# Double dosing ivermectin and neck threadworms



## natisha (Jan 11, 2011)

A friend accidentally gave her very young foal a full dose when the syringe broke as she was giving it. Vet said the foal would be fine & he was.
Ivermectin has a very large safety margin.


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## walkinthewalk (Jul 23, 2008)

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3rdTimestheCharm said:


> I have 2 questions for you guys:
> 
> 1) I was just curious about anyone's experiences with giving a double dose of ivermectin? I've always heard that ivermectin is very safe, but I've never known anyone that's given a double dose.
> 
> ...


I only had to double dose my Arab twice in two separate years, I was just as nervous the second time as I was the first time, lol

Partly because I was using two full tubes at one time (of pure Ivermectin).
Partly because he was in his early 20's.

As long as your horse doesn't have any known health issues, has always been fine with paste wormers, he should be fine.

*What will happen is an explosion of the sores getting worse before they get better.*. Generally within 12 to 48 hours.

That is because the Onchocerca worms are really microfiliae that burrows under the skin. These intrusive/very itchy eruptions are them dying off and making the horse miserable one last time.

Keep a mix of hemorrhoid ointment and diaper rash cream on hand to help with itching, healing and keep the flies off.

If your horse has an extremely bad case, I have read of people double dosing again in four weeks. I didn't have to.

Studies have been done as to how much wormer it really takes to harm a horse. 

I can't remember the amount but it's a lot more than two tubes. Still, it's nerve wracking

I know when I de-worm my big Walking Horses, they get a full tube, even if it says for 1,300 pounds. They're big but not that big

Good luck with whatever you decide. I know how nervous you are


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## Ryle (Jul 13, 2007)

While ivermectin does generally have a wide safety margin, it is still possible to have horses suffer from ivermectin toxicity even at the labelled dose. It is best to talk to your vet about the possibility of neck threadworms prior to just dosing with ivermectin.


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## 3rdTimestheCharm (Jan 18, 2015)

Thank you natisha and walkin- I always find both of your posts very helpful! I really appreciate hearing your experiences =)

Walkin- It's reassuring to know that you were as nervous as I am! 

I have read that vets are usually very apprehensive to diganose neck threadworms, so I'll ask another question on here that I was going to ask him.

I'm glad to see conformation that ivermectin does has a very high safety margin, but one of my main concerns with giving the double dose is that I haven't dewormed my gelding since December. So, will deworming him with a double dose now be too much?

I'm sorry if that sounds like a dumb question. I know I'm probably over thinking this, but I just want to make sure I'm going about this the best I can =)
_Posted via Mobile Device_


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## 3rdTimestheCharm (Jan 18, 2015)

Thank you Rlye =)

That's why I'm so nervous about this. He's never had any problems with any dewormer, but toxicity is something that I always have in the back of my mind.

I'll call the vet tomorrow and hear his thoughts =)
_Posted via Mobile Device_


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## LoriF (Apr 3, 2015)

I've dealt with neck threadworms. My older mare had the symptoms for it and I found that veterinarians don't really give much thought to it. I finally came across an article about them and she had all of the classic symptoms. I double dosed her with equimax and two weeks later double dosed her with ivermectin. She got really itchy for two or three more days after the first treatment and then the sores started healing. You can't kill the adult NTW's, you just have to wait for them to die naturally which takes several years, 7 to 12 I believe. Keep killing the babies or nymphs or whatever you want to call them every year while you are waiting for the adults to die off.
I do my girl once a year now but don't do the second dose two weeks later like I did the first time


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## walkinthewalk (Jul 23, 2008)

3rdTimestheCharm said:


> I'm glad to see conformation that ivermectin does has a very high safety margin, but one of my main concerns with giving the double dose is that I haven't dewormed my gelding since December. So, will deworming him with a double dose now be too much?
> 
> I'm sorry if that sounds like a dumb question. I know I'm probably over thinking this, but I just want to make sure I'm going about this the best I can =)
> _Posted via Mobile Device_


As long as you have had a steady and consistent de-worming program, you shouldn't have any worries. 

When I treated my Arab for NTW's, we were already on this 23 acres and I only de-wormed everyone 3 times yearly. The double-dose would be the 4th treatment if needed.

