Laminitis Flashcards
What 3 things do you often see laminitis with?
SID (Systemic inflammatory disease)
Endocrine dz
Steroid administration
Which feet do you expect to see laminitis in first?
Front feet b/c bear more weight
If only one foot is involved, is it likely laminitis?
Not usually.
Exception is if horse is non-weight bearing on the other foot (eg. really bad musculoskeletal injury), so the sore foot has had extra weight for a long period of time.
What is the typical signalment of laminitis?
Older horses (not less than 1 yoa)
Why don’t young horses seem to get laminitis (3 things)?
They’re lighter
Don’t usually get significant displacement
Respond quickly to therapy so no long term consequences
What must you consider laminitis as?
A syndrome.
T/F: Laminitis is a secondary dz/complication of a primary dx.
True
What does laminitis have a high association with?
SIRS (systemic inflammatory response syndrome)
What 4 risk factors pre-dispose a horse to laminitis?
Obesity
Insulin Resistance (IR)
Hyperinsulinemia
Mild hypertriglyceridemia
What is the most common laminitis research model?
Sepsis laminitis
What are 3 causes for potential laminitis?
CHO overload (grain or oligofructose/fructans from luch green pastures) Black walnut extract (NEVER bed down on black walnut shavings) Intravascular insulin clamp (hyperinsulinemia with euglycemia)
What are the 3 broad etiology categories for laminitis?
Sepsis model
Endocrinopathies
Trauma/Excessive weight bearing
What are 2 possible divisions in the sepsis model?
Inflammatory
Vascular
What is the current thought on the sepsis model?
Sepsis associated mostly inflammatory
What is important to remember about the inflammatory branch of the sepsis model?
Will have vascular implications.
Changes to matrix metaloproteinases are responsibe for the controlled letting go of epithelium so hoof can grow. Excessive activation = detachment of lamina
What may cause matrix metalloproteins to become active?
Acute disease
What is the more heavily weighted theory of the sepsis model?
Vascular theory
What are the components of the vascular theory?
Vasoconstriction -> ischemia -> reperfusion -> compatmental syndrome -> localized DIC
What role might insulin have in laminitis?
Insulin resistance or high insulin disrupts glucose metabolism locally at lamellar epithelial cell and may precede the onset of clinical laminitis in susceptible animals
What does lamellar hypoxia cause an upregulation of?
MMPs (matrix metaloproteins)
What do MMPs (matrix metaloproteins) do?
Control letting go of epithelium so hoof can grow. Excessive activation = detachment of lamina
What 3 forces are involved in the mechanical disruption?
Shear forces (tissue sliding against each other) Vertical forces (weight through bony column of the foot) Tensile forces (pull from DDF)
What type of horse do you need to watch for major vertical forces?
QH (muscular horse on little tiny feet)
What two things affect the amount of vertical load?
Weight of animal
Size of foot
What does “rotation” refer to?
Aignment between dorsal wall of hoof and dorsum of P3
What is the prognosis for a horse with 0-5% rotation?
Can return to normal function
What is the prognosis for a horse with 5-10% rotation?
Can be managed and be comfortable
What is the prognosis for a horse with 10-12% rotation?
Not good
Where is the disconnect with rotational displacement?
Dorsal lamina
What 2 forces can the rotational displacement be attributed to?
Tensile force from the DDF
Shear from the dorsal hoof wall
Can cut the DDF, but athletic career will be over (horse probably still rideable)
What does “vertical displacement” refer to?
“Sinking” of P3 without rotating.
Where is the disconnect with vertical displacement?
Circumferential release of the lamina
What 2 forces can the vertical displacement be attributed to?
Shear from the hoof wall
Vertical from weight of animal
What happens over time in the case of rotational displacement?
DDF pulls P3 away from the wall more and more
What 5 things do you look at on a foot exam?
Stance and gait Heat, swelling and pulses in multiple feet Feel coronary band (heat and swelling) Hoof tester response External hoof exam
What do you expect to see with hoof testers on a laminitic horse?
Painful at toe
Can also be sore throughout sole, but that doesn’t confirm laminitis, can be sole sore without being laminitic
What is the most subtle clinical sign you will see with laminitis?
Weight shifting
If you use pedometers, can see 2-4 hours before you can visually note shifting
What stance do you see in a horse with laminitis in front feet?
Front limbs extended, resting on heel
What stance do you see in a horse with laminitis in all 4 feet?
Inverted tripod to get equal weight distribution
NOTE: These horses tend to “plant themselves” and not move
What gait do you see with a laminitic horse?
“Walking on eggshells”
How can you evaluate a horse for sinking or vertical displacement?
Run thumb down dorsum of pastern and try to get thumbnail under coronary band.
Should NOT be able to do this.
What is white line detachment?
A breakdown between the laminar interdigitations
If one foot is more affected that the other, what 2 things will you see in bahviour and stance?
