Laminitis

Question 1

what is laminitis

Answer 1

degeneration then failure of interdigitation between P3 and inside of hoof wall —> breakdown and separation

Question 2

How are laminae made up

Answer 2

Dermal lamellae (P3) and epidermal lamellae (hoof) are strongly bonded

Question 3

Name 2 endocrine cause of laminitis

Answer 3

obesity/ equine metabolic syndrome
Pars Pituitary intermedia dysfunction (PPID)

Question 4

what occurs in equine metabolic syndrome

Answer 4

Increased bodily fat reduces the cellular response to insulin – insulin resistance / dysregulation
This causes more insulin to be released
excess insulin in blood stream stimulates excess MMP production increasing risk of laminitis

Question 5

how does increased insulin lead to increased MMP production

Answer 5

not understood

Question 6

How does PPID lead to laminitis

Answer 6

Excess Adrenocorticotrophic hormone (ACTH) also causes hyperinsulinaemia
stimulates excess MMP production increasing the risk of laminitis

Question 7

List some non-endocrine causes of laminitis

Answer 7

toxic - compromised bowel or sever infection
support limb laminitis
corticosteroid induced
stress

Question 8

Describe how severe infections lead to laminitis

Answer 8

Bacterial endotoxin enters the blood stream – endotoxaemia
MMP production is increased

Question 9

Describe support limb laminitis

Answer 9

Severe lameness in 1 limb causes excessive weight bearing in contra-lateral limb–> reduces blood flow to laminae causing hypoxia –> inflammation and MMP production
therefore support limb laminitis is often unilateral

Question 10

Describe the importance of MMP in laminitis

Answer 10

MMP are catabolic enzymes
they release the bond between dermal lamella (P3) and epidermal lamellae (hoof)

Question 11

how can corticosteroids administration lead to laminitis

Answer 11

exogenous glucocorticoids
Induce hyperinsulinaemia and subsequent increase MMP production as above
Risk greater in animals that are already susceptible

Question 12

describe how stress can lead to laminitis

Answer 12

endogenous glucocorticoids increase- due to fight/ flight situation
Induce hyperinsulinaemia and subsequent increase MMP production as above
Risk greater in animals that are already susceptible

Question 13

describe the signalment of laminitis

Answer 13

age- no consistent predisposition
breed- occurs in all breeds of horse but native breeds/ ponies predisposed
sex- no predisposition

Question 14

when is the peak incidence of equine laminitis

Answer 14

spring and autumn
linked to grass growth
but can occur all year round

Question 15

what signs in the horses stance suggest laminitis

Answer 15

leaning backwards
weight shifting

Question 16

List 4 signs of PPID

Answer 16

hirsuitism- long curly winter coat
decreased muscle mass
‘pot belly’ appearance
supra orbital fat pads become more evident

Question 17

List 2 signs of EMS

Answer 17

excess body condition
abnormal fat distribution

Question 18

which limbs does laminitis generally affect

Answer 18

often affects both front limbs
May be all 4 limbs, just 1 limb or just the hind limbs

Question 19

List 2 signs of laminitis in the foot

Answer 19

increased digital pulse
hooves warm to touch

Question 20

what on the foot can suggest severe laminitic disease

Answer 20

Depression at coronary band and loss of concavity of sole (sinking of the pedal bone )

Question 21

what do you look for on limb specific exam in laminitis cases

Answer 21

Visible growth rings indicate previous episodes
Able to lift legs
often show pain to hoof testers at point of frog
Depression at coronary band and loss of concavity of sole suggest severe disease (sinking)

Question 22

describe what we see on dynamic exam with laminitis

Answer 22

Degree of lameness varies
Usually worse when turning and on hard ground
Foot lands heel first to spare the toe region from weight bearing
Sometimes show a high stepping gait with hind limb laminitis.

Question 23

what 2 radiographs are taken when investigating laminitis

Answer 23

latero-medial view
dorso-palmar view

Question 24

describe the limits for rotation of the pedal bone on radiography in laminitis

Answer 24

<5 mild
5-10 moderate
>10 severe

Question 25

List the 2 ways to test for EMS

Answer 25

baseline insulin (serum) oral sugar challenge test

Question 26

describe the baseline insulin (serum ) test

Answer 26

Feed only hay / grass for 12 hours prior Positive result (increased baseline insulin) is diagnostic for EMS Negative result (normal baseline insulin) does not rule the disease out – lots of false negatives

Question 27

Describe the oral sugar challenge test

Answer 27

Feed only hay / grass for 12 hours prior Feed Karo light corn syrup or dextrose powder Blood sample for insulin 60-90 mins later

Question 28

List the 2 ways to test for PPID

Answer 28

Baseline ACTH (EDTA)- usually diagnostic Thyrotropin Releasing Hormone stimulation test

Question 29

Describe the baseline ACTH test

Answer 29

Usually diagnostic Reference range changes through the year Usually most accurate in the autumn

Question 30

Describe the Thyrotropin Releasing Hormone stimulation test

Answer 30

Rarely required because baseline ACTH test usually diagnostic for PPID Collect baseline ACTH Inject TRH Collect another ACTH 10 minutes later

Question 31

what do you need to consider when testing for EMS and PPID

Answer 31

Results are inaccurate if animal is in pain – maybe wait a few days until more comfortable (after given pain relief)

Question 32

Describe the initial management of laminitis

Answer 32

pain relief -NSAIDs (phenylbutazone), paracetamol, opiates Vasodilator support feet

Question 33

what/why vasodilators are used in laminitis cases

Answer 33

Improve blood supply to distal limbs Acepromazine

Question 34

describe how to support feet in laminitis cases

Answer 34

confine to stable on deep shaving beds remove shoes use frog supports

Question 35

Describe diet changes in cases of laminitis

Answer 35

1.5-2% body weight dry weight hay, soaked for 1 hour to reduce sugar content Tiny amount of low sugar food (alfalfa) to put medication in Vitamin / mineral balancer

Question 36

List 3 drugs that can treat EMS

Answer 36

metformin, levothyroxine, ertugliflozin

Question 37

List 2 drugs that can be used to treat PPID

Answer 37

pergolide, cabergoline

Question 38

what can farriers do to support horses with laminitis

Answer 38

trim heels and toes heart bar shoes

Question 39

what is a salvage procedure in laminitis

Answer 39

deep digital flexor tenotomy used if we can't stop the rotation of the P3 this removes the palmar traction on P3 salvage only

Question 40

List 5 factors that affect prognosis of lainitis

Answer 40

lameness severity Degree of rotation Sinking Patient weight Ability to control endocrine disease

Question 41

Describe how laminits occurs

Answer 41

dermal lamellae and epidermal lamella are strongly bonded - to allow the hoof to grow, MMPs release the bonds and allow the lamina to slide, laminitis occurs due to degradation of the interdigitation - often a result of excess MMP activity