Which of the following is NOT a tool used in routine breeding management of the mare?

Answer: Progesterone assays

Progesterone assays may be used on a very limited level, usually when there is a question of the mare still being in the vernal transition or if the CL function is suspect.  Progesterone assays are not used in routine breeding management, whereas the other three tools are used on many mares most days they are evaluated.

Which of the following is NOT a useful indicator of when a mare might ovulate naturally?

Answer: Serum progesterone concentrations

Usually follicles are between 40 and 50 mm, and almost always bigger than 35 (almost always).  The shape of the follicle changes as it is in the process of ovulating.  The follicle becomes softer as it gets closer to ovulation.   Uterine edema generally decreases the day prior to ovulation.

BUT Serum progesterone does not rise until AFTER ovulation in the mare.

Which of the following drugs is useful in inducing ovulation in the mare?

Answer: deslorelin 

Answer: HCG is a LH analog 

Which drug can be used to short-cycle a mare?

Answer: PGF-2 ALPHA

Which treatment is the most predictable and practical in getting mares to cycle early in the breeding season?

Answer: Lighting regimens 

Lighting is the one that has the best predictability and practicality. These other drugs aim at shortening the transition, but either are cumbersome or not very predictable in their efficacy.

How do lighting regimens most predictable/practical method work to get mares cycling early in the season?

Answer: Shifts the vernal transition period 

Lighting takes the transitional period and starts it sooner by mimicking the natural effects of the sun.

Answer: Progesterone

Estrogen does enhance/encourage the display of receptive behaviors in the mare, but is often unnecessary.  Progesterone has a profound inhibitory effect on reproductive receptivity in the mare and simply the absence of progesterone is enough in some mares to encourage receptivity.

Transrectal ultrasound 

There are no hormone assays to detect twins.  Palpation can indeed detect twins, but only after about 25 days of gestation and the sensitivity is much lower than using ultrasound, both because feeling the bulge in the uterus at that stage can be difficult, especially for a novice, and detecting that there are 2 bulges instead of one if the embryos are right next to each other (which they are about 70% of the time) can be very difficult, even for the experienced practitioner. Ultrasound, on the other hand, can very reliably detect twins by 13-15 days gestation.  With regard to palpation being less expensive than ultrasound, given the lower efficacy of palpation I just explained, I would ask the rhetorical question of how much less expensive is palpation if you are wrong and are stuck later with twins?  The cost to reduce one twin, the lack of success you can expect, and the resultant economic loss on the entire season dwarf the $25 you might have saved the client by only palpating instead of also scanning the mare with ultrasound.

18-21 days 

It is true that a pregnant uterus will have very good tone and a closed cervix at 14-16 days of gestation, but so will a non-pregnant uterus because it is still in diestrus at that stage.  And if the mare is pregnant, you will not be able to feel the embryonic vesicle at 14-16 days. By 18-21 days, a non-pregnant mare should be returning to (or already in) estrus.  The consequent uterus of a non-pregnant, estrous mare will be more flaccid and the cervix will be open.  This is in contrast to the pregnant mare at 18-21 days that, even though you still cannot palpate the actual pregnancy, will still have excellent uterine tone and a toned, closed cervix.  Therefore, 18-21 days is the correct answer.  I have also, however, given credit for 25-30 days, because this is the stage that you can first actually palpate the bulge in the uterus created by the fluid surrounding the embryo.

Answer: Signal its presence to the mare 

As discussed both today and last week, the embryo signals its presence to the mare by making contact with multiple sites along the endometrial surface between when it drops into the uterus at 5.5 days of gestation and 16 days of gestation, when it fixes in place.

Answer: 37-38 days 

 As stated in the lecture, and in the reading, endometrial cups form from trophoblastic cells from the embryo that invade the endometrium and form the endometrial cups.  This happens around days 37 to 38 of gestation.  The reading did mention that at day 25 "a specialized annular band of the trophoblast undergoes cellular changes to form the chorionic girdle."  It then goes on to explain that these cells go on to form the endometrial cups at day 38.  

Which of the following is NOT a routine component of a mare breeding soundness evaluation?

When should you recommend always first checking for pregnancy in a mare (days after ovulation)?

