Equine Metabolic Conditions

Question 1

Endocrine dz of horses

Answer 1

Pituitary conditions: PPID
Adrenal: adrenal insufficiency, phaeochromocytoma
Anhidrosis
Thyroid: neonatal hypothyroidism, thyroid tumours
Parathyroid: hyperparathyroidism, pseudohyperparathyroidism
Pancreas: DM, hypoglycaemia

Question 2

Metabolic dz’s

Answer 2

Hyper/Hypo-Ca
Cu, Se
Hyperlipidosis/hyperlipemia
hepatic lipidosis
hepatic encephalopathy

Question 3

Adrenal insufficiency Hx

Answer 3

stressful event

Question 4

Adrenal insufficiency causes

Answer 4

• endotoxaemia, colic - haemorrhage & adrenal necrosis
• chronic admin of corticosteroids: Pred, triamcinolone

Question 5

Clin signs of adrenal insufficency

Answer 5

• poor condition, poor performance, lethargy
• depression, anorexia, wt loss
• Clin path: HypoNa, hypoCl, hyperK, hypoglycaemia

Question 6

Dx of adrenal insufficiency

Answer 6

• ACTH gel 1 IU/kg IM - pre-sample 8-10 am, post-sample 2-4 hrs later
• 2-3x increase in [cortisol] in normal horse

Question 7

Txt of adrenal insufficiency

Answer 7

Rest, lower stress
long-term corticosteroids, taper dosing

Question 8

Phaeochromocytoma

Answer 8

Fxnl adrenal medullary tumour causing XS catecholamine prod’n

Question 9

Catecholamines produced by medulla or adrenal

Answer 9

epinephrine
norepinephrine
dopamine

Question 10

Clin signs of phaeochromocytoma

Answer 10

• increased HR/RR
• dilated pupils, sweating, anxiety
• recurrent colic
• D, muscle tremors
• PU/PD

Question 11

Dx of phaeochromocytoma

Answer 11

• DI - ltd w/o Sx
• Bloods: non-specific - neutrophilia, lymphopaenia, haemoconcentration; hyperglycaemia, uraemia, hyperK
• measure catecholamines in bloods
• 24 hr urine collection - Vanillylmandelic acid in urine

Question 12

Txt for phaeochromocytoma

Answer 12

• Medical not attempted - supportive for renal fxn
• Sx possible; guarded prognosis

Question 14

Anhidrosis

Answer 14

Hot, moist climates
* Horses introduced from cooler climates prone to dvlp’ing anhidrosis w/i 1-3 mos
* Sweat glands shrink, Δ structure
* Linked to exercise & environmental stress: ↑’r lvls of circulating adrenaline
* Down-reg & insensitivity of the B2-adrenoceptors of sweat gland
* Overheat
* Horses don’t pant usually → This is the one time you may see panting b/c they are not able to sweat & dissipate heat
* Suspect in warm environments when exercise intolerance

Question 15

Clin signs of anhidrosis

Answer 15

• Poor stamina & exercise tolerance
• Panting, distress, lethargy after exercise
• Heat overload & collapse

Question 16

Dx of anhidrosis

Answer 16

• CS
• Intradermal inj of B2 agonists (Salbutamol sulphate, Adrenaline bitartrate, Terbutaline sulphate)

Question 17

Mgmt of anhidrosis

Answer 17

• Move to a milder, less humid climate
• Compete during the winter mos only
• Daily electrolyte supplement
• Provide cool environment (Air conditioning, fans, etc.)
• Adeq shade, cool water in pasture
• Body clipping
• Hosing w/ cool water after exercise

Question 18

Neonatal hypothyroidism is due to

Answer 18

Iodine deficient in diet of mare during gestation OR nitrates in diet of mare
ingestion of goitrogens by dam - interferes w/ iodine uptake in gland; equine placenta permeable

Question 19

2 categories of neonatal hypothyroidism

Answer 19

• hypo-metabolic state w/ low thyroid hormones - looks like dummy foal
• dvlpmtl lesions w/ normal [thyroid hormones] - hormone deprivation occured during critical dvlpmtl period

Question 20

Clin signs of Neonatal hypothyroidism

Answer 20

• lack of suckle reflex, neurologic - dummy foal like
• dysmature, incoordination, poor suckling & righting reflexes - hypomyelination, CNS lesions
• hypothermia - decreased BMR
• tendon contracture, rupture
• retarded bone dvlpmt
• undershot jaw possible
• limb deformity
• goitre

Question 21

Dx of neonatal hypothyroidism

Answer 21

Clin signs, Hx
Mare feed during gestation
TSH response test
PM

Question 22

Prognosis of neonatal hypothyroidism

Answer 22

guarded to poor

Question 23

Adult hypothyroidism is…

Answer 23

overdx’d

Question 24

clin signs of thyroidectomised horses

Answer 24

• lethargy, poor exercise intolerance, muscular problems
• lowered temp, appetite
• scaly hair coat

Question 25

Dx of adult hypothyroidism

Answer 25

low serum T3/T4 TSH stim tests

Question 26

Factors affecting T3/T4 conc

Answer 26

Bute, food deprivation, illness

Question 27

Txt for adult hypothyroidism

Answer 27

Thyroxine 20 mcg/kg SID PO

Question 28

Hyperthyroidism

Answer 28

undocumented thyroid carcinomas, adenomas - non fxnl

Question 29

Hyperparathyroidism primary vs secondary

Answer 29

primary = RARE secondary = nutritional

Question 30

Bran dz is due to

Answer 30

XS dietary PO4 -> decreased absorption of Ca in GI -> Ca def -> PTH secreted; limb & facial bones demineralised

Question 31

Clin path of secondary hyperparathyroidism

Answer 31

* serum Ca & PO4 normal * Urinary PO4 increased

Question 32

Clin signs of secondary hyperparathyroidism

Answer 32

* Loose teeth & shifting, intermittent lameness * Failure to reach expected height in weanlings & yrlings * Swollen facial bones, thickened jaw bones & difficulty chewing * Ruptured tendons & ↑d risk of traumatic & spontaneous fractures * Obstruction of nasal passages, which may cause noise &/or D/c due to bone swelling in head

Question 33

Txt of secondary hyperparathyroidism

Answer 33

can take up to 12 mos for remineralisation of bone

Question 34

Prevention of secondary hyperparathyroidism

Answer 34

Ca supplementation if pasture increase in oxalates

Question 35

DM

Answer 35

Rare Pancreatic destruction from abscesses or migrating strongyles

Question 36

Hypoglycaemia

Answer 36

insulin-producing tumour of pancreas