Lecture 14: Laminitis Flashcards

1
Q

The ___phalanx is suspended by the laminae inside of a hoof capsule

A

Third

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2
Q

When the laminae of the foot are weakened by injury the normal forces on the digit cause ___

A

Shearing/tearing of the laminae which results in slipping of the digit inside the hoof capsule downwards and rotation from pull of DDFT

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3
Q

What are the clinical signs of laminitis

A
  1. Lameness (usually front feet)
  2. Stiffness
  3. Weight shifting
  4. Reluctance to move
  5. Worse on turns
  6. Increased hoof temp
  7. Increased digital pulses
  8. Sensitivity to hoof tester
  9. Hoof wall changes
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4
Q

What is a grade 1 on the obel grading scale

A

Shifting weight, but no apparent lameness at the walk, stilted trot

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5
Q

What is grade 2 for laminitis

A

Willing to walk but have stilted gait and can pick up foot if asked

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6
Q

Wha is grade 3 laminitis

A

Reluctance to ambulate resistant to having foot picked up

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7
Q

What is grade 4 laminitis

A

Horse reflexes to move, cant lift foot or down, can’t stand

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8
Q

What are some causes of laminitis

A
  1. Endocrinopathic (equine metabolic syndrome, Cushing)
  2. Enzymatic (SIRS, endotoxemia)
  3. Support limb overload
  4. Black walnut toxicity
  5. Steroid induced
  6. Heat induced
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9
Q

What model do we use to study endocrinopathic laminitis

A

Hyperinsulinemic model

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10
Q

What model do we use to study enzymatic associated laminitis

A

Starch overload

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11
Q

What is the pathophysiology of enzymatic laminitis

A

Accumulation of leukocytes in lamellar tissue, matrix metalloproteases are unregulated and cause basement membrane damage

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12
Q

What is the pathophysiology endocrinopathic laminitis

A

Lamellar epithelial cell stretching

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13
Q

What is the pathophysiology of support limb laminitis

A

Load cycling through walking or shifting weight when standing helps maintain blood flow to lamellar tissue, if not using one limb and offloading on others it will induce laminitis in the limbs that are supporting weight

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14
Q

How do you dx laminitis and describe procedure

A

Radiographs- stand horse on blocks and take lateral and DP views

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15
Q

What are some abnormal findings in acute laminitis radiographs

A
  1. Jet line- edema over laminae
  2. Possible to have no overt changes
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16
Q

What are some abnormal findings for chronic laminitis on radiographs

A
  1. Ski tipping of p3
  2. Loss of parallel between dorsal hoof wall and dorsal P3
  3. Medial to lateral asymmetry
  4. Sinking
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17
Q

What wrong and what do you see

A

Laminitis- not parallel, ski tipping, sinking

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18
Q

Where do you measure for founder distance and what is normal measurement

A

Coronary band to extensor process
Normal: 2-15mm

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19
Q

What does the founder distance determine

A

Presence of sinking if length increased

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20
Q

What does the Cobb angle determine

A

Rotation, hoof wall and dorsal P3 should be parallel

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21
Q

What is normal Cobb angle

A

0

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22
Q

What is the normal sole depth

A

15-20mm

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23
Q

What is normal dorsal wall thickness

24
Q

What is normal palmar angle

A

3-10 degrees

25
Identify the measurements indicated by the blue, purple, green, yellow, orange and black lines
blue: founder distance Purple: Cobb angle Green: wall thickness Orange: palmar angle Yellow: sole depth Black: bony alignment
26
which normal vs abnormal and what is wrong
Left: normal Right: laminitis
27
What are venograms
Vascular contrast study of foot
28
To do a venogram you inject radiopaque contrast into the ___to evaluate the arterial and venous structures of the digit
Palmar digital vein
29
With laminitis what does venogram look like
Venous compression and distortion of vascular structures
30
normal or abnormal
Normal
31
How do you perform a venogram
1. Abaxial block 2. Tourniquet above fetlock 3. Contrast injected into palmar digital nerve 4. Immediately a LM and DP rads taken 5. Foot is lifted for solar projection and then repeat LM and DP after being unweighted All films must be taken within 45 seconds of dye injected
32
What areas are evaluated in venogram
1. Terminal arch 2. Coronary papillae that make up coronary plexus 3. Sublamellar vascular bed 4. Circumflex vessels 5. Lamellar circumflex junction with terminal papillae
33
Identify 1-5 and red arrow
1. Coronary papillae/ coronary plexus 2. Sublamellar plexus 3. Terminal papillae 4. Terminal arch 5. Heel vessels Red arrow: circumflex vessels
34
Venograms are useful to determine ___ or ___
Progress or deterioration
35
A return to normal of a venogram within the first __weeks indicates an excellent chance for return to use
4weeks
36
Which normal vs abnormal
Left: abnormal- decreased blood supply Right: normal
37
What are the pharmacological treatments for acute laminitis
1. Phenylbutazone/ NSAID 2. DSMO 3. Pentoxyphylline 4. Acepromazine 5. Opioids- butorphanol/ fentanyl patches 6. Anticoagulant therapy- heraprin
38
What is dose for phenylbutazone to tx acute laminitis
2.2-4.4mg/kg IV or PO q12hrs
39
How does DSMO work
Free radical scavenger that aids in reduction of edema and may reduce ischemia
40
What is dose for DSMO to tx acute laminitis
0.1-1gram/kg IV q12-24 hrs diluted to <10% to avoid hemolysis
41
How does pentoxyphylline work
Phosphodiesterase inhibitor that alters RBC membranes to make them more deformable and improve blood flow. Also anti-inflammatory
42
How does acepromazine work to tx acute laminitis
Increases digital blood flow and relaxes them
43
What is dose for acepromazine to tx acute laminitis
0.03-0.06mg/kg IM or IV q6-8hrs
44
What anticoagulant can you give to tx acute laminitis and what does it do
Heparin- reduces micro-thrombi that may compromise vasculature in foot
45
What are some physiological treatments for acute laminitis
1. Farrier care- elevate heel with wedge, deep bedding, trim toes (maintain sole depth though) 2. cryotherapy 3. Frog support 5. Stall rest, lie down
46
You can perform a ___ for rotating laminitis (not sinking) as a salvage therapy
DDT tenotomy
47
What two structures do we need to reduce tension on when tx acute laminitis
DDFT (elevate heal) Suspension apparatus (stall rest)
48
What is the prognosis for acute laminitis
Wait and see if respond to tx Perform venogram
49
What ix tx for chronic laminitis
Farrier care and control underlying disease
50
What is most common cause of chronic laminitis
Endocrinopathic laminitis- Cushing or equine metabolic syndrome
51
What should farrier do to tx chronic laminitis
1. Realign bony column: remove excess toe and heel 2. Shortened cycle, every 2-4 weeks
52
what drug do you give to tx PPID/cushings associated laminitis
Prascend
53
What drugs do you give to tx insulin dysregulation causing laminitis
Metformin, levothyroxine
54
What diet should horses be fed to manage chronic laminitis
Low starch <10% NSC Caloric restriction for weight loss
55
What drugs can be given to tx chronic laminitis
NSAIDS 1. Phenylbutazone 2. Firocoxib
56
What is dose for firoxoxib when managing chronic laminitis
0.1mg/kg PO q24