Answer: 13-15 days 

Evaluating at 10-12 days risks missing the pregnancy or the presence of a twin.  Also, if twins are present, it is too early to crush then at 10-12 days.  Anytime after 16 days you risk that if there are twins they will have fixed right next to each other and make reduction by crushing very difficult.

Which of the following is NOT a common pathogen affecting fertility in the mare's reproductive tract?

Answer: Pasteurella multocida

While many bacteria may potentially cause an infection, the four bacteria listed (excluding Pasteurella) make up 80% of confirmed cases of endometritis in mares.

Which of the following treatments for endometritis in the mare has been shown scientifically to have a positive effect on subsequent pregnancy rates?

Intrauterine antibiotic infusion 

All of the options given were mentioned as treatments used in mares with endometritis, but none of them, except for antibiotic infusion, have been tested, or they have been tested and have yielded conflicting results.

It is late May and a client presents with a mare for a pregnancy evaluation.  You have never seen this mare before and the breeding date is uncertain (pasture breeding).  In your evaluation, you determine that the mare is likely 65 days pregnant, and you find two viable twins, separated, one at the base of each horn. What is your best option to recommend to the owner?

Answer: Do a colpotomy and use craniocervial dislocation to reduce one of the twins.

All of the options mentioned, for the most part, could be responsible decisions at different stages of gestation.  Prostaglandin will only work effectively to permanently lyse the CL before the formation of the endometrial cups (38 days gestation). A twin may only be crushed effectively up until about 30 days gestation, and only then if each twin is in a separate horn. Transvaginally guided aspiration of a twin works effectively up until about 55 days of gestation.  After that, the fetus is usually too large to manipulate for this procedure. You could wait and do the intracardiac infusion, but that procedure has a 50% success and the craniocervical dislocation has a 65% success.  Using benign neglect at this stage does not gain you any real advantage.  It is very unlikely that a twin will die spontaneously within a few weeks at this late stage.  Better to be proactive and do something while you still can and give the remaining twin the best chance possible.

As part of a breeding soundness evaluation, you submit a uterine biopsy specimen and a few days later receive the following report:

choose BOTH a prognosis for this mare AND a recommendation for treatment.

Answer: 10-50% chance of conceiving and carrying a foal to term

Bacterial Infection 

Twinning used to be the #1 cause prior to the advent of ultrasound as a tool in equine reproduction.  It is still the top noninfectious cause, but the overall most important cause is bacterial infection, leading to either endometritis or placentitis.

Taylorella equigenitalis 

Equine herpesviruses and influenza virus are transmitted via the aerosol route.  E. coli is an environmental opportunistic infection.  West Nile virus is mosquito-borne.  Brucella equus  and EIV are fictional.  The only true venereal pathogen on this list is T. equigenitalis.

You have an 11 year-old Paso Fino mare who was barren last year, despite multiple breedings.  She was confirmed pregnant twice, but lost the pregnancies early in gestation.  This year, you have performed an endometrial culture and the results were a moderate, pure growth of Klebsiella pneumoniae, sensitive to gentamicin. You started treatment with intrauterine gentamicin 6 days ago and treated for 3 days.  On the 4th day, the mare was bred and given deslorelin.  The day after breeding, the mare received another treatment of gentamicin.  On day 6 (today), ovulation was noted.  How many more days of treatment would you give of the antibiotics?       

Answer: Day 8 (but day 6-9 was ok) 

Different decisions could certainly be made and defended for this situation.  If you use what was taught to you either in lecture or from the reading, you will remember that I said I generally treat mares at least for 4 days, and up to 6 or 7 days, depending on the severity of the infection.  The chapter from the reading advises to treat for 3 days for mild infections (based on endometrial biopsy), 5 days for moderate infections, and 7 days for severe infections.  I would argue that this mare has a significant (severe?) infection based chiefly on her history and the pure growth of bacteria.  One might argue that it is only moderate, based solely on the description of the bacterial growth as "moderate."  I think this is a narrow interpretation and that whole clinical picture should be considered.  You would also need to remember that the upper limit of time after ovulation that you can treat with intrauterine antibiotics is usually 2 days, but both I and the reading allowed for up to 3 days.  5 days treatment would have been day 6 in this example, 7 days would have been day 8, and 3 days after ovulation would have been day 9.  I allowed for any answer between 6 and 9 days.  In practice, I would have chosen day 8 because I think this infection is serious, as described to you, with the history of repeated pregnancy loss and the pure growth of a known reproductive pathogen.  And I do not like to push it to 3 days unless I haven't gotten the number of treatments in I think we need.

