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What is big head disease or bran disease?
Nutritional 2' Hyperparathyroidism
High Phospherous diet
How does Phosphorous affect vitamin D?
- Excess P=
- Stimulates parathyroid gland=
- Inhibits vit D Synthesis=
- Low vit D=
- Stimulates parathyroid gland
Expected serum Ca with hyperparathyroidism?
- Dz is slowly progressive
C/S associated with nutritional hyperparathyroidism? 6
- Facial bone enlargement
- Difficulty chewing dt bone loss
- Molar fractures
- Spontaneous long bone fractures
Tx for nutritional hyperparathyroidism? 4
- Eliminate grain and oxalates from diet
- Supplement Ca (want ratio 3 or 4:1)
- NSAIDs +/-
- Confinement +/-
Complete recovery may not be possible
Hypothyroidism is a rare condition in horses. What are lab findings that support this diagnosis?
- Decreased T4
- Increased TRH and TSH
C/S associated with hypothyroidism? 5
- Anhidrosis (inability to sweat)
Common thyroid neoplasia?
Benign or malignant?
- (enlarged and palpable)
Expected T4 with thyroid adenoma?
Recommended Yx for thyroid adenoma?
- Tx unnecessary
- Unless compresses trachea/esophagus - then thyroid supplement is warranted
Equine cushings syndrome is AKA?
- Pars Pituitary Intermedia Dysfunction
- (minimal adrenal involvement in equine cushings)
what is common age and most common sign associated with PPI/Cushings?
- Middle aged to older (>15yr)
Role of dopamine in equine cushings?
Inhibits melanotrope hormone
- No Dopamine
- Inc. Melanotrope Horm.
- Hypertrophy/hyperplasia of PPI
Hypertrophy of pars intermedia causes excess release of ____, and therefore...
- *increased POMC* ⇩
- α-MSH (melanocyte stim hormone)
- CLIP (corticotropin like intermediate lobe peptide)
What leads to C/S's associated with cushings?
- Enlarged/highly active pars intermedia *POMC*Compression of adjacent hypothalmic tissues
How does cushings affect immune system?
- Decreases immune response
- Chronic infections & poor wound healing
how does cushings affect physical appearance? how does it affect behavior?
- Coat color change
- Guard hairs on chin
- Abnormal fat deposition
How does cushings affect limbs?
- Laxity in suspensory ligament
- Chronic laminitis
What is another endocrine disorder 2' to cushings?
Type 2 DM
Dx tests for cushings? 4
- Endogenous ACTH
- ACTH Stim
- Measure for Hyperinsulinemia
- TRH stim (directly stimulates melanotropes)
How is dexamethasone suppression test done in the horse?
What is indication of +?
- T0 (Baseline cortisol)
- T15 Hrs
- T20 Hrs (overnight)
+Cushings if fail to suppress cortisol
What is MOA of pergolide as treatment for cushings?
- Dopamine antagonist
- (side effects include V/D, anorexia)
MOA of Cyproheptadine as Tx for cushings?
- Blocks Serotonin
- = Interferes with POMC
- (expensive and not readily available)
Prognosis for horse with cushings?
- Can be managed for years with pergolide and good husbandry/foot care
- (most common reason for euthanasia is laminitis complications)
what is cause of laminitis related to endocrinopathy?
What characterizes equine metabolic syndrome?
- Regional adiposity (fat deposition)
- Insuline resistance
- "easy keepers"
What is signalment of affected horses?
- Adult (>5yr)
- No sex predilection
Dx for metabolic syndrome?
Resting hyperinsulinemia >30 uu/ml defines
Combined Glucose-Insulin test to ck for insulin resistance
How is glucose-insulin test done?
- Baseline glucose
- IV dextrose + insulin
- Elevated BG >45min = insulin resistance
how is metabolic syndrome treated/managed? 6
- Wt loss is critical (remove CHO, feed grass hay)
- Soak hay to decr. CHO
- Grazing muzzle
- Manage laminitis
what are goals of using levothyroxine to manage metabolic syndrome?
- Lower body weight
- Improves insulin sensitivity
- (Short term only, stop when ideal body weight or <6 mo)