Pituitary Disorders

Question 1

What clinical signs are associated with pituitary disorders?

Answer 1

Neurological signs referable to intracranial dysfunction (RARELY seizures)

Alterations in BCS, size and growth

Altered cycling, libido, fertility

PU/PD

Question 2

What intracranial effects can pituitary disorders have ?

Answer 2

Various, non-specific rarely seizures

Depression under responsive to external stimuli

Behavioural changes

Symmetrical changes due to central location of pituitary

Question 3

What is hypersomatotrophism?

What does it cause?

Answer 3

Increased GH production

Increased IGF1

Tissue proliferation -> phenotype changes
insulin resistance -> DM

Question 4

What causes HST in dogs ?

Answer 4

Ovarian tumour -> Intact females ——now UNCOMMON due to early neutering

History of progestin administration

Question 5

Describe some phenotype changes associated with HST.

Answer 5

Thick set facial features
Increased interdental spaces
Insulin resistance -> difficult to control DM
PUPD if DM

Question 6

Does acromegaly always cause phenotypic changes?

Answer 6

NO

Question 7

What should you do before you measure IGF-1 ?

Why?

Answer 7

Give insulin

Insulin required for liver to make IGF1

Question 8

What are the clinical characteristics of feline hypersomatotrophism?

Answer 8

PU/PD 
Increased appetite 
prognathism 
Increased body size 
Organomegaly 
Insulin resistance 
DM

Question 9

What happens if you leave HST untreated?

Answer 9

Develop HCM

Question 10

What is the best treatment of acromegaly?

If not?

Answer 10

Hypophysectomy and replacement hormone therapy

Aggressive insulin treatment - long term instability

Question 11

How common is HST in cats?

Answer 11

1 in 4 diabetic cats

Question 12

How can you increase your index of suspicion for HST?

How can you confirm

Answer 12

Serum IGF

Demonstration of pit mass

Question 13

What drugs are required after a hypophysecotomy long term?

Answer 13

Most off insulin within a month
Thyroxine SID
Cortisone SID
DDAVP (synthetic AVP)peri-ocularly SID

Question 14

What is central diabetes insipidus?

Answer 14

Absolute vasopressin deficiency

Primary pituitary problem

Question 15

What is nephrogenic DI?

Answer 15

Vasopressin “resistance”

A metabolic problem resulting in renal dysfunction

Question 16

What are the clinical signs of central diabetes diabetes insipidus?

Answer 16

Marked and unrelenting polydipsia
Secondary polyuria

Otherwise unremarkable

Question 17

What are the possible explanations of a polydipsic patient?

Answer 17

Primary polydipsia due to DI -> polyuria appropriate

Renal dysfunction and reduced concentrating ability

Question 18

How can you investigate DI?

Answer 18

Hospitalise and observe 
USG less than 1.008
Urine osmolality and SG fixed and unchanging
Water deprivation test 
Desmopressin response test

Question 19

How do you perform a water deprivation test

Answer 19

Measure USG/osmolality before

Dehydrate patient - 5% body weight reduction or increased PCV
Measure USG/osmolality
- LOW in DI

Give desmopressin, measure USG/osmolality

• same in normal
• increase in DI

Question 20

How do you treat central DI?

Answer 20

Conjunctival desmopressin SID/BID

Adjust based on patient response

Question 21

Describe the appearance of a patient with hyposomatotrophism

Answer 21

Smaller animal with proportional stature

Non-chondrodystrophic

Sometimes have immature hair coat

Persistent oestrus, males infertile

Normal life expectancy

Question 22

What can cause Hyposomatotrophism?

Answer 22

Adenohypophyseal malformation
GH deficiency
Gonadotropin deficiency
Thyrotrophin deficiency

Question 23

What diagnostic aids can be used for hyposomatotrophism?

Answer 23

Serum IGF

Radiography- persistent epiphyseal plates