Reproduction Flashcards
Proactive vet role in managing reproduction
Cycle manipulation/advancing breeding season
Pre-breeding soundness examinations
Use of estimated breeding values
Reactive vet role in reproduction
Investigating infertility
Abortion outbreaks
Dystocia
What are caruncles?
Placental attachment site
Follicle key features
Contains oocyte (egg)
Fluid filled (anechoic on US)
Secretes oestradiol that drives oestrus
Multiple stages of development
Corpus luteum key features
Highly vascularised, transient endocrine gland
Solid (homogenous, medium echogenicity on US)
Progesterone production
Bigger than a follicle
Length of oestrus cycle in a cow
21 days
Length of luteal phase in a cow
17 days
Length of proestrus in a cow
3 days (no signs)
Hormone changes during proestrus in a cow
Decreasing progesterone, increasing oestrogen
What happens 24 hours after an LH surge in the cow?
Ovulation
When should a cow be artificially inseminated?
6h after onset of oestrus (so really as soon as it is observed)
Reason: LH surge mid oestrus, ovulation 24h after LH surge/12h after end of oestrus
How many follicular waves does a cow have per cycle?
2 or 3
Can a cow have more than one follicle at a time?
Yes, new and regressing follicles may be present at the same time
If a cow has an old CL, a large follicle and a small follicle which phase of its cycle is it in?
Follicular phase
Is it possible to determine the difference between a small follicle and a regressing follicle?
No
What phase of the cycle is a cow in with a CL and a large follicle present?
Mid luteal phase (CL is dominant)
Duration of oestrus in the cow
5-18h
Oestrus cycle length in the ewe
17 days
Duration of oestrus in the ewe
24-36h
Time of ovulation in the ewe
30-36 hours from beginning of oestrus (towards end of oestrus)
Oestrus cycle length in the sow
21 days
Duration of oestrus in the sow
48-72h
Timing of ovulation in the sow
35-45 hours from beginning of oestrus
Main challenge with insemination of the cow
Detecting oestrus (for artificial insemination)
Main challenges with insemination of the ewe
Correct ram:ewe ratio and identification of mated ewes
When should a sow be artificially inseminated?
2nd day after onset of standing oestrus, usually two inseminations
What initiates return to oestrus in the sow?
Weaning (LH surge, oestrus within 7 days)
How does the suckling effect prevent oestrus in the sow?
Early follicular activity occurs
Prolactin suppresses LH so ovulation does not occur
Short term acting GnRH actions
Induces LH/FSH surge to hasten ovulation
Hastens impending oestrus
‘Force’ ovulation/leutinisation of cystic structures
How soon after GnRH administration will cows ovulate? How soon after GnRH administration should fixed AI occur?
Ovulation: ~26 hours
AI: ~6 hours (no oestrus signs)
FSH actions
Stimulates antral follicular growth
Product with FSH-like action
eCG
Clinical use of FSH
Superovulation (administer early in follicular wave, often requires repeated doses)
Action of LH
Stimulates maturation of follicles and luteinisation
Provides luteal support
Drug that binds to LH receptor and has LH-like activity
HCG
Clinical uses of LH
Induce ovulation when animals are in oestrus
Force ovulation when there is repeated failure of conception
Treatment of cystic ovaries
Effect of progesterone
Negative feedback on hypothalamus/pituitary (suppresses hypothalamic-gonadal axis), mimics luteal phase and cow will immediately enter follicular phase
What forms do exogenous progestogens come in for cows/ewes?
Vaginal sponges for oestrus induction/synchronisation
What forms do exogenous progestogens come in for mares/sows?
Oral liquid for oestrus suppression, induction or synchronisation (Regumate)
Prostaglandin F2a action
Lysis of mature CL and smooth muscle contraction (termination of luteal phase or induction of abortion/parturition)
Clinical uses of the ecbolic effect of exogenous prostaglandin
Treatment of chronic metritis or pyometra if CL is present
Methods of stimulating onset of cyclicity in ewes
Melatonin
Progestogen sponges for ~14d in combination with eCG/GnRH
Ram effect
Excess fluid accumulation in the allantois (placental origin)
Hydroallantois
Clinical signs of hydroallantois
Bilateral abdominal distension
Uncomfortable
Inappatent
Reduced/absent rumen function due to compression
Recumbency
Tight uterine wall palpable per rectum
Prognosis with hydroallantois
Guarded to poor (if survives cull recommended as poor reproductive performance/recurrence likely)
Excess fluid accumulation in the amnion (fetal origin)
Hydroamnoin
Do hydroamnion or hydroallantois come with fetal abnormalities?
Hydroamnion (fetus not swalling or digesting fluids)
Future breeding prognosis of dam in hydroamnion
Reasonable
Which condition would you suspect if there was a large volume of thick, syrupy fluid and fetal abnormalities at parturition?
