ENDOCRINE Hyperadrenocor3cism (Cushing’s) Middle aged to older dogs (7-12 y.o) Yorkies, mini poodles, boxers Rare in cats Ae3ology: pituitary dependent adenoma (ACTH levels ↑) Rarely: adrenal dependent adenoma (ACTH levels normal) PUPD (SpG <1020 – dilute urine = ↑ UTIs) Polyphagia Bilateral symmetrical flank alopecia Calcinosis cuCs – can be due to long term use of steroids Pot-bellied appearance Muscle weakness (cor2sol is catabolic) Hepa3c lipidosis In cats: Poor hair coat, seborrhea, pyoderma Thin, fragile skin with hyperpigmenta3on ↑ ALP , ALT, CHOL, GLU ↓ BUN due to PUPD ↑ UPC Stress leukogram: SMILED Seg. Mono ↑, Lym EOS ↓ hyperCHOL, thombocytosis ↑ ALKP , isosthenuria Low dose dexamethasone suppression test (cfms HAC but unable to dis4nguish btwn pituitary/adrenal – need high dose dex suppression test/imaging/ACTH measurement) Cushingoid = no suppression at 4 & 8h point // can rule out HAC if cor3sol suppressed Can induce pulmonary thromboembolism & cause sudden death à blood work will show: hypercholesteremia, thrombocytosis, increased ALP, ALT, isosthenuria Tx: trilostane, mitotane, radia3on Hypoadrenocor3cism (Addison’s) – the great pretender Young to middle aged dogs 70% females Std poodles, great danes, WHWT Ae3ology: bilateral idiopathic adrenocorCcal atrophy (autoimmune destruc3on of the adrenal gland = no cor3sol) High whipworm burdens can present similarly to Addison’s, hence if not ruled out, be sure to do fecal flota4on/count PUPD, ↓ SpG - isosthenuric (<1030) ∴↓BUN Moderate hypogylcemia (due to ↓ glucocor0coids) Gastric ulcera3on Hyponatremia, hyperphosphatemia, ↑ BUN, hypochloremia Hyperkalemia (due to ↓ aldosterone ie: principle mineralocor3coid) = ECG anomalies à tall tented T waves, absent P wave, ↑ P-R interval, wide QRS Important to monitor Na & K with mineralocor4coid tx to ensure dose & freq. is suitable ACTH SCm Test – measure before & a`er admin (will have no response) - <2𝜇g/dl = diagnosCc Basal cor3sol (<2; likely, >2: unlikely) HyperK tx - 0.9% NaCL bolus/shock - +/- Ca gluc., GLU, insulin, bicarb IV glucocor3coids: DEX Maintenance tx: Glucocor3coid – Pred Mineralocor3coid – DOCP Always measure serum Na levels when on pred as can increase dras2cally Go Find Rex Make Good Sex: glomerulosa = mineralocor3coid, fasiculata = glucocor3coids, re3cularis = sex hormone Hyperthyroidism Older cats > 6y Less common/rare in dogs Ae3ology: thyroid adenoma (occasionally thyroid adenocarcinoma) Hyperthyroidism à HCM à feline aor3c thromboembolism (FATE) Palpable goitre PUPD, Polyphagia Hyperac3vity Hypertension (>160 mmHg) – sudden blindness due to re3nal detachment In severe cases: Degree of hypertrophic cardiomyopathy (will hear murmur + gallop beat) Serum total T4 level (>4.0 ug/dl) If not conclusive, further tests: o Free T4 o TRH response test o T3 suppression test (T3 is the physiologically ac3ve form) Elevated liver enzymes Tx: oral methimazole (can cause facial excoria4ons, thrombocytopenia, hepatopathy) Thyroidectomy (can cause iatrogenic hypoparathyroidism – hypocalcemia, hypothyroidism, Horners, laryngeal paralysis) I-131 radioac3ve iodine To take note: hyperthyroidism masking renal failure due to ↑ metabolism which falsely ↑ GFR – when hyperthyroidism treated, cat will fall into renal failure very quickly Hypothyroidism Middle aged (4-10y) large breed dogs Less common in miniature dog breeds & cats Can occur in foals where mares have ↑ iodine & goitrogens during pregnancy (rarely due to adenomas in foals) Ae3ology: lymphocyCc thyroidiCs // idiopathic thyroid gland atrophy Foals Can occur in adult horses with EMS/PPID = predisposing factor Weight gain Pelvic limb weakness Derm: symmetrical patchy alopecia & thinning (without alopecia), seborrhea/pyoderma Nervous: FN paralysis, ataxic, knuckling ↑ CHOL (classic sign) Lipemic serum + ↑ triglycerides ↓ PCV with normocy3c, normochromic anaemia of chronic disease Weak at birth Absent/abn. suckle reflex Hypothermia Flexural deformi3es + incomplete ossifica3on of carpal & tarsal bones Thyroid s3m. Hormone (TSH) test Tests the resp. of the thyroid hormone to exogenous TSH, if hypothyroid, pre & post TSH, T4 ↓ T4 + TSH levels FREE T4 by equilibrium dialysis Tx: Levothyroxine Note: PUPD is not seen in hypothyroidism Hyperparathyroidism 4x parathyroid glands à