More affected foot will be ore forward
Difficulty picking up the LESS affected foot
How do you determine the agree of rotation?
Measuring the degree of the angle formed on xray between the dorsum of the hoof wall and the dorsum of P3
What is the normal distance between the dorsum of the hoof wall and the dorsum of P3?
less than 18mm
Can you evaluate “sinking” on n xray?
Can look at distance between coronary band (marker) to top of P3, but there is a lot of range for “normal”
What 3 radiolucent densities might you see in a laminitic foot on RADs?
Air (could be just air from an opening OR gas from bacteria)
Serum (seroma)
Hemorrhage (won’t be as dark because has more density than serum or air)
What will happen if you have complete detachment of the lamina?
Horse will walk out of hoof. Can grow new hoof, but takes close to a year so difficult to manage.
What are the 4 stages of laminitis?
Developmental
Acute
Sub-acute
Chronic
Describe the developmental stage of laminitis.
No clinical signs
Describe the acute stage of laminitis.
Clinical signs present, NO mechanical disruption, short time (~72 hours)
Describe the sub-acute stage of laminitis.
Clinical signs present, NO mechanical disruption, longer time
Describe the chronic stage of laminitis.
Clinical signs WITH mechanical disruption
NOTE: Time can be within 24 hrs
What are the 3 radiographic markers to check for laminitis?
Dorsal hoof wall (rotation)
Coronary marker (distal displacement)
Tip of frog (used to determine specific location of P3)
What can you use on the hoof to help counter the pull from the DDF?
Heart bar shoe
What is the scoring system that grades lameness associated with laminitis?
Obel Scoring System
What are the 4 Obel grades of lameness associated with laminitis?
I - Constantly lifts feet, no lameness walking, short gait trotting
II - Will walk, but gait is laminitis
III - Reluctant movement, resists lifting forefoot
IV - Must be forced to move
What are the 5 clinical scoring grades of lameness associated with laminitis?
CS-1 - Return to full athletic fxn
CS-2 - minimum pleasure riding
CS-3 - Cannot be ridden, can be bred or left on pasture with minimal analgesics
CS-4 - Needs systemic analgesics
CS-5 - Euthanasia d/t severe unresponsive pain
What can be used to identify perfusion deficits?
Digital venogram
What prognosis does a perfusion deficit indicate?
Poor
What are the 2 treatment generalities for laminitis?
Address systemic nature of dz
Specifically treat the feet
What is treatment of laminitis related to?
Treatment of endotoxemia
What is the number 1 therapy for laminitis?
Cryotherapy
How do you specifically address and treat the feet?
Cryotherapy
What is the best therapy in the developmental stage?
Cryotherapy
What is the mechanism of action for cryotherapy?
Helps slow down metabolism in the epithelial cells to match the decreased perfusion and minimize the glucose dysregulation
What do you want to promote in laminitis?
Digital perfusion
What are 3 drugs you can use to promote digital perfusion?
Acepromazine
Isoxuprine
Nitroglycerine
NOTE: Very small dose of ace.
NOTE: Isoxusprine usually used for navicular dz
NOTE: Nitro may not be all that helpful
What should you do with an endotoxemic horse that you wan tto use Ace on?
Stabilize cardiovascular
Why should you not give steroids to a laminitis horse?
Because steroids can e a cause of laminitis/make it worse.
What is a very important component in treatment of laminitis?
Analgesics because pain is associated with spasms of the DDF.
If you use Flunixin and Pheylbutazone together, what must you do with the doses?
Considder them as one drug and be careful not to overdose.
What would you worry about with using Flunixin and Phenylbutazone together for a long time?
GI Ulcers
How does a CRI of lidocane help treat laminitis?
It helps limit damage by decreasing production of chemokines and inflammatory mediators
What are two types of local therapy to help treat laminitis?
Bedding (bed them deeply)
External support to the hoof
Will the laminae reattach once they’ve separated?
Nope!
What does a “lily pad” do in a case of laminitis?
Supports the heel and frog
What is the purpose of taping a gauze roll to the foot?
Support
What type of construction styrofoam is the best for support?
Pink stuff because it has the best density without causing pain
What is another benefit to using styrofoam on horses with laminitis?
If they also have a subsolar abscess, you can dig out the parts where you don’t want them to bear weight
When placing styrofoam for support, you expect the horse to walk off funny, but when do you decide to try a different support option?
If animal is still really uncomfortable after a few hours
What is an EDSS?
Equine Digital Support System
What 3 things does an EDSS incorporate?
Frog support
Wedge (to relieve tension fro the DDF)
Easier breakover
When is a DDF tenotomy indicated?
Rotated more than 12 degrees in first 30 days
Extensor process distal 1cm in first week
Unresposive
Chronic where other methods unsuccessful
What does the functional outcome correlate to?
Clinical grade
What does the functinoal outcome NOT correlate to?
Degree of rotation and distal displacement
Which horses have a worse prognosis?
Those with distal displacement