1. Check the expiration date on the boxes the worm meds come in.

2. Check the lot numbers for a possible recall. Highly unlikely but it's one less worry.

3. Treat on a day you don't have work or school. Do it first thing in the morning, then turn the horse out so it can move around at its leisure.

Be sure there is plenty of fresh/clean water and salt available.

4. Don't treat when the weather is in one of its extreme hissy fits. My area's weather has been up and down with 70's, then down in the 30's, then a day with highs in the 50's.

You don't want the day time temps to be beastly hot either. Wait for a week of steady tolerable temps, you have a day off to observe, then have at it

EDITED TO ADD:

I keep forgetting to say, that I had my vet do skin scrapings and they didn't show anything. No neck threadworms, nothing.

So I waited another few months and the sores on my Arab's face got worse and there were more.

I re-read everything I had already read twice, bought the Ivermectin and put two tubes in him.

Within 48 hours the sores under his mane and on his face erupted horribly and drove him crazy. I washed those areas with a microbial wash and kept the hemorrhoid ointment and diaper rash cream on them.

They disappeared and didn't come back for around two years.

So the. Et said there wasn't anything, yet that "nothing" disappeared for a few years after one double dosing. Plus his hair got really soft and became a deep rich medium bay, like when he was young.

I think the vets have to play it safe when it comes to things like this. They know more than they say and keep quiet to cover their own butts.


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## Ryle (Jul 13, 2007)

There are several other conditions that can present with the same signs, so it's best to have your vet examine your horse and take a full history to help ensure that you are treating appropriately.


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## natisha (Jan 11, 2011)

Ryle said:


> There are several other conditions that can present with the same signs, so it's best to have your vet examine your horse and take a full history to help ensure that you are treating appropriately.


Ryle, what would the tests be? 
Not to hijack the thread but with my mare I did blood work, skin scrapings, deep tissue biopsy, allergy testing. The allergy testing showed reaction to fly saliva so she was on allergy shots. I know I stopped them too soon but the only relief she had was in cooler months & after each shot she was miserable with itching. I didn't want to torture her all year long.


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## 3rdTimestheCharm (Jan 18, 2015)

LoriF said:


> I've dealt with neck threadworms. My older mare had the symptoms for it and I found that veterinarians don't really give much thought to it. I finally came across an article about them and she had all of the classic symptoms. I double dosed her with equimax and two weeks later double dosed her with ivermectin. She got really itchy for two or three more days after the first treatment and then the sores started healing. You can't kill the adult NTW's, you just have to wait for them to die naturally which takes several years, 7 to 12 I believe. Keep killing the babies or nymphs or whatever you want to call them every year while you are waiting for the adults to die off.
> I do my girl once a year now but don't do the second dose two weeks later like I did the first time


Thanks Lori! I'll be sure to keep this in mind.


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## 3rdTimestheCharm (Jan 18, 2015)

walkinthewalk said:


> As long as you have had a steady and consistent de-worming program, you shouldn't have any worries.
> 
> When I treated my Arab for NTW's, we were already on this 23 acres and I only de-wormed everyone 3 times yearly. The double-dose would be the 4th treatment if needed.
> 
> ...


Thanks walkin! This is very helpful.


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## 3rdTimestheCharm (Jan 18, 2015)

Ryle said:


> There are several other conditions that can present with the same signs, so it's best to have your vet examine your horse and take a full history to help ensure that you are treating appropriately.


I know that there are other conditions with similar symptoms, so I'll call the vet today to see what his thoughts are (he's coming out to the barn within the next 2 weeks to do spring shots, so I can talk to him about this again if needed). 

But, since there are other conditions with similar symptoms, and since it seems that vets are apprehensive to diagnose NTW, I will also continue to do a lot of research and will make a side-by-side comparison of the symptoms that NTW present, along with the conditions similar to it. That way it's easier for me to compare the symptoms.


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## 3rdTimestheCharm (Jan 18, 2015)

natisha said:


> Ryle, what would the tests be?
> Not to hijack the thread but with my mare I did blood work, skin scrapings, deep tissue biopsy, allergy testing. The allergy testing showed reaction to fly saliva so she was on allergy shots. I know I stopped them too soon but the only relief she had was in cooler months & after each shot she was miserable with itching. I didn't want to torture her all year long.


I'm curious about this, as well.