Considering the same mare on the same cycle as in question #1, and using ovulation as the new Day 0, you check this mare for pregnancy at 14 days and find a 20 mm embryonic vesicle, but you do not see a visible CL and there is a mild amount of uterine edema (1 out of 3).  You start the mare on altrenogest and oral antibiotics for a few days.  On day 18, you submit a serum sample for progesterone and it comes back as 0.49 ng/mL (normal range for a pregnant mare is > 4.0 ng/mL).  How long would you supplement with altrenogest before checking her serum progesterone concentrations again?

Answer: Test again on gestational day 48 

Altrenogest is given as a daily, oral supplement and gloves must be worn to administer the product to avoid absorption through your skin.  It also becomes expensive after 11 months.  For these reasons, if we do not need to administer altrenogest, we would rather not do it.  So, if we can test the mare to determine the necessity, that is good.  And we can.  Altrenogest does not (as I said in class) cross-react with progesterone and so assays may be run while the mare is on treatment (this is not true for progesterone in oil, which will cross-react).  So then the question is when to next test, if the first test was performed at day 18.  By day 18 a non-pregnant mare (or a mare who did not have successful maternal recognition of pregnancy) would have lysed the primary CL and progesterone would be baseline.  A pregnant mare who had successful maternal recognition of pregnancy would have elevated progesterone concentrations. This mare was pregnant, but had baseline concentrations.  This indicates that the primary CL is not functioning.  We will need to maintain the pregnancy with altrenogest for now.  But at 37-38 days the endometrial cups will form and begin to secrete eCG, which will cause follicular growth and luteinization.  It will take some days for this to happen, but when it does, progesterone will be supplied by the secondary (accessory) CL's until the fetomaternal unit takes over around 100 days gestation to produce 5-alpha pregnanes.  So, testing this mare again at day 28 would be useless because nothing would have changed from the test at day 18.  Testing this mare at 37 days is a nice thought because that's when the endometrial cups form, but do you think the progesterone immediately shoots up?  No.  First eCG must stimulate follicular growth and luteinization.  That takes some days to happen.  How about 11 days?  Day 48?  Yes.  Progesterone should be elevated before then, certainly by then.  Waiting to day 90 is just wasting time.

Dizygotic 

While there is documentation of some monozygotic twinning in mares, dizygotic twins are much more common and part of the reason why we do not recommend checking for twins routinely earlier than 13 days gestation; in the case of asynchronous ovulations, one of the twins may be too small to easily detect.

What has been shown to be the primary causative agent of Mare Reproductive Loss Syndrome (MRLS)? 

Ascending placentitis is evident 

The area at the base of the "F" is pale or avillous.  This indicates separation from the endometrium, indicating placentitis.  Because this is the area that is next to the cervix, the most likely etiology is an ascending placentitis.  The cervical star would appear as a radiating pattern, not this diffuse pattern with relatively smooth borders.

In a foaling mare, how long after stage II labor is complete should the fetal membranes be shed?

Bilateral Hip flexion

TWINS 

If you were presented with this case, you would do a vaginal examination/palpation and you would feel 3 or 4 legs, and likely not readily be able to feel the body (maybe with a very long reach...).  Your two possible differential diagnoses would be a transverse presentation (pictured) and twins.  If both twins were facing the same orientation (cranial or caudal) then you could differentiate by noting that there were more than 2 forelimbs or more than 2 hindlimbs.  But if one twin was caudally presented and the other cranially presented, that might be difficult since it would be hard to reach the body and determine for sure that you had one contiguous body or two separate bodies.

Refer immediately for possible C-Section

If the fetus is still alive and referral for possible c-section is an option, you would IMMEDIATELY send this in for a c-section.  You would tell the referral hospital veterinarian that you have a true breech that is viable.  Minutes will matter and the prognosis, because of the problem of time, will be guarded.  But it is worth a try, and is the only option for a viable foal.

cranial/anterior longitudinal, dorsosacral, left shoulder flexion

Attempt mutations with the mare standing 

This maldisposition is relatively simple to correct by pushing the fetus back into the abdomen and sliding the leg back into the normal posture.  Delaying correction, even for minutes, can result in a rectovaginal fistula.

