# Effects of De-Wormers on Horse Health



## SueNH (Nov 7, 2011)

What timing!

I'd love to see the finished paper and I'm willing to bet a lot of people here would.

I have 3 horses. None would I class in anything using the word performance. 2 are in advanced old age and the other in her mid teens and just ridden lightly. They are at very low risk for parasite infestation. They don't come in contact with other horses and are wormed regularly. I rarely even see another horse ride by. They wander 20 acres.

Mostly I use whichever brand of ivermectin is on sale but I do dose with EquiMax, which is ivermectin/praziquantel mixed and occasionally some Pyrantel.
No side effects noted ever. The smallest and oldest one, 40yrs is regularly double dosed because of a neck threadworm issue during the warm weather.


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## Ryle (Jul 13, 2007)

Michael, if you are doing research for a paper I would recommend making use of an online survey setup like survey monkey so that you can gather more detailed information on each horse, product used and alterations in performance (if any). Using a survey also helps to generate your statistical data in usable forms. 

Also consider contacting local veterinarians and ask them if they would send home a survey link with horse owners after they deworm their horses. This way you have owners who can specifically look at fecal consistency, appetite, etc after deworming with an eye to being able to report what they see.
The kind vague anecdotal evidence you will get here will be of limited value in a research setting. 

That being said: 
ivermectin use in 5 horses (ages 9, 11, 15, 19 and 35) produced no changes in performance
moxidectin/praziquantel use in the same 5 horses has produced no changes in performance.


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## Smilie (Oct 4, 2010)

Ryle said:


> Michael, if you are doing research for a paper I would recommend making use of an online survey setup like survey monkey so that you can gather more detailed information on each horse, product used and alterations in performance (if any). Using a survey also helps to generate your statistical data in usable forms.
> 
> Also consider contacting local veterinarians and ask them if they would send home a survey link with horse owners after they deworm their horses. This way you have owners who can specifically look at fecal consistency, appetite, etc after deworming with an eye to being able to report what they see.
> The kind vague anecdotal evidence you will get here will be of limited value in a research setting.
> ...


The information I have, is that Ivermectin has been shown that some geographical areas have parasites that have become significantly resistant to Ivermectin
Thus, I use Quest plus, at least once ayear.
I would be surprised that Ivermectin+ praziquantel would be compared to Moxidectin without the prazquantel.
Sorry,, not questioning your stats,but as a human lab tech, having that background and applied it to horses that I have raised, I do deleve into horse based data and research

The past two decades have seen increasing reports of parasite resistance to deworming products...including in our area! We are seeing the most resistance to fenbendazole and ivermectin products. There are no new deworming drugs being developed and it is unlikely that this will change anytime soon. Therefore it is our responsibility to use what options we have prudently to minimize the further development of parasite resistance. This will help us to prevent the recurrence of the terrible diseases parasites caused our horses in the past. Newer deworming protocols aimed at achieving these goals focus on the individual horse.


here is a study that pooled different geographical area data, on efficacy of moxidectin versus Ivermectin

Parasites & Vectors | Full text | Moxidectin: a review of chemistry, pharmacokinetics and use in horses

Quest is also effective against a growing parasite concern, that of encyted small strongles, while Ivermectin is not, so another reason I use Quest
Of course, with growing amount of parasite resistence, and no new class of de-wormers on the horizon, strategic de-worming programs are recommended, based on fecal egg counts of individual horses in a herd


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## Ryle (Jul 13, 2007)

Smilie, yes there are some areas where specific parasites---ascarids--have developed a significant resistance to ivermectin. *Ivermectin and moxidectin are currently the two dewormers without significant resistance issues in small strongyles* which are the main concern in adult horses. So, for adult horses ivermectin and moxidectin are going to be the two most effective products.
http://lacs.vetmed.ufl.edu/files/2011/12/kaplanparasites.pdf These Ain't Your Father's Parasites: Dewormer Resistance and New Strategies for Parasite Control in Horses. Ray M. Kaplan, DVM, PhD, DEVPC, Department of Infectious Diseases, College of Veterinary
Medicine, University of Georgia, Athens, Georgia

