Term
| Is primary hypoparathyroidism common or rare in the horse? |
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Definition
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Term
| What are the lab values consistent with primary hypoparathyroidism in horses? |
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Definition
-hypocalcemia
-hyperphosphatemia
-hypomagnesemia
-dec pTH |
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Term
| What are the clinical signs seen with hypocalcemia due to primary hypoparathyroidism in the horse? |
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Definition
-msucle fasciculations, hyperexcitability, seizures
-ataxia
-synchronous diaphragmatic flutter
-recumbency
-colic |
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Term
| What are the common causes of altered calcium homeostasis in the horse? |
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Definition
-renal failure
-cantharidin toxicosis
-GI dz: colic, colitis
-pseudohypocalcemia: hypoalbuminemia
-acid base disorders
-iatrogenic |
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Term
| Describe the pathogeneisis of hypocalcemia in the horse? |
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Definition
-renal loss
-sweat loss
-GI inflammation
-tissue sequestration of Ca: part of Cantharidin toxicosis
-dec pTH secretion = hypomagnesemia
-impairment of Ca release in response to PTH |
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Term
| What is the most common cause of hyperparathyroidism in the horse? |
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Definition
-secondary nutritional hyperparathyroidism
-leads to improper dietary calcium:phosphorus ratio |
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Term
| What causes primary hyperparathyroidism in the horse? |
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Definition
| -tumors of the parathyroid gland secrete PTH |
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Term
| What causes pseudohyperparathyroidims in the horse? |
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Definition
| -neoplastic secretion of PTH-like hormone |
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Term
| What are the common names for second nutritional hyperparathyroidism? |
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Definition
| -Big Head or Bran disease |
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Term
| What diet can lead to second nutritinal hyperparathyroidism? |
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Definition
-low calcium
-high phosphorous |
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Term
| Why does inc PTH cause issues with calcium stuff? |
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Definition
| -the inc PTH activity results in excessive osteoclastic activity and inc bone resoption |
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Term
| What are the clinical signs of SNH in the horse? |
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Definition
-generally occurs in young horses (<2y)
-symmetrical thickening of the facial bones
-intermittent, shifting lameness is often the first sign
-difficult mastication, loose teeth
-alveolar bone is resorbed |
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Term
| HOw do we diagnose SNH in the horse? |
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Definition
-signalment
-clinical signs
-serum Ca adn P levels usually normal
-ration analysis
-rads
-urinary P is elevated |
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Term
| What levels of P and Ca indicate SNH in the horses? |
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Definition
-FClp > 4 indicates excessive dietary intake
-FClca < 2.5 indicates inadequate dietary intake |
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Term
| One of the ways we treat SNH in the horse is to correct the dietary imbalances by feeding certain things. Give some examples. |
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Definition
-Alfalfa hay: high in calcium
-Calcium carbonate, ground limestone
-Avoid calcium suppleents that contain phosphorous
-Rx is necesary for a prolonged time |
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Term
| How do we prevent SNH in the horse? |
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Definition
-avoid predisposing factors
-diet should consist of Ca:P ratio of 1-2:1
-avoid oxalate cotaining plants |
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Term
| True thyroid disease is uncommon in the horse. What are two examples? |
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Definition
-Congenital hypothyroidism and dysmaturity syndrome in foals: seen with goiters
-Thyroid neoplasia in aged horses |
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Term
| What are some of the clinical signs of experimentally thyroidectomized horses? |
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Definition
-sensitive to cold
-coarse hair coats
-mild alopecia
-delayed shedding
-thickened facial features
-True hypotyroidism is very very uncommon in adult horses
-limb edema
-dec fed comsumption/weight gain
-lower rectal temp
-lower HR
-dec CO
-exercise intolerance
-stallions are fertile |
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Term
| What can cause hyperplastic goiter in neonatal foals? |
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Definition
| -excess ingestion of iodine by dam during pregnancy: seaweed products, oxalates in plants |
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Term
| What is the common signalment for congenital hypothyroidism in horses? |
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Definition
-foals in western Canada
-inc incidence in Pacific NW |
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Term
| Why do abnormal iodine levels mess up foal thyroid function? |
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Definition
-abnoraml iodine elvels = permanently altered thyroid function
-effects on foal are severe |
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Term
| What are the cuases of hypothyroidism in horses? |
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Definition
-idiopathic
-goitrogenic sugstances
-mares typically asymptomatic
-diet history during gestation
-foals improve when excess iodine is removed |
