Laminitis

Question 1

What is laminitis?

Answer 1

Inflammation of the soft tissue of the hoof

Question 2

What is the laymens term for laminitis?

Answer 2

Founder- typically refers to the chronic process

Question 3

What is the classic experimental model for laminitis?

Answer 3

CHO overload

Gave rise to the Obel lameness grading system

Question 4

T/F: Laminitis has specific sex and breed predilections.

Answer 4

No- some correspondence to weight to foot size though

Question 5

T/F: Laminitis is typically not seen in young animals.

Answer 5

True

Question 6

What are some classical signs of laminitis?

Answer 6

Heat in feet, palpable digital pulses, splayed stance

Question 7

Do younger or older animals typically respond better to symptomatic laminitis therapy?

Answer 7

Younger- in older animals it’s typically a secondary condition and symptomatic treatment will not be as effective

Question 8

What are some primary causes of laminitis?

Answer 8

Sepsis, endocrinopathies, trauma (road founder)

Question 9

What plant toxicity discussed is known to cause laminitis?

Answer 9

Black walnut extract

Reasons why dark wood bedding is avoided in stables

Question 10

What poundage of grain at one time may result in CHO overload syndrome?

Answer 10

> 4lb

Question 11

Grazing what kind of pastures can result in development of laminitis?

Answer 11

Lush green pastures, higher non-structural CHO content

Question 12

What are some sepsis related causes of laminitis?

Answer 12

Endotoxemia, SIRS, GI disease, black walnut toxicity, CHO overload

Question 13

What kind of endocrinopathies can result in laminitis?

Answer 13

Anything in results in an increase in circulating glucocorticoids

PPID, equine metabolic syndrome, exogenous administration

Question 14

What is road founder syndrome?

Answer 14

Non-weight bearing lameness in one foot causing excessive concussive force on the contralateral foot

Question 15

What is the pathophysiology of laminitis?

Answer 15

Structural failure of the attachment between the epidermal laminae and the dermal laminae resulting in the loss of suspension of the foot within the hoof

Question 16

T/F: Laminitis may be associated with systemic illness or with local factors.

Answer 16

True- stress, concussive forces, endotoxin, steroid use, trauma, etc

Question 17

T/F: Regardless of the cause, the process and end result of laminitis is the same.

Answer 17

True

Question 18

Why does SIRS cause laminitis?

Answer 18

• Leukocyte infiltration/migration to laminae
• Uncontrolled activation of metalloproteinases
• Vasculitis

Question 19

What enzymes are directly involved in controlled detachment of laminae as required for normal hoof growth?

Answer 19

Matrix metalloproteinases

Question 20

What is the vascular hypothesis towards the development of laminitis?

Answer 20

Initial development of reduced perfusion and digital ischemia followed by constriction of digital circulation culminating in the development of lameness

Question 21

T/F: According to the vascular theory, any vascular issues are secondary to inflammatory mediators.

Answer 21

True

Question 22

What clinical signs of laminitis support the vascular theory?

Answer 22

Reflex hyperemia and development of increased hoof temperature

Question 23

What manifestations of compartment syndrome are found in laminitis?

Answer 23

Development of edema, swelling, and cell death which can be self-perpetuating

Question 24

Is there experimental support for reperfusion injury implicated in laminitis?

Answer 24

Yes- production of oxygen free radicals that contribute to cell death and inflammation upon reperfusion of a hypoxic environment

Question 25

What denotes the development of a chronic laminits?

Answer 25

Structural failure- earliest signs are microscopic and can develop into a gross lesion and clinical disruption

Question 26

Why is hyperinsulinemia theorized to contribute to development of laminitis?

Answer 26

Results in the sensitization of the structures of the hoof so that they are at increased risk for laminitis

Question 27

Could hyperinsulinemia be a contributer to the pathophysiology of sepsis and endotoxemia?

Answer 27

Yes

Question 28

What is though to be central to the mechanism of endocrinopathies in causing laminitis?

Answer 28

Glucose metabolism dysfunction

Question 29

T/F: Hyperinsulinemia also results in vascular dysfunction which can contribute to inflammatory mechanisms of laminitis.

Answer 29

True

Question 30

What are some proposed causes of traumatic laminitis?

Answer 30

- Traumatic tearing of tissues - Traumatic induced vasospasm - Tissue fatigue and vasocompression (in unilateral weight bearing)

Question 31

What are the major forces involved in disruption of the laminae?

Answer 31

Vertical load, shear forces, tensile forces, and solar fulcrum

Question 32

What is the dominant factor for displacement?

Answer 32

Vertical load

Question 33

What is the vertical load dependent on?

