It's quite possible that nasal bot fly may be the cause of the problem.
Ivomec (ivermectin) sheep drench .08 percent can be used to control nasal bot flies. The drench form of ivermectin is to be given orally and is not the same as the injectable form.
You are correct about the lack of other symptoms. I would also include sneezing or snorting as typical symptoms which are not present in this case. Even though the other symptoms are absent, bot flies could be causing the symptom you're seeing. Therefore, the recommendation to treat.
I agree with you regarding soremouth. The cases I have seen have all involved the lips.
Before I give you any recommendations regarding oral use of injectable ivermectin, I need to contact the manufacturer. It's too late in the week to make contact, so allow me a little time and I will contact you on Monday.
I called Merial today.
I was told the .08 percent drench is available.
I am waiting for a call from technical services to address the injectable/oral question.
I will email you when I have the information.
The technical services veterinarian told me that the oral product does a better job of killing the nasal bot larva. The oral suspension is extremely effective against nasal bots. This is why it is recommended on the label to treat orally.
The injectable product will work, but not as well. Using the injectable product to kill sheep bot flies is not an on-label use.
Using the injectable product orally will probably not work because it is not well absorbed from the gut.
Prevention of reinfection can be a problem. You may eliminate the bot fly larva today and have a reinfection a few weeks later. If this becomes a recurrent problem, you may have to treat every month during the fly season.
BotXXXXX XXXXXne: Find out what the cost of the oral suspension is. I think the smllest size is approximately 900 mL. Unless you have a large flock, this may be more than you can
If the oral suspension isn't practical, injectable ivermectin is the next best thing.
I hope this is helpful.