EQUINE LOCOMOTOR Flashcards
Laminitis
Characterised by the failure of attachment of the epidermal cells of the insensitive laminae to the underlying basement membrane of the dermal (sensitive laminae)
3 stages of laminitis
- Development stage (72 hours!!) - cannot tell when in this stsage 2. Acute laminitis 3. Chronic laminitis (depending on how effective treatment is)
Pathogenesis of Laminitis
Inflammation- thought that something to do with hindgut fermentation of carbohydrates
Vascular events in the early stages of laminitis include…
Digital vascoconstriction and consequent laminar oedema. Vascoconstriction may be caused by platelet activation. Amines from hindcut fermentation are also vasoactiv
Characteristic stance for laminitis
Leaning back on heels (trying to transfer weight OFF toe), bounding digital pulse, increased hoof wall temperature, palpable depression at coronary band. Pottery gaut,
Which radiographs would you take for diagnosis of laminitis
Lateromedial radiographs. Need to put markers on feet inc dorsal hoof wall, starting at coronary band, one at point of drog. . Founder distance = sinking
Medical therapy for Laminitis
Medical emergency, Analgesia (NSAIDs PBZ, Flunixin, Carprofen) or Opiods in hospital setting. Use of vasodilator therapy is controversial (only ACP shown to work)
Why might a sick endotoxic horse be placed in ice bucket
Decrease risk of laminitis as ice is vasoconstricting blood vessels.
What diet changes can be implemented to help laminitis
Box rest changing diet so it includes no grass, 1.5-2% body weight poor quality hay. Cinnamon- claimed to be insulin sensitising?? Chromium thought to potentiate action of insulin?? Magnesium: Modulates action of insulin???
Prognosis of Laminitis
Dependent on clinical signs. ROTATION BETTER THAN SINKING If depression that extends all the way around coronary band = suggests sinking (20% survival) Rotation of >11.5deg is poor prog.
How can laminitis be prevented
Associated with an over consumption of NSC (Fructan+Starch+Sugar) which provides energy for plant growth. Decreased in growing plants, increased when photosynthesis (high light, low temp i.e. EARLY SPRING = HIGH NSC= HIGH LAMINITIS RISK) Ideally want <10% NSC
When would it be preferable to graze a horse which is prone to laminitis
Consider zero grazing. Turn out late at night or early morning (Low NSC) Restrict in Spring/Autumn Avoid if frost with bright sunshine. Muzzle horse.
Majority of the hoof in inaccessible for palpation, except
- Dorsal DIP joint capsule 2. DIP joint collateral ligaments 3. Collateral cartilages 4. Distal recess DFTS+ DDFT Nerve Blocks are not very specific in the hoof,
Correct nail placement for horse shoeing
Driven obliquely through hoof wall/ Tip of the nail is placed at inner edge of white line with bevel of nail tip facing inwards. When the tail hits the dense hoof wall the nail will start to curve outwards
Septic Pedal Osteitis treatment
Persistant infection = radiolucency. More often front legs as 60% of horse weight distributed here. Curettage and wound care
Coffin bone =
Coffin bone = Pedal bone = Distal phalnx = PIII!
Hoof wall avulsions are the result of
Damage to the cornonary band. Permantely disturbed growth
Keratoma presentation and treatment
Columnar thickening of hoof extending towards inside of hoof. Mostly dorsal wall. Increased local pressure can result in typical lysis of the distal phalanx (on radiograph) Treatment is surgical removal.
Difference between thrush and canker
Thrush: Infection leading to necrotic process’ in frog area. Usually limited to lateral and medial sulci of the frog. CANKER: Mixed bacterial infec of deeper layers. White pus, pungent odour and tendency to bleed.
Treatment of White Line Disease in Horse
Debridge all necrotic and diseased horn. Protect sensitive lamina. Hardening soluitions e.g. formalin. METICULOUS DAILY HOOF CARE AND STALL HYGIENE
An important differential diagnosis for navicular bone fracture of
Bipartitie Navicular Bone (congenital abnormality) can result in chronic lameness and DIP joint OA. Normally lamer with fracture.
Cause of Navicular Syndrome
Palmer Heal Pain. No point cause or pathophysiology. No one cure. 1/3RD IF all forelimb lameness. Usually bilateral
Characteristic gait for Navicular Syndrom
Normally bilateral. 1/3 of all chronic forelimb lameness. 6-12 year old horses. Toe first gait. Toe elevation increase lameness?
Diagnostic approach to Navicular syndrome a) hoof testers b) nerve block
Toe elevation may increase lameness. a) Hoof testers: normally negative b) Positive response to Navicular bursa analgesia/ DIP joint analgesia.
Diagnostic plan for Osseous cyst-like lesions
Nerve blocks to verify significance. Normally midline but can get there near navicular bone and middle phalanx
5 types of Distal Phalanx fracture
Type I: Wing-non articular Type II: Wing-articular Type III: Sagittal Type IV: Extensor process Type V: Communuted Type VI: Solar margin
Type IV Distal phalanx fractures involve…
Type IV Distal phalanx fractures involve the DIP joint. Displacement by common digital extensor tendon
How do treatments for different types of Distal Phalnax fractures vary
Wing (Type I or II) - box rest for 6 months Midsag (Type III) lag screw/bar shoe Extensor process (Type IV) - Box rest 4-6 months and Arthrotomy for removal.
