SMZ for better breeding results

[SHWarmblood]

I've just learned that some breeders are using SMZ (Sulfamethoxazole) to increase the conception rate of their mares. I learned of one very well known breeder/vet who used SMZ for his mares and all of them are in foal, even a 25-year old mare with frozen semen! I've been asking for the breeding protocol he used but have not received a response.

Has anyone heard of using SMZ for breeding purposes? And if so:

Is it the same dosing, 1 pill per 100 lbs?

Is it just SMZ or SMZ-TMP?

After trying SETTLE and Immunall without any results, I'm curious to know more about this SMZ protocol.

Thanks for your help!

[Hillside H Ranch]

To my knowledge there is no research to back this up. Perhaps if you are dealing with a mare with a chronic type, low-grade infection you may have some success using oral antibiotics in conjunction with other treatments. Using SMZ's as you mention is not something that I would reccomend, b/c of the problems we are now seeing with antibiotic resistant bacteria. Using antibiotics without a very good reasons, i.e. treating a specific pathogen IMHO is irresponsible and is greatly contributing to the resistance problem. I have, however, seen SMZ's used as a prevention in mares who have aborted in the past due to placentitis. Sometimes in these mares SMZs are used from about 5 months on, for 1 week each month until parturition, in the hopes that it will prevent that mare from developing another cases of placentitis.

In your mare's case, what have the diagnostics shown? I.e. what have her culture and biopsy results shown?

[SHWarmblood]

No, my mare isn't on SMZs, I am looking at purchasing a mare who is at a breeders now who was put on SMZs along with all of his other mares to get in foal. To my knowledge, none of the mares had any repro issues, including the mare I'm interested in and none are currently on SMZ now that they have been confirmed in foal. The breeder, who is also a vet, is using it to increase their conception rate, similarly to how some individuals are using SETTLE even with mares who don't have endometriosis or other conditions.

[siegi b.]

I think it's quite irresponsible of this vet to use SMZ for the purpose of "getting mares in foal" and would certainly question him/her about it.
Just my opinion...

[Hillside H Ranch]

I'm sorry; I read the last part of your post as you not having luck using Immunal or Settle. I assumed that you meant on a problem mare.

Regardless, I stand by the opinion that there is no evidence to back up the use of SMZs and I personally wouldn't do it. I'm guessing that most of those mares would have gotten pregnant anyway without the SMZs. FWIW I did breed a 23 year old mare with frozen this year and got a pregnancy on one shot, so that can certainly happen. Definitely have to appreciate those "older" mares who still settle easily!

[SHWarmblood]

Yes, "appreciate" mares like yours... more like envy! :-)

After spending SO much money last year and this past year trying to settle several mares with frozen semen that had no repro issues and not having a single mare in foal (and using 2 very well known repro vets), I'm willing to try just about anything to hopefully change my luck. Nixed my Chin Chin contract on one of my mares. Ouch!!!