannon below  compressive force!
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Faulty conformation (back at the knee) 
predisposed
Decreased incidence in European racehorses as
opposed to American  why?
The Knee Joint
Front Limb - Fetlock
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Bones of the Fetlock Joint: Cannon, Proximal
Sesamoid Bones (2), Long Pastern Bone
Fractures
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Fairly common!
Usually on the medial side of the long pastern bone, less
often on end of cannon
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Former seen in race horses on hard surfaces, latter when training
begins
Lameness most obvious at trot
Gets worse with work
Usually can’t produce pain with palpation, but can feel heat
Use opposite limb as comparison
Lameness – Fetlock
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Fracture of sesamoid bones:
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Common in racing Thoroughbreds, Standardbreds and
Quarter Horses
Forelimbs most commonly
affected in TB and QH,
hindlimbs in STB
Lameness is very pronounced –
often non-weightbearing
Swelling, heat, pain
Fetlock held rigid during
movement
Front Limb – Pastern Joints
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TWO joints (Long pastern-short pastern and
short pastern-coffin bone)
Ringbone
New bone growth on bones of pastern joint(s)
leading to arthritis and fusion of joints
 High = top joint
 Low = bottom joint
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Pastern Joint - Ringbone
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Articular vs. Non-articular
Non-articular due to inflammation of the
periosteum
Most common in
non-speed horses with
coarse boxy pasterns
 Horses with high heels
and short toes with
trappy gaits
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Pastern Joint – Ringbone
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Articular High ringbone
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Horse used for high speed that make quick stops, short turns
or rapid twisting movements
Overly upright
pasterns  increased
concussion on joint
Signs of lameness are
not specific
Fusion of pastern joint
common
Ringbone
Front Limb – Navicular Bone
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“Navicular Syndrome” aka Podotrochleosis
Most common cause of intermittent, shifting forelimb
lameness
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Most common in horses
4-15 years old
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Hereditary (small feet,
faulty conformation)
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Most common lameness
of horses between 4 and 9 yo
Highest incidences in Quarter Horses
and Standardbreds
Geldings > Stallions > Mares
Lameness exhibits as heel pain
Navicular Syndrome
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Predisposing factors:
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Poor conformation
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Inappropriate exercise
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Resilient surfaces
Improper/irregular trimming
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Upright pasterns
Long toe-low heel (broken-back axis)
@ walk and trot
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Lands toe first  excessive wear of the toe, bruising
Lower limb flexion test  aggravates 80% of horses
Stiff shuffling gait with high head and rigid neck
When circled, limb on inside will be worse, head held to
outside of circle
Hind Limb – Stifle
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Bones involved: femur, tibia, patella (knee cap)
Most commonly mis-diagnosed lameness area
(overdiagnosed)
Hard to discern differences due to stifle vs. hock
Common Problems:
DOD …
 Upward Fixation of the Patella
 Arthritis and inflammation (gonitis)
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Upward Fixation of the Patella
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Locked Stifles
Middle and medial patellar ligaments get
“caught” on the femur
Patella should be able to slide during movement,
if ligaments stuck, patella can’t move
May be intermittent or complete
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Acute = hindlimb locked in extension
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Stifle and hock can’t flex (but fetlock can)
Catching (not complete locking) also possible
Upward Fixation of the Patella
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Diagnosis:
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Catching most noticeable when horse is turned in a tight
circle towards affected limb
Walk up and down slope – crouched position going up, jerky
gait down
Toe drag if limb locked
Palpation – patella locked in extension
Treatment:
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Training to improve muscle tone
Avoid exercise in soft areas
Surgery as last resort
Locked Stifles
NORMAL
LOCKED
Stifle – Arthritis and Gonitis
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Gonitis = inflammation
Many causes
 Distension of the stifle joint
 Gluteal muscles may be atrophied
 Wearing of toes in the hind end (toe drag)
 More lame when ligaments or cartilage involved
 Shortened stride (failure to reach forward)
 Hip hike
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Arthritis = bony changes
Hind Limb – Hock
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Bone spavin
Bog spavin
Fractures
Curb
Stringhalt
Shivers
Capped Hock
Soft Tissue
When the stifle flexes
DOD (Nutrition Course) the hock also flexes
and vice versa!
The Hock Joint
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6 cuboidal bones, tibia, cannon, 4 joints
Hock works as a hinge
Most movement occurs between the tibia and
the tibial tarsal bone
Hock is the pivotal hind limb joint – all equine
exercise disciplines rely on it for performance
The hock absorbs most concussive forces
Most common site of stress related injuries!
Hock Lameness
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First noticeable sign is stiffness/soreness in
lumbar region of back
Poorly trained chiropractors may “adjust” a
horse that really has a primary hock problem!
Pain around inside splint bone
Swelling and pain in the joint itself
Specific Conditions
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Bone Spavin:
General term for degenerative joint disease or
osteoarthritis in the hock joint
 Often in both hocks
 History = back stiffness/soreness with lameness that
may go away with exercise
 Excessive wear on the outside of the shoe/hoof
 Bony enlargement just below and behind the
chestnut
 Flexion test!
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Specific Conditions
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Bog Spavin:
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General term for distension of
joint capsule
Present on inside front of the hock!
Usually representative of an
underlying hock problem!
Curbed Hock
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Sprain of the ligament that runs
down the back of the hock
Common in horses with sicklehocked conformation
Specific Conditions
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Capped Hock
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Hematoma at the point of the
hock
Often due to trauma (kicking
walls, etc.)
Avoid drainage due to potential
for infection
Stringhalt
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Excessive involuntary flexion of
the hock joint
Usually isolated
Causes unknown
Specific Conditions
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Stringhalt Study in Australia:
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Appears in Late Summer  peaking in February
Associated with droughty summers
All breeds affected but TBs more, ponies less
Recover when removed from paddocks containing
catsear or dandelion
Specific Conditions
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Shivers
Involuntary muscle movements of limbs and tail
 May be caused by EPSM – most other causes
unknown
 Usually most visible when trying to back a horse
 Jerks foot and holds it above the ground in flexed
position
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Treatment Terminology
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Rest with Controlled Exercise:
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Out of work (time off!); moderate controlled
exercise such as daily hand-walking
Physiotherapy:
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Hydrotherapy
COLD – up to 48 hours post-injury to reduce
inflammation
 HOT – 48 hours after injury to reduce tension, relieve
pain
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Treatment Terminology
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Joint Lavage:
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Washing dead tissue out of joint with large amounts
of sterile fluid
DMSO (dimethyl sulfoxide):
Topical application can reduce joint inflammation
 Wear gloves!
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Corticosteroids:
Anti-inflammatory – helps reduce harmful enzymes
in synovial fluid
 Usually directly injected into joint
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Treatment Terminology
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NSAIDs:
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Non-steroidal anti-inflammatory  pain relief for
soft tissue injuries (Bute, Banamine, Aspirin)
Hyaluronic Acid (HA):
Natural part of synovial fluid used to treat synovitis
injected directly into joint (after steroids)
 Horses often show immediate, long-lasting relief
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Joint Fusion:
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Surgical repair of arthritis
Treatment Terminology
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Counterirritation:
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Blistering, firing, ultrasound to speed healing