Final: Iodine (I)

Question 1

What is the function of iodine?

Answer 1

Synthesis of thyroid hormones thyroxine and triiodothyronine (regulate energy metabolism)

Question 2

When is thyroid production increased?

Answer 2

During cold weather

Question 3

When is thyroid hormone levels the highest (body-wise)?

Answer 3

In lactation and growth

Question 4

What 3 processes does production of thyroid hormone involve?

Answer 4

1. Active transport of iodide from plasma across thyroid cell mem. (inhibited by cyanogenic goitrogens)
2. Synthesis of thyroid hormones (inhibited by cruceiferous goitrogens)
3. Secretion of thyroid hormones

Question 5

How much iodine is absorbed and where does unabsorbed iodine go?

Answer 5

80-90%; excreted in urine and milk

Question 6

What happens to milk iodine content when dietary iodine content increases?

Answer 6

it also increases

Question 7

What are diet sources of iodine?

Answer 7

Forage and grains (depend on soil)
Seafood = high
Thyroid glands

Question 8

What happens as a result of iodine deficiency?

Answer 8

Reduction in thyroid hormone production

Enlargement of the thyroid = goiter

Question 9

What signs can iodine-deficient newborns show?

Answer 9

Hairless, weak, or dead

Question 10

What signs does a mother show that gives birth to an iodine-deficient animal?

Answer 10

Shows no signs; took up all iodine from circulation, leaving the fetus deficient

Question 11

What is hyperthyroidism in cats blamed on?

Answer 11

High iodine content of cat food due to thyroid glands being in rendered meat and bone meal

Question 12

What are inorganic sources of iodine?

Answer 12

Iodides of Na, K, and Ca
(K iodide is easily oxidized and volatilizes before the animal can ingest it)
Salt licks

Question 13

What is goiter?

Answer 13

Lack of thyroxine that stimulates the pituitary gland to make TSH –> enlargement of thyroid

Question 14

What are goitrogens?

Answer 14

Compounds that interfere with synthesis or secretion of thyroid hormones

Question 15

What are the 2 types of goitrogens?

Answer 15

1. Cyanogenic goitrogens

2. Progoitrins/Goitrins

Question 16

What do cyanogenic goitrogens do and what are some examples?

Answer 16

Impair iodide uptake by thyroid gland.

Soybeans, beet pulp, corn, sweet potato, white clover, millet

Question 17

What can be done to overcome cyanogenic goitrogens?

Answer 17

Increasing supplemental iodine

Question 18

Whatdo progoitrins/goitrins do and what are some examples?

Answer 18

Inhibit thyroperoxidase

Rape, kale, cabbage, turnips, mustard, onions

Question 19

What can be done to overcome progoitrins/goitrins?

Answer 19

Offending feedstuff needs to be reduced or removed from diet (cannot supplement with iodine)

Question 20

How does foot rot relate to iodine deficiency?

Answer 20

High iodine levels will prevent bacteria from occurring thus preventing foot rot

Question 21

What does excess iodine do to ruminants?

Answer 21

Depression
Salivation
Oculonasal discharge
Tachycardia
Hyperthermia
Circulatory collapse
Abortion

Question 22

What effect does iodinated casein have on cows?

Answer 22

Feed addtive with iodine attached to tyrosine residues of casein = boost milk production
- Works for 2-3 weeks, then cow dies

Question 23

What is Frank’s iodide?

Answer 23

Old IV tx for “lumpy jaw”

Question 24

What is a diet treatment for hyperthryroid cats?

Answer 24

Hill’s y/d diet

Question 25

What is milk goiter in goats?

Answer 25

NOT IODINE DEFICIENCY
Seen in fast-growing goats/sheep;
Thymus gland is developing in these animals