Hydroamnion
Treatment for dropsical/’dropsy’ conditions in cows
Induce/terminate pregnancy (prostaglandin/steroids)
Fluids (correct hypovolaemia and electrolyte disturbances)
Trochar and drain fluid
Common fetal malformation causing limb ankylosis
Arthrogryposis
Management of neonates with arthrogryposis
Euthanasia (unable to stand)
Most important cause of arthrogryposis in sheep, goats and cattle (should test if there are multiple cases)
Schmallemberg virus
Name for ‘inside out’ fetus (rare genetic malformation)
Schistosomus reflex
How to manage dystocia of schistomosus reflexus calf
Fetotomy/c-section
How is schistomosus reflexus differentiated from a uterine rupture?
Thorough clinical and vaginal examination to establish whether intestines belong to cow or fetus
What causes short legs, domed head and brachygnathia inferior (undershot jaw)
Congenital chondrodysplasia
Teratogenic viruses that cause hydrocephalus
BVDv
BTV/blue tongue virus
Akabane virus (not UK)
Why does hydrocephalus cause dystocia?
Head is too big, require partial fetotomy (remove head) or c section
What condition causes large neonates (2x average size), dystocia and macroglossia?
Large offspring syndrome/abnormal offspring syndrome
Are calves with large offspring syndrome usually alive?
Yes but require caesarean
Ancephaly
No head
Otocephaly
Some head structures present but no skull
Bicephaly
Two heads
Options for correction of dystocia
Manual correction and delivery per vaginum
Caesarean options
Fetotomy
Euthanasia (dam +/- fetus)
What can be helpful for manual correction of dystocia?
Epidural
When is caesarean contraindicated?
Decomposing calf
Indications for subcutaneous fetotomy
Correction achievable through limb removal only (but as for percutaneous)
Make incision through skin and only dissect limb away from body (less tiring, less equipment)
Indications for percutaneous fetotomy
Feto-maternal disproportion
Pathological fetal oversize
Congenital fetal malformations
Malpresentation that cannot be corrected
What drives puberty in cattle?
Weight (~2/3rd of adult BW)
Problems with unwanted pregnancy in heifers
Poor heifer growth (won’t catch up after calving)
Increased risk of dystocia (especially with poor heifer growth)
Management options for unwanted pregnancy in heifer
Wait and see (caesarean likely needed, less optimal outcome in emergency)
Elective caesarean (scan to know gestation duration)
Induce parturition (viable but small fetus)
Terminate pregnancy (prostaglandin, glucocorticoid steroids)
Effect of glucocorticoid steroids on pregnancy
Reduces placental secretion of progresterone leading to pregnancy loss or induce parturition after day 270
Pregnancy termination in cows
Early pregnancy: prostaglandin
Mid pregnancy (>150d): prostaglandin and dexamethasone
Late pregnancy (even in last month): dexamethasone
Adverse affect of glucocorticoids and prostaglandin on cows when terminating pregnancy
Increased likelihood of retained fetal membranes
Effect of teratogens on a zygote
Embryonic death
Effect of teratogens on an embryo
Abnormalities developed
Effect of teratogens on fetus
More resistant to environmental teratogens but late developing structures are still susceptible to being affected
At what age does BVDv cause teratogenic effects?
80-150 days
Common viral teratogens
BVD (calves)
Border disease (lambs and kids)
Schmallemberg
Bluetongue
Akabane and Aino virus not currently in UK
Environmental teratogens
Hemlock
Nitrates/nitrites (nitrate accumulating plants e.g. sugar beet and nitrite based fertilisers)
Ergotism (mouldy feed)
Lead
Pharmacological teratogens
Benzimidazoles (sheep)
Tetracyclines
Steroids
Prostaglandins
Xylazine
How does oestrus behaviour compare between high yielding dairy cows and other cows?
High yielding cows exhibit shorter oestrus periods and standing times
Which structure is fundamental to pharmacological manipulation of the bovine oestrus cycle?
Corpus luteum
Treatment for non-cycling cow 80 DIM with pyometra
Treat with prostaglandins and recheck
(Not antibiotics)
Treatment for a follicular cyst
OvSynch protocol
Gonadotrophin
CIRDSynch protocol
(Not prostaglandin)
Common cause of anoestrus in beef suckler cows
Presence of suckling calves
Poor nutrition/body score second most common
Are cattle abortions more commonly infectious or non-infectious?
