We just picked up an 18 year old mare who probably hasn't been dewormed in over a year according to the owner. She is underweight and has a rough hair coat. We've got equimax we were planning to give all our horses next week but I'm afraid if she's super wormy she could colic. What do y'all suggest? Should I give her something like a dose of safeguard this week then equimax a week later? Or safeguard power pack her? I really like to keep all our horses on the same product and schedule so one doesn't shed worms for the others to pickup. 

Also I should add I plan to start her on probios  for a few days and Forco for at least a month when I can get it. 

Ivermectin is a great one to dose with first, and then what ever dewormer you want to use 2 weeks later.

If she was underweight and you just got her, I would call my equine vet and ask him what to do. 

If it was me I would buy some cheap wormer and give 1 tube everyday for 7 days and keep horse seperated from your others just so you can watch it and clean up after it. I probabaly wouldnt start pouring grain until he starts feeling better but I would if you are in a position to do so feed 3 times a day which will help put weight on and keep hay and clean water in front of him at all times. 

Good thought. I was thinking of calling him to double check. I'll do that. 

I would take a fecal sample to your vet and for about $25 they will tell you exactly what worms etc you will need to treat and how bad the situation really is.   spending your money on random dewormers then waiting weeks to see if it works seems a waste of time and money and also contributes to the increasing problem with worms being resistant to the current dewormers.  I typically check fecal samples on all my horses a couple of times a year and for the most part they dont need to be dewormed.  They are all on a large pasture so we havent had any issues.  If you read any articles on the subject checking a fecal sample is the best way to go for a lot of reasons.  It also is a lot safer considering your horse sounds a little fragile. 

My vet had me go ahead and use Equimax - keeping her separated for now because of other issues - then in two weeks or a month repeat. Thanks everyone!