Exotics endocrinology Flashcards
What hormone does the hypothalamus produce when an animal encounters a stressor?
CRH - corticotropin release hormone
What is the main glucocorticoid release during the stress response in mammals?
cortisol
What is secreted instead of cortisol from the adrenal glands of reptiles, birds, amphibians and rodents?
Corticosterone
Why is calcium important in birds?
Bone strength
biochemical reactions
Egg laying
Describe vitamin D sources in birds and reptiles
D3 form required (cannot use D2 like mammals)
Sources:
- plants have D2
- supplements
- can convert D2=>D3 if sufficient UV-B light exposure
Describe calcium homestasis in rabbits
Plasma Ca levels higher than mammals
Need more calcium for constantly growing teeth
Excess Ca precipitates as calcium carbonate in urine => cloudy urine (can cause urine to sludgy if too much => UTI)
All is passively absorbed in intestine
Not vitamin D dependent
Describe ecdysis in reptiles and amphibians
= shedding of skin
Lymph infiltrates between top and new underlying layers, forms cleavage zone, enzyme release, shed upper layer
Controlled by thyroid hormones
Describe the role of thyroid hormones in birds
Stimulate new feather growth (regulate moulting)
Control metabolism
Regulate heat and growth
Regulate reproduction and egg production
Describe the clinical relevance of thyroid hormone in birds
More susceptible to hypothyroidism and thyroid hyperplasia (goitre)
Clinical signs:
- skin and feather abnormalities
- depression and lethargy
- increased infection susceptibility
- visible goitre
- regurgitation and weight loss
- respiratory abnormalities
Describe the diagnosis of hypothyroidism in birds
T4 lower in birds - need bird-specific assays to detect
T4 levels have diurnal rhythm (fluctuate over 24 hrs)
TSH stim test used to assess T4
Describe the pineal complex in reptiles
Pineal gland/organ:
- endocrine gland in brain
- produces melatonin
- controls sleep/wake cycles (responds to light)
Parietal eye:
- photoreceptive structure
- produces and secretes melatonin
- response to light
- controls sleep cycles, hormone production and thermoregulation