Answer 33

Weight of the horse and the size of the foot Heavier horses with smaller feet have an increased vertical load which may predispose them to laminitis

Question 34

What is rotational displacement mostly attributed to?

Answer 34

Tensile forces from the pull of the deep digital flexor on P3

Question 35

What contributes additionally to rotational displacement of the hoof?

Answer 35

Lack of sufficient dorsal hoof dermal-epidermal interface

Question 36

T/F: The heel growing faster than the toe has a tendency to make heel lengthen and causes flexion of distal interphalangeal joint

Answer 36

True

Question 37

What type of displacement has a poorer prognosis: vertical or rotational?

Answer 37

Vertical

Question 38

T/F: Vertical displacement is often associated with damage/disruption throughout the entire foot.

Answer 38

True

Question 39

Is P3 typically in a fairly normal position in vertical displacement?

Answer 39

Yes

Question 40

In what kind of displacement is it possible for a horse to entirely lose a hoof?

Answer 40

Vertical displacement

Question 41

What is typically the presenting complaint in laminitis?

Answer 41

Lameness and reluctance to move/walk

Question 42

What is the typical stance in acute laminitis cases?

Answer 42

Standing in one place continually shifting weight with the front feet forward and more weight loading on the heel

Question 43

T/F: Variation of stance does occur depending on severity and number of feet involved.

Answer 43

True

Question 44

What is the stance of a horse with all four feet affected with laminits?

Answer 44

All four feet are under belly

Question 45

Is single foot involvement very rare?

Answer 45

Yes

Question 46

What is the most common situation where only one foot is involved?

Answer 46

Non-weight bearing injury to the contralateral limb

Question 47

What situation will present with the most normal stance?

Answer 47

In very severe cases, especially if it's sinking or mechanical collapse

Question 48

What is the typical gait of a laminitis horse?

Answer 48

"Walking on eggshells" Accentuated when on uneven or hard surfaces, esp. gravel

Question 49

T/F: Laminits horses are very reluctant to turn or rotate.

Answer 49

True, may be the only sign in very subtly effected horses

Question 50

What is a useful exercise to assess improvement and therapy in a recovering horse?

Answer 50

Turning/circling

Question 51

What is the typical pattern of involvement for laminitis?

Answer 51

Both forelimbs

Question 52

Clinical signs may not be as dramatic in what presentation of laminitis?

Answer 52

Hindlimb

Question 53

Hindlimb laminitis is typically associated with severe or mild systemic illness?

Answer 53

Severe systemic illness- CS may not be as severe though

Question 54

What are some strategies to diagnose laminitis?

Answer 54

1. General physical exam 2. Lameness exam 3. Limb/foot exam 4. Radiography

Question 55

Digital pulses can only be palpated in what kind of horses?

Answer 55

Abnormal horses

Question 56

What is the typical pulses you're able to palpate in a laminitis case?

Answer 56

Strong bounding digital pulses

Question 57

Why is checking for pulse symmetry important?

Answer 57

To ensure that the condition is affecting multiple feet and to assess severity

Question 58

T/F: Laminitis is the only condition that creates palpable digital pulses.

Answer 58

False- solar abscesses, penetration wounds, etc

Question 59

What happens to the temperature of the hoof in a laminitis case?

Answer 59

Increases

Question 60

What pathology occurs at the coronary band?

Answer 60

Swelling and edema in severe cases

Question 61

What is an indication of sinking at the coronary band?

Answer 61

Depression when palpated with the thumb

Question 62

Where is pain typically detected in laminitis cases?

Answer 62

At the toe May have positive test on the sole area if coffin bone is penetrating

Question 63

T/F: Hoof testers are very specific for laminitis.

Answer 63

False- many horses will respond diffusely

Question 64

What is the most important thing to assess radiographically to determine severity/prognosis of a laminitis case?

Answer 64

Coffin bone position relative to the hoof

Question 65

Should radiographic changes be evaluated regularly on active cases?

Answer 65

Yes

Question 66

Are radiographic changes closely linked to prognosis?

Answer 66

Yes

Question 67

Where is the most typical place to put a marker to assess laminitis radiographically?

Answer 67

On the dorsal wall of the hoof on lateral view

Question 68

How do you evaluate rotation on a radiograph?

Answer 68

Compare the angle of the coffin bone to the angle of the dorsal wall of the hoof Can also measure the distance for the hoof wall to the dorsal surface of the coffin bone at repeated sites and comparing

Question 69

What does marking the tip of the frog assess?

Answer 69

Gives you the relationship between the coffin bone and the tip of the frog in order to properly fit corrective shoes

Question 70

What are the four phases of a laminitis case?

Answer 70

1. Developmental 2. Acute 3. Subacute 4. Chronic

Question 71

What is the developmental phase?

