Reproductive Problems in the Mare Flashcards
Why do mares come into stud?
Mares present in one of the following categories:
•Maiden
–Establish is mare is normal
–Establish stage of the cycle and attempt to get into oestrus as soon as possible
•Pregnant
–Aim to breed at the ‘Foal Heat’
- 5 – 10 days post partum
- Foal develops diarrhoea
- Oestrus may be silent
- No endometrial sloughing after parturition
–Should you cover at the foal heat?
- Easy to identify and useful in mares that foal late
- But, lower conception rate and increased pregnancy loss
- Do if: post-partum events normal, mare foaled late in year
- Don’t if: poor involution of fluid present (see case in Week 2)
- Barren
–Understand previous breeding management
–Establish diagnosis and likely prognosis
–Treat any undetected endometritis
–Establish stage of the cycle and attempt to get into oestrus as soon as possible
It is 28th February. Dimple is a 6 year old TB mare that has been under lights since 1st December. She was teased 10 days ago and showed good oestrous behaviour and so was covered. She has been bred every other day since then.
Ultrasound imaging of the ovary and uterus, and speculum examination of the cervix are shown
Describe the features
What is going on?
What do you need to do?
- Video at bottom is speculum exam of cranial part of vagina, can see cervix
- Middle pic – US of uterus
- Top – ovaries
- Left top – at least 4 follicles, 2 are close to 3cm ish.
- 2 big ovaries with lots of follicles
- Anechoic – its dark, is it in the lumen? Can we see a lumen? Its oedema, within endometrial folds – so oedema in uterus.
- Big ovaries, lots of follicles, uterine oedema and big soft, flabby service à she’s in oestrous and under influence of oestrogen, and has been for 10d. She’s in transitional phase. She’s put under lights since February – trying to bring transitional phase earlier on so hopefully when she reaches beginning of breeding season, she is close to ovulating
- Is there a single follicle that looks like will ovulate? No, all follicles are the same size – this mare is still in transitional phase, late in it
- Could just carry on teasing and breeding every other dya, she will ovulate at some point… but every time you breed you contaminate her uterus and don’t want post breeding endometritis
- What do we do? Do we try and suppress with progesterone and hope we can cause a follicle to ovulate once we remove progesterone. Or can we force a follicle to ovulate? The fact there is no difference in size of follicle – forcing her to ovulate will be less effective than the progesterone. If one follicle was larger than all of the others, might ty to force it. So in this mare 7-10d regime of progesterone, remove it, then surge and hopefully then she will ovulate
- The day we stop giving regumate, hopefully we get an LH surge- might give another drug at the same time – hCG (LH like) or could be GnRH (higher up in cascade). 10d of regumate and then of day 11 or 12, give these drugs and hope she will ovulate on days 13/14
It is March 25th. Glossy Girl foaled in February and the foal heat was observed 7 days ago
Ultrasound imaging of the ovary and uterus, and speculum examination of the cervix are shown
Describe the features
What is going on?
What are you going to do?
What is the arrow pointing to?
- Video at bottom is speculum exam of cranial part of vagina, can see cervix
- Middle pic – US of uterus
–No oedema which is telling us that is she in anoestrous or in luteal phase
•Top – one of the ovaries
–Can see CL on the ovary
- Relatively homogenous, quite echogenic
- Likely that on palpation, uterus will obvious be under progesterone
- The cervix – smaller in diameter and closed, under influence of progesterone
- This mares has progesterone, luteal phase, history says heat was observed 7d ago, don’t know when she ovulated, but presumably she is in the early part of the luteal phase.
- If we want to breed her – need prostaglandin
–Early luteal phase wont cause lysis of the CL, first 5d, prostaglandins has little effect – so 7d might be possible to response but might not – so would try this likely
•After injected with prostaglandin, when should we tease her again? 3ds roughly. Progesterone will fall
–17d luteal phase normally
–Day 21 normal length
–4d after fall of progesterone might be time you expect ovulation – so tease 3-4d from now. Could be slower or faster depending on where you are in breeding season. Tease and see the response
Jacinda is an 7 year old Irish Draft mare. She was inseminated with chilled semen shipped from Ireland yesterday.
