QUESTIONS

1. Hypothalamic hypogonadism exists in humans as well as dogs and can be treated w/GnRH. Should you give it as a steady infusion (like maybe an implant)?
    
2. On a related note, how might you go about estrus synchronization for a prize herd of bitches?
    
3. You are treating a bitch who won't come out of estrus. On ultrasound you find what  looks like a follicular cyst. What would you use to treat it?
    
4. What might be a good protocol for induction of estrus in a bitch?
    
5. What are some uses of the HCG challenge test?
    
6. Daily mibolerone can be used to suppress estrus. Why shouldn't it be used in bitches < 1 year old?
    
7. Why might it be a bad idea to use estrogens to treat prostatitis?
    
8. Why is it pointless to attempt to increase spermatogenesis using exogenous testosterone?
    
9. You are treating a bitch who you think has an ovarian remnant. She appears to be in proestrus now. What are the disadvantages of running an estradiol level at this point to confirm an ovarian remnant?
    
10. You are treating a queen who you think has an ovarian remnant. She does not appear to be in estrus now but she recently was. Will a progesterone level at this point tell you if she has an ovarian remnant?
    
     
11. You are treating a pregnant bitch near term and it is starting to look like she is going to deliver dangerously prematurely.
    
    a) What would you expect her progesterone level to be at this point?
    
    b) How do you stop the abortion?
    
    
    
    
     

ANSWERS

1. Steady infusion (like an implant) appears not to work; you need a pulsatile delivery of the hormone.
   
   
   
   
    
2. Synchronizing this herd could be done w/pulsatile delivery of GnRH and - yes - there are gadgets that will attach to a dog harness & deliver pulsatile GnRH. These gadgets cost about $2000 though.  Implants can work but are not as reliable.  In one study, proestrus occured within 3 days of the implant insertion but not all bitches responded. There is a TID GnRH protocol that is promising but it is still in the works.
   
   
   
   
    
3. Use either GnRH or HCG to luteinize your follicular cyst.
   
   
   
   
    
4. Trick Question.  There is no good estrus induction protocol but here is a promising one:
   
   DES 5mg/day PO until proestrus is evident & then give the same dose DES for 2 more days. If she has not gone into proestrus by day 7, increase to 10mg/day but if she is not in proestrus after 7 days at this dose forget about it.  On the 5th day of proestrus, give 5mg LH IM. Give 10mg FSH on days 9 & 11 & breed on Day 13. What's wrong w/this picture?  Neither LH or DES are commercially available :(
   
   
   
   
    
5. The HCG challenge test can be used to test a bitch for intersexuality, for ovarian remnant or to test a male dog for a retained testicle.  Give 44 ugm/kg & draw a progesterone (or testosterone if looking for  retained testis) level 4 hours later. Intact males have test. levels 4.6-7.5 ng/ml. Bitches w/luteinized follicles will have > 1 ng/ml progesterone levels.
   
   
   
   
    
6. Mibolerone will close physeal plates in young dogs. Other caveats: do not use > 6 months or beware of liver disease.  Do not use in bitches with known liver disease. You are also not supposed to use it in bitches intended for breeding.
   
   
   
   
    
7. Aside from the risk of marrow suppression, you'll get squamous metaplasia which will predispose your patient to bacterial prostatitis.
   
   
   
   
    
8. Spermatogenesis is stimulated by local high levels of testosterone produced by Leydig cells, not by the serum level of testosterone which is much lower.  If you give testosterone exogenously, you will drop LH by negative feedback. Dropping LH will drop Leydig cell stimulation and thus drop the local level of testosterone in this testis which is exactly the opposite of what you want to do.
   
   
   
   
    
9. If she is really in estrus and not proestrus & you measure estradiol in estrus, it wil be declining & you will not get a diagnosis.  (Vaginal smear may be your only way to tell proestrus from estrus & you can't really reliably make this distinction with this test.) Instead of measuring estradiol in proestrus, it is better to measure progesterone in diestrus.If the serum level after heat signs are over is > 2 ng/ml,she has a CL in there somewhere. Obviously, determining diestrus is much easier by vaginal smear.
   
   
   
   
    
10. The progesterone in diestrus method used in the bitch above willl not work for the cat. In the cat, there won't be a CL unless she has been bred (induced to ovulate) & the chances are she hasn't been bred. This means you'll need to use a stimulation test. Next time she is in "heat" give either HCG which has luteinizing properties on its own or GnRH which will release LH. NOW you'll have a CL & now you can draw a meaningful progesterone level. (Recall,the cat brings up a wave of follicles but doesn't ovulate them unless physical mating leads to the LH surge.)
     
11. a) When progesterone levels are < 1.5ngm/ml whelping occurs within 12-40 hours. Anything less than 2.0 ng/ml is living dangerously in terms of maintaining the pregnancy.
    
    b)  Altrenogest is an oral progesterone. Start giving some. Calculate her correct whelp date w/LH surge date as DAY 1 w/63 or so days to go (or you can use her cytologic diestrus date as DAY 1 with 57 days to go). Discontinue the progesterone 2-4 days before the correct whelp date. If you continue the progesterone too long (>2 days after the correct whelp date) the still birth risk is increased.