Exam III (Causes of Lameness) Flashcards
What is the most common tendon injury?
Internal strain of the superficial digital flexor tendon (SDFT) in the MC region (AKA bowed tendon)
What are the causes of a mechanical injury of the flexor tendon (SDFT or DDFT)?
Toed-in or toed out conformation
Long toe and low heel
Muscle fatigue
Uneven surfaces and mud with sudden turns
Improper bandaging
Unbalanced trimming and shoeing
Phases of Tendonitis
- Tendon Degeneration
- Acute Inflammatory Phase
- Reparative Phase
- Remodeling Phase
Tendon degeneration
The first phase of tendonitis
Subclinical signs
Acute Inflammatory Phase
The onset of clinical signs (swelling, pain, heat)
Lasts 1-2 weeks
Reparative Phase
Cleans up any damage done
Angiogenesis and fibroblast migration
Angiogenesis
The creation of new blood vessels to increase blood flow to an injured area
Remodeling Phase
Lasts several months
Repairs tissue stronger but less elastic and prone to reinjury
Hyperechoic
White appearance
More echoing back
Hypoechoic
Black appearance
Less echoing back
Why is an Ultrasound the best imaging option for soft tissue injuries?
There is a field version which makes it much easier to diagnose out of the clinic
What are two common ultrasound views used to look at soft tissue structures in the distal limb?
Cross-section/horizontal View
Longitudinal View
What are the treatments for the acute inflammatory phase of tendonitis?
Cold therapy, NSAIDs (bute), rest
What are treatments for the repair/remodeling phase of tendonitis?
Extracorporeal shockwave
Intralesional Regenerative Therapies (PRP, stem cells)
Pin-firing and blistering
A transection of the proximal check ligament of the superficial digital flexor tendon
Rehabilitation and Controlled Exercise
Where is Superficial Digital Flexor tendonitis more likely to occur?
In the fore-limb
Mid-proximal (top 2/3rds)
Where are superficial digital flexor tendon injuries in the distal limb more likely to occur?
In the forelimb
Outside of the digital flexor tendon sheath
Where are deep digital flexor tendon injuries in the distal limb more likely to occur?
In the hind-limb
Inside the digital flexor tendon sheath
What do DDFT injuries often result in?
Sheath effusion and chronic tenosynovitis
What are the signs of tenosynovitis?
Distention (effusion) of the tendon sheath
Pain on palpation
Heat/swelling
What are the treatments of tenosynovitis?
Cold hosing, NSAIDs
Transection of the annular ligament for SDF/DDF tenosynovitis at the fetlock
Thoroughpin
Non-septic tenosynovitis of the DDFT sheath at the level of the hock
Septic Tenosynovitis
an infection in the tendon sheath most likely from a wound that enters the tendon sheath
What does septic tenosynovitis result in?
Damage to the tendon
Adhesion formation
Possible erosion of the tendon sheath and progression of the infection
Which prognosis is better:
a laceration of a flexor tendon or a laceration of an extensor tendon and why?
A laceration of an extensor tendon is better because the horse can learn to flick its limb forward but a horse can not learn to use its limb with a laceration of the flexor tendons
Causes of Suspensory Desmitis
Straight hocks (conformation)
Hyperextension of the carpus/tarsus or the fetlock
Deep, soft footing
Excessive rotational movements of the limbs
Secondary to a fracture splint (either from the fracture itself or the formation of a callus)
Churchill sign
A technique that uses finger pressure applied to the posterior head of the medial splint bone where a positive response elicits an upward and outward movement of the leg.
What are the possible treatments of suspensory desmitis?
NSAIDs and rest
Cold/warm therapy
Surpass
Shockwave
Intralesional Injection (PRP, Stem cells)
PRP
Platelet Rich Plasma
What is the signalment of a horse with proximal suspensory desmitis?
Sports horses (eventers, jumpers, western performance horses)
What was Reggie’s DDx?