Treatment for Type VI Distal Phalanx fracture
Type VI= Solar margin. Bar shoe? Box rest for up to 6 months
Which type of Distal Phalanx fracture can have Laminitis as a complication
Communitured (Type V) Transfixation cast or Euthasnasia
How to prepare equine foot for radiograph
Prepartion vital for good radiographs- brushing or washing off dirt. Placement of marker on dorsal hoof wall, aligned with coronet. Shoe removal only essential if obscures region of interest. May compromise further lameness examination
Routine views for equine radiographs (4 views)
1) Lateromedial 2) Dorso-60deg-proximal palmarodistal oblique 3) Dorso-45deg proximal palmarodistal oblique 4) Palmaro-45-proximal palmarodistal oblique
How are radiographs named?
Point of entry to point of exit. e.g. Lateromedial. Radiograph taken side of foot towards contralateral limb.
Extensor process on Lateromedial radiograph
Commonly diagnosed as problem but there is a wide variation in anatomy between extensor process’ of the extensor process of p3 in clinically sound horses.
Chip fracture of the extensor process of p3 on radiograph DDx=
Secondary ossification centre? or chip?
Variations in normal radiographic anatomy.
Attachment of collateral ligaments of DIP joint.
Articular margin.
Also normal variation in extensor process’ of p3 in sound horses
Dorso-60-proximal palmarodistal oblique radiograph positioning….
Xray front of limb
Good view of the palmer process’, solar canal, solar margin
On the 60DP view (from front of leg). variations in normal radiographic anatomy include
Attachement of collateral lig of DIP joint (also lateromedial) and Crena differences (either flat or dip) both normal
Palmaro-45-proximal palmarodistal oblique radiograph aka
Flexor /Skyline view, taken from back of leg.
Can see Dorsal (Articular) Surface and Palmar (Flexor) Surface
Laminitis measures
Angle dorsal hoof wall and dorsal wall distal phalanx >15% = poor prog.
Prognosis measurements Lamintis
- hoof wall angle
- Founder distance
- Dorsal hoof wall thickness
Angle dorsal hoof wall and dorsal wall distal phalanx >15% = poor prog
Founder distance: >13 mm = indication of sinking.
Dorsal hoof wall thickness >3cm in horses, 2cm in ponies is indicator of chronic laminitis
What does this radiograph demonstrate
Severe laminitis.
Orange: Lucent line in dorsal hoof wall = seperation of lamina
Blue: Horizonal lucent line at coronet= Sinking
Red= Remodelling ‘‘slipper’ and fracture of solar margin
The only pathognominic radiological sign of navicular disease is
Flexor cortex erosions (mistaken for cysts)
DPrPaDi obl view
The metacarpophalngeal joint is normally permenatly hyperextended. What happens when there is pain in the limb?
Decreased with reduced weight-bearing (pain)
Also decreased with a fibrosed (stiff) tendon)
Pick up contralateral limb to make weight bearing
When would the metacarpophalangeal joint have INCREASED extension (is normally a permenantly hyperextended joint)
Decreased if pain/fibrosis
INCREASED with severe SDFT/SL injuries
ELEVATING TOE = DDFT rupture
An elevating toe is pathopneumonic for…(in horses)
DDFT rupture,.
Diagnosis of proximal suspensory disease
Lameness - often lamer with the limb on outside of circle - pain on palpation.
Normally inside leg that is ++ lame so proximal suspensory disease is exception
Suspensory Ligament Desmitis is most common in
Schooled horses
Hindlimb
Straight hock, overextending MTP joint
Desmitis of the accessory ligament of
the deep digital flexor tendon
-Where would you expect the swelling?
Clinical signs?
Swelling in the
proximal metacarpal
region
Dorsal to SDFT
Variable lameness, often absent!!
Ultrasonography: Generalised enlargement
Preceding tendon degeneration with superimposed sudden over-extension most commonly affects which tendons
SDFT and SL
C.F. Just sudden over extension normally DDFT?
Diagnosis of Suspensory body and branch desmitis
Variable lameness.
Ultrasonography - branches need imaging from medial and lateral aspects
Focal or generalised lesions, enlargement, periligamentar fibrosis common, bilateral involvement common.
Radiography: Conccurent bony abnormalities
DDFT Tendinopathy =
Usually within digital sheath or navicular bursa.
Examples of Intra-thecal tendon tears and where they normally occur
DDFT: Usually lateral border of FORELIMBS
Manica flexoria - usually HINDLIMB
3 types of Tenosynovitis
Dysfunction
- Digital sheath: Idiopathic distention, 2. Non-septic inflammation (primary or secondary)
- Penetrating injuries- sepsis
Where is the Annular ligament found?
fibrous band that wraps around the flexor tendons as they pass over the fetlock sesamoid bones on the palmar/plantar surface of the limb.
