Exam III - Normal Hoof Care and Hoof Conditions Flashcards
Hendrickson
What are the three layers of the hoof?
The sensitive laminae is the continuation of periosteum of the coffin bone.
Insensitive laminae interdigitates with hoof wall.
3 hoof layers:
§ Stratum externum
§ Stratum medium
§ Stratum internum:
§ Interdigitation of
laminae:
§ Corial – Sensative
§ Epidermal -
Insensitive
Feet grow slow. How slow?
Depends on where you live, time of year…
Growth occurs at 8 - 10 mm per month
§ ~12 months for the toe
§ Longer in a cold or dry environment.
n Transverse lines
average sized quarter horse could take a full year to grow from coronary band to ground. Coronary band history (trnasverse lines) can be told on the foot…
When does a horse “need” a shoe?
It’s owners preference bu, if you are asked: In general if the foot wears faster than it grows it needs a shoe
There are five main forces we deal with in the horse’s foot, what are they?
- Tension directed towrd the wall laminae (the wall attached all the way around the coffin bone)
- Tension from the DDFT, there is an oppoing force on the other side and it is tested when the toe is overgrown…
- Downward compression from P2
- Upward compression from the sole
- Forces acting on extensor process; extensir branches of the suspensory ligament; common digital extensor tendon (remember, extensor tendons only have one job, not that strong)
What structures are involved in the suspension and support system?
Normal Forces: Redden
The suspension system involves the DDFT and lamina.
The support system involves the sole digital cushion, and wall.
What forces are exhibited on impact in the equine foot?
the heels strike first, followed by the bars, quarters, and toe.
concussion during the impact is transferred from the distal phalanx to the stratum internum.
The sole is slightly depressed as it counters the downward force.
the frog acts with the sole to support the inner structures of the foot, and to dissipate the force on the distal phalanx.
the venous plexi are compressed forcing the blood into the digital veins.
the venous plexi act as a hydraulic shock absorbers.
you are assessing a horse’s balance and realize that it has broken back (in the foot), when would it be contraidicated to trim the toe to fix this problem?
sometimes you have to trim the heel becasue sometimes it will draw the toe forward instead of up.
What are some predispoing conditions to laminitis in a horse?
Endotoxemia (examples could be from the GI tract where we have colic, grain overload, pertionitis, enterocolitis). glucose deprivation: the cells of the lamina preferentially consume glucose, with a lack of glucose comes and inflammatory response, the release of MMPs and the breakdown of the basement membrane.
systemic metabolic dysfunctions like cuching’s disease, PPID, and metabolic syndrome.
For non-weightbearing lamenss we know we are talking about fractures which could also include a septic synovial structure
What are the clinical signs of lameness in the horse and some diagnostics to check?
front feet> hind feet
signs of inflammation: heat, increased digital pulses, positive to hoof testers (pain) especially at the toe.
in chronic cases we can use a hoof tester and nerve blocks (abaxial sesamoid). we wouldn’t block in an acute lameness in this case because we don’t want the horse using the foot. we obviously have radiographs and there is a venogram which assesses the blood distribution to P3
The treatment varies for developmental, acute, and chronic lamin itis cases. What are some of these differences?
In developmental, you want to prevent clinical signs, so you treat the systemic disease, remove inciting agent or prevent from reaching lamina (cryotherapy), give anti-endotoxin serum or plasma, anti-inflammatories, mineral oil/activated cahrcoal (I’m assuming thats for a case with colic), and give the sole support.
In acute laminitis, they are painful, give the some pain maangement, increase perfusion to that foot (heel elevation, no support for clinical methods yet), treatb wind-up (gabapentin, acupuncture/chiropractic), and prevent oberload of the hoof wall (with sole support)
for chronic lamintis, decrease tension on the DDFT (like de-rotation or increasing perfusion to the foot), realign the hoof-pastern axis (the hoof wall actas as a tourinquet for the foot, maybe removing the hoof walla allows for perfusion of the lamina, and of course remove asbscesses), think about the normal mechanical forces on the foot, maybe it needs trimming, and treat the sytemic disease (cushing’s, insulin resistance)
What is navicular disease/syndrome?
what is the usual signalment?
it’s caudal heel pain
it’s a bilateral forlimb lameness in middle-aged horses that can be treated with shoeing and medical management.
Navicular disease/syndrome i.e. caudal heel pain, causes a lameness where the will often land on the toe, or flatly on the foot to avoid excess concussion. the horse may also stumble at the walk or trot. 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.
The horses foot anatomy can also change over a long period of time due to lesser use, the heels contract and the foot narrows across the quarters.
Signalment:
n Middle Aged horses
n Quarter horses
n Small hooves, big bodies
n Forelimb lameness
§ Often Bilateral
How can navicular diease be treated or managed?
after diagnosis (clincal exam, local anesthesa, etc.) and confirmations with imaging, the most conservative treatment is stall rest, non steroidal therapy, trimming, and shoeing and corrective trimming should be done before other therapies are considered.
Medical management includes NSAIDs, Injections in the DIPJ or navicular bursa of triamcinolone +/- sodium hyaluronate or IRAP, and biphosphonates which come with side affects like renal disease,= and colic. It is better to use if the horse has been lame for less than 6 months or if there are problems with future bone healing. Biphosphanates are contraindicated due to their nature to increase the likelihood of fractures and keeping bones from being absorbed therefore it is not used in young horses or thorough breds.
Before treating a horse for an abscess, what must you do? What are the treatment options?
rule out a fracture
these horses are very painful, sometimes you can see a drainage at their coronary band. create a ventral drainage, can prevent the coronary band rupture, careful if using nerve blocks so you do’t pare out too deep and soak the foot in hyperosmotic solution - MgSO4/salt. bandage the foot, put on a plate, give a tetanus toxoid, and some exercise is good