Proximal Suspensory Desmitis with an Avulsion Fracture
What is the signalment of a horse with body and branch lesions in the suspensory ligament?
SBs and Jumping horses
What was Teddy’s DDx?
A lesion of the lateral branch of the left front suspensory ligament
What causes a suspensory ligament rupture?
extreme overextension of the fetlock
What causes a dropped fetlock and an acute onset of lameness?
Suspensory Ligament Rupture
Treatments of a suspensory ligament rupture
immobilization of the limb (cast, splint, fetlock arthrodesis)
Euthanasia
Signalment of inferior check desmitis
SB trotters and pacers
What causes inferior check desmitis?
Long toe, low heel
Unbalanced foot
Tarsal plantar desmitis
AKA curb
Inflammation of the long plantar ligament
What causes curb?
Conformation (sickle-hocked, cow-hocked)
Trauma
What is the acute cause of annular ligament constriction?
Damaged via trauma
Strained tendon in the tendon sheath (tenosynovitis)
What is a chronic cause of annular ligament constriction?
Thickening of the annular ligament
What is the treatment for annular ligament restriction?
Surgical resection of the annular ligament with bandage application and return to exercise to prevent adhesions
Upward fixation of the Patella
The patella becomes fixed over the medial trochlear ridge
What causes an upward fixation of the patella?
Poor conformation (a steep angle between the femur and tibia)
What are the treatments of a mild case of upward fixation of the patella?
Hill work and NSAIDs
Injection of counterirritants to the middle and medial patellar ligaments
What are the treatments of a severe case of upward fixation of the patella?
Medial patellar desmoplasty or desmotomy (which would affect the stay apparatus)
What causes a peroneus tertius rupture?
overextension of the hock joint
What is a sign of a peroneus tertius rupture?
Flexion of the stifle with the extension of the hock
Still weight-bearing
What are the treatments for a peroneus tertius rupture?
Stall rest for 8-12+ weeks
Euthanasia
How are muscle injuries diagnosed?
Physical exam
Thermography
Ultrasound
Nuclear Scintigraphy
Electromyography
Muscle Biopsy
What is muscle atrophy?
A degenerative process that causes a decrease in muscle mass
What are the causes of muscle atrophy?
Denervation
Trauma
Ischemia
Lack of use
Excessive use
Ischemia
Lack of blood supply
Sweeney
The paralysis of the suprascapular nerve which causes atrophy of the supraspinatus and infraspinatus muscles
What are the causes of Sweeney?
Ill-fitting harness
Trauma
Fibrotic Myopathy causes
Repeated tearing and straining of the semitendinosus muscle fibers
Acute trauma resulting in scar formation
Repeated IM injections
Fibrotic Myopathy Signs
Goose-stepping Gait with a shortened cranial phase
Limb pulled down before the foot hits the ground
What is the treatment for Fibrotic Myopathy?
Transection of the muscle/tendon at the scar level or insertion (semitendinosus tenotomy)
Stringhalt
Involuntary hyperflexion of the hock when the horse moves
What are the causes of stringhalt?
Trauma to the muscle/tendon (unilateral)
Ingestion of a toxic weed (bilateral)
When are signs of stringhalt exaggerated?
When the horse is backing up
In cold weather
After a period of rest
What are the treatments for stringhalt?
Conservative: rest, controlled exercise, nutritional changes
Surgery: remove a portion of the lateral digital extensor tendon
Shivering
Involuntary flexion of the limbs
Where is shivering most likely to occur?
In the hind limbs
What is the only treatment for shivering?
A high-fat, low-carb diet
Cellulitis
A subcutaneous bacterial infection caused by a wound or infection within the blood or lymph (hematogenous/lymphogenous)
What are some systemic diseases of the muscle?
Tetanus
Botulism
Lyme Disease
Hyperkalemic Periodic Paralysis (HYPP)
Exertional Rhabdomyolysis
Equine Polysaccharide Storage Myopathy (EPSM/PPSM)
What is Exertional Rhabdomyolysis (ER) also known as?
