ATTITUDE The people who get on in this

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

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.

Hormones

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

Hypothyroidism

Thyroid Gland • Gland not usually palpable • Located at ventral cervical region along lateral margins of trachea • Hormones produced – T 3 (__________) and T 4 (___________), 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 T 4 (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

Hypothyroidism

Hypothyroidism

Hypothyroidism

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 nonregenrative) – 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 T 4 – Test total T 4(TT 4), +/- T 3 levels – Free T 4: Free T 4 is thyroxine that is not protein bound (ED is most accurate test for f. T 4 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 T 4 levels. (_________) – Wait and re-test after treatment of underlying cause if clinical signs persist. • Greyhounds have low T 4 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 (1 st 6 -8 months) • Test levels and adjust dose until T 4 normal – Want to test 4 -6 hours after dose is given (when serum levels are highest)

Thyroid replacement hormone (levothyroxine sodium)

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 T 4 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 in cats

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 Wt loss Polyphagia Tachycardia Blindness with retinal detachment Palpable enlarged Thyroid gland Aggressive unkempt haircoat

Hyperthyroid cat: Goiter

Hyperthyroidism • Diagnosis – Palpate enlarged thyroid gland – Elevated T 4, FT 4 – 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 – I 131 • 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