Ultrasound imaging of the ovary and uterus are shown
Describe the features
What is going on?
What are you going to do?
•Top pic – ovary
–Follicle is large, pointing to LHS, starting to form its beak like appearance – so she was inseminated yesterday, hasn’t yet ovulated.
•bottom – uterus
–Can see fluid in the uterus
–Luminal fluid with some echogenic particles
–She has post mating endometritis – fluid should all have gone now and it hasn’t
–She is still in oestrous as can see oedema pattern in uterus and endometrial folds
–If there wasn’t any fluid and could see this large follicle and the fact its chilled semen – might consider making her ovulate so she ovulates soon, but unlikely to do in this situation as more worried about endometritis – want more time to treat endometrium
•What are we going to do
–Lavage uterus
–Antibiotics
–Oxytocin or prostaglandins for spasmogenic reasons
–Go back again tomorrow and repeat the same thing!
–Hopefully we will resolve endometritis quickly and will get pregnant and stay pregnant
–As its chilled semen – do we need to redo this?? We caused endometritis with one insemination, if we do another – will cause it again, wouldn’t re-breed this mare – normally with chilled semen, just try and do 1 AI
–If trying to make her ovulate – use GnRH (Deslorelin) or hCG (LH like)
How can we shorted the luteal phase?
- Most common method of manipulating the cycle is administration of prostaglandin
- Remember that this causes lysis of CL and a return to oestrus: the speed of response depends upon the stage of follicle growth at the time you administer the PG
- Single dose of PG between day 5 and 12 causes return to oestrus in 4 to 6 days(but ovulation may take up to 10 days early in the breeding season)
How can we hasten ovulation?
- Optimum time for mating in a normal mare is 24 to 48 hours before ovulation
- If ovulation could be hastened a more accurate breeding day might be predicted – here a drug might be given prior to breeding with breeding planned some time later
- GnRH Agonists (Ovuplant) or hCG (Chorulon)
–Place GnRH implant or inject hCG when follicle 3.5 cm in diameter
–Ovulation should occur within next 48 hours
–Therefore plan breeding 24 hours after injection
What is the optimum time for mating in a normal mare?
Optimum time for mating in a normal mare is 24 to 48 hours before ovulation
How can GnRH agonists be used to hasten ovulation?
•GnRH Agonists (Ovuplant) or hCG (Chorulon)
–Place GnRH implant or inject hCG when follicle 3.5 cm in diameter
–Ovulation should occur within next 48 hours
–Therefore plan breeding 24 hours after injection
What are the most common problems that cause mares to present as barren or with abnormal reproductive function?
- Abnormalities of cyclicity
- Other common reproductive abnormalities contributing to infertility
- Important findings that may be incidental
In some sort of order relating to how common they are, what are the most common abnormalities of cyclicity?
•Prolonged dioestrus
–Extended luteal phase
- Erratic oestrus during transitional phase
- Absent oestrus post-partum
- Silent oestrus
What are the most uncommon abnormalities of cyclicity?
- Nymphomania
- Granulosa cell tumour
- Failure to reach puberty
- CYSTIC OVARIES DO NOT OCCUR
How common are cystic ovaries in mares?
CYSTIC OVARIES DO NOT OCCUR
Why do mare get prolongued dioestrous?
- Caused by persistence of secondary CL in absence of pregnancy
- Up to 24% of cycles (i.e. it is common)
- Occurs as a result of a dioestrus ovulation
- CL can persist for up to 3 months
- Uterus and cervix typical of luteal phase
- Ovaries may be large as follicle growth continues; this may confuse the inexperienced
What are the signs and treatment for prolongued dioestrous in mares?
