28. Diseases of the hypophysis in dogs and cats. Flashcards
Hypophysiotropic hormones
hypothalamus hormones?
GHRH - growth hormone
LHRH - luteinising hormone
TRH - thyrotropin
CR - corticotropin
another name for the hypophysis
pituitary gland
Pituitary hormones
ACTH
GH
PRL
TSH
LH
FSH
aMSH
ADH
Oxytocin
Congenital hyposomatotropism
pituitary dwarfism
autosomal recessive inheritance
Pathogenesis of congenital hyposomatotropism
cyst formation of the anterior pituitary lobe causing decreased GH -> decreased TSH –> decreased T4
What does decreased T4 result in
secondary hypothyroidism
Predisposed to congenital hyposomatotropism
g. shepherd
karelian bear dogs
Clinical signs of congenital hyposomatotropism
Poor growth in puppies
retention of lanugo
alopecia
thin skin
hyperpigmentation
brachygnathia inferior
after 2-3 years —— decreased activity, appetite
Diagnosis of congenital hyposomatotropism
Skin biopsy - decreased elastic fibres
Insulin like growth
Xylazine - stimulation test
Clonidine - stimulation test
GHRH - stimulation tests
Treatment of congenital hyposomatotropism
Bovine - GH
Porcine - GH
Human - GH
(not permanent solution) (autoantibody development)
T4 therapy
Prognosis of congenital hyposomatotropism
max 5yrs
euthansia due to anorexia and renal failure
Alopecia X
arrest of hair cycle
umbrella term for
- GH-responsive dermatosis
- Castration-responsive dermatosis
- Oestrogen-responsive dermatosis
- Biopsy-responsive dermatosis
- Adrenal hyperplasia-like syndrome
Pathogenesis of Alopecia X
not completely understood
Predisposition of Alopecia X
Nordic breeds
Poodle - fluffy breeds
Pomeranian
Chow- chow
Samoyed
Possible causes of Alopecia X
increased androgen production
mild cushing’s
Clinical signs of Alopecia X
Cosmetic
symmetrical non inflammatory alopecia
hyperpigmentation on neck, trunk & caudal surface of thighs
Treatment of Alopecia X
Castration - testosterone therapy
Trilostane
Melatonin
Pathogenesis of Acromegaly
Middle aged bitches - exogenous progestogens, mammary tumour, metoetrus, ovarian cyst
Middle/ old aged male cats - pituitary tumour
Clinical signs of Acromegaly
large head
large paws
increased interdental space
distended abdomen
loose skin
snoring
dyspnoea
pupd
protruding skin
Lab d of Acromegaly
Glucosuria
Treatment of Acromegaly
Insulin therapy
Progestogen & agleprisone
Ovariectomy
Hypophysectomy, cobalt irradiation (cats)
Cause of Diabetes Insipidu
Decreased ADH
Cause of decreased ADH
Decreased Production
Decreased sensitivity
Role of ADH
renal water resoprtion control
urine production & concentration
Predisposed to Diabetes Insipidus
middle aged/ old bitches
Types of Diabetes Insipidus
Central
Nephrogenic
Central Diabetes Insipidus
Most severe
Partial (low ADH) or complete (no ADH)
Due to; tumour of - pituitary, hypothalamic, hypophysectomy, inflammation, trauma
Nephrogenic Diabetes Insipidus
Most common
Impaired action of ADH on kidneys
decreased sensitivity
Potentially reversible
Due to; kidney/ liver failure, hypercalcaemia, addison’s, cushing’s, pyometra
Clinical signs of Diabetes Insipidus
PU/PD
Dehydration
death
Diagnosis of Diabetes Insipidus
Blood sample
abdo US
cortisol measurement
Urinalysis
How to distinguish nephrogenic from central Diabetes Insipidus
Modified water deprivation test
Desmopressin Test
Modified water deprivation test
Be careful as dehydration is risky in Diabetes Insipidus patients
CDI - USG >1.030
NDI - no change
Desmopressin test
Give desmopressin for 7 days
CDI - decreased pu/pd by day 7. increased USG
NDI - minimal improvement
Treatment of Central Diabetes Insipidus
Desmopressin
Treatment of nephrogenic Diabetes Insipidus
decreased Na diet
provide continuous source of water
thiazide diuretics