When talking about resistance, you really have to consider what parasites you are talking about resistance in because the main parasites of concern change with the age of the horse and because resistance is seen at different levels to differnent drugs. So, you have to know which parasite is resistant to a given drug and what parasites are likely to be a problem in your horses to know which drugs are or are not likely to be effective. For instance, ivermectin and pyrantel both have issues with resistance in ascarids which are mainly parasites of concern in young horses. Small strongyles are resistant to benzimendazoles (such as fenbendazole-Safeguard) and to a lesser extent pyrantels (Strongid) in many areas of the world. Small strongyles are the main parasite of concern in horses over 18 mo. of age and also an issue in young horses. Resistance of small strongyles to ivermectin and moxidectin is not common, though it may be seen on specific farms where long-term use of a single drug (typically ivermectin) has been practiced. So, in a very young horse where you wanted to target ascarids, you wouldn't choose to use ivermectin or likely pyrantel (and certainly not moxidectin just from a safety standpoint). Likewise, in an adult horses (or a young horse) where you were targeting small strongyles you wouldn't want to use fenbendazole (Safeguard) as your first choice. 

Moxidectin does kill 2 stages of encysted small strongyles (L4 & L5) which means that it reduces the risk of high numbers of small strongyles emerging from the intestinal walls after the adults are killed. It also means that there is a longer period from dosing to the reappearance of eggs in feces because it takes longer for adult parasites to be present in the GI tract. However, moxidectin also has a drawback in that the safety margin with this drug is much smaller than ivermectin and appropriate levels of body fat are necessary to ensure safe use. So, while ivermectin is not equivalent to moxidectin it can be used in younger horses, underweight horses and senior citizens who tend to have a lower body fat content with less risk of toxicity.

As for comparing ivermectin/praziquantel to straight moxidectin, I'm not sure what you are talking about. I didn't compare the products. The OP asked what drugs we use and what change in performance we have seen. I listed the drugs and the lack of change in performance. I certainly didn't compare the efficacy of the two products used. If I were to compare ivermectin/praziquantel to moxidectin without praziquantel, this would be my comparison:

Ivermectin/praziquantel: kills the same types of parasites as moxidectin though it is ineffective against encysted small strongyles where moxidectin kills two of the 3 stages of encysted small strongyles. The addition of praziquantel to ivermectin adds effectiveness against tapeworms which neither ivermectin or moxidectin kill. Ivermectin has a much larger margin of safety and can be administered to very young, debilitated and underweight horses which is not recommended with moxidectin. 

Just FYI, I have a degree in veterinary technology which included classes in veterinary parasitology and pharmacology and have a special interest in equine parasite control. I've spent lots of time and money staying up-to-date on the subject and actually write continuing education for veterinary technicians on the topic.  

References: 
Brady, H. A., & Nichols, W. T. (2009). Review: Drug Resistance in Equine Parasites: An Emerging Global Problem. Journal Of Equine Veterinary Science, 29(Proceedings of the 21st Equine Science Society Symposium), 285-295. doi:10.1016/j.jevs.2009.04.186

Samson-Himmelstjerna, G. v. (2012). Anthelmintic resistance in equine parasites - detection, potential clinical relevance and implications for control. Veterinary Parasitology, 185(1), 2-8. doi:10.1016/j.vetpar.2011.10.010

Reinemeyer CR (2012). Anthelmintic resistance in non-strongylid parasites of horses. Vet Parasitol. 2012 Apr 19;185(1):9-15. doi: 10.1016/j.vetpar.2011.10.009. Epub 2011 Oct 18.

Lyons ET1, Tolliver SC, Ionita M, & Collins SS (2008). Evaluation of parasiticidal activity of fenbendazole, ivermectin, oxibendazole, and pyrantel pamoate in horse foals with emphasis on ascarids (Parascaris equorum) in field studies on five farms in Central Kentucky in 2007. Parasitol Res. 2008 Jul;103(2):287-91. doi: 10.1007/s00436-008-0966-8. Epub 2008 May 10.

