1. 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

2. ENDOCRINE SYSTEM DISEASES ‘CRINE’ – to secrete

3. Endocrine System Diseases

4. Main trigger: Hypothalamus

5. 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 _____________.

7. 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.

8. Hormones

9. 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

10. DISEASES OF THE THYROID GLAND HYPERTHYROIDISM HYPOTHYROIDISM

11. Hypothyroidism

12. 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

13. 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)

14. 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)

15. 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

16. Hypothyroidism

20. 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

21. 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

22. 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.

23. 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 T4 normal – Want to test 4-6 hours after dose is given (when serum levels are highest)

24. Thyroid replacement hormone (levothyroxine sodium)

25. 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.

26. 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 ____________

27. Hyperthyroidism in cats

28. Hyperthyroidism Clinical Signs – Multi-systemic: reflects increase in metabolism _________________ __________________ Vomiting/diarrhea _____________________ Tachypnea/dyspnea Hyperactivity Aggression

29. Hyperthyroidism Clinical signs cont’d – ____________________(thickening of LV and heart muscle) – Hypertension – Poor body condition – Thickened nails – Unkempt appearance – ______________________ gland 70% - bilateral

30. Hyperthyroid cat Middle age to older catsBlindness with retinal detachment Wt lossPalpable enlarged Thyroid gland PolyphagiaAggressive Tachycardia unkempt haircoat

31. Hyperthyroid cat: Goiter

32. Hyperthyroidism Diagnosis – Palpate enlarged thyroid gland – Elevated T4, FT4 – X-rays for associated heart disease

33. Hyperthyroidism: Scintigraphy Normal cat Normal uptake in salivary glands and thyroid glands Hyperthyroid cat Unilateral thyroid adenoma

34. Hyperthyroidism: Scintigraphy Hyperthyroid cat Bilateral thyroid adenoma Hyperthyroid cat Ectopic (intrathoracic) thyroid adenoma Hyperthyroid cat Functional thyroid carcinoma (represents regional metastasis)

35. 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

36. Hyperthyroidism: Medical Rx METHIMAZOLE ORAL DRUG, BUT CAN BE FORMULATED INTO A TRANSDERMAL OINTMENT

37. 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

38. 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