Diseases of the foot Flashcards
What structures does the broken back hoof pastern axis stress and strain the most?
Navicular apparatus, DDF, dorsal hoof wall, heel region (prone to bruising, abscessing)
How should you compensate for a broken back conformation?
-Trim more toe than heel to improve axis, apply shoe to reduce toe lever and increase base of support
-wedge up the heel, ease breakover through modifying toe, provide larger shoe
What structures are under more strain with a broken forward hoof pastern axis?
Suspensory ligament, dorsal hoof wall, SDFT, distal sesamoidean ligaments
Describe a trimming/shoeing plan for the broken forward conformation associated with pathogenesis of suspensory ligament?
Wide toe, more narrow in heels (increases tension on DDF, decreases strain on SDF)
-or use fish tail bar shoe or egg bar (lever on heel to engage DDF to help support the fetlock)- works well in hindlimbs
Describe a treatment plan for a broken forward conformation due to club foot (congenital)?
Don’t lower heel! Will increase strain on DDF which already has too much strain
-physiologically strain DDF to encourage it to relax
-inferior check ligament desmotomy, or DDF desmotomy in severe cases
-requires vet/farrier team
What structures are under increased strain when there is a club foot?
Dorsal lamellae (can lead to mechanical laminitis), entire toe, entire P1 (also P2 and P3)
Describe a shoeing/trimming plan for a club foot deformity.
Ease breakover in toe region, lower heel (slightly), load frog and sole
-best addressed when young
Define wry foot
A distorted hoof capsule- deviating either medial or lateral
How should wry foot abnormalities be addressed?
Bar or extension on side that is more straight up (fill the triangle)
T/F: hoof is designed to expand in the heel region when limb is loading
True
What are some causes of wry foot?
base narrow horse
- will grow more straight on medial side, flare laterally on outside
-predisposes to quarter cracking and sheared heels
What does wry foot predispose to?
Quarter cracks due to increased stresses and strains on side more upright, as well as on collateral ligaments
Describe “sheared heels”
One of the heel bulbs is displaced proximally to the other
-predisposes to abscessation, quarter cracks
what is a good trimming/shoeing plan for wry foot?
Decrease load in more vertical heel (wider shoe, extension)
-make that side non-weight bearing-can put pad onto that side
What are some things you can do in terms of shoeing with thin soles or thin hoof wall?
Not much room for error with nails
-use glue on shoes!! -eliminate nails
What are some disadvantages of glue on shoes?
-Expensive, can trap dirt and bacteria in causing white line/abscess, need to have the skill set
-soft rides, rest
-wooden clog-cast on
-can create artificial hoof wall (very time and labor intensive)
What are the advantages/disadvantages of glue on shoes?
Expensive, less time consuming, more frequent replacements
T/F: you can glue on any shoe made to be screwed on
True
Should you be able to see the growth rings of a horses hoof?
Yes
What can disruptions to the rings on a horses foot be due to?
Disrupting diet, changes in environment
-should be parallel to coronet
-if wider at heel than toe- indication of laminitis or structural limb deformity
-wider growth rings on side growing faster
What causes solar bruising?
Thinning of sole, increased stress/strain in the area
-can be painful or non painful
-predisposes to abscesses
What are some of the treatment options for solar bruising?
Frog pad, heart bar, fit shoe wide with air in between it and the frog, pour in pad (soft)
What is thrush?
Bacterial infection of the epidermal portion of the frog
What are some disadvantages of using koppertox for treatment of thrush?
-Stains the horse, stains you
-caustic to the tissue, can lead to scarification and entrapment of bacteria underneath the upper layer
What are the recommended treatments for thrush?
Most importantly: change the environment (clean and dry)
-debride to healthy margins
-Can follow with topicals: Dry powders, betadine
-shoe/pad to act as 6-8 week bandage
Describe canker.
Infection affecting the germinal layers of the frog
- vascular growth pattern
-often a complication of thrush
What is the treatment for canker?
-surgical debridement after block with a tourniquet
-then treat topically (10% benzyl peroxide dissolved in acetone and crushed metronidazole powder)
-place in clean/dry environment
-place in hospital plate
Define a keratoma
Benign tumor of keratin producing cells of hoof wall
What is the classic presentation of a keratoma?
Chronic and Recurrent subsolar abscesses in one portion of the horses foot
-can also present as changes in the white line
-quarter cracks
What radiographic view is diagnostic for a keratoma?
65 degree DP
-will see disruption to distal phalynx with sclerotic rim around it
Describe the pathogenesis of why bone is degraded in keratoma cases
Pressure necrosis and resorption from the tumor growing between the hoof and the bone
What is the most aggressive treatment for keratomas?
Surgical resection-involves removal of entire hoof wall over area of tumor. Usually requires GA
-be sure to have support on opposing limb
-can also do window style resections- lower risks of cracking, earlier return to work, lower risk of excessive granulation tissue
What should you do to protect the foot after hoof wall resection for keratoma?
External fixation, sole support
Describe the conservative method for treatment of keratoma
Shoes and pads, keep area clean
How do you treat toe cracks?
Reduce toe lever, recruit sole and frog into load bearing
-debride the crack-reduce to healthy margins, rebuild and reinforce (fiberglass, vectran, polyester, equilox)
What are the properties of molding materials to support the hoof wall?
Stronger than hoof wall in tension and bend, not compression
How can you relieve compression forces on cracks?
Metal bars- aluminum, brass, steel over coronet
How do you deal with quarter cracks?
Treat underlying problem (angular limb deformation)
-rest
-if continuing work need to stabilize through debridement and patching
What structure does white line disease affect?
The non-pigmented stratum medium (aka NOT THE WHITE LINE)
-caused by opportunistic microbes that are keratinolytic leading to separation and crack formation
-wont become as lame as laminitis cases
How is white line disease treated?
Trimming and shoeing
-as long as you are foot is growing faster than microbes can grow
-need to expose microbes deep to all dirt and debris- must debride to healthy margins (bugs die when exposed to UV light and air)
-follow up with tinctures of iodine
-bandage/shoeing, think about opposite foot
What radiographic changes do you see with pedal osteitis?
Rim fractures of solar margin
-treat with shoes, pads, rest, NSAIDs
What should you do about hoof wall avulsions?
Debride, keep clean and dry
-otherwise can result in abnormal growth patterns
Is sidebone an actual disease condition?
No- as long as they don’t fracture
-due to ossification of collateral cartilages of distal phalanx
What is quittor?
Infection of the collateral cartilages, often secondary to puncture wound
-often waxes and wains