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## updownrider (Mar 31, 2009)

It has become standard practice for our horses that live in Florida to double dose at two week intervals. The fly season is long and relentless in Florida but the results have been astounding with Ivermectin. 

The exact dose is determined by our vet. I advise anyone that wants to start a new treatment plan to consult their vet, not strangers on a bulletin board.


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## Smilie (Oct 4, 2010)

far as I have been told, at equine conferences, Ivermectin has a very wide safety zone, far asd dose, unlike Quest, in fact,a round the range of 40 times, versus Quest which is toxic at 4 times
Also, foals are mainly affected by roundworms, and I was also told by my vet, that Ivermectin is not that effective against round worms, so should be used at double dose for foals

Far as reaction:

'2. Some horses have experienced reactions with swelling and itching shortly after treatment. In most such cases, the horses have been diagnosed as carrying heavy infections of Onchocerca microfilariae, and it is assumed that the reactions were the result of microfilariae dying in large numbers. Although the signs have resolved spontaneously in a few days, symptomatic treatment may be advisable. Consult your veterinarian should these symptoms persist.

This site, has it up to 60 times, as being the limit a horse can tolerate, so 2 times is nothing to worry about, and a reaction would likely be due, as per above, and not to the actual chemical
When I gave it to foals, I always used at least a double dose


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## 3rdTimestheCharm (Jan 18, 2015)

updownrider said:


> It has become standard practice for our horses that live in Florida to double dose at two week intervals. The fly season is long and relentless in Florida but the results have been astounding with Ivermectin.


That's very interesting. I never thought about it, but now that you say it, that makes sense.



updownrider said:


> The exact dose is determined by our vet. I advise anyone that wants to start a new treatment plan to consult their vet, not strangers on a bulletin board.


Yes, as I've mentioned, I will consult my vet. I called earlier today, and I'm now waiting for a call back.


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## 3rdTimestheCharm (Jan 18, 2015)

Smilie said:


> far as I have been told, at equine conferences, Ivermectin has a very wide safety zone, far asd dose, unlike Quest, in fact,a round the range of 40 times, versus Quest which is toxic at 4 times
> Also, foals are mainly affected by roundworms, and I was also told by my vet, that Ivermectin is not that effective against round worms, so should be used at double dose for foals
> 
> Far as reaction:
> ...


Thank you, Smilie! This is very helpful information.  
Knowing that the safety margin is that large makes me feel better.


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## updownrider (Mar 31, 2009)

3rdTimestheCharm said:


> Yes, as I've mentioned, I will consult my vet. I called earlier today, and I'm now waiting for a call back.


I know you had said you were consulting a vet, but I put that in there in case someone else might not read every word on the thread or if in the future my post comes up in a search.


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## 3rdTimestheCharm (Jan 18, 2015)

Oh ok gotcha! =)
_Posted via Mobile Device_


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## 3rdTimestheCharm (Jan 18, 2015)

I got a call back from the vet this morning, and he isn't totally dismissing that it could be NTW, but he does think it's unlikely.

So, what he thinks I should do is give 1 dose of ivermectin this week, and if my horse does have a reaction to the NTW larvae dying, then give another dose next week.


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## LoriF (Apr 3, 2015)

3rdTimestheCharm said:


> I got a call back from the vet this morning, and he isn't totally dismissing that it could be NTW, but he does think it's unlikely.
> 
> So, what he thinks I should do is give 1 dose of ivermectin this week, and if my horse does have a reaction to the NTW larvae dying, then give another dose next week.


The problem with giving one dose of ivermectin is that it's ineffective on NTW's which is why the double dose. In my opinion, one dose to treat NTW's is a waste of time and money.


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## Smilie (Oct 4, 2010)

Ivermectin is very safe, far as dose range, so I would go with the double dose. 

I am not very familar with this parasite,living where I do, thus used good old google.
I found this info, from the following link, and I did not know that the intense itching after Ivermectin is diagnostic, thus typical:
'A dose of ivermectin-based wormer is the quickest way to tell if your horse has them. If the microfilariae are present, the horse usually responds with intense itching – and I mean, manically intense, demented itching – around 48 to 72 hours after worming.

The Disturbing Truth About Neck Threadworms and Your Itchy Horse - The Horse's Back


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