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ATTITUDE. “The people who get on in this world are the people who get up and look for the circumstances they want, and if they can’t find them, make them. ” - George Bernard Shaw. ENDOCRINE SYSTEM DISEASES. ‘CRINE’ – to secrete. Endocrine System Diseases. Main trigger: Hypothalamus.
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ATTITUDE “The people who get on in this world are the people who get up and look for the circumstances they want, and if they can’t find them, make them.” -George Bernard Shaw
ENDOCRINE SYSTEM DISEASES ‘CRINE’ – to secrete
Review of the basics • Endocrine ____________- basic units of the endocrine system. • Secrete hormones ___________ into the bloodstream. • Circulate throughout body and produce effects when attach to receptors in or outside of cells. • __________ glands. • Exocrine glands- units that secrete their products onto epithelial surfaces through tiny tubes called _____________.
Hormones • ___________ messengers produced by endocrine glands and secreted directly into blood vessels. • Produce effects when find their receptors in or on cells. • Each body cell has specific receptors to certain hormones (___________). • If body does not have receptor, hormone will pass by. • Only certain hormones can _______ to receptors and when it occurs, then it changes the activity of the cell.
Control of Hormone Secretion • “Negative Feedback System” • Endocrine glands will be stimulated to produce more hormone when it drops below a certain amount in the body. • If hormone is of adequate levels, gland will either slow or stop production of the hormone which is called negative feedback. • Direct Stimulation of Nervous System • Secretion of some hormones is stimulated by sympathetic nerve impulses when an animal feels threatened. • Fight or flight response from sympathetic nervous system
DISEASES OF THE THYROID GLAND HYPERTHYROIDISM HYPOTHYROIDISM
Thyroid Gland • Gland not usually palpable • Located at ventral cervical region along lateral margins of trachea • Hormones produced • T3 (___________________) and T4 (_____________________), iodine containing hormones. • Produced by follicular cells • ______________ – Causes Calcium deposition in bone which decreases blood Calcium concentrations • Produced by parafollicular cells
Hypothyroidism • Definition: clinical state associated with ____________________ which causes low cell metabolism in most tissues of the body • Primary acquired – 90% of dogs • Caused by ________________or _________________________ • Also by iodine deficiency, neoplasia, infection • Secondary acquired- RARE • Anterior Pituitary dysfunction or destruction from neoplasia – leads to ↓TSH • Congenital Hypothyroidism-RARE • Cretinism (newborns)
Hypothyroidism • MOST COMMON ENDOCRINE DISEASE IN____________; rare in cats • Breeds: Golden Retriever, Doberman, Irish Setter, Schnauzer, Cocker Spaniel, Dachshund, others • 4-10 yrs of age • Females • Greyhounds and Scottish deerhounds physiologically have lower T4 (thyroxine)
Hypothyroidism • Clinical Signs - COMMON • __________________________________ • Skin changes • Bilaterally symmetric truncal alopecia (which other disease has this clinical sign? ) • ______________________ neck, axillae, and other areas of friction • Seborrhea • Superficial pyoderma • Dry, lusterless haircoat • Hyperpigmentation • Cold intolerance (why?) • Lethargy/sleeping • Exercise intolerance
Hypothyroidism • Clinical signs/Bloodwork – Less common • ___________________– generalized weakness, ataxia, facial paralysis/paresis, seizures (secondary to cerebral atherosclerosis) • _______________– Constipation, Regurgitation caused by megaesophagus • Bloodwork abnormalities –_____________lipidemia is most common, gross lipemia ( milky appearance to the serum), ____________________cholesterolemia (80%), anemia (mild non-regenrative) • Eye – hyperlipidemia => corneal lipidosis and anterior uveitis *Virtually all body systems are affected, clinical signs are generally non-specific
Hypothyroidism: DIAGNOSIS • Blood Tests • Hypothyroid dogs have lowered level of T4 • Test total T4(TT4), +/- T3 levels • Free T4: Free T4 is thyroxine that is not protein bound (ED is most accurate test for fT4 measurement) • Basal TSH concentration • Measures TSH in blood, should be used in conjunction with other tests and clinical signs *ED = equilibrium dialysis
Hypothyroidism: Considerations • Remember sick animals and animals on certain medications (anti-epileptics, glucocorticoids) may have depressed T4 levels. (_________________) • Wait and re-test after treatment of underlying cause if clinical signs persist. • Greyhounds have low T4 levels naturally diagnose based on clinical signs as well as test results; treat if clinically evident.
Hypothyroidism • Treatment • Thyroid supplement – _________________ • Oral, synthetic levothyroxine (0.02 mg/kg BID) • Daily administration (after cs resolves consider SID) • Steady state levels – 4/8 wks (1st 6-8 months) • Test levels and adjust dose until T4 normal • Want to test 4-6 hours after dose is given (when serum levels are highest)
Hypothyroidism • Client Education • Supplement for ________________ • Daily dosing required • Overdose => hyperthyroidism • Regular rechecks are recommended including bloodwork. • PU/PD; nervousness, weight loss, panting, weakness, inc. appetite • Vet may recommend a reduced fat diet until body weight is satisfactory and T4 levels are normal.
