Causes of Lameness: Muscles

Question 1

How do you diagnose muscle injuries?

Answer 1

○ Physical exam
§ Fibrosis, atrophy, inflammation
○ Thermography
○ Ultrasound
§ Hematoma, seroma
○ Nuclear Scintigraphy
§ Soft tissue phase (~15 minutes)
○ Electromyography
§ Record electrical impulse
○ Muscle biopsy

Question 2

What is muscle atrophy?

Answer 2

○ Atrophy = wasting away or decrease in size
§ Degenerative process
§ Generalized or localized

Question 3

What are the causes of muscle atrophy?

Answer 3

Denervation

Trauma

Ischemia

Lack of use

Excessive use

Question 4

What is sweeney?

Answer 4

○ Paralysis of suprascapular nerve –> atrophy of supraspinatus and infraspinatus muscles

Question 5

What causes sweeney?

Answer 5

Ill-fitting harness

Trauma

Question 6

What causes fibrotic myopathy?

Answer 6

Repeated trauma and straining of semitendinosus muscle fibers

Acute trauma with resulting scar formation

Repeated IM injections

Question 7

What are the signs of fibrotic myopathy?

Answer 7

Goose-stepping gait with shortened cranial phase

Limb pulled down before foot hits ground

Question 8

How do you diagnose fibrotic myopathy?

Answer 8

Signs

Palpation of scar tissue

Question 9

How do you treat fibrotic myopathy?

Answer 9

Transection of muscle/tendon at scar level or insertion (semitendinosus tenotomy)

Question 10

What is stringhalt?

Answer 10

Involuntary flexion of the hock when horse moves

Lateral digital extensor muscle/tendon involved?

Question 11

What are the causes of stringhalt?

Answer 11

Trauma to muscle/tendon (unilateral)

Ingestion of toxic weed (bilateral)

Question 12

What are the signs of stringhalt?

Answer 12

Mild to severe hyperflexion of hock
□ Spasmodic with every step

Signs exaggerated
□ Horse is backing
□ Cold weather
□ After period of rest

Question 13

How do you diagnose stringhalt?

Answer 13

Clinical signs

Rule out fibrotic myopathy, shivering, and upward flexion of patella

Question 14

How do you treat stringhalt?

Answer 14

Conservative - rest, controlled exercise, nutrition changes

Surgery - remove portion of lateral digital extensor tendon (70% improve)

Question 15

What is shivering?

Answer 15

Involuntary flexion of limbs

Progressive, worsen over time

Hindlimbs > forelimbs

Question 16

What causes shivering?

Answer 16

Cause unknown

Linked to influenza, strangles, and EPSM

Question 17

What are the signs of shivering?

Answer 17

Random hyperflexion of any limb

Tail elevated, tail and leg quivers

Question 18

How do you diagnose shivering?

Answer 18

Clinical signs, backing may exacerbate

Question 19

What is the treatment for shivering?

Answer 19

Feed high-fat, low-carb diet

Question 20

What is the prognosis for shivering?

Answer 20

poor because progressive

Question 21

What is cellulitis?

Answer 21

Subcutaneous bacterial infection

Question 22

What causes cellulitis?

Answer 22

Wound

Hematogenous/lymphogenous

Question 23

What are the signs of cellulitis?

Answer 23

Swelling, pain, heat, pitting edema

Fever

Moderate to severe lameness

Question 24

How do you diagnose cellulitis?

Answer 24

History of wound

Clinical signs

Rule-out fracture

Question 25

How do you treat cellulitis?

Answer 25

Wound care Cold hosing Antibiotics, NSAIDs DMSO/furacin sweat bandage, nasogastric intubation with DMSO

Question 26

What are some systemic diseases of muscle?

Answer 26

Tetanus Botulism Lyme Disease Hyperkalemic Periodic Paralysis (HYPP) Exertional Rhabdomyolysis (ER) Equine Polysaccharide Storage Myopathy (EPSM)

Question 27

What is exertional rhabdomyolysis?

Answer 27

AKA Monday morning sickness, tying up, azoturia

Question 28

What causes exertional rhabdomyolysis?

Answer 28

Return to work after rest Post-anesthesia

Question 29

What are some theories for exertional rhabdomyolysis?

Answer 29

Changes in blood supply within muscle Fluid and/or electrolyte imbalance Genetic predisposition Nutritional influence

Question 30

What are the signs of mild rhabdomyolysis?

Answer 30

Slight change in gait especially hind limbs Poor performance Pain or stiffness upon palpation of neck and gluteal muscles Increased HR, RR, and temp

Question 31

What are the signs of severe exertional rhabdomyolysis?

Answer 31

Extreme pain Reluctance to move Severe stiffness Sweating Myoglobinuria Recumbency

Question 32

How do you diagnose exertional rhabdomyolysis?

Answer 32

History, clinical signs Elevated Creatine Kinase (CK) w/ exercise Muscle biopsy - swollen fibers

Question 33

How do you treat exertional rhabdomyolysis?

Answer 33

Analgesia Reduce further muscle damage □ Don’t move Restore fluid and electrolyte balances

Question 34

What is equine polysaccharide storage myopathy?

Answer 34

Disorder of glycogen storage QHs, WBs, and drafts Heavily muscled horses with calm demeanor

Question 35

What are the signs of equine polysaccharide storage myopathy?

Answer 35

Muscle atrophy, abnormal gain, repetitive ER

Question 36

What is the diagnosis of Equine Polysaccharide Storage Myopathy (EPSM or PSSM)?

Answer 36

Muscle biopsy of semimembranosus/tendinosis Blood sample

Question 37

How do you prevent Equine Polysaccharide Storage Myopathy (EPSM or PSSM)?

Answer 37

Replace grain with rice bran/fat Provide daily exercise

Question 38

What are the steps of an orthopedic exam?

Answer 38

1. Observed the horse from afar and asking history questions i. How long has it been going on ii. Signalment iii. Medical history iv. What is their job v. When is it worse? vi. Owner input, sometimes they say things that could help vii. Is the horse on medications 2. Muscular palpation i. Limbs ii. Range of motion iii. Feet - hoof testers 3. Movement - baseline walk and trot i. Baseline walk and trot and then canter 1) The transition down from the canter is where lameness pops up 4. Flexions - a minute longish