After examining a fetus in anterior longitudinal, dorsosacral, left shoulder flexion

 , you now must make a decision as to what to do for a treatment or recommendation.  The fetus is alive. Your initial efforts to correct it were without any progress (you tried for about 5 minutes). There is a referral hospital 20 minutes away and a trailer is available.  The owners are willing to do what you recommend. What is the best decision?

REFER THE CASE NOW

The flexed shoulder malposture can be very difficult to correct in a standing mare, and may still be difficult in some circumstances in an anesthetized mare.  If referral is an option and you have not made any initial headway in your mutations, referral is a great decision.  You may be fine trying further on the farm either in the standing mare or trying to anesthetize her and elevate her hind limbs, but if you are not, and chances are iffy that you will be successful, then it certainly would have been better to refer.

XXY

Which viral disease do we test for in a stallion BSE?

Which of the following should NOT be a component of most routine stallion BSE?

XXY (Klinefelters)
 XX sex reversal

  Chimera

I have three cats from the same litter: a black male, an orange female, and a calico female.  What were the parents colors?  Choose two answers: one for the sire, one for the dam.

Orange, calico female

A black male means that you must have an X chromosome with a black allele in the dam (since the Y chromosome came from the sire).  An orange female means that you must have an X chromosome with an orange allele from both dam and sire.  And since the sire only has one X chromosome, that means the sire MUST be orange.  And we have just established that the dam must have a black allele, and an orange allele, so that makes her tortoiseshell (or calico).  The calico female got the orange allele from her sire (all he had to contribute by way of X chromosomes) and got the black allele from her dam.

Freeze epididymal sperm 

You needed to communicate that you understood HOW or WHERE we would get semen from a stallion postmortem.  We collect semen from a stallion postmortem by flushing the cauda epididymides.  The ductus deferens are ligated and transected and the testes are removed along with the epididymides to prevent retrograde leakage of semen.  But the useful, mature spermatazoa are not present in the testes, nor in the caput or corpus epididymus.  Those sperm are too immature to be useful except using ICSI protocols (tomorrow's lecture will cover this).  A much more routine, affordable, easy answer is to flush the cauda epididymus and freeze those sperm.  This protocol works very well so long as the testes are harvested and the sperm flushed less than 24 hours after death.  

Recent studies have shown that you can reduce the insemination dose from a stallion to what level and still achieve good pregnancy rates?

1:7, 1:8, 1:9

As I advised you in yesterday's lecture, please learn the two equations so that you just have to plug in numbers and then not only will these questions be easy, but so will the situation when you are on clinics or have a job and need to figure this out under pressure.  Equation 1a: 400 x 10⁶/mL divided by 25 x 10⁶/mL = 16.  Equation 1b: 16 -1 = 15.  This gives you a 1:15 ratio of semen:extender.  You could have used 50 x 10⁶/mL instead of 25 x 10⁶/mL and that would have resulted in a 1:7 ratio.  Both of these ratios are within the allowed range given to you in class of 1:4 to 1:15.  So, at this point, any ratio between 1:7 and 1:15 would seem OK.  However, when you figure out the amount of semen needed for each dose (which is the next question) and come up with 5 mL, and you remember that you only have 50 mL worth of space in the centrifuge tube, you can only do one of the following:

You have a client who would like to use a Quarter horse stallion for reproduction, but he has been unable to produce any babies in the last season.  A breeding soundness evaluation reveals testes that are smaller and softer than expected.  You collect semen and find only about 3% total motility, with maybe 1% progressive motility.  Which of the following will offer the best solution for the client in terms of appropriateness, success, and cost? (cost of each procedure is given in parentheses) 

ICSI 

All of these techniques were discussed in your reading and the acronyms were used extensively.  OT = Oocyte transfer and therefore would not be used directly in this patient (since it is a stallion).  Gamete IntraFallopian Transfer (GIFT) is also performed on mares.  Ditto for Embryo Transfer.  In Vitro Fertilization does not work well in horses.  Gamete rescue would not yield a better population in a stallion that seems to have testicular degeneration, as this one does.  Nuclear Transfer (cloning) would work, but is very expensive.  IntraCytoplasmic Sperm Injection would be a very nice, affordable (relatively) solution for this patient.  A singular sperm cell is selected that appears motile and is injected directly into an oocyte, which is then transferred to a recipient mare.