Matthews, JB (2014). Anthelmintic resistance in equine nematodes. Int J Parasitol Drugs Drug Resist. 2014 Oct 25;4(3):310-5. doi: 10.1016/j.ijpddr.2014.10.003. eCollection 2014.


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## Smilie (Oct 4, 2010)

As for comparing ivermectin/praziquantel to straight moxidectin, I'm not sure what you are talking about. I didn't compare the products. The OP asked what drugs we use and what change in performance we have seen. I listed the drugs and the lack of change in performance. I certainly didn't compare the efficacy of the two products used. If I were to compare ivermectin/praziquantel to moxidectin without praziquantel, this would be my comparison:

Ivermectin/praziquantel: kills the same types of parasites as moxidectin though it is ineffective against encysted small strongyles where moxidectin kills two of the 3 stages of encysted small strongyles. The addition of praziquantel to ivermectin adds effectiveness against tapeworms which neither ivermectin or moxidectin kill. Ivermectin has a much larger margin of safety and can be administered to very young, debilitated and underweight horses which is not recommended with moxidectin.

Yes, I know these facts concerning safetly margins, age of horse and condition.
My comment was, it is hardly fair to compare one class of chemical dewormer against another, when the one de-wormer has an additional chemical added, against tape worms, and the other does not.
Would be more fair to compare both with the praziquantel added-Ie Quest plus versus Ivermectin Gold


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## Ryle (Jul 13, 2007)

I didn't compare either in my initial post. 

As for "fair" comparison of different drugs allows for appropriate choices in treatment options. That is why there are comparison charts out there for the different deworming drugs that list many different products with varying composition--to allow an educated choice to be made.


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## MikeZulch (Mar 15, 2015)

Sue, Ryle, and Smilie
Thanks for your opinions, ideas, and references. My project is in its infancy and I value your insights very much. Though there may not be any obvious signs of health loss when a horse is infected and treated with the drugs that does not mean there are no long term side affects. Small strongyles do terrible things to the gut of the horse and can prevent the horse from nutrient uptake when they encyst. You probably can imagine that this means the horse will not be able to uptake vital nutrients fed to him or her and as a result have developmental problems. Over time this can amount to some great troubles and depreciation of the horse's value.

Though there is greater need for the development of more effective and dynamic drugs to combat parasite infection, my research focuses on the digestion itself. As I have previously said the effects on the health of the horse will not be very obvious. My original question sought to inquire whether owners noticed this and Ryle you gave me great advice to go to a vet! However, over time there might be problems associated with the drugs that are used. To give a relatable example, please do not take the severity literally, consider asbestos and how it was used to insulate homes for many years. It was thought harmless for a long time and then all of a sudden studies showed the danger of the compound to human respiration. Im investigating something along these lines; a common drug used for a purpose and the possibility and its ability to cause long term health related problems in the horse.

The bacteria that work with mammals in the gut, on the skin, and else wear outnumber the cells of that animal, humans also, 10 to one. These bacterial cells carry out a whole lot of functions. The ones I am worried about act on digestion. If a species of bacteria that is supposed to help break down food so that it can be taken up by the horse and use as energy or muscle building is depleted or maybe even lost due to a treatment than there we have a serious problem. Further investigation into this topic can really help you ladies and your horses out by providing pharmaceutical companies with a complete analysis of their drugs effects on gut biodiversity and encourage them to invest in research and development into more effective treatment plans.

I really appreciate any insight, suggestions or further articles that you have provided and anymore anyone can steer me towards.

Thank you,
Mike


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## Smilie (Oct 4, 2010)

Sorry, Ryle, I mis read your original post, going back and reading it again!

'That being said: 
Ivermectin use in 5 horses (ages 9, 11, 15, 19 and 35) produced no changes in performance
Moxidectin/praziquantel use in the same 5 horses has produced no changes in performance. '

You were answering the op's question as to effect de-wormers had on performance, with that data, and not comparing efficacy between the two.
Got IT!


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## Luv equins (Oct 10, 2014)

I use Diatomaceous earth!


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## Foxhunter (Feb 5, 2012)

Hen running a small breeding stud farm I would rotate wormers each year. I wormed three times a year. 

