Endocrine Disease - Equine Flashcards Preview

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Flashcards in Endocrine Disease - Equine Deck (27):

What is the pathogenesis of hyperlipidemia?

negative energy balance
- triggers excessive mobilization of fatty acids from adipose tissue
- increased hepatic triglyceride synthesis and secretion of low density lipoproteins


What is hyperlipidemia?
What is hyperlipema?

hyperlipidemia - increased amount of all lipids and serum triglycerides (TG < 500 with clear plasma)

hyperlipemia - serum TG > 500 with cloudy serum


What are the risk factors for hyperlipidemia?

- ponies, miniature horses, donkeys
- obesity
- stress
- pregnancy


Describe the actions of the hormones involved in fat mobilization

lipoprotein lipase - activated by insulin, favors TG accumulation in adipose tissue

hormone sensitive lipase - expressed in adipose tissue, mobilizes stored fats
- inhibited by insulin


What are the 3 components of equine metabolic syndrome?

- increased adiposity (fat depositions)
- hyperinsulinemia
- insulin resistance


Which breeds are predisposed to equine metabolic syndrome?

ponies and Morgans


What is the biochemical cause of hyperlipemia?

overproduction of triglyceride


What are the complications associated with hyperlipidemia?

- hepatic failure
- renal failure
- death


What are the possible clinical presentations of equine metabolic syndrome?

- generalized obesity
- regional adiopsity
- laminitis


What is compensatory insulin resistance?

production of higher levels of of insulin, trying to overcome the resistance
- will be hyperinsulinemic


What is non-compensatory insulin resistance?

pancreatic insufficiency develops due to beta cell exhaustion


How is equine metabolic syndrome diagnosed?

- cresty neck
- fasting insulin levels
- insulin tolerance test
- oral sugar test
- combined glucose insulin test


Describe the insulin tolerance test

- insulin is administered and glucose concentration is measured over time
- normal if the concentration of glucose decreases by 50% within 30 minutes


Describe the Oral Sugar test

- fast the horse overnight
- administer corn syrup orally
- collect blood at 60 and 90 minutes
- measure insulin concentration
(> 60 at either time indicates post-prandial hyperinsulinemia)


Describe the combined glucose insulin test

- collect baseline blood sample, then IV infusion of dextrose followed by insulin
- if insulin resistant: BG concentrations remaining above baseline for > 45 minutes
- stress can alter results


What is the treatment for equine metabolic syndrome?

- increase activity and weight reduction
- limit sugars and carbs
- restrict pasture access
- Levothyroxine sodium, Metformin, Metaborol


What are the 3 types of hypothyroidism?

primary - iodine deficiency or excess

secondary - pituitary or hypothalamic dysfunction

tertiary - defect of hormone use at the periphery


What are the clinical signs associated with hypothyroidism?

- weight loss
- decrease in temp, HR, and CO
- increased sensitivity to cold
- lethargy, limb edema, decreased appetite


How is hypothyroidism diagnosed?

- baseline T3-T4
- T4 radioimmunoassay (most reliable)
- TRH or TSH stimulation test


How is hypothyroidism treated?

Levothyroxine supplementation


What is melanocyte stimulating hormone?
What are its functions?

- a primary product of POMC cleavage
- role in metabolism and obesity
- anti-inflammatory hormone
- reduces neutrophilic oxidative burst, chemotaxis, and adhesion
- antipyretic


What is the function of ACTH?

stimulates the adrenal glands to produce large amounts of cortisol


What are the functions of cortisol?

- stimulates gluconeogenesis
- activates anti-stress and anti-inflammatory pathways
- counteracts insulin
- diuretic, increases GFR, Na retention, and K secretion


What is the pathophysiology of Equine Pituitary pars Intermedia Dysfunction?

- a neurogenerative disease with loss of dopaminergic inhibitory input to the melanotropes of the pars intermedia
- hyperplasia of the pars intermedia
- slow progressive disease


What are the signs associated with PPID?

- hirsutism
- behavioral abnormalities
- muscle atrophy (epaxial and gluteal)
- abnormal fat distribution
- hyperhidrosis
- infertiliy
- neurologic disease
- laminitis


How is PPID diagnosed?

- plasma ACTH concentration
- Dexmethasone suppression test
- MSH plasma concentration
- Domperidone stimulation test
- ACTH stimulation test
- TRH stimulation test
- combined DST and TRH stimulation test


What are the treatments for PPID?

- Peroglide (dopamine agonist)
- Cyproheptadine
- Trilostane