Equine 4 Flashcards
what does FSH do to stallions
stimulates sperm prod
what does LH do to stallions
necessary to complete process of sperm prod
what does testosterone do to stallions
promotes development and function of accessory sex glands, secondary sex characteristics, responsible for mating behaviour
tell me the timeline of testicular growth/sperm development
- testicular descent: 30 days before to 10 days after birth
- LH and FSH increase @ 9mo
- growth and fast development of testes at 12mo
- spermatozoa seen as early as 14mo
- testosterone increases at 20mo = promotion of puberty
should you turn a yearling colt out with mares?
yes! if the mare and the stallion are physically compatible then they absolutely can breed
when is puberty in males
22-24mo
when is the best time to castrate?
8-12mo
easier to castrate than mature males
are stallions seasonal in their reproduction?
yes, but produce sperm all year long
out of season, they have lighter testes, fewer Leydig cells, fewer Sertoli cells, 50% less sperms, blood conc of hormones lower
but they can still breed (and will if you let them)
is it important to test semen extenders with each stallion you do a BSE on?
yes! different stallions respond differently to different extenders
what is the cutoff for good testicle size?
> 8cm
highly correlated with daily spemr output
can you use acepromazine for chemical semen collection?
nope
what can you use for chemical semen collection?
imipramine, xylazine + imipramine
what does the epididymus do?
transport sperm to the deferent duct, concentrates/matures/stores sperm
what does the ampullae do?
widening of deferent duct, surrounded by smooth muscle that contracts to push sperm into urethra, these create common issues in stallions!!!
what do the vesicular, prostate, and bulbourethral glands do?
functions to add gel and fluid to semen
what are the reasons for cryptorchidism in horses?
- genetic
- insufficient androgen
sperm prod in cryptorchid testes is _____, and testosterone prod in these testes is ______.
sperm: no prod
testosterone: undisturbed (high levels)
how can you dx cryptorchidism?
- U/S (external inguinal region and abdominal cavity)
- hCG stimulation test
- blood sample for AMH
- baseline estrone sulfate
explain how to do an hCG stimulation test to dx cryptorchidism
this is the gold standard :)
- take baseline blood sample
2.inject hCG - take second blood sample 1-2 hours after hCG
- measure testosterone
castrated: little to no increase in testosterone
normal function: in normal ranges for both blood samples
cryptorchid: elevated basal testosterone compared to castrated, then increased testosterone after hCG
a cryptorchid will have _____ AMH
high
how can you use estrone sulphate to test for cryptorchids?
mature testicles produce this, so cryptorchid won’t
what is azoospermia?
absence of sperm in ejaculate
how do you diagnose the cause of azoospermia?
- completed ejaculatory process?
- if yes to 1, want to assess if seminal emission occurred (measure alkaline phosphatase AP levels)
- if no to 1, then evaluate collection area, AV, pharmacotherapy, rule out pain, rule out environmental factors
tell me how to use alkaline phosphatase (AP) levels to dx azoospermia etiology
AP should be high in seminal fluid!!!
<100 IU/I = low = no seminal emission = blocked ampullae, retrograde ejaculation
7,000-20,000 IU/I = seminal emission is yes = further ddx, could be testicular defect
what does it mean when there are larger # of sperm with separated tails when there’s a blocked ampulla?
blockage is resolving, occurs often after sexual rest
what is the tx for blocked ampullae?
trans-rectal massage, oxytocin
how do you dx blocked ampullae for certain?
azoospermia, low AP levels, then U/S
what is retrograde ejaculation?
semen goes into bladder, caused by failure of bladder sphincter
how do you dx retrograde ejaculation?
azoospermia, low AP, then look at urine (sometimes see right in sample, sometimes have to spin down)
how do you tx retrograde ejaculation?
imperamine (promotes closure of sphincter)
- can help but not curative
tell me about hormones during testicular degeneration
low E2 + inhibin, high FSH = advancing degeneration (often age related)
low testosterone, high LH = more advanced degeneration
true or false: sexual rest is necessary when there’s hemospermia
true
what are the C/S of hemospermia?
- you can see blood in sperm (sometimes!)
- infertility (because RBCs are pro inflammatory in mare)
what is EHV3 called? other than herpesvirus lol
equine coital exanthema
what are the C/S of EHV3/equine coital exanthema
nodule, vesicle, pustules appear then rupture
ulcers found on teats, lips, nasal mucosa
secondary bac t infections common
healing within 3 weeks = white scars
stallions = reluctant to breed
no systemic illness, doesn’t impact fertility or abortion
what is the tx for EHV3?
sexual rest, Abx ointment
true or false: EHV3 causes abortion storms and systemic illness
false! no impact on fertility or abortion, and doesn’t cause systemic illness
what does CEM stand for? what is it caused by?
Contagious equine metritis
Taylorella equigenitalis
true or false: CEM is reportable in Canada
true!!!
what are the C/S of CEM
vaginitis, cervicitis, endometritis, muco-purulent vag D/C, abortion, infertility
stallions typically show NO C/S!!!
true or false: chronic carriers happen in CEM in mares but not stallions
false! chronic carriers happen in both!!!!
what breed of horse has a high transmission rate of CEM?
TB
in QH and warmbloods, what is effective at preventing the spread of CEM?
Abx in semen extender
how do you dx CEM?
mares: swabs from cervix/uterus, clitoral fossa, clitoral sinus
stallions: swab erect penis
need charcoal swabs
how do you tx CEM?
wash external genitalia w/ disinfectant soap, apply topical Abx 5x
what does EVA stand for and what causes it?
equine viral arteritis
Arterivirus
what are the C/S of EVA?
edema of prepuce and scrotum, short-term sub fertility (high fever fucks up thermoreg), abortion storms in mares, systemic signs
true or false: EVA has carriers
true
how do you prevent EVA? what impact does this have on preggerwS?
vaccinate
it’s a live vaccine = shedding, so separate vaccinated horses from preg mares!
before vaccinating for EVA, what must you do? why?
explain this process
serological testing to see if they’re carriers
no antibodies –> never been exposed = vaccinate
antibody titre –> infection or vaccination? –> virus testing of semen:
- positive = carrier
- negative = vaccinated
what is the second most common tumor in horses?
squamous cell carcinoma
SCC’s are more likely to develop in what type of skin?
deficient in melanin
commonly in mucocutaneous junction