Answer 71

Time spanning from the occurence of the causative event/illness and development of identifiable lameness aka PRIOR to clinical sign development

Question 72

What is the goal of intervention during the developmental stage?

Answer 72

Prevent development rather than treat affected patient

Question 73

What is the acute phase?

Answer 73

Begins with the first identifiable typical CS and ends after the development of either 1. 72 hours without physical/radiographic evidence of progression or 2. development of mechanical digital collapse which can occur in less than 24 hours

Question 74

What is the goal of intervention during the acute phase of laminitis?

Answer 74

Limit the severity to optimize progression into subacute as opposed to chronic

Question 75

What is the duration of the subacute phase of laminitis?

Answer 75

Can be variable ranging from days to months/years

Question 76

What is the minimum duration of the subacute phase?

Answer 76

8-12 weeks typically

Question 77

What is happening with the foot of the horse during the subacute phase?

Answer 77

The hoof is healing but still weakened and prone to structual failure

Question 78

T/F: Most horses in the subacute phase of laminits make a full recovery.

Answer 78

True

Question 79

What is the goal of intervention during the subacute phase of laminitis?

Answer 79

Limit progression into the chronic phase of the disease Ie prevent mechanical disruption in a compromised hoof

Question 80

What is the determinant of the chronic phase of laminits?

Answer 80

Mechanical disruption and collapse

Question 81

T/F: The chronic phase of laminits can occur during any stage of the disease.

Answer 81

True, in serious cases it can occur during the first 24 hours

Question 82

What are the two types of mechanical disruption that can occur in the hoof?

Answer 82

Rotational and vertical dispacement

Question 83

Do horses in the chronic phase ever fully recover?

Answer 83

No

Question 84

What is recovery and treatment based on during the chronic phase of laminitis?

Answer 84

Severity of collapse and clinical signs

Question 85

What is the chronic phase most often associated with?

Answer 85

Vascular insufficiency, localized sepsis, metabolic and growth dysfunction

Question 86

What is the goal of intervention during the chronic phase?

Answer 86

Rehabilitation- full recovery is usually never attained once horses are in the chronic phase

Question 87

What is an important to consider with treatment no matter what phase of laminitis the horse is in?

Answer 87

The inciting cause of the laminitis

Question 88

T/F: Replacing or removing the shoe on a horse with laminitis will help with treatment and recovery.

Answer 88

FALSE- any manipulation of the hoof can severely worsen the condition and as such shoes should be left alone during treatment

Question 89

What is an important aspect of treatment of laminitis no matter what the cause?

Answer 89

Pain management and reduction of inflammation

Question 90

What does the promotion of digital vascular perfusion do to aid in treatment and recovery?

Answer 90

1. Limit edema 2. Promote vasodilation in developmental phase 3. Normalize digital perfusion in later stages

Question 91

What drug is used at the coronary band to help reduce inflammation?

Answer 91

DMSO- helps with reduction of local edema

Question 92

What is nitroglycerine used for in laminitis treatment

Answer 92

Over saved PD arteries in oder to promote vasodilation

Question 93

What other vasodilatory agents are used during the developmental stages?

Answer 93

Acepromazine, isoxuprine, l-arginine

Question 94

Isoxuprine is typically used in what modle of laminits?

Answer 94

Navicular model Effectiveness is questionable

Question 95

T/F: Pentoxyfiline is used to help promote digital perfusion/

Answer 95

True

Question 96

What is the benefit of ice baths in the treatment of laminitis?

Answer 96

Promote local vasoconstriction and prevents infiltration of pro-inflammatory mediators

Question 97

Is digital support always beneficial in laminitis cases?

Answer 97

No- depends on severity and stage

Question 98

What are some non-invasive support techniques?

Answer 98

- Deep soft bedding - Styrofoam insulation - Rolled gauze taped to foot over frog area - Cast padding booties

Question 99

What are some shoeing/invasive support techniques?

Answer 99

- Egg bar shoe - Heart bar shoe - Elevated heel shoe - Equine digital support system - Redden shoe

Question 100

What is the ultimate goal of the treatment of laminitis?

Answer 100

Limit progression of collapse

Question 101

What are some choices for treatment if collapse does occur?

Answer 101

- Dorsal hoof wall resection - Heart bar shoe - EDSS - Redden shoe

Question 102

What are some determinants of prognosis?

Answer 102

1. Cause 2. Finding on physical and diagnostic evaluation 3. Response the therapy

Question 103

What is an indicator for grave prognosis?

Answer 103

Sinking (vertical displacement)

Question 104

Does the long-term outcome correlate well with degree of rotation?

Answer 104

No

Question 105

Is clinical assessment or radiographic findings more reliable means to determine final outcome?

Answer 105

Clinical assessment