Equine Hoof Flashcards
Is the forefoot or hindfoot generally larger
forefoot
-weight distribution
-shape of phalanx
Where is the hoof wall thickest
at the toe
What are the 3 hoof layers *
1) Stratum externum
2) Stratum medium
3) Stratum internum (contains interdigitation of laminae)
-Corial (sensative)
-Epidermal (insensitive)
What layer of the hoof has the interdigitation of laminae *
Stratum internum has corial (sensative) and epidermal (insensitive)
How fast do horse hoofs grow*
8-10mm per month (~12 months for the toe)
longer in cold or dry environment
What do transverse lines tell you
how long ago there was a insult with hoof forming
the weight-bearing structure in horses important for footing and needs good conformation to take weight off of the hoof wall
sole
a weight bearing strucuture in the horse that blends into the heel and is softer than the sole (50% water)
good indication of overall hoof health
frog
What structure in the horse’s hoof is a good indication of overall hoof health
frog
a shock absorbing structure in a horse’s hoof
between ungual (collateral) cartilages
made of connective tissue, adipose tissue, and cartilage
digital cushion
What cartilage is the ungual cartilage made of?
hyaline > fibrocartilage
ungual cartilages
hyaline > fibrocartilage
ossification
-side bones
-secondary centers of ossification
thinner in hind hoofs
What are the 5 normal forces in the equine hoof *
1) Tension directed toward wall laminae
2) Tension from DDFT
3) Downward compression from P2
4) Upward compression from the sole
5) Forces acting on extensior process; extensor branches of suspensory ligament; common digital extensor tendon
What is the difference between suspension system and support system of the equine foot
Suspension system: DDFT and lamina
Support system: sole, digital cushion, and wall
Describe the horse’s forces exhibited on foot impact *
1) Heel strikes first followed by bars, quarters, and toe
2) Concussion during impact is transferred from the distal phalanx to the stratum internum
3) Sole is slightly depressed as it counters the downward force
4) The frog acts with the sole to support the inner structures of the foot and to dissipate the force on the distal phalanx
5) Venous plexi are compressed forcing the blood into the digital veins
6) Venous plexu act as a hydraulic shock absorber
Concussion during toe impact is transferred from the _______ to the ______
distal phalanx to the stratum internum
the frog acts with the sole to
support the inner structures of the foot and to dissipate the force on the distal phalanx
what forces blood into the digital veins
compression of the venous plexi
venous plexi act as
hydralic shock absorbers
What are the goals of routine equine hoof care
preventative: balance, maintain healthy hoof structures
corrective: alterations to influence gait and conformation
therapeutic: protect/support an injured hoof
if you want to decreased pressure on the DDFT and laminae, you want the heel
high
If you want to take stress of the laminae, DDFT, and navicular bone do you want the toe to be long or short
short
T/F: the frog should not have contact with the ground
False- it needs to have contact with the ground
55% of the horse’s weight bearing needs to be behind the
extensor process
when should you shoe a horse
when the hoof wears faster than it grows
When should you trim vs shoe based on *
Based on:
-Genetics: hoof growth and horn quality
-Horse use/surface: traction and protection
-Owner preference
in general if the foot wears faster than it grows it needs a shoe
What time of year does the horse’s hoof grow slower in?