- Signs are failure to return to oestrus
- Treatment is single dose of PG
How can another follicular wave cause a porlognued dioestrous - describe what happens and when for this to happen
- Concept of prolonged dioestrous in mare. In most cases in normal luteal phase has rise of progesterone, plateau, prostaglandin produced, progesterone falls and oestrous starts
- Often have other waves of follicular growth that occur at different stages of the cycle e.g. could be in middle of luteal phase – haven’t reached right size to ovulate. They get these waves because high FSH during luteal phase. Sometimes seen in cows and horses and little know about it in other species
- Unusual – can get high FSH and ovulation in middle of luteal phase – results in long luteal phase, as the CL doesn’t respond to prostaglandin, new CL occurs in middle of luteal phase and new CL doesn’t respond as its too young – so persistence of CL that arose from 2nd ovulation (rare but can happen). Luteal phase ovulation – doesn’t respond to uterus prostaglandin
- Must remember that you can have big follicles and mare not be in oestrous
When mares get erratic oestrous during their transitional phase - what are some treatment options to control this?
–Providing 16hrs artificial light and additional nutrition from 1st December
•Some clinicians also adminsiter GnRH agonists at this time but efficacy is unproven
–Once the mare is within the transitional period (follicles greater than 2.5 cm in diameter) progestogens are administered to suppress the release of LH
- Normally Altrenogest (Regumate) is given in feed for approximately 10 days
- Follicles continue to grow during progestogen treatment
- When follicles reach 4.5 cm progestogen treatment stops and there is a surge release of LH which induces ovulation
–Some clinicians also administer GnRH at this time to enhance the LH release
•Ovulation normally occurs 8 – 12 days after last dose (why is this so slow?)
Its 4th April. Sheena foaled 32 days ago. She showed vague signs signs of oestrus on day 8 but was not covered because she had dystocia.
She has been teased daily since day 26 but has shown no signs of oestrus.
When should oestrus return?
How might you establish what is the stage of the cycle of this mare?
Had Sheena foaled on 2nd January might you be considering anything else?
–In terms of history, if we artificially breed a mare early so she has a foal early, foaled early but why should she come into oestrous as its not breeding season! So not uncommon for mares that foal early, will show vague signs of foal heat, but then go into anestrous as its winter and this is normal for her
–So they often put pregnant mare under lights as well, in December, so when she foals, she thinks its spring time
•
- She should be cycling every 21d – which she isn’t doing.
- What would we do in this mare?
–Reproductive exam – feel cervix and uterus, palpate and scan ovaries
–Looking for if there is a CL (tone in uterus and closed cervix) and if no CL then she hasn’t recently ovulated, so she might be in an anoestrous period
- Most concerned that she did come into oestrous, did ovulate, and now is in anoestrous
- Does she have a CL? Prostaglandin
- Could have small ovaries and no activit
Pudson has a 20cm diameter large left ovary (see ultrasound). The right ovary is small at 4 cm diameter.
When an in season mare is presented to Pudson, this mare lifts her tail and squirts at Pudson.
Describe the features of the ultrasound
Consider what the hormonal environment in this mare is likely to be
Why is the right ovary so small?
What are you going to do?
- Multi-cystic with solid areas
- Pudson showing male like behaviour and is teasing the oestrous mare
- Mares that have big ovaries
–2 big – pregnancy and transitional phase, pseudopregnancy or prolonged dioestrous
•One big ovary and one small could be neoplasia, the other ovary is small due to negative feedback – from androgen, reduced production of GnRH and reduced production of FSH and LH so drive to the other ovary is reduced
Hetty is 8 years old and presents in February for a BSE
Her vulva slopes slightly cranially but is not far from normal (something like Figure 3)
Ultrasound of the uterus is shown
Describe the features you can see on the ultrasound image
What is going on?
What do you need to do?
- Sloping vulvar
- Can see in the uterus
- Air in the uterus – gas is echogenic, what she has sucked in due to her abnormal conformation
- Has pneumovagina and a small volume pneumouterus