Annular ligament syndrome (ALS) is caused by a thickening of the annular ligament (can be primary or secondary)
Clinical signs of Annular Ligament Syndrome (ALS)
Lameness: Mild to moderate, minimally responsive to rest. Occasional irregular gliding of tendons (Annular ligament surroudns flexor tendons)
Distended digital sheath.
NOTCH AT LEVEL OF PAL. (at fetlock sesamoid bones on the palmar aspect)
Diagnosis of Annular Ligament Syndrom
ALS.
Ultrasonography >2mm thickness.
Notch at level of PAL.
3 stages of tendonitis
- Acute (inflammatory phase) 0-2 WEEKS - Minimise inflamm
- Subacute phase (fibroplasia) 1 week to 6 months - promote fibroplasia
- Chronic (remodelling phase)
Treatment for Tendonitis in subacute phase
1 week to 6 months.
Clinical signs: Reduction or absence of lameness, resolution of signs of inflamm, tendon still palpably enlrged and soft.
MOBILISATION: Early / Progressive (introduce trotting after 3 months)
Regular ultrasonographic monitoring
Treatment of tendonitis in acute phase
Application of cold ice
Compression
Rest
Short acting steroids (only within 24/48 hours)
CARE LAMINITIS
NSAID’s analgesia
What type of cells can be implanted to attempt to induce regeneration rather than repair
Scaffolds: ACell (lyophilised pig bladder submucosa)
MESENCHYMAL STEM CELLS.
Chronic cases of tendonitis CLINICAL SIGNS
3-18 MONTHS- Remodelling phase
Clinical signs: Tendon size decreases, tendon less pliable, reduced fetlock extenson.
Collagen transformation from III to I.
Treatment of Chronic phase of tendonitis
Surgery
Desmotomy of the accessory ligament of the superficial digital flexor tendon (Check ligament)
Extracorporeal shock wave therapy
Specific therapy for Proximal Suspensory Desmitis
Also Fasciotomy and Neurectomy for hindlimb PSD that has failed to improve after first two treatments
Prognosis for a) Manica flexoria tears
b) DDFT tears
a) Manica Flexoria tears= H/L: Good prog with removal
b) DDFT F/L Debridgment but poor prog.
Difference between Type 1 and Type 2 Distal interphalangeal joint flexural deformity
Type 1: Dorsal hoof wall less than vertical
Exercise/Physio/ Toe extension shoe, Desmotomy of ALDDFT
Type 2: Dorsal hoof wall past vertical
TYPE 2 = SURGURY NORM REQUIRED desmotomy of ALDDFT
Acquired- 6 months of age
Metacarpophalangeal joint flexural deformity.
Can be congenital or Aquired in yearlings.
Also secondary to chronc SDFT tendinopathy in adults
Treatment of Metacarpophalangeal joint flexural deformity
Exercise/physio
Toe extension and rasied heal shoe
Splint/braces
Surgery - desmotomy of ALDDFT/ ALSDFT/ SDFT
Fracture patient immediate chemical restraint =
a2 agonist: Xylazine, Detomidine, Romifidine
AVOID AVOID Phenothizine tranquilizers (ACP- hypotensive effects in the presence of circulating catecholamines)
How does the type of splint vary between lower limb cast on forelimb and hindlimb
Forelimb: Dorsal splint
Hindlimb: Planter splint (HP)
Distal carpus to Distal radius: Robert jones bandage with caudal and lateral splint for fore
Robert jones bandage with plantar and lateral splint for hind
Where would you find the tarsal crural joint
Equine hock between tibia and calcaneus.
Conservate management of Calcanean rupture in dog
NO
Only surgery 3 piece suture quicker than 2 piece.
Repair must be protected e.g. screw to take off pressure but still needs protection with cast.
Prog good if done promptly
Prognosis of common calcanean tendon repair
If digits are hyperflexed = superficial digital flexor intact.
Prog is good for soundless if done promptly and repair is protected with screw and cast for 6 weeks.
May reoccur in contralateral limb if secondary to degenertion of tendon
Presentation and test for common calcanean tendon
Calcanean tendon = extensor mechanism.
Radiograph (mediolateral): Periosteal new bone growth over calcaneus/ soft tissue swelling.
Affected hock LESS EXTENDED
Digits might be hyperflexed if superficial digit flexor intact
Which imaging modality is 90% effective at diagnosing navicular syndrome
MRI = Diagnostic in 90% of cases.
CT = little information on soft tissue
Also nuclear scintigraphy (high sensitivity/low specificity)
Ultrasound= limited use for feet
Typical presentation for Navicular Syndrome
1/3 of all chronic forelimb lameness.
6-12 year old horses
Taller, lighter breeds
Some evidence of hereditary traits
Usually bilateral
Insidious onset
TOE ELEVATION = WORSE
SOMETIMES TOE FIRST GAIT
What blocks for distal interphalangeal joint
- Dorsal midline approach
- Approach lateral/medial to extensor tendon
- Palmer/Planter approach
Navicular bursa block
- Midline- Navicular position horizonal approach
- Midline- Navicular position 30 degree oblique approach
- Lateral palmar/ planter approach