We took part in testing worms in sheep being immune to Ivermectin- which proved that they were. 

Any horse new to the farm was wormed. We also had cattle and sheep grazing which can help with breaking down worm cycles. 

We also poo picked. 

The only times I have had adverse reactions is when a horse is heavily worm burdened and a 'strong' wormer has been used, this, one horse, having used Moxidectin, showed some strong colic symptoms. It did have a high infection of ascarids. 
Another older horse in very poor condition, was just 'off colour' for 24 hours. After this I would use a five day dose of Panacure, give it a break and then worm with whatever I was using that year.


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## LittlemanRob (Sep 14, 2010)

Luv equins said:


> I use Diatomaceous earth!


As do I. No resistance is possible with DE since it kills mechanically instead of chemically. Does not affect the bacteria in the gut. win/win.


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## Luv equins (Oct 10, 2014)

LittlemanRob said:


> As do I. No resistance is possible with DE since it kills mechanically instead of chemically. Does not affect the bacteria in the gut. win/win.


Yup! :lol::lol::lol::lol:


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## Foxhunter (Feb 5, 2012)

LittlemanRob said:


> As do I. No resistance is possible with DE since it kills mechanically instead of chemically. Does not affect the bacteria in the gut. win/win.


In controlled tests on goats and sheep feeding DE did nothing towards worm control. 

I tried it and it was a failure.

The horses looked well enough but as the droppings were picked up daily and I rotated grazing with sheep and cattle, they have never been heavily worm burdened.

I fed it to the chickens for worming and that was a failure totally. As it was in killing Red Mite that can invest hen houses and will actually kill the birds. 

Show me scientific papers on the effects of DE against worm control amd I might think differently.


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## walkinthewalk (Jul 23, 2008)

Mike, If I understand your post #8:

1. The horse in my avatar was 27 when I laid him to rest last Fall, he had been with me 24 years and always on a de-worming program to match our living environment and the time of year.

The De-wormers were rotational, as that thinking has only recently changed. He was such a drug-sensitive horse that half tablet of bute dropped him to the ground, yet he never had a negative reaction to worm meds.

We're they the underlying cause of his Equine Metabolic Syndrome, or his hind gut ulcers, or the strangulating lipomas that ultimately caused his demise via a major colic? I'm not smart enough to answer that but here's the info for speculation.

2. I rescued my now 29 yr old Arab 22 years ago. Once the vet cleared him, he began the same de-worming regimen as horse #1.

He has always been a hard keeper and has dealt with gastric stomach ulcers since 2005. He is not aging gracefully, something the vet says is common in certain Arabs, and has certainly become worse with the passing of his pasture mate of 22 years. Again, nothing I see that could be blamed on years of worm med.

3. I have another TWH who has been with me nearly 18 years, therefore the same rotational worming. He is now 21 and developed digestive issues 3-4 years back that were so serious the vet ran all kinds of tests and nothing. By digestive, I mean this horse could have set the barn on fire with his constant gas and I could hear him pass gas, 1,100 feet away, up on the ridge.

He finally cleared up with some prescription herbs and I am pretty sure his issues are tied to things he eats in the spring and fall.

Meaning, over the long haul, I have used every combo of de-wormers on these horses, including the dreaded Quest Plus. None of my horses ever had short-term reactions and I am hard-pressed to connect any of their current issues to long-term de-worming.

I hope this is in keeping with what you are looking for


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## jaydee (May 10, 2012)

Very quickly - 
I've been using wormers for many years
I've worked in two riding schools that both had a min of 30 horses/ponies where worming was done 4x a year 
I worked for 10 years on a breeding/competition/selling/boarding yard where the horses including youngstock were all wormed regularly
I've had my own boarding/selling yard with a regular turnover of horses - all wormed regularly
Some of my horses/ponies were with us until they were in their late 20's and one in his 30's - all wormed regularly
I've used all the products you mention
I've never had any negative after effects from any of them

I often worked with local vets from mixed animal practices when they needed an assistant who was used to horses and I've seen many suffering terrible health problems from worm burdens due to lack of (effective) preventative medication and several that had to be euthanized when nothing more could be done for them as the damage the worms had caused was too great 
And 
I am getting sick of hearing about the use of DE as a wormer - it is totally useless when wet so it will not work - the moment it hits the saliva in a horses mouth its effectiveness is zero.
It is just some minerals and finely ground down silica and fossil shells - you might as well feed your horse fine sand - sand is silica.