Monday morning sickness
Tying up
Azoturia
What are the causes of ER?
Return to work after rest
Post-anesthesia
What are some of the theories about what causes ER?
A change in blood supply within a muscle
Fluid/electrolyte imbalance
Genetic Predisposition
Nutritional influence
What are signs of mild ER?
A slight change in gate (hind limb)
Poor performance
Pain or stiffness on palpation of the neck/gluteal muscles
Increased HR, RR, and Temp
What are signs of severe ER?
Extreme pain
Reluctance to move
Severe stiffness
Sweating
Myoglobinuria
Recumbency
How is ER diagnosed?
History, clinical signs
Elevated Creatine Kinase (CK) with exercise
Muscle biopsy –> swollen fibers
What is EPSM?
Equine Polysaccharide Storage Myopathy
A disorder of glycogen storage
What horses are most likely to get EPSM?
QHs, WBs, and draft horses
Heavily muscled horses with calm demeanors
What are signs of EPSM?
Muscle atrophy
Abnormal gait
Repetetive ER
How is EPSM diagnosed?
Muscle biopsy of the semimembranosus or semitendinosus muscles
Blood Sample
Prevention of EPSM?
Replace Grain with rice bran/fat
Provide daily exercise
What are the causes of laminitis (give at least 4)?
Carbohydrate Overload (large ingestion of grain)
Lush grass consumption
Cold water ingestion after exercise
Septicemia/endotoxemia from infection
Excessive concussion/impact of the feet
Hormonal (cushing’s disease, metabolic syndrome)
Viral (high fever)
Pharmacologically induced (Corticosteroids)
What is the pathophysiology of laminitis?
- blood supply to the lamina gets compromised (vasoconstriction)
- Increased arteriovenous shunting
- Decreased capillary perfusion
- Ischemic necrosis of the laminae
- Pain
- Less time bearing weight on the limb so not as much blood flow (continuation of the process)
What are the consequences of necrosis of the laminae?
PIII lacks suspending support, PIII then moves distally (sinking) so the DDFT pulls PIII palmarly or plantarly (rotation)
What are the three phases of laminitis?
- Developmental phase
- Acute phase
- Chronic phase
What happens during the developmental phase of laminitis?
the horse is exposed to causative factors
Ends when the signs begin
What happens during the acute phase of laminitis?
1-4 feet are affected
Increased/bounding digital pulse, pain, heat
Rotation and/or Sinking on radiographs
How long does the chronic phase of laminitis last?
Can last days to years
What are the clinical signs of laminitis (list at least 5)?
Walking on eggshells, rocked back
Hesitant to pick up feet
Shifting weight
Increased digital pulses and heat
Increased HR, RR, and temp (TPR)
Positive to hoof testers along the solar margin
What are the clinical signs associated with chronic laminitis (list at least 3)?
Hoof rings
Flat sole
Widened white line (seedy toe)
Bruised soles
How is laminitis diagnosed?
Clinical signs and radiographs (lateral view)
What are the treatment options for laminitis (list at least 5)?
- Anti-inflammation (banamine/bute, DMSO, Ice therapy)
- Anti-endotoxin (banamine, polymixin B, pentoxifylline, plasma)
- Anticoagulation (aspirin)
- Vasodilation (isoxsuprine, ace, nitroglycerine)
- Red blood cell deformability (pentoxifylline)
- Frog pressure and foot support (deep bedding, lily pads, styrofoam, heart bar shoes, elevated heel)
- Deep digital flexor tenotomy or distal check ligament desmotomy
- Dorsal hoof wall resection
What is navicular syndrome also known as?
Podotrochleosis
In what types of horses and where is navicular most likely to occur?
Horses between the ages of 4 and 9
Forelimb > hind limb
Bilateral > unilateral
Males > Females
QHs and SBs
What structures are involved in Navicular syndrome?
