Lesson 71 Hormones and hormonal disorders

hormonal changes in estrus cycle

• high estrus in follicular phase. estrogen decreases in luteal phase

• high progesteron in luteal phase→ peaks near the end

• uterus releases PGF2a if no pregnancy detected peaks near end of luteal phase. PGF2a causes decrease in progesterone

• FSH sharp increase and LH surge causes by estrogen prior to ovulation

what hormones control the length of estrus cycle

prostaglandin

Other clinical application of prostaglandin

estrus synchronization in cattle and horses by terminating cycle earlier→ induces heat sooner

how long is estrus cycle in horses and cows

21 days

• primary and accessory CL produces progesterone

• Endometrial cups form day 35 of pregnancy and produces ECG

• ECG mimics FSH and works like LH in mares

• foetal gonads produce estrogen sulphate (pregnancy specific)

How long is canine diestrus

2 months

how long is canine heat phase?

9 days

how long is canine gestation

63 days

relaxin

produced by placenta in dogs and detected day 20 of pregnancy

function: maintenance of pregnancy and during parturition it loosens the muscle for easier passage of fetus

Prolactin

increases in late gestation.

function: produce milk

estrogen during pregnancy

peaks again in late stage of gestation

hormones used to diagnose pregnancy in mares

EcG-produced by endometrial cups but will still be present until end of pregnancy regardless of termination

hormones used to diagnose pregnancy in dogs

relaxin since its specifically from the placenta

5 alpha pregnanes

metabolite of progesterone. increases in late gestation

function:progesterone like functions

What is the average size of a normal preovulatory follicle in cows?

1-2 cm

cystic ovarian disease in cattle

1 or more cystic structure on ovary that stay longer than 7-10 days and prevent normal cyclic activity

why is cystic ovarian disease common in dairy cows

bc producing lots of milk causes stress and they are also in a negative energy balance.

follicular cysts

thin walled, less than 3 mm thick

several large cyst or multiple small cysts

produces estrogen

clinical presentation for follicular cysts

anaestrus, nyphomania (estrus like behavior), virilism (male characteristics)

luteal cysts

thick walled, more than 3 mm thick

single cysts

produces mainly progesterone

clinical presentation luteal cyst

anestrus

why does a cow with luteal cyst commonly present with anestrus

negative feedback from increased progesterone

difference between progesterone secreting vs estrogen secreting ovarian cyst

progesterone: signs of estrus

estrogen: signs of estrus, attraction to male dogs, swelling of vulva, discharge, hyperestrogenism if prolonged (alopecia, hyperpigmentation)

hyperestrogenism signs

bilateral alopecia, hyperpigmentation, bone marrow suppression, nonregenerative anemia, luekopenia, thrombocytopenia

how to treat follicular cyst on large animal

LH supplement or GnRH analog

-both acts as the missing LH surge to turn the follicle into a CL

follicular cysts form

when dominant follicle fails to ovulate due to lack of LH surge

how to treat follicular cysts in small animals

spay/ ovariohysterectomy

types of vaginal epithelial cells

anuclear, superficial, iintermediate and parabasal

which vaginal cell types are cornified

anuclear and superficial

which vaginal cell types are noncornified

intermediate and parabasal

which cell types are under estrogen influence (shows animal is in heat)

cornified cells (anuclear and superficial)

pyometra

accumulation of pus in the uterus in presence of functional CL

Why does CL advance pyometra

secretes progesterone, closed cervix, lowered uterine defense, and increased gladnular secretion

How does pyometra appear on ultrasound

thick uterine wall and hypoechoic fluid in the uterine lumen

What causes pyometra?

reoccuring infection, active CL, fetal death in closed uterus, bacterial organisms

clinical signs of pyometra in cattle

no systemic illness, closed cervix= no discharge, anestrus, non cyclic

rectal exam: enlarged uturus, fluid filled, thick walled atonic, and CL

pyometra in mares

similar to chronic closed abscess

-caused by inability of cervix to open(fibrosis)

endometrium becomes too damaged and fertility is impacted

-does not show signs of systemic illness

What hormones downregulates the uterine defense mechanism and results in closure of the cervix

progesterone

cystic endometrial hyperplasia (CEH)

progressive hyperplasia and cystic degeneration of endometrial glands with each nonpregnant cycle

-predisposes bitches to infertility and bacterial infection

-exogenous progesterone or estrogen can predispose to CEH

how does CEH look on the uterine horn

cobblestone appearance

E.coli

gram negative rod that causes 98% of the canine pyometras

clinical signs of pyometra in bitches

systemically ill, endotoxemic shock from endotoxins released form bacteria

renal dysfunction- prerenal azotemia (dehydration/shock), glomerular disease, decreased GFR, decreased ability to concentrate urine from endotoxemia

closed vs open cervix pyometra

closed- less sick

open- more sick

How does pyometra look on ultrasound in dogs

uterine lumen is more anechoic because pus is more watery in dogs than other species

which hormone more closely associated with development of pyometra in dogs

progesterone→ decreaes uterine defense, promotes CEH, closure of cervix

hypoluteidism

low plasma progesterone→ pregnancy loss

benign prostatic hyperplasia

most comonly diagnosed prostatic disease in dogs. mostly seen in 6+ yr old intact dogs

what causes prostatic hyperplasia

since prostate in androgen dependent

more testosterone which are reduced to dihydrotestosterone (DHT) which are biologically active and promotes prostatic hyperplasia

how many accessory sex gland in horses and bulls

4

how many accessory sex gland in pigs

3

how many accessory sex gland in cats

2

how many accessory sex gland in dogs

1

clinical presentation prostatic hyperplasia

can be aymptomatic, serosanguinous prepuital discharge (bloody discharge from penis), reddish semen,

straining to defecate

hematuria (NO dysuria or stranguria)

caudal abdominal pain

infertility

prostatic metaplasia

secondary to estrogen stimulation, low grade inflammation

dx: squamous epithelial cells on cytology

prone to cyst, prostatitis/abscess