Endocrine - equine Flashcards
(36 cards)
What are the 3 endocrinopathies of horses? How common are they?
Pituitary pars intermedia dysfunction - common
Hypothyroidism - rare
Granulosa-theca cell tumour
What is PPID?
Decrease in production of dopamine from hypothalamus
Decrease in inhibition of pituitary so pituitary adenoma
Overproduction of POMCs (pro-opiomelanocortins)
What are the clinical signs of PPID?
Long curly coat
Insulin resistance - causing laminitis
PUPD
Weight loss - high cortisol, immunosuppressed so high parasite burden
Docile
Sweat more (hyperhidrosis)
What is the best first line/in field test for PPID?
Resting plasma ACTH concentration
(not ACTH stim - this is test in dogs)
What tube do you use to collect blood for a resting plasma ACTH concentration test?
In a cold plastic EDTA tube, centrifuge for plasma
What is the most sensitive test for PPID (done in hospital usually)?
TRH stimulation test
How do you do a TRH stimulation test for PPID?
Take bloods - for baseline ACTH
Inject TRH
Take bloods 10 and 30 mins after
What findings will you get on a TRH stimulation test if the horse has PPID?
Massive response of ACTH to the TRH if positive
How do you treat PPID medically?
Pergolide - dopamine agonist, calms down pituitary (the purge for PPID)
With management eg. farriery, clipping, parasite control
What causes hypothyroidism in foals?
Too much/too little iodine intake by mare during gestation
What are the signs/tests of hypothyroidism in foals?
Thyroid enlargement - due to excess TSH secretion from low TH negative feedback
Measure T4 levels
TSH/TRH stimulation test
What is the prognosis for hypothyroid foals?
Very poor - cant be reversed as happened during development of foetus
What type of thyroid tumours do horses get?
Adenoma - unilateral enlargement but usually no thyroid dysfunction
What is a granulosa-theca cell tumour?
Benign tumour causing enlarged ovary, poor fertility
Stallion like behaviour (but not always)
How do you diagnose granulosa-theca cell tumour?
Rectal - enlarged ovary
Anti-Mullerian hormone test - elevated testosterone
How do you treat granulosa-theca cell tumour?
Surgical removal - standing laparoscopic assisted or laparotomy
What are the 3 most common metabolic diseases of horses?
Equine metabolic syndrome
Hyperlipaemia
Hypocalcaemia
What are the 3 main features of equine metabolic syndrome (EMS)?
Obesity or regional adiposity
Insulin dysregulation/resistance
Subclinical/clinical laminitis
What is the difference between EMS insulin dysregulation/resistance and type 2 diabetes mellitus?
EMS has COMPENSATED insulin resistance - high blood insulin but normal glucose levels
Type 2 diabetes - uncompensated, high insulin and glucose
What directly causes laminitis in EMS?
The hyperinsulinaemia directly causes laminitis - too high insulin
What breeds of horse are predisposed to EMS?
Hardy breeds - can eat less and survive as high insulin means can mobilise energy stores more easily
What two factors increase EMS?
Obesity - increases insulin resistance
Lack of exercise - exercise promotes insulin sensitivity
What is the best test for EMS?
Oral glucose tolerance test -
Starve overnight
Take resting glucose/insulin
Feed glucose in breakfast
Take insulin/glucose at 2-3 hours
If has EMS then will get hyperinsulinaemia and normoglycaemia
How do you manage EMS?
Low carb, no concentrate diet
If thin then give calories in oil
No grass - grass muzzle
Exercise
Weight loss
Metformin - increases insulin sensitivity if diet isnt working