Non-infectious
Preferred method for passing a trans-cervical catheter in a cow
Insert hand rectally to manipulate cervix over catheter, taking care to avoid peri-cervical pockets
Appropriate BCS for tup at breeding
2.5-3.5
Hock conformational trait that makes it difficult for bull to mount cows/more likely to develop lameness
Post legged
Effect of pyrexia on male fertility
Bad effect, testes need to operate below body temperature or sperm will be killed off
Safest method to collect a semen sample from a bull
Electroejaculation (no need to be under bull)
Magnification to assess progressive motility of a semen sample
x200
Indications for caesarean section
Fetal oversize
Maternal undersize
Fetal deformity
Inadequate cervical dilation
Uterine rupture
Uterine torsion
Uterine inertia
Narrow/abnormal pelvis
Malpresentation of fetus
Perioperative drugs in a caesarean section
Sedation (a2 agonist IV: xylazine/detomidine)
NSAIDs (flunixin, IV)
Uterine relaxants (b2 adrenergic agonists IV: clenbuterol hydrochloride)
Antibiotics (IM, pen/strep for good penetration/broad spectrum)
Local anaesthetic (procaine hydrochloride and adrenaline)
Caudal epidural? (lidocaine/procaine)
Closing after caesarean section
Uterus: continuous inverting, absorbable
Lavage? Saline
Suture peritoneum/transverse abdominal muscle, oblique muscle, (subcutaneous?), skin
Post operative drugs for caesarean section
Oxytocin (IM, facilitate uterine contraction)
Antibiotics (4d)
NSAIDs (following day or longer if required)
Techniques to restrain cows for teat surgery
Standing in milking parlour
Raise hind leg in foot trimming crush
Tail jack
Sedation
Factors of teat laceration with better prognosis
<4h, near base, vertical, streak canal not involved, superficial (no milk leaking, just apply bandage)
Factors of teat laceration with worse prognosis
> 12h, distal end, horizontal, streak canal involved, depth of teat canal (requires immediate three-layer surgical repair)
Basal abnormalities causing obstruction/slow milking
Congenital in heifers or adhesions resulting from chronic inflammation due to infection in dry period
Hudson’s teat probe and spiral to clear obstruction, debride wound
Mid teat abnormalities causing obstruction/slow milking
Chronic inflammation, milk calculi (teat peas), neoplasia (bovine papillomatosis) or congenital obstruction
Fragmented and removed via streak using a papillotome
Indications for teat amputation
Irreversible trauma
Severe/gangrenous mastitis
Local anaesthetic for teat surgery
Teat cistern infusion, ring block, inverted V block, IVRA
Lidocaine (unlicensed, under cascade as no adrenaline)
Three layers of teat that must be sutured following a laceration/trauma
Mucosal layer
Submucosal layer
Skin
Infectious teat lesions
Mastitis (various organisms)
Bovine herpes mamillitis
Non-infectious teat lesions
Lacerations
Photosensitisation
Hyperkeratosis
Udder oedema
Ischaemic necrosis
Transition period for cows
3 weeks pre-calving to 3 weeks post-calving
Post partum physiology
Uterine involution 3-6w
Lochia normal ~23d (red/brown-white discharge, lacks odour)
Late gestation immunosuppression continues in early post-partum
Physical barriers to infection are compromised
Non-expulsion of fetal membranes beyond 24h post calving (sheep 18h)
Retained fetal membranes
(Normal expulsion within 6h of calving)
Placental physiology (including separation)
Cotyledonary placenta
Fetal cotyledon + maternal caruncle = placentome
Collagen links interface
Placental separation: breakdown of collagen links, relaxin secretion and decline of progesterone
Risk factors for retained fetal membranes
Induced parturition
Shortened gestation
Infectious disease that leads to abnormal calving
BDVv
Uterine trauma (caesarean, dystocia, fetotomy)
Nutritional deficiency (Vit. E/selenium)
Abortion
Immunosuppression
Flunixin meglumine
Treatment of retained fetal membranes
Manual (5-7d, if it comes away freely, no benefit, risk of haemorrhage/uterine tear)
Systematic antibiotic therapy (signs of systemic illness, amoxicillin 3-5d)
Benign neglect (2-11d)
Retained fetal membrane impact on production
Milk drop
Reproductive (delayed return to cyclicity, longer time to 1st service)
Increased culling risk
Increased risk of secondary health problems (metritis, endometritis, ketosis, displaced abomasum, mastitis)
Clinical metritis
Not systemically ill
Abnormally enlarged uterus
Purulent uterine discharge
Within 21 days post partum
Puerperal metritis
Systemic signs of illness/pyrexia
Abnormally enlarged uterus
Fetid watery red-brown discharge
Within 21 days post partum
Treatment of metritis (do not treat grade 1, just grade 2/3)
Systemic antimicrobials (penicillin 3-5d)
TLC/NSAIDs/oral fluids/calcium borogluconate
Uterine lavage? (Saline, must remove fluid)
Clinical endometritis/whites
Purulent/mucopurulent uterine discharge >21 days after parturition
Subclinical endometritis
Neutrophils in uterine cytology sample >21 days after parturition, no uterine discharge
Endometritis diagnosis
Delayed uterine involution
‘Doughy’ feeling uterus on transrectal palpation
Ultrasound
Cytology
Pathogens most commonly identified in endometritis
E. coli
T. pyogenes
F. necrophorum
Treatment of endometritis
PGF2a (stimulate uterine defenses, increase uterine tone and open cervix)
Intrauterine antibiotics (cefapirin: first generation cephalosporin)
Pyometra
Purulent or mucopurulent material within uterine lumen, causing uterine distension, in the presence of a closed cervix and functional corpus luteum
Diagnosis of pyometra
Transrectal palpation and ultrasonography
History of anoestrus
Treatment of pyometra
PGF2a (luteolytic)