winter and dry
How often do you trim the horse’s hoofs *
every 6-8 weeks
more frequent to influence hoof conformation
Hoof growth is dependent on season, moisture, and diet
(take less of in the winter)
hoof care for farrier
goals for proper trimming/ shoeing - soundness of the hoof, can hoof hold nails
Correct angles (hoof pastern angles)
Correct toe length- long toe/low heel, club feet
if not take a radiograph
What does a broken forward horse mean
a horse that does not have >55% of weight bearing behind the lin drawn from the extensor process
angle of the hoof and pastern are not even
when should you start routine hoof care in foals
by 1 month of age unless there is an angular limb deformity (trim and balance)
What do reverse shoes “Bank Robber” shoes do
-Improve breakover
-Relieve pressure off of the toe
-Bring weight bearing backwards
inflammation of the lamina of the foot
systemic disease and clinical signs when the the lamellar tissue is already damaged
leads to failure of attachment between distal phalanx and hoof wall
laminitis
Laminitis leads to
leads to failure of attachment between distal phalanx and hoof wall
When are laminitis clinical signs noticed
when the lamellar tissue is already damaged
What is the clinical importance of equine laminitis
-painful condition
-terminate an athletic career
-life threatening
-economic losses to equine industry (diagnosis, tx, and loss of animal)
Why does the dorsal laminae have more issues than other parts of the laminae
mechanical forces
What are predisposing conditions to equine laminitis **
1) Endotoxemia
-GI tract (colic, grain overload, peritonitis, enterocolitis)
-Pleuritis/Pleuropneumonia
-Placentitis (retained placenta)/ metritis
2) Systemic metabolic dysfunction
- Cushing’s Disease (PPID), Metabolic syndrome
3) Non-weightbearing lameness
-Fracture/Septic synovial structure
What equine systemic metabolic dysfunctions can lead to laminitis *
Cushing’s Disease (PPID), Metabolic syndrome
What can cause endotoxemia and subsequent laminitis in horses *
-GI tract (colic, grain overload, peritonitis, enterocolitis)
-Pleuritis/Pleuropneumonia
-Placentitis (retained placenta)/ metritis
How might a non-weight bearing lameness lead to lamnitis in horses *
fracture of septic synovial structure
Deprivation of _____ can lead to laminitis
glucose
Why does glucose deprivation lead to laminitis *
Cells of the lamina preferentially consume glucose
-Lack of glucose
-Inflammatory response
-Release of MMPs
-Breakdown of basement membrane
What might traumatic/mechanical cause laminitis
-Road founder- concussive forces
-Support limb laminitis
-Injuries
In horses, is laminitis in the front or hind feet more common *
front feet > hind feet
Signs of inflammation seen with equine laminitis *
-heat
-increased digital pulses
-positive to hoof testers (pain) especially at the toe
What grading score is used for equine laminitis
Obel grading score
What are the stages of laminitis *
1) Developmental Stage- no lameness or clinical signs (horses at risk)
2) Acute- lameness, clinical signs. active separation of dermis from epidermis
3) Chronic- displacement of distal phalanx: chronic lameness, abscesses, abnormal hoof growth
What is seen in horses with development laminitis
no lameness or clinical signs (horses at risk)
What is seen in horses with acute laminitis
lameness, clinical signs. active separation of dermis from epidermis
What is seen in horses with chronic laminitis
displacement of distal phalanx: chronic lameness, abscesses, abnormal hoof growth
What diagnostics can you use for equine laminitis
1) Lameness evaluation +/- in chronic cases: hoof tester and nerve blocks (abaxial sesamoid) - might not do nerve blocks on acute
2) Radiographs (P3)- lateral and DP: assess vertical or rotational displacement and serial radiographs to assess progression
3) Venogram to assess blood distribution to P3
What radiograph views is important for assessing the progression of equine laminitis
lateral and DP of P3
used to assess distribution of blood flow of P3 for prognostic laminitis determination
venogram
What are the treatment goals of developmental laminitis *
-Prevention of clinical signs
-Treat systemic disease
-Remove inciting agent or prevent from reaching lamina (cryotherapy)
-Anti-endotoxin serum or plasma, anti-inflammatories, mineral oil/activated charcoal
-Sole support
In developmental laminitis, how might you remove inciting agent or prevent from reaching lamina *
cryotherapy