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## MikeZulch (Mar 15, 2015)

walkinthewalk said:


> Mike, If I understand your post #8:
> 
> 1. The horse in my avatar was 27 when I laid him to rest last Fall, he had been with me 24 years and always on a de-worming program to match our living environment and the time of year.
> 
> ...


Wow, this is very helpful. Unfortunately, I can not say whether or not the microbiota was the cause of your avatar horse's death. However, his case is very interesting and we probably could have learned a lot from him if he was around to study.

Your third case, however, strikes me the most. For my research I am focusing on the Gastrointestinal System. As food gets pushed through the intestines bacteria and other chemicals break down bigger pieces into smaller constituent pieces which eventually expose nutrients needed for a healthy horse. If your horse's gut had a bacteria, or lack of bacteria, for any period of time than there could be side effects resulting in terrible gas and other issues. 

Your post was really insightful! Thank you so much. For me to tell you that worming regiments over a long period of time resulted these misfortunes would be inappropriate as of yet. However, I think you have experience that would be very helpful for me to get to the bottom of some of the issues I'm studying, at least guide me anyways.

If your up to it would you contact me [email protected] with the subject "HorseForumHelp"

Thank you very much!
Mike


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## Tnavas (Nov 29, 2011)

I have wormed with many substances over the years - including those in my youth where the horse had to be given a week off work to recover from being wormed.

Modern wormers are effective and despite all the fuss about resistance I have not yet found this to be true.

Over the years I have worked in stables with 100+ horses or more and myself owned many.

Now down to just 1 Clydesdale mare who I have owned since she was 6 months old - she is now 11½ - she has been wormed four times a year for all her life with Parade wormer - this contains Ivomec and Praziquontal. Her worm count is 0 and has been for several tests. 

As she shares grazing with horses whose worming programs are not quite so regular I continue to worm her every 3 months.


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## piglet (Oct 2, 2012)

I am confused. 

Anecdotal evidence - relying on people to tell you their stories of what they THINK wormers do to their horses - is not very scientific.

It would be much more valuable to actually measure before and after gut populations of a real horse or their poop.


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## MikeZulch (Mar 15, 2015)

piglet said:


> I am confused.
> 
> Anecdotal evidence - relying on people to tell you their stories of what they THINK wormers do to their horses - is not very scientific.
> 
> It would be much more valuable to actually measure before and after gut populations of a real horse or their poop.


You are certainly right. However my purpose for this thread is supplemental information gathering for the project. Hidden in peoples responses are insights and other information that, when i see it, prompts me to do further literature investigation. The benefits of that literature research helps me interpret the data and support my conclusions with stronger factual basis from both previously published work which i would have been led to by these responses and wet lab experiments.

here is my actual experiment
https://www.youtube.com/watch?v=yq6aeSmRToI

Thank you,

Michael Zulch
Elms College Biology
What's the Scoop on Poop
https://www.youtube.com/watch?v=yq6aeSmRToI
[email protected]


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## Corporal (Jul 29, 2010)

Interesting thread. I am sad to read, but not surprised, that there is now resistance to Ivermecterin, which I first starting using in 1985. I have not stopped rotating my de-worming chemicals. For newbies, you need to read which chemical makes up the de-worming product lest you use the same chemical 2x in a row, inadvertently, but dose with two differently name products. Don't know why I remember, but 1.87% of most Ivermecterin paste is the drug, and the rest is the paste. Strong chemical, indeed, and now used for humans for some heart conditions.
I do not deworm them all winter. We have had two back to back wicked cold winters where I live. I also try to de-worm my horses when it's going to be dry, whether cold dry or hot dry, and that should also be part of your parasite control plan, as well.
I see de-worming chemicals as a invitation to overuse, like amoxicillin resistence to bacteria in humans. Strep throat, in an otherwise healthy adult, should be let to run it's course and let the antibodies develop.
*Clean
Pay attention to your horse's physical appearance (glossy coat, alert, active, interested in surroundings)
De-worm on time
Don't overdo the de-worming products*
Your horse can develop his own resistance if he is healthy, to _some_ of the parasites that live in his body and fight them off.


