PTH & Ca+P
Name the most powerful regulator of Ca-P. Where is this regulator produced? (name the specific cell or general location).
ParaThyroid Hormone
Chief cells or parathyroid gland embedded in the thyroid tissue (2 pairs)
Explain the difference between negative feedback and positive feedback.
Negative Feedback: T4 rises -> hypothalamus relays info to pituitary to reduce excretion of TSH to bring T4 back to normal levels
Positive Feedback: the increase of a hormone sends a signal to the hypothalamus to continue to produce said hormone so it gets higher and higher until something inhibits it (can also use example)
Name the hormones NOT released by the anterior pituitary. Where are they released?
Posterior Pituitary: ADH & Oxytocin
Pancreas: Insulin & Glucagon (along with amylin)
Which reproductive hormone(s) is produced in both males and females?
Testosterone, luteinizing hormone, follicle stimulating hormone, GnRH, and E2
A 2 yr old, NM, pothound dog has the following values.
BG: elevated
Fructosamine: WRI
Insulin: elevated
What could be causing these levels?
He just ate.
Describe the general relationship between bone and PTH.
*PTH stimulates bone resorption of Ca-P salts via osteoclasts which increases Ca & P*
What is the name of the tumor located in the adrenal medulla?
Pheochromocytomas
What consequences may arise due to dysfunction of the pineal gland?
Melatonin production would be affected.
Certain reproductive cycles may be affected (i.e. horses & sheep)
Name the 4 phases of the estrous cycle. Name what cause ovulation and when.
Proestrus, estrus, metestrus, diestrus
Ovulation is caused by an LH surge, estrogen is at its peak and happens at the end of estrus
Roxy, Female, 2 yr old golden retriever just had her first litter of puppies! Roxy had 8 puppies in this first litter and over the last few weeks the puppies are growing very quick! Roxy's owner noticed Roxy has been panting more along with general whining and vocalizations, she also noticed Roxy has been twitching. What could be happening with Roxy? How would we confirm?
Roxy likely has eclampsia due to losing so much calcium during lactation and her body isn't able to compensate fast enough causing hyperexcitability due to moderation of sodium channels leading to the channels conducting faster
Name the active form of vitamin D. What significant effect does Vit D have regarding Ca-P?
Active Vitamin D = Calcitriol = 1-25 Dihydro-vitamin D
Stimulates Ca & P absorption in GIT
Which system does not fall under the hypothalamic-pituitary access?
Pancreas - BG - insulin & glucagon
Explain the difference in function of GH and IGF-1.
GH: dominates in low energy situations, provides energy (as glucose & FFAs) and reserves glucose for glucose-dependent tissues
IGF-1: dominates in high energy situations, provides energy to all tissues, maintenance, repair, and growth
Name the 4 accessory glands of the Male reproductive tract.
Ampulla of the ductus deferens, seminal vesicles, prostate, bulbourethral glands
Pablo comes into the clinic, we run bloodwork, as Pablo's symptoms make us suspect Cushing's disease and these are the results.
LDDST: No suppression @4hrs, No suppression @8hrs
ACTH stim: Cortisol >20 ug/dL
By this result, can we say that Pablo has Adrenal-dependent hyperadrenocorticism?
No, although typically PDH cases do show suppression @8hrs; it could also be a case of a really large pituitary tumor. Still need differentials to confirm cause (i.e. HDDST and/or imaging and/or eACTH)
Describe the "background activity" of PTH & bone.
PTH is released in short pulses independent of free Ca which stimulates ONLY osteoblastic activity and bone anabolism
**crucial for bone health**
What percentage of diabetic cats may suffer from acromegaly?
25-30%
Given what scenario would you supplement oxytocin? (Hint: think of the stimulus of oxytocin)
Stimulus: Cervical dilation (parturition) & Suckling of teats (lactation)
OT stimulates the force & frequency of uterine contractions during parturition therefore if there was dystocia you could supplement oxytocin to help mama push out baby
What are the functions of the pampiniform plexus?
Temperature regulation
counter current exchange of testosterone
Little Man, a 4 yr old neutered male, domestic short hair is brought into the clinic. The owner complains he looks too skinny and won't stop trying to steal her food. He's been drinking a lot more water and it seems like he just never stops moving. The owner biggest worry is his weight and asked about sedatives to prevent him from being so crazy.
During your physical examine you find a suspicious palpable lump next to Little man's trachea. What tests do you want to run due to concerns of hyperthyroid?
TT4, fT4 and TSH
gold standard= TT4 for cats
Certain species rely on UV exposure for the liver to produce Active Vit D; what species might that be? What is the consequence if there is not enough UV light exposure? Why does this occur?
Reptiles (also due to lack of calcium in diet)
Metabolic Bone Disease
Without active vit D the GIT doesn't properly absorb calcium leading to chronic hypocalcemia which causes calcium to be removed from the bones leading to rubbery, soft and radiotranslucent bones
What may you mistake a severe trichuris vulpis infection for, if you just looked at bloodwork and zero fecal?
Addison's disease
Lower than 6 basal cortisol, signs of dehydration
There are 2 pathological consequences of excess GH-IGF Axis Dysfunction. Which do we commonly see in our companion animals? What is the typical cause?
Acromegaly (hypersomatotropism) which occurs after puberty
Cats: functional pituitary tumors
Dogs: extended periods of high P4 stimulate GH release from mammary glands (more physiological than pathological)
If progesterone secretion inhibits estrogen secretion; and estrogen secretion is vital for the estrous cycle; then how does the cycle continue if an animal is not pregnant?
Luteolysis caused by PGF2a
Johnny has decided to breed his horses. Unfortunately, Johnny isn't having much luck, he started late in the season and it's now September. Johnny's friend said he'd be better off waiting till next spring or he can add a blue light in the horses stalls and leave it on for a few hours after the sun goes down. Johnny decides to add the blue light in the stalls and noticed a week later the horses showed signs of "heat". Explain this phenomenon.
Horses are long-day breeders which means they need less melatonin to trigger reproductive hormones and "heat". The blue light tricked the brain into waiting to produce melatonin, mimicking "long-days" sending johnny's horses into estrus.