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Clinical Endocrine, Metabolic and Dermatology > Equine PPID and EMS > Flashcards

Equine PPID and EMS Flashcards

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1
Q

What does Equine PPID stand for?

A

Equine Pituitary Pars Intermedia Dysfunction

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2
Q

What causes Equine PPID?

A

Hyperplasia of the pituitary pars intermedia

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3
Q

What is Equine PPID often confused with?

A

Cushing’s

note: it is not the same thing
Cushing’s is caused by a tumor of the adrenal gland or an adenoma of the pituitary corticotrophs

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4
Q

What is the physiology of the normal Pituitary pars distalis?

A
  • Hypothalamus releases CRH
  • Corticotroph cells produce Pro-opiomelanocortin (POMC)
  • POMC is then cleaved to ACTH and Beta-lipotropin
  • ACTH stimulates the adrenals to produce Glucocorticoids (from the adrenal cortex zona fasiculata)
  • Glucocorticoids then have a NFB on the corticotrophs in the pars distalis to decrease ACTH levels
    note: there is a normal circadian rhythm with this- concs highest in the morning, plateau in the day and low at midnight
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5
Q

What are the 3 zones of the Adrenal cortex and what do they do?

A
  • Zona glomerulosa: mineralcorticoids
  • Zona fasiculata: glucocorticoids
  • Zona reticularis: androgens
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6
Q

What is the physiology of the normal Pituitary pars intermedia?

A
  • In response to CRH, Melanotropes produce POMC, which is cleaved into ACTH and Beta-lipotropin
    ACTH –> MSH and CLIP (Melanocyte stimulating hormone and Corticotropin like intermediate lobe peptide)
    Beta-lipoprotein –> Beta-endorphin (BEND)
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7
Q

Which neurotransmitter inhibits Melanotropes?

A
  • Dopamine, released from the hypothalamus
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8
Q

What is the pathophysiology of PPID?

A
  • There is a Dopamine deficiency released from the Hypothalamus, causing a lack of inhibition on the Melanotropes
  • Without inhibition, the Melanotropes respond by proliferating and releasing excess hormones (ACTH and Beta-lipotropin)
  • Which causes an increase in the hormones: MSH, CLIP and BEND
  • Also causes the loss of the circadian rhythm
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9
Q

What is the signalment of PPID, what animals is it seen most often in?

A
  • All breeds and types: particularly ponies and Morgan horses
  • Mean age of 18 - 23 years
  • No gender predilection
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10
Q

What are some of the clinical signs associated with Equine PPID?

A
  • Hirsutism (A long and curly hair coat that fails to shed): up to 80% of cases
  • Poor hair coat
  • Laminitis: 50% of cases
  • PU/PD: up to 76% of cases
  • Muscle Wasting + Weight Loss: up to 88%
  • but Increased appetite
  • Docility + Decreased response to pain: due to increased levels of Beta-endorphins
  • Lethargy
  • Hyper-hidrosis: excessive sweating
  • Narcolepsy
  • Blindness
  • Recurrent Infections
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11
Q

70% of horses with Equine PPID have what else?

A

Insulin resistance

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12
Q

Equine PPID predisposes the horse to what problems?

A

increased glucocorticoids cause the following:

  • Delayed wound healing
  • Recurring infections
  • Suppression of Immune Function
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13
Q

What findings may be seen on blood analysis? (CBC and Biochem)

A
  • Anemia
  • Stress leukogram: neutrophilia + lymphopenia
  • Hyperglycemia
  • Elevated liver enzyme activity
  • Elevated cholesterol
  • Elevated triglycerides
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14
Q

How can Equine PPID be diagnosed?

A
  • Resting ACTH concentration: gold standard
  • Thyrotropin Stimulation test: useful in horses with laminitis, but hard to get hold of TRH, but is safer than Dex supp test
  • Dex suppression test: has side effects though (laminitis)
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15
Q

What treatments are available for Equine PPID?

A
  • Medication: Pergolide, Cyproheptadine, Trilostane (questionable use of Trilostane)
  • Management: good hoof care, dentistry, deworming, and a diet that is easily digestible and low in soluble CHO’s
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16
Q

What is the gold standard medication for treatment of Equine PPID?

A
  • Pergolide
    It is a Dopamine agonist, thus giving the horse the hormone it is deficient in

Start 1mg/day, reassess in 4-6 weeks, if no improvement in signs then increase 0.5mg q 3-4 weeks

17
Q

What is Cyproheptadine, and its dosing?

A
  • Cyproheptadine
    It is a Serotonin antagonist
    Only 1/3 of horses improve

Start 0.25mg/kg orally, SID, for 4-8 weeks

  • If no improvement, increase to BID for 4 weeks
  • Still no improvement, switch to Pergolide
18
Q

What does EMS stand for?

A

Equine Metabolic Syndrome

aka Insulin Dysregulation Syndrome

19
Q

What is EMS caused by?

A

Equine metabolic syndrome (EMS) is a characteristic collection of clinical signs due to the dysregulation of insulin

20
Q

What is the difference between Compensated insulin resistance and non-compensated insulin resistance?

A

Compensated insulin resistance: reduced insulin sensitivity, high insulin produced but normal glucose levels are maintained
(Most commonly seen)

Non-compensated insulin resistance: reduced insulin sensitivity, high or normal insulin produced but glucose is high
(Less commonly seen but more severe)

21
Q

What is the signalment of horses with EMS?

A
  • Young to middle aged (8 - 18 years old)
  • Regional to general fat stores
  • Insulin resistance
  • Sub-clinical to clinical laminitis
  • Ponies > Horses
  • More common in Warmbloods, Morgans, Arabians, Saddlebreds and American Quarter Horse
  • Lack of exercise
  • Diet: abundant lush pasture + high levels of grain
22
Q

What are the clinical signs associated with EMS?

A
  • Obesity
  • Laminities
  • Colic: due to deposition of fat in and around of the intestines
  • Hyper-lipemia

note: a significant overlap with PPID, therefore it should be tested for

23
Q

How can EMS be diagnosed?

A
  • Insulin levels: horse is fasted for 6 hours and then sample is taken. Normal = <20uIU/mL
  • Oral glucose/ sugar test: fast overnight, then give 0.5/1g/kg powder in morning feed, then take blood 2 hours later. Abnormal = >80 - 90 iU/mL
  • Combined Glucose Insulin Test: insert catheter previous day, withhold feed for 6 hours, collect baseline sample, then administer 150mg/kg of 50% dextrose IV with 0.1U/kg Insulin IV
    Serum glucose and insulin is measured at 45 and 75 mins
    Normal: Glucose should be less than the baseline at 45 mins
    Insulin should be <30uU/mL at start and at 100uU/mL at 45 mins
24
Q

What is the treatment for EMS?

A

Diet: lose weight via diet restriction, soaking of hay, no concentrates and limit pasture (grazing muzzle)

Exercise: start exercise program if possible, or manage laminitis with a farrier

Medications:

  • Levothyroxine sodium: increases metabolism
  • Metformin: increases glucose uptake into tissues and inhibits gluconeogenesis

Encourage the Owner: repeat tests and measurements of the horse

Clinical Endocrine, Metabolic and Dermatology (17 decks)

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