-distal limb icing to constrict circulation and stop the cytokine storm and cytokine release
-submerged in an ice and water slurry for a minumum of 48 hours
can be kept in the ice bath for a full week
-up to the level of the fetlock
What is the thought behind cryotherapy being used to treat laminitis *
-distal limb icing to constrict circulation and stop the cytokine storm and cytokine release
-submerged in an ice and water slurry for a minumum of 48 hours
can be kept in the ice bath for a full week
-up to the level of the fetlock
What are the treatment goals in acute laminitis *
1) Pain management (Phenylbutazone, DMSO, opioids, ice)
2) Increase perfusion (Pentoifylline, isoxsuprine) and heel elevation (to decrease the pull of DDFT)
3) Treat Wind-up (Gabapentin, acupuncture/chiropractic)
4) Prevent overload of hoof wall with sole support
YOU MUST SUPPORT THE FEET- minimizes laminae disruption- elevate heels and give support to frog
In acute laminitis cases, what can you do for pain management *
(Phenylbutazone, DMSO, opioids, ice)
In acute laminitis cases, what can you do to increase perfusion
1) Pentoifylline
2) isoxsuprine
3) heel elevation (to decrease the pull of DDFT)
In acute laminitis cases, what can you do to treat Wind-up
-Gabapentin
-Acupuncture/chiropractic
In acute laminitis cases, what can you do to prevent overflow of hoof wall
Sole support- decrease the strain on the lamina
-use sand substrate
-foam shoes
What can you do to decrease the pull of the DDFT *
Heel elevation
What are the treatment goals with chronic laminitis? *
1) Decrease tension on DDFT
2) Realign hoof-pastern axis
-normal mechanical forces on foot
-trimming
3) Treat systemic disease (Cushing’s, Insulin resistance, etc)
What surgery can be done for laminitis
Deep digital flexor tenotomy (cutting the DDFT)
-De-rotation and increase perfusion to the foot
What might hoof wall resection/ grooving do for laminitis
the hoof wall acts as a tourniquet for foot
removing hoof wall allows for perfusion of lamina
good for removing abscesses
How should you manage laminitis after treatment?
1) Dietary- decrease grain and legume content, methionine to provide better hoof growth
2) Exercise- depends on type of and response to therapy
In horses with laminitis what should you change in their diet
decrease grain and legume content, methionine to provide better hoof growth
What is the prognosis of equine laminitis
Depends on clinical signs - mild, moderate, and severe
response to treatment
guarded: some can do well and return to full function
What kind of horses does navicular disease typically occur
middle aged horses
quarter horses
small hooves and big bodies
Is navicular disease typically in the forelimb or hindlimb
forelimb lameness - often bilateral
Is navicular disease typically unilateral or bilateral
bilateral, typically forelimb lameness
What block do you do for chronic laminitis vs navicular disease
chronic laminitis- basilar or axial sesamoid block
navicular - palmar/ plantar digital block
What lameness is seen with navicular disease *
history of intermittent, shifting leg lameness and a short shuffling gait
What is navicular disease typically misdiagnosed as
shoulder lameness
How do you distinguish navicular disease *
history of intermittent, shifting leg lameness and a short shuffling gait
commonly forelimbs, although one of limbs may be more severely affected
when standing the horse will often “point” the most severely affected limb
if both limbs are equally affected, the horse will either alternately point the limbs or will stand with both front limbs held forward in the classical camped in front stance
-when moving the horse will often land on the toe, or flatly on the foot to avoid excess concussion
-horse will stumble at walk or trot
In horses with navicular disease, what will you see with a hoof tester examination
pain at the center of the frog and across the heels but its not always diagnostic
How might lameness from navicular bone disease be exacerbated *
turning the horse in a circle (inside leg most sore)
With navicular bone disease, does the foot change shape over time?
yes- change shape as the heels contract and the foot narrows across the quarters
How do you diagnose navicular bone disease*
depends almost completely upon clinical examination
typical histroy, gait, and hoof tester response
lameness often exacerbated when a 3/4” board is placed under the toe as it places more pressure on the DDFT and navicular area
How might you diagnostically make navicular bone lameness worse?
