Wormer side effects?

I wormed my 16 year old Perch/Standard mare the other day. I used Ivermectin and now she's different. Yesterday she acted spooked. I lead her around the yard and she ate a lot of grass but last night she barely touched her hay. This morning she ate maybe a flake or two of hay and I only gave her half of the usual scoop of grain. She hasn't drank much at all today either. Maybe 1/4 of a 5 gallon pail. She doesn't show any signs of colic but on her chest behind her front shoulders there's two lump on each side. They're hard and they don't hurt her. My g/f was thinking maybe the wormer killed a crap load of worms. Anyone have any idea what could be wrong with her?

If it killed a bunch of worms, you're in big trouble. You give wormers on a regular basis so that the wormer works to prevent worms, not kill them. If your horse has worms that you know of, giving him a wormer is a BAD idea. Wormers should be given at correct intervals, never skipping. In dogs at least, giving a wormer to a dog that has heart worm is the kiss of death. Are you alternating between 2 wormers? I usually alternate between Zymectrin Gold and Strongid.
As for the bumps, they could be hives. My paso fino had them for a week or two. Not sure though....
Hope this helped some:)

Well I just got her a month ago. The previous owner said she was wormed 6 months ago. I didn't believe she had worms but as you said preventative measures I wormed her. Now that I know the bumps could be hives they don't worry me too much. Just the eating and drinking less kind of worries me because she eats a whole bale a day.

Yea....So you know what wormer the previous owner used last time, or if the horse has any allergies? It could be an allergic reaction to something in the wormer

I've also known horses to hold a grudge against their owners for a few days after worming.....could that be it?

Well I don't think they're hives, they are long and tubular and just behind the girth line on the bottom of her belly, they split where her rib cage meets on the belly. Hives seem to be more of spots and like bug bites and this is tubular and about say... 4 inches long and 2 inches wide on both sides. When I pushed on them there was no sign of pain or discomfort and they were hard, not fluid like, just felt like pushing on her normally, there was nothing out of the ordinary. With her change in attitude it worried me after I thought about it. She off her hay, or almost off her hay, but eats the grain like normal, she was showing her normal signs of energy this morning, but last night seemed very jumpy and uneasy. I was thinking it was a bruise or bump, like maybe she kicked herself but with no pain I doubted it, Then I though colic because she showed evidence of nipping at her sides, but no rolling and she is pooping normally. With her also not drinking so much it worries me because she could get dehydrated. Any ideas on this guys?!


David, you should get pics of it so people can see and give them a better idea about what were talking about.

Also I am the gf he was talking about incase your wondering how I got all this haha

Yeah I'll try to get pics up but I'm working all day tomorrow. I put her in before my training tonight and gave her fresh water and a whole bale. She's drank a little water and she's just thrown her hay all over and doesn't look like she's ate any. It seems like she's pissed at me. Hahaha

This doesn't sound like something caused by giving Ivermectin.

Have you ridden her in the last couple of days? Put on fly sprays or any other topical product? Have you checked her temperature?

It wouldn't be a bad idea to call your vet after checking her temp and seeing how she looks in the morning. You can discuss exactly what you are seeing with him and decide if you should have her seen.

Having been dewormed 6 months ago with an adult horse it's unlikely that you are looking at a heavy parasite burden. Contrary to the old way of thinking and doing things, about 1/2 of the adult horses will control intestinal parasite infections on their own with minimal deworming (twice a year). You can check out this link: www.thehorse.com/Video.aspx?vID=183 It takes about an hour to watch and is really in-depth and detailed on the best way to plan a deworming program for adult horses. Deworming 6 times a year is more than necessary even if you have a horse that doesn't have a good resistance to parasites.

I haven't ridden her in a few weeks. No sprays or topical products either. I don't have a thermometer but I get paid tomorrow so that would be a good investment! Other than barely eating or drinking she's fine. She ran, jump and kicked when I let her out to pasture this morning. All pumped and fired up as usual. She did eat her grain though.

Edit: my mom has been giving her old apples out of the fridge. They were withered but not rotten.

Oh yeah I totally forgot about that! She has been eating apples from your mom. Also she showed evidence of nipping at her stomach, could it just be a mild case of a stomach ache and she was a bit swollen in one part? I really hope it's nothing serious! She's so amazing!!