Horses that have suffered as a result of worm infestation

[soloequestrian]

I'm interested in knowing whether all horses can suffer permanent damage as a result of a high worm burden, or if this only happens in those who are compromised in some other way. I've heard from two different organisations (one who use ponies for conservation grazing and the other a well known equine charity) who use worm egg counts that the horses with the highest worm burden are often the ones that look the most sleek and healthy. Some of the burdens mentioned have been vastly higher than what would be considered 'safe' in a normal worm control programme (I'm reliably informed that the 'safe' level was a number plucked out of the air some time ago - there is no actual scientific evidence behind it). The worm counts used have only been for redworm (and presumably roundworm), not tapeworm.
So I wondered if anyone on here has experience of any animals that have definitely suffered illness as a result of past or current worm burden, having not also been undernourished or ill in any other way first?

 

[BWa]

Interesting thought, I am following this as I currently have a pony which has damage from a previous high work burden and colics quite often as a result. She was also in poor condition when she arrived but I think that was down to her teeth more than anything. Her last worm count was clear but she certainly can't be described as in good condition yet.

 

[SO1]

my pony got ill due to a tapeworm burden {despite worm counts being clear and being wormed for tape twice a year}. He lost a lot of weight when he is normally a good doer, it also affected his breathing and energy levels. He also may have had some ulceration from worm damage as vet did an occult test on his poo and blood was present.

However the damage does not seem to be permanent as he has returned to his normally podgy self after worming and treatment of the ulcers and a weight gain diet it took about 6 weeks for him to recover and he has recovered so well he is back on the dieting. I think he was lucky though as it could have been much worse.

With the conservation ponies it may be that they are naturally good doers and if they are having a lot of grass they don't lose weight they just don't get as fat as they might normally have done.

 

[Orangehorse]

A few years ago Russian horses started appearing for sale. In fact I know of a dealer who used to go to Russia and buy a lorry load and bring them back to the UK and sell them. I asked her if it was worthwhile financially and she gave a definite yes. I think she was selling for around £2,000 as ordinary riding horses, the odd one or two were quite nice but most of them could only be described as distinictly ordinary with strange conformation, and these were the best ones remember. Must have bought them for about £100 each!
Of course they had never been wormed.

Two or three years later I was talking to a rep on a wormer stand at the Royal Show and asked the above question, basically. He said that yes, worm damage does show up later, for instance for a while there were Russian horses around and people would buy them and then get them fit to go eventing or hunting and they would drop dead and a pm would show worm damage. It got to the point where insurance companies would not insure horses born in Russia.

 

[Dry Rot]

Well, wormer salesmen would day that, wouldn't they?

Good question, OP, and I have been trying to find the answer myself. I didn't worm the foals last year until they were six MONTHS old and the book says to worm every six WEEKS.

Yes, young animals can suffer permanent damage to the intestine due to a heavy worm burden, but I kept an eye on these foals and at no stage did they look anything but the picture of health.

Animals do develop a resistance to worms but young animals are susceptible. At one time I kept sheep at a very high stocking rate. It worked for a couple of years, then the worms built up and I had a lot of unthrifty wormy lambs. So it is important. I used to worm the puppies, probably twice, and then not bother. One year there was an infestation of hook worm which affected most of the dogs. My vet looked it up in his little book and told me the eggs were killed by frost. So we waited for a hard frost and wormed them all. There were no more worms.

Currently experimenting with regular harrowing and resting and once a year worming. The jury is still out but it seems to be working. But I have 11 ponies on 15 acres.

 

[Mike007]

Our local riders association held a very interesting lecture on worming ,by a prominent local vet . He explained that in a population of horses ,probably about 80 % will have a great deal of immune restance to worms , and that worm counts were the way forward. WE ONLY HAVE FOUR LICENSED DRUGS FOR WORMING AND TWO ARE NOW ALMOST USELESS DUE TO RESISTANCE.Spot the 20 % with the highest worm burden and treat . By unnecessarily treating the other 80 % we drasticly increase the risk of them becoming immune to our only two effective wormers. Other interesting info regarding worm counts was that to get a true reading,the sample needs to be from at least 3 very fresh nuggets of poo. Also ,sending it off by post to a lab ,you run the risk of the sample getting warm and the small strongyls (the greatest threatthese days) eggs will hatch into larvae. They cannot count larvae or empty egg cases so a false negative will occur. FIND a local sampling service and keep your samples below7 degrees C.

 

[Mike007]

Our local riders association held a very interesting lecture on worming ,by a prominent local vet . He explained that in a population of horses ,probably about 80 % will have a great deal of immune restance to worms , and that worm counts were the way forward. WE ONLY HAVE FOUR LICENSED DRUGS FOR WORMING AND TWO ARE NOW ALMOST USELESS DUE TO RESISTANCE.Spot the 20 % with the highest worm burden and treat . By unnecessarily treating the other 80 % we drasticly increase the risk of them becoming immune to our only two effective wormers. Other interesting info regarding worm counts was that to get a true reading,the sample needs to be from at least 3 very fresh nuggets of poo. Also ,sending it off by post to a lab ,you run the risk of the sample getting warm and the small strongyls (the greatest threatthese days) eggs will hatch into larvae. They cannot count larvae or empty egg cases so a false negative will occur. FIND a local sampling service and keep your samples below7 degrees C.