Coffin joint, navicular bone, navicular bursa, DDFT
What are the causes of Navicular syndrome?
- Poor conformation (small feet, low heels, long toe) and concussion
- DDFT stresses the bone
- Arterial Constriction within the foot
What are the clinical signs of navicular (list at least 3)?
Intermittent, progressive lameness that improves with rest
Shortened stride
Positive hoof testers across the heels***
Positive distal limb flexion
Contracted raised heels, concave sole, narrow quarters
What are the two radiographic views used to diagnose Navicular syndrome?
Navicular skyline (45 degree palmar proximal-palmarodistal oblique)
Dorsoproximal-palmarodistal oblique
How is navicular syndrome diagnosed?
Hoof testers (positive across heels)
PD nerve block
Radiographs (lollipop lesions, cysts, osteophytes/spurs on wings)
Intrabursal anesthesia
What are the treatments of Navicular?
Corrective shoeing and trimming
Medications
Alleviation of pain (PD neurectomy)
What are some medications used to treat Navicular syndrome (at least 2)?
Isoxsuprine (vasodilator)
NSAIDs
Tildren/Osphos (decrease bone resorption)
Legend, adequan, oral supplements
Intrabursal injections of corticosteroids and HA
Street Nail
A puncture into the navicular bursa often from a nail or stick
What are the treatments of street nail?
Surgical debridement
Topical and systemic antibiotics
NSAIDs
Sidebone
Ossification of the collateral cartilages of PIII
What causes sidebone?
Poor conformation
Improper shoeing/trimming
What are signs of sidebone?
Lameness
Hard and painful cartilage on palpation
Quittor
Chronic inflammation and infection of the collateral cartilages of PIII
What are the clinical signs of Quittor?
Lameness
Purulent discharge at the coronary band
Heat, swelling, and pain
How is Quittor diagnosed?
Contrast radiographs
What is the only treatment of quittor?
Radical surgical excision with distal drainage
Gravel
An opening in the white line that causes infection within the sensitive laminae which cannot drain distally so it travels to the coronary band for drainage
What causes gravel?
Dry foot
A sequel to laminitis
Puncture wound
What are the clinical signs of gravel?
Lameness
Draining tract at the coronary band
Changes to the white line
Heat
What is the treatment for Gravel?
Establish drainage for the infection
Prevention of a secondary infection
What disease is more widespread than gravel?
White Line Disease
What causes white line disease?
Poor foot hygiene
Opportunistic bactera/fungus proliferate in the stratum medium of the hoof capsule
Signs of White line disease?
+/- lameness
A dark black line along the sole-wall junction with a foul odor
Separation of the outer hoof wall
What are treatments of white line disease (name at least 3)?
Proper hygiene
Cleaning with antiseptic
Hoof wall resection
Soaking
Bandaging
White Lightening
What is the most common cause of lameness?
Foot abscesses
What causes foot abscesses?
A puncture from a foreign object entering the sensitive areas of the foot –> bacteria invade and reproduce
Thrush
an infection within the sulci of the frog due to dirty, moist conditions (often caused by fusobacterium necrophorum)
What are signs of thrush?
characteristic odor
Black purulent discharge
Lameness if the infection invades into the sensitive tissues
How is thrush treated (at least 3)?
Proper hygiene
Cleaning with antiseptic
Antibacteria/antifungal medications
thrush buster
white lightening
Canker
chronic hypertrophy of the horn-producing tissues of the foot that often occurs in the hind feet of draft horses
Signs of Canker
Foul-smelling
Necrotic horn covered with caseous, cream colored exudate
Oily ragged frog
Keratoma
Excessive keratin produced by the epidermal cells of the coronary band which grow distally sandwhiched between the hoof wall and PIIII
What is the only treatment for keratomas?
Complete surgical removal
Which hoof cracks are more painful?
Quarter and heel cracks because they often involve the sensitive laminae