lameness often exacerbated when a 3/4” board is placed under the toe as it places more pressure on the DDFT and navicular area
local anesthesia for navicular bone dusease
1) PD nerve block- most diagnostic test, horses may become lame on other leg
2) DIP joint anesthesia (10-15 minutes)
3) Navicular Bursa Anesthesia (Dorsal to DDFT) for 5-10 min
What is the most diagnostic test for navicular bone disease
PD nerve block- most diagnostic test, horses may become lame on other leg
Why might the horse have failure to become completely sound after PD block
fibrous adhesions between navicular and DDFT
Possible arthritis of the coffin joint
accessory nerve supply sole bruising
concurrent traumatic arthritis of the fetlock
improper or incomplete anesthesia
T/F: diagnosis of navicular bone disease is made with radiology
FALSE- radiographic evidence of navicular disease may only be present in 40% of navicular cases and also in normal horses
make sure to remove shoes and clean foot well
pack sole
What are the radiographic abnormalities seen with navicular bone disease
-Enlarged vascular foramina
-Cysts
-thinning/roughening of flexor cortex or loss of corticomedullary junction
-impar ligament: evulsion fx sometimes
What is the best method for diagnosing navicular bone disease
MRI
What do you look for in ultrasound for navicular bone disease
hard to get visualization
-Collalteral ligaments DIJ
-DDFT
-Suspensory/collateral ligament of navicular bone
-Impar ligament
-Requires preparation
T/F: with navicular bone disease you need bony changes to make a diagnosis
false- use to think if the bone was okay everything was fine
underdiagnosed soft tissue injury
MRI especially has helped
treatments still very similar
How do you treat navicular bone disease *
1) Stall rest
2) NSAIDs
3) Trimming- correct the hoof pastern axis and balancing the foot
Increase the angle of the foot by raising the heel or shortening the toe to remove excess pressure from navicular bone
What should you consider when shoeing a horse? *
-Balance foot: dorsal-palmar and medial-lateral balance is really important
-Squaring or rolling the toe for easier and faster breakover
-Provide caudal, lateral, and medial support
-Shoe (wedge pad or shoe with wide web)
at least some type of corrective trimming and/or shoeing be performed before other therapy is begun
many horses will respond to balancing od diet
What should you do for medical management of navicular bone disease *
1) NSAIDs
2) Isoxsuprine hydrochloride
3) Injections (DIP and/or Navicular bursa) with Triamcinolone +/- sodium hyaluronate or IRAP
4) Bisphosphonates- but beware renal disease, colic . better if lame less than 6 months, problems with future bone healing
What are the issues with bisphosphonates for navicular bone disease *
1) renal disease, colic (No NSAIDs)
2) Fractures- problems with future bone healing
. better if lame less than 6 months,
What is used for injections of the DIPJ and/or navicular bursa to help treat navicular bone disease *
Triamcinolone +/- sodium hyaluronate or IRAP
-beware of abnormal mineralization with this, might want to use more natural
What can you do surgically to treat navicular bone disease
Navicular Bursoscopy
-Adhesions
-DDFT lesions
-Flexor cortex lesions
Palmar Digital Neurectomy
-Side effects of palmar digital neurectomy
-Loss of proprioception
What causes subsolar abscesses in horses *
rain
poor husbandry
very common
What are the clinical signs of subsolar abscesses in horses *
1) Mild to severe lameness “Fracture lameness” (insidious to acute)
2) Usually single limb
3) Digital pulses: bounding (R/o laminitis)
4) Hoof tester instability- can be blunted w hard soles
5) Drainage at coronary band
How do you treat subsolar abscesses? *
1) create ventral drainage
-hoof testers to guide
-black area on sole
-can rupture at coronary band if dont create ventral drainage
-nerve blocks help to pare out but might allow going too deep
2) Soak- hyperosmotic MgSO4/Salt
3) Bandage foot- keep debris out and allow tract to close, Boot/IV bag
4) Treatment plate for large abscesses
5) Tetanus toxoid
6) Exercise- some is good
What do you use to soak subsolar abscesses
hyperosmotic MgSO4/Salt
do not use betadine
What is the prognosis of subsolar abscesses in horses
acute lameness should improve once establish drainage
residual lameness if coronary band rupture
good to excellent prognoses
if recurrent abscesses- look for inciting causes with radiographs and MRI
How do you treat navicular syndrome vs subsolar abscess
1) Navicular syndrome: shoeing and medical managemetn
2) Subsolar abscess: create ventral drainage
Are subsolar abscesses in horses typically unilateral or bilateral
unilateral