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Term
| What are the clinical signs of hypothyroidism? |
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Definition
-goiter
-prematurity
-hypothermia
-weakness, lethargy, poor sucking reflexes
-slow growth
-developmental abnormalities: rupture of common digital extensor tendon, mandibular prognathism (sow mouth), incomplete ossification (carpus/tarsus) |
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Term
| What is the most common adenoma in the horse? |
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Definition
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Term
| What is anhidrosis in the horse? |
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Definition
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Term
| What is the typical age of anhydrosis in the horse? |
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Definition
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Term
| What three factors influence the rate of heat loss by evaporation of sweat? |
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Definition
-air movement
-ambient humidity
-akin blood flow |
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Term
| What controls equine sweat glands? What stimulates it? |
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Definition
-sweat glands are under beta-adrenergic control
-stim by catecholamines or by dirct postganglionic adrenergic innervation |
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Term
| What are the two mechanisms of control of anhidrosis in the horse? |
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Definition
-Humoral control: adrenergic agonists secreted from the adrenal medulla
-Nervous control: autonomic adrenergic nerves |
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Term
| What are the two possible physiologic causes of anhydrosis in the hrose? |
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Definition
-dec stim of the sweat gland
-lack of response of the sweat gland of stimulation |
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Term
| What is the typical signalment of anhidrosis? |
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Definition
-any horse living in a warm, humid climate
-horses imported from temp climates appear to be predisposed
-no breed, sex, or color rpedisposition |
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Term
| What are the clinical signs of anhidrosis in the horse? |
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Definition
-occurs in summer and regresses during cooler season
-hyperhidrosis may be noted before the onset of anhidrosis
-dec or absence fo sweat
-sweat does not lather
-fatigue and dec athletic performance
-inability to cool down after exercise
-tachypnea
-dry, flaky hair coat, alopecia
-dec water consumption
-inc rectal temp |
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Term
| How do we diagnose anhidrosis in the horse? |
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Definition
-history and clincial signs
-resposne to exercise: sweat, HR, RR, temp
-sweat response tests |
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Term
| Describe the itnradermal sweat response test in the horse to diagnose anhidrossi. |
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Definition
=epi sol injected intradermally along the neck
-sweating at all 4 injections sites within minutes is normal
-anhidrotic horses usually sweat only at 1:1000 site and only after an extended period |
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Term
| What is the one common side effect of intradermal sweat response test in the horse? |
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Definition
| -white hair may grrow at injection sites |
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Term
| HOw do we treat anhidrosis in a horse? |
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Definition
-an artificially cooled environment or relocation to a more temp climate
-stall fans and cold water baths during the hottest period of the day are useful
-avoidance of exercise during heat of the day
-body heat pdcd by digestion can be minimized by avoiding excess feeding of concentrated feed
-feed early morning and late evening
-glands may regenerate in absence of thermal stress
-IV or oral electrolytes
-L-tyrosine
-Catecholamines >> Dopamine, NE, Epi |
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Term
| How does Dopamine work to treat anhidrosis? |
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Definition
| -prevents vasoconstriction at the sweat gland |
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Term
| What is a pheochromocytoma? Are most functional or non-functional? |
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Definition
-tumor of the adrenal medulla
-most are non-functional but functional tumors secrete catecholamines |
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Term
| What are the clinical signs of pheochromocytoma? |
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Definition
-sudden onset of hyperhidrosis
-dialted pupils
-tachycardia
-tachypnea
-muscle tremors
-anxiety
-abdominal pain: due to rupture |
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Term
| HOw do we diagnose a pheochromocytoma? |
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Definition
-definitive antemortem diagnosis is difficult
-measurement of catecholamines in plasma or urine is not performed by msot labs |
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Term
| How do we treat pheochromocytomas? |
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Definition
-not reported in horses but could treat surgically
-can do short term tx with drugs that inhibit catecholamine synthesis |
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Term
| What causes adenal insufficiency in horses? |
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Definition
| -iatrogenic due to steroids or sepsis |
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Term
| What are the clinical signs of adrenal insufficiency in the horses? |
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Definition
-lethargy, exercise intolerance
-anroexia, weight loss
-laminitis
-hyponatremia
-hypochloremia
-hypoglycemia
-hyperkalemia