 

[Mike007]

Dont blame me forv the double post blame HHo s clunky system.

 

[soloequestrian]

Just to be clear, which I obviously haven't been in the original post, the comments that have been made about these groups of horses don't reflect their just doing well in spite of having a large worm burden. They actually seem to do better with a larger worm burden, i.e. there is a noticeable difference in condition score/ coat health - those with lower burdens look less well.

 

[Rollin]

Well, wormer salesmen would day that, wouldn't they?

Good question, OP, and I have been trying to find the answer myself. I didn't worm the foals last year until they were six MONTHS old and the book says to worm every six WEEKS.

Yes, young animals can suffer permanent damage to the intestine due to a heavy worm burden, but I kept an eye on these foals and at no stage did they look anything but the picture of health.

Animals do develop a resistance to worms but young animals are susceptible. At one time I kept sheep at a very high stocking rate. It worked for a couple of years, then the worms built up and I had a lot of unthrifty wormy lambs. So it is important. I used to worm the puppies, probably twice, and then not bother. One year there was an infestation of hook worm which affected most of the dogs. My vet looked it up in his little book and told me the eggs were killed by frost. So we waited for a hard frost and wormed them all. There were no more worms.

Currently experimenting with regular harrowing and resting and once a year worming. The jury is still out but it seems to be working. But I have 11 ponies on 15 acres.

I don't worm my foals till they are six months but follow the advice given by Robert Eustace, Laminitis Trust in an interesting paper he wrote - he says foals should not be wormed in first 6 months.

HOWEVER, I do operate a strict pasture management system. This years foal is on a clean field which has not been grazed by a foal for several years and has been rested all winter and poo picked before.

Last year's foal field is not being used and will be cut for hay in June - it will then be the field for next year's foal.

All our fields get rotated to hay at some time. We have 30 acres in 10 paddocks.

 

[rowan666]

Just to be clear, which I obviously haven't been in the original post, the comments that have been made about these groups of horses don't reflect their just doing well in spite of having a large worm burden. They actually seem to do better with a larger worm burden, i.e. there is a noticeable difference in condition score/ coat health - those with lower burdens look less well.

i am following this thread with intrest and hope someone can offer some evidence. When i bought my sec A he had never been wormed in his life (4yrs) and also was not fed hard feed, non of the ponies there had ever been wormed (approx 40) but all looked great! Shiney coats, good weight etc
i wont be happy if turns out all the money ive spent on wormers over the years have been for nothing!

 

[FairyLights]

Just got a worm count back for mine. its 150. will not be worming but will worm in about 8 weeks time

 

[zaminda]

A friends horse had issues due to worm damage including lung capacity being reduced, and bursting a blood vessel in her hindquarters. It was before I met him, but apparently he was told they had literally eaten through the blood vessel. I will say though, if as he was told she is operating on 75% lung capacity, she must have been some horse before!
I also know someone who lost a horse to colic, and a pm said it was due to long term worm damage.

 

[soloequestrian]

A friends horse had issues due to worm damage including lung capacity being reduced, and bursting a blood vessel in her hindquarters. It was before I met him, but apparently he was told they had literally eaten through the blood vessel. I will say though, if as he was told she is operating on 75% lung capacity, she must have been some horse before!
I also know someone who lost a horse to colic, and a pm said it was due to long term worm damage.

Would the first have suffered from lungworm infection? This is fairly rare in horses, as far as I know only really occurring when they have contact with donkeys. The blood vessel thing could be to do with large redworm, but it seems unlikely that they would be in the hindquarters - are you sure that wasn't some sort of misinterpretation?
For the colic horse, would you have known if it was compromised at any point in its life (underweight or ill and not treated for worms)?

 

[soloequestrian]

Bump. Seem to have ground to a halt.

 

[Hetsmum]

Bump. Seem to have ground to a halt.

I have a cob (now 15 years old) with most probably no worming history prior to being 5 years old. Whilst he looks great and holds his weight very well he is very susceptable to changes of pasture. When the spring grass first comes and if I ever have to change fields I always have to put him on a pre and probiotic or he will start to scoure. Is that from worm damage? I don't know but I do know he is tough as old boots in every other way

 

[Dry Rot]

For a few years, I lived in the Scottish islands. There was a scare at the time about Echinococcus granulosus, also called the Hydatid tape worm. It infects sheep with the dog as an intermediate host. The hot spots in the UK were apparently some of the Scottish Islands! To be brief, this is a particularly nasty infection because when humans are infected, cysts can form in the vital organs which, if they burst, can distribute further cysts in every part of the body having an effect similar to cancer!