Hyperthyroidism Definition: Pathologic, sustained, high overall metabolism caused by high circulating concentrations of thyroid hormones • Most common Endocrine disease in ____________ (one of the big 3 diseases of older cats) • Very rare in dogs • Pathophysiology • Autonomously ___________________________, no physiologic controls (functional thyroid adenoma) • Secrete _______ and ____________
Hyperthyroidism • Clinical Signs • Multi-systemic: reflects increase in metabolism • _________________ • __________________ • Vomiting/diarrhea • _____________________ • Tachypnea/dyspnea • Hyperactivity • Aggression
Hyperthyroidism • Clinical signs cont’d • ____________________(thickening of LV and heart muscle) • Hypertension • Poor body condition • Thickened nails • Unkempt appearance • ______________________ gland 70% - bilateral
Hyperthyroid cat Middle age to older cats Blindness with retinal detachment Wt loss Palpable enlarged Thyroid gland Polyphagia Aggressive Tachycardia unkempt haircoat
Hyperthyroidism • Diagnosis • Palpate enlarged thyroid gland • Elevated T4, FT4 • X-rays for associated heart disease
Hyperthyroidism: Scintigraphy Normal cat Normal uptake in salivary glands and thyroid glands Hyperthyroid cat Unilateral thyroid adenoma
Hyperthyroidism: Scintigraphy Hyperthyroid cat Bilateral thyroid adenoma Hyperthyroid cat Ectopic (intrathoracic) thyroid adenoma Hyperthyroid cat Functional thyroid carcinoma (represents regional metastasis)
Hyperthyroidism • Treatment • ______________________ (Tapazole) – anti-thyroid drug – block incorporation of iodine into thyroglobulin. • Monitor: q 2-3 weeks • COMMON AND PRACTICAL FOR CLIENTS • Radioiodine treatment – I131 • Effective • Emitted radiation destroys functioning follicular cells • ______________________________________________ • Surgical removal of gland • May cause hypothyroidism • May result in hypocalcemia due to hypoparathyroidism
Hyperthyroidism: Medical Rx METHIMAZOLE ORAL DRUG, BUT CAN BE FORMULATED INTO A TRANSDERMAL OINTMENT
Hyperthyroidism • Complications • Renal disease/failure unveiled when thyroid levels controlled • 2-3 months after medication started • Occasionally tapazole will no longer be effective usually after 2-3 years of treatment • Prognosis • Excellent if uncomplicated • If labs show ___________________ prior to treatment, prognosis more guarded
Hyperthyroidism: Client Info • Cause of disease is unknown • Surgery or Radiation are only cures • Cat may become hypothyroid following Rx – usually not clinically significant and supplementation can be initiated if necessary • Following Tapazole, Blood pressure and kidney values should be checked routinely
EDUCATION Education is learning what you didn’t even know you didn’t know. -Daniel J. Boorstin
DISEASES OF THE PARATHYROID GLANDS HYPERPARATHYROIDISM HYPOPARATHYROIDISM
Thyroid/Parathyroid glands 1=normal thyroid gland 2 and 3=parathyroid gland 4=enlarged thyroid gland
Parathyroid gland • Secretion: Parathyroid hormone (PTH, Parathormone) • Function: ↑ plasma Ca2+ concentration • 1. ↑ osteoclast activity • 2. ↑ Ca++ absorption from GI tract • 3. ↑ Ca++ reabsorption from kidney tubules • Hyperparathyroidism →hypercalcemia • Hypoparathyroidism →hypocalcemia
Hyperparathyroidism • Causes: • 1º hyperparathyroidism—adenoma or carcinoma • 2º hyperparathyroidism—poor diet; low Ca intake • Clinical signs: • Many animals show no clinical signs • signs occur as organ dysfunction occurs • urinary/renal calculi (high plasma Ca++) • cardiac arrhythmias, tremors (Ca++ necessary for normal muscle contraction • Anorexia, vomiting, constipation • weakness
Hyperparathyroidism Dx: • Routine chemistry panel • ↑ blood Calcium (normal: ~8-10 mg/dl)) • +/- ↓ blood Phosphorus (normal: ~2-6 mg/dl) • PTH assay • normal PTH: dogs ~20 pg/ml, cats ~17 pg/ml • In a normal animal: if blood Ca++ is high, PTH is low (neg feedback) • 1º Hyperparathyroidism: Ca++ high, PTH elevated • Ultrasound of neck – enlarged glands, abdomen - uroliths
Hyperparathyroidism Tx: 1. Surgical removal of diseased parathyroid (generally 4 lobes are imbedded in thyroid gland) Other options: 2. Ultrasound-guided chemical (ethanol) 3. Ultrasound-guided heat (laser) ablation Post-Op Care: 1. Hospitalize for 1 wk; ↓PTH may predispose animal to hypocalcemia 2. Calcium therapy (oral tabs, liquid) 3. Vit D supplements (promotes Ca intestinal absorption)
Hyperparathyroidism Client Info • Most hyperparathyroid animals show no signs when first diagnosed • Run yearly chem panels on all normal, older animals
Hypercalcemia: Other causes • Causes • Neoplasia (lymphoma, perianal gland tumors) • Renal failure • Hypoadenocorticism • Vitamin D rodenticide • Drugs or artifacts (ex lipemia) • Clinical signs vary with cause • PU/PD, anorexia, lethargy, vomiting, weakness, stupor/coma (severe), uroliths
Hypercalcemia • Tests • Elevated serum calcium levels • Low to low-normal phosphorus concentrations
Hypercalcemia • Treatment • Fluids: 0.9% NaCl • No Ca2+ containing fluids • Diuretics (furosemide) • Steroids • Complications • Irreversible renal failure • Soft tissue calcifications
Hypocalcemia Causes: • Parathyroid disease • Inadvertent removal of parathyroid during thyroidectomy (most common cause • 1º Hypoparathyroidism (uncommon in animals) • Chronic renal failure— • may cause ↑ serum P, which can result in ↓ serum Ca (Ca:P inverse relation) • Vit D normally activated in kidney • Protein-losing nephropathy results in loss of albumin-bound Ca • Puerperal Tetany (Eclampsia)—late gestation thru post-partum period • Improper prenatal nutrition • Heavy lactation • Inappropriate Ca++ supplementation http://www.thepetcenter.com/gen/eclampsia.html#The_video