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## Ryle (Jul 13, 2007)

Resistance to ivermectin is seen in equine ascarids mainly. Resistance of small strongyles to ivermectin has been seen in very limited areas, typically where ivermectin was the only drug used and used many times a year for several years. Since ascarids aren't typically an issue in adult horses their resistance to ivermectin is less of a concern for most horse owners. 

Rotation of dewormers is an old idea and at this point not terribly useful in adult horses because resistance is so widespread to fenbendazole and pyrantel in small strongyles. Limitation of deworming to only when necessary, not under dosing and utilizing pasture/paddock management practices to manage parasites are our best options to slow the development of further resistance. 

For horses under 1 year of age, rotation is recommended less to prevent resistance and more because resistance is such an issue that you have to rotate in order to actually kill both ascarids and small strongyles.


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## WWLTHR (Mar 18, 2016)

Thank for this detailed info!
I have always used invermectin and never had problems. Any comments on this Medication?


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## KigerQueen (Jun 16, 2013)

now i have an issue regarding wormer. my vet thinks my horse has a bad infestation by his blood results and says i need to give my horse a powerpc wormer then equamax for the next 3 months. i feel that may not be the healthiest for him considering he has ulcers. is that something safe to do?


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## Tnavas (Nov 29, 2011)

KigerQueen said:


> now i have an issue regarding wormer. my vet thinks my horse has a bad infestation by his blood results and says i need to give my horse a powerpc wormer then equamax for the next 3 months. i feel that may not be the healthiest for him considering he has ulcers. is that something safe to do?


I've bomb drenched a few horses over the years - wormed weekly for 3 weeks with an ivermectin and praziquontal wormer.

Better to get the worms gone and then trteat the horse for the ulcers.


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## piglet (Oct 2, 2012)

WWLTHR - Many people recommend rotating ivermectin with other wormers.

Some small strongyle resistance has been reported, and ivermectin is not effective for all stages of the parasite's life-cycle in the horse.


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## KigerQueen (Jun 16, 2013)

my only worry is that if his worm load is that bad would a mass dieoff like that colic him?


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## ChitChatChet (Sep 9, 2013)

I use Ivermecterin..... whatever is on sale.

Started when I first got into donkeys 24 years ago. Somebody had told me if I wormed with Ivermecterin in the fall, donkeys would shed nicely come spring. They where correct.

I use it for the horses and ponies we now have. We worm about twice a year.


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## Tnavas (Nov 29, 2011)

ChitChatChet said:


> I use Ivermecterin..... whatever is on sale.
> 
> Started when I first got into donkeys 24 years ago. Somebody had told me if I wormed with Ivermecterin in the fall, donkeys would shed nicely come spring. They where correct.
> 
> I use it for the horses and ponies we now have. We worm about twice a year.


Fall and spring are the most important time of the year to worm, fall will get any bot larvae and others and will set your horse up to manage well through the winter. You'll be feeding your horse not parasites. 

Spring time gets anything left and means your horse can make the best use of Spring grass.

Piglet, the bomb drenching is effective because the first dose kills the active parasites, when the gut has been cleared the encysted ones hatch and migrate to the gut as there is no no competition for the food. The second dose gets them, and the third clears any remains or newly hatched parasites.

KigerQueen I've not experienced that problem of mass die off and colic, I've had problems with other types of tapeworm workers with most of the school horses having mild colic type symptoms, but the vet said it was a common side effect of the particular wormer.

Discuss all this with a knowledgeable equine vet 

How often you worm will also depend on your pasture management


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## KigerQueen (Jun 16, 2013)

well considering this horse has never seen a pasture in his life pasture management is not an issue lol! but my vet is telling me to worm him 10 times within a 5 month period basically and i fell thats excessive 0.0' (wormed him with ivamectrin and a week later with the tapeworm one). then he wants me to do the power pac (5 panacur wormers, 1 a day so 5 months worth in 5 days) and then a equimax once a month for the next 3. kinda why im a little concerned about the amount.