-cortisol/ACTH stim |
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Term
| What are the two types of diabetes insipidus in the horse? Which one is more common? |
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Definition
-Neurogenic: vasopressin deficiency
-Nephrogenic: insensitivity of renal colelcting duct epi cells to vasopressin
-Nephrogenic more common in horses |
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Term
| What are the etiologies of neurogenic DI in the horse? |
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Definition
-INherited: autosomal dominant disease = dec in neurosecretory cells in the hypothalamus
-Acquired: trauma, vascualar abnormalities, infection, or neoplasia |
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Term
| What is the etiolgy behind nephrogenic DI? |
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Definition
0resisitance of cortical and medullary collecting ducts to antidiuretic action of vasopressin
-inherited or acquired
-drug therapy, metabolic disease, infection, mechanical disorders |
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Term
| What causes the PU/PD of DI in the horse? |
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Definition
| -polyuria due to lack of vasopressin activity = net water loss, inc plasma osmolality = thirst and compensatory inc in water cosumption |
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Term
| How do we diagnose DI in the horse? |
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Definition
-SG < 1.010
-failure to ocncentrate urine following water deprivation test
-exogenous vasopressin while monitoring USG |
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Term
| What results do we expect with neurogenic DI with an exogenous vasopressin test? Nephrogenic? |
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Definition
-Neurogenic will begin concentrating
-Nephrogenic will not cnectrate |
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Term
| How do we treat neurogenic DI in the horse? |
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Definition
| -supplement vasopressin (drugs that potentiate the effect of vasopressin) |
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Term
| How do we treat nephrogenic DI in the horse? |
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Definition
-does not respond to hormone therapy
-restrict sodium and water intake
-thiazide diuretic
-prostaglandin inhibitors or amiloride |
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Term
| Describe the two levels of severity of hyperlipidemia in the horse. |
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Definition
-Hyperlipidemia if triglycerides <500 mg/dl
-Hyperlipemia if triglycerides >500 mg/dl |
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Term
| What arethe inciting factros of equine hyperlipidemia? |
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Definition
-dec caloric intake results in a negative energy balance: anorxia, starvation, severe parasitism, gestation, lactation
-causes a disruption of normal fat metabolsim and subsequent clinical signs |
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Term
| What is the role of insulin in equine hyperlipidemia? |
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Definition
-normally inhibits tissue hormone sensitive lipase
-activates lipoprotein lipase
-ponies have a relative tissue insulin insensitivity |
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Term
| What is the typical signalment of equine hyperlipidemia? |
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Definition
-primarily ponies and miniatures
-rarely can occur in horses
-gemales > males
-obese w/ recent history of stress or wt loss
-often during a time of high metabolic demand: ate gestation, early lactation, winter months |
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Term
| What are the clinical signs of equine hyperlipidemia? |
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Definition
-anorexia, icterus
-weakness, depression, lethargy
-ataxia
-fever
-dependent edema
-mild sings of colic possible
-diarrhea is common
-if death occurs, within 6-10 days after first clinical signs |
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Term
| How do we diagnose equine hyperlipidemia? |
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Definition
-gross appearance of blood or plasma
-triglycerides > 500 mg/dl
-evidence of liver disease: inc SDH, GGT, total bilirubin, and ammonia & dec glucose, BUN, and albumin |
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Term
| What ndo we see on necropsy of equine hyperlipidemia? |
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Definition
-fatty infiltration of the liver and kidneys
-kidneys pale and swollen, greasy texture
-may have ruptured liver, hemorrhage
-lesions of a primary disease causing anorexia |
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Term
| What are our five main treatment objectives equine hyperlipidemia? |
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Definition
-improve energy intake and balance
-eliminate stress or treat concurrent disease
-treat hepatic failure
-inc triglyceride uptake by peripheral tissues
-inh fat mobilization from adipose tissue |
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Term
| How do we treat equine hyperlipidemia? |
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Definition
-fluid therapy (oral or IV): correct electrolyte imbalances, correct acid/base imbalance
-nutrition: oral or IV
-inculin: inh lipolysis and promotes lipogenesis
-Heparin: inc activity of lipoprotein lipase, enhances remobal of TG from plasma |
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Term
| What is the prognosis of equine hyperlipidemia? |
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Definition
-poor for hyperlipemia
-60-100% mortality |
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Term
| How do we prevent equine hyperlipidemia? |
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Definition
-client education
-avoid stress in predisposed ponies
-proper nutrition to avoid negative energy blaance or obesity
-routine exercise for predisposed ponies to improve insulin sensitivity
-traet anorectic ponies aggressively |
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