chief cell secretes parathyroid hormones Older dogs Ae3ology: adenoma of the parathyroid gland (rarely, adenocarcinoma) à chief cells produce excessive ionised Ca & vit D abs. 3 main hormones in Ca regulaCon: parathyroid hormone (PTH), 1,25-dihydroxyvitamin D -3 (Vitamin D3), calcitonin (regula3on of Ca levels) *nutri(onal 2° hyperparathyroidism does not cause hypercalcemia* PUPD Lethargy, weakness Hypercalcemia, hypophosphatemia Urinary calculi due to hypercalcemia (calcium oxalate) Hypercalcemia ddx: Paraneoplas3c hypercalcemia (lymphoma) ↑ ionised Ca hypercalcemia Measure serum PTH levels = ↑ PTH despite high Ca (normally if Ca high, PTH is low) Imaging: U/S – enlarged PT glands Rx – renal calcifica3on, urinary calculi Treatment 0.9% NaCL diuresis Sx removal of PT adenoma o Post op period v crucial as high risk of hypoCa à need to provide Ca gluconate IV & calcitriol +/- serial ionised Ca Hypoparathyroidism Small breed dogs esp. mini schnauzers Ae3ology: idiopathic diffuse lymphocy3c parathyroidi3s Ataxic with intermirent tremors Progression to tetany & convulsions Hypocalcemia, Hyperphosphatemia Vit D unable to be converted into ac0ve form = unable to absorb Ca Measure serum PTH levels = ↓ Persistent presenta3on with hypocalcemia & NM excitability Tx: saline + Ca gluc. Diets – high in Ca, low in PO4 Vit D supplementa3on Acromegaly *most common cause of non-insulin dep. DM* Older (8-14 yo), male, diabe3c cats Ae3ology: GH secre3ng tumour within the anterior pituitary gland *uncontrolled DM* Weight gain Organomegaly, CHF, azotemia prognathism Hyperkalemia without azotemia Measure plasma GH/insulin like GF-1, GLU & insulin CT scan of head (iden4fy pituitary adenoma) Tx: mainly to control DM (regular insulin, glargine/prozinc) Radia3on therapy to reduce tumour size (best tx op0on if tx acromegaly) Pheochromocytoma Older animals (dogs > cats, horses, cows) Rare disease process (may or may not be func3onal) Ae3ology: adrenal tumour arising from the chromaffin cells (resp. for catecholamine secre2on) ~50% malignant *signs are very non-specific* Hypertension with 2º blindness PUPD, lethargy Anorexia, V+, D+ Neuro signs (ataxia, seizures, tremors) HL oedema Epistaxis Ascites May present with invasion into the vena cava – but this is not a nega0ve px factor Abdominal U/S, CT BP, bloods Rx, ECG Tx: surgical removal o Pre-op: - main goal is to control hypertension & arrhythmias over 2-3 w prior to sx – phenoxybenzamine (prasozin)/propolanol o Intra-op: phentolamine + NA nitroprusside/propolanol Post-op concerns: hypotension (colloids, fluids), MST 18m-2y post-sx MST = 18m – 2y | 22% pre-op (stabilisa3on period) mortality Diabetes Mellitus Type 1 = dogs Beta islet cells within the pancreas are unable to produce insulin, so there is insulinemia with hyperglycemia Middle aged dogs (mini poodles, cairn terriers, daschunds, schnuazers) + FE at dioestrus Type 2 = older, fat/obese cats ↓sensi0vity to insulin so insulin is normal, but hyperglycemic à can result in beta cell exhaus0on & become Type 1 PUPD, polyphagia Prone to UTIs due to presence of GLU in the urinary tract Cataracts (dogs) DiabeCc neuropathy in cats o Plan3grade stance o Weak HLs o Incoordinated Urinalysis = GLU ++, SpG <1010 Blood GLU o Dog: > 6.2 mmol/L o Cat: > 6.6 mmol/L *Blood GLU* Urinalysis 24h GLU curve (hospitaliza3on) Fructosamine in cats (GLU levels can be falsely increased if cat is stressed) Tx: o Dogs: Caninsulin (PZI) o Cats: glargine/prozinc o DKA pa3ents: regular/natural insulin Obesity is an extremely huge RF to DM Insulin resistance is commonly seen in cats with infec4on, Cushings, hyperthyroidism & acromegaly Diabe3c Ketoacidosis Sequelae of DM Occurs when DM goes untreated & pa3ent does not have any insulin hence no GLU uptake = shi`ing to produce ketone bodies from FA mobilisa3on = hepa3c lipidosis + lac3c acid forma3on = acidosis PUPD Increased RR V+, d+ Lethargy, weakness Hx of DM ↓ blood GLU, PO4, K Concurrent diseases Dogs: hyperadrenocor3cism, pancrea33s, bacterial infec3ons Cats: heart disease, pancrea33s, bacterial infec3ons, hyperthyroidism Blood GLU markedly high Urinalysis = ketones Blood pH = <7.3 = acidosis Metabolic acidosis, hyperosmolality, electrolyte disturbances Tx: REGULAR INSULIN - IV fluids with K suppl. - Tx all other underlying issues