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## jaydee (May 10, 2012)

The 5 day power pack is easier on a horse that's maybe got a heavy burden than using a single full dose of Moxidectin
Chitchat - the worms you're horse is shedding in spring (if I'm reading your post correctly) are emerging encysted small strongyles (cyathostomes) that have been buried in your horses digestive system for a year or maybe longer.
They do a huge amount of damage in their lifecycle, causing ulceration and bleeding, they can result in severe colic and even death and that is why its now advised to worm with Moxidectin or a 5 day Powerpak to kill them early in the encysted stage. Those are the only effective products
They rarely show up on fecal counts and Ivermectin will not kill them in the encysted state
cyathostomes- pathogenesis


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## Tnavas (Nov 29, 2011)

What he is suggesting is OK if the worm burden was so high. I'd be inclined to agree


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## KigerQueen (Jun 16, 2013)

ok so i feel a little better about that. never had an worn issue like this with our other 4 so thats why i was so thrown off. my mare might get wormed once a year and she dose not even need that.


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## KigerQueen (Jun 16, 2013)

he is thinking worms from a blood test so i guess he has a heavy worm load. wanted to get a fecal done before i got over $100 in wormers.


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## KigerQueen (Jun 16, 2013)

btw thank you guys! never even herd of cyathostomins! now can i give him 2 doses wait a few days and hit him again with 3 days in a row? im leaving the state and i cant be horse to give it all at once and kinda cant afford it all at once.


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## Ryle (Jul 13, 2007)

jaydee said:


> The 5 day power pack is easier on a horse that's maybe got a heavy burden than using a single full dose of Moxidectin


That is not true. There was a study done a few years ago that showed that Powerpac dosing with fenbendazole caused more GI inflammation than using moxidectin when encysted small strongyles were killed. The inflammation with Powerpac dosing can even lead to the same symptoms as Larval Cyathostominosis, which is what appropriate treatment of small strongyles is aimed at preventing.


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## KigerQueen (Jun 16, 2013)

i was talking to someone who said that your horse can only contract them on pasture and this horse has never seen a pasture in his life and has only been turned out in arenas (yay az horse boarding!). they also said they are not prevalent in the us much less arizona.


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## jaydee (May 10, 2012)

Ryle said:


> That is not true. There was a study done a few years ago that showed that Powerpac dosing with fenbendazole caused more GI inflammation than using moxidectin when encysted small strongyles were killed. The inflammation with Powerpac dosing can even lead to the same symptoms as Larval Cyathostominosis, which is what appropriate treatment of small strongyles is aimed at preventing.


I've not seen that study - and obviously all the vets that are still advising using the Powerpac to treat horses that they think might have abnormally high burdens or are somehow 'at risk' haven't seen it either
It sounds as if its a Catch 22 situation as there are a lot of documented cases of colic from using the Moxidectin (Quest/Equest in the UK) on horses in that category.


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## Ryle (Jul 13, 2007)

It might be that the vets are missing the colic caused by Powerpac dosing because it's assumed to be too long after treatment to be associated with deworming. The severe inflammation caused by Powerpac dosing of fenbendazole killing encysted small strongyles occurs about 2 weeks after treatment. 

Not the study, but does refer to the results in the last paragraph above the conclusion Equine cyathostomins: a review of biology, clinical significance and therapy

Here it is: (had to go find it) Small strongyle infection: consequences of larvicidal treatment of horses with fenbendazole and moxidectin. - PubMed - NCBI

This is a different, newer study, showing less risk of serious adverse reaction to killing encysted small strongyles with moxidectin than with the 5 day double dose of fenbendazole: Comparison of the larvicidal efficacies of moxidectin or a five-day regimen of fenbendazole in horses harboring cyathostomin populations resistant ... - PubMed - NCBI


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## KigerQueen (Jun 16, 2013)

dose not help that this horse has ulcers. this will be fantastic...


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