Anyway, when I got back to the Mainland I thought it might be a good idea to get tested as I kept a lot of dogs. The results came back that I tested "positive for everything" (the doctor's very words!). Thirty years on and I am still here with a glossy coat and cold damp nose and I've never been wormed in my life. Go figure!

 

[Switchthehorse]

I have an IDxWB so quite a chunky girl. She had recurrent colic which was eventually pinned down to a ridiculously high tape worm burden... and you would NEVER have known, she was marginally overweight but very marginally, she had a shiny coat, was full of beans (when not colicing!) and was one of the healthiest horses on the yard to look at, it was mid winter, others had dull coats, ribby etc. Thankfully i have a vet who knows her well and knows that no matter what she looks like she can still be really poorly (she has had near fatal hepatitis and still looked a picture of health!!?) So may be just her but i would definitely say she is a shining example of a horse that despite huge worm problems looked fab!

 

[cptrayes]

Redworm migrates through the artery walls. Does anyone know if that leaves permanent scarring?

 

[Orangehorse]

I think it does, that is why sometimes horses just drop dead, particularly fit horses working hard. A horse that is just going about its daily life will probably be OK. It isn't really worth worrying about though, because there are so many things that horses get, this is just one more thing to be added to the risk factor of being a horse - and a horse owner.

 

[soloequestrian]

Large redworm migrate through the blood vessels, but are rare now due to intensive worming in the 80s and 90s. Small redworm hibernate within the gut wall but don't go beyond it. There is a suggestion that modern minimal worming might lead to the large redworm becoming more common again, but I don't think there is strong evidence for this yet.

 

[zaminda]

The colic horse had been poor in the past, and was of unknown history.
The other horse had been very quiet for her before the lung damage. She collapsed at an endurance ride, my friend was devastated to be told that there was something wrong with his horse, it was at first felt to be a virus, although they weren't sure if the damage had compromised her immune system.
As to the blood vessel, that is definitely what he was told, he nearly lost the horse, and it took a long time to sort her out.

 

[Goldenstar]

When I was a welfare officer I dealt with a mare who was seized in very poor condition she had an enormous worm burden particularily red worm she almost died several times during the first couple of months and although she survived her health was permanently compromised .

 

[soloequestrian]

The rescue charity has had many that are in very poor condition and have worm damage, but I'm interested in horses that have a big worm burden but aren't compromised in other ways ie undernourished or ill. Perhaps these are just very rare - most people whose horses are in good condition also control the worm burden.

 

[Gloi]

The rescue charity has had many that are in very poor condition and have worm damage, but I'm interested in horses that have a big worm burden but aren't compromised in other ways ie undernourished or ill. Perhaps these are just very rare - most people whose horses are in good condition also control the worm burden.

How can you tell in some cases if the reason the horse looks undernourished or ill is simply because of the worm burden.

 

[soloequestrian]

How can you tell in some cases if the reason the horse looks undernourished or ill is simply because of the worm burden.

It might be - there might be a tipping point. The point of my original question though is to ask about healthy horses with very large worm burdens. They do exist and as before, in this section of the horse popoulation there is an anecdotal correlation between worm burden and appearance of health ie shiny coat, excellent body condition are associated with HIGHER worm burdens, not lower as would usually be expected. This is the end of the spectrum I'm interested in!

 

[Tnavas]

Well, wormer salesmen would day that, wouldn't they?

Good question, OP, and I have been trying to find the answer myself. I didn't worm the foals last year until they were six MONTHS old and the book says to worm every six WEEKS.

Yes, young animals can suffer permanent damage to the intestine due to a heavy worm burden, but I kept an eye on these foals and at no stage did they look anything but the picture of health.

I find this attitude really irresponsible, if you are going to breed then you should care for these youngsters to ensure that their current health and future health has been safeguarded.

Round worm can kill so fast, foals can look good one week and die from a blockage the next. The migration of the immature worms also damage lungs as they migrate through the lungs.

Your youngsters need to be sold with a health warning!

 

[soloequestrian]

Lots of assumptions in there - if you have clean pasture and worm egg count (you can see roundworm eggs), why would you treat youngstock? Even without the discussion of really high egg counts, it isn't necessarily healthy for any horse to have a zero worm burden, and for youngstock there needs to be consideration of their developing immune system - worming too often is not a good thing.

 

[Goldenstar]

This whole area is really interesting .
I usually give new horses a five panacur guard when they arrive they ewc about six weeks later and see wants going on.
I have had 2 who arrived and then had a moderate worm burden for a while the vets advice was to monitor but not worm over a few months they came to zero ( that's normal for ours ) and stayed that way .
I think they do develop immunity .
It's many years now since I had to worm a horse after a ewc but I do worm for tapeworms twice a year .
Does anyone have experience of blood testing rather than just worming for tapeworms ? I have considered this as this mean our land has zero exposure to wormers it is more expensive though .

 

[soloequestrian]

I had a conversation about this the other day - the trouble with the tapeworm blood test is that it tests for antibodies, which decrease quite slowly after the tapeworms have gone. I also only worm for tapeworm now because the cost of the blood test is massively higher than worming once or twice per year.