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Colic, Peritonitis and Worms

What do these three conditions have in common? Colic and Peritonitis are serious conditions that require immediate veterinary treatment, and both can be caused by worms!
This is something I discovered recently when my 6yo Arabian stallion Finn, suffered a colic episode that also resulted in hypothermia as he went down on a cold wet day. Thankfully, I went to his paddock again at lunchtime (the boys had been fed at around 9am) to get the float for re-filling with hay, and found him laying down in the rain. When I got closer, I saw he was in a lot of pain so immediately gave him some rescue remedy (always carry some in the car) then raced back home for a warm rug, the Equine Colic Relief (ECR) and the stethoscope.
After administering the ECR I waited the 45 minutes suggested to see if his condition would improve. In that time, I took his heart rate which was up to 48bpm and allowed him to lay down as he was quiet and not wanting to roll. His 3 paddock mates all stood around us looking concerned, with the most senior gelding occasionally trying to chew on Finn to get him up.
When there was no noticeable difference in his pain levels, gut sounds or heart rate after the 45 mins I called the vet who arrived within 30 minutes.

After checking all his vital signs he administered some painkillers and muscle relaxant then did a rectal exam which confirmed an impaction, so Finn was then stomach tubed with Parrafin and Tympanel to help the impaction pass.
I was very proud that he handled his first rectal exam and stomach tube without even a twitch!
Finn then seemed much better (the drugs were working) so I walked him home on the vet’s advice as movement would help the impaction shift, and with his mates following, he strode home and happily tucked into some hay in the barn and yard overnight.
The next morning though he was quite depressed again and not eating and after I’d fed all the others, he was laying down again obviously in pain. Another visit from the vet confirmed a high temperature indicating an infection so he was treated aggressively with antibiotics for peritonitis.
He seemed to improve the next day so was moved to fresh pasture, but by the following day he was down again. This time the vet suggested worming him again (he’d been wormed 10 days prior with Panacur) with Equest Plus for tapeworm as they have been known to cause an impaction colic.
So we did that immediately and gave more painkillers to keep him comfortable.
The next morning he was fine and his manure was already passing a large amount of tiny hair like worms which I believe were small strongyles.
After passing that burden, he made a complete recovery thankfully - many horses get seriously ill or die if not treated correctly.

Finn may be one of the 20% of horses that carry 80% of the worms so it's possible he had a large number of encysted stongyles that upon worming with a single dose of Panacur, emerged to take the place of the cleaned out worm population. This mass emergence would have caused both peritonitis and the impaction colic.
My intention had been to worm him with Panacur for 5 days in a row to kill any encysted strongyles, but I couldn’t get the horses to take it in their feed and dosing four strong and protesting boys with the drench gun every day for 5 days (with limited success on my own – liquid wormers are very easy to spit out), I gave up and decided to just use Equest next time they were due.
And that was my mistake as it had been exactly 12 months since they were wormed with Equest so they were overdue. I’ve since realised I should have been worming twice yearly with Equest for encysted strongyles (Dr Ann Nylands book – Horse & Donkey Worms & Worming ) gives good schedules to follow.
So what are encysted strongyles? They are a 3rd stage larvae of the small strongyle (cyathostomes) that are eaten and go into the lining of the horse’s colon and form a cyst. This is why they are called encysted strongyles and the only chemicals that will kill them are moxidectin with a 90% success rate (in Equest/Quest wormer) and Fenbendazole in Panacur 100 if it’s used for 5 consecutive days at 10ml per 100kg. No other wormer will be able to kill them.
Encysted stronglyes can stay in a horse for years (or as little as 8 weeks) before they develop into 4th stage larvae and enter the colon.
If there’s a huge amount of them, the emerging may kill a horse and I suspect many ‘mystery’ deaths could be attributed to them. If there are less but a lot emerging, the horse may get colic, and/or scour and/or get edema.
So it’s vital to worm your horse at least twice yearly with Equest/Quest or Panacur (if you can get them to take it effectively) to ensure that the emerging encysted strongyles won’t harm your horse.
Also useful to know is that worm counts will not show how infested a horse is with encysted strongyles!
There is a lot more in depth info on this in Ann Nylands book which I highly recommend to every horse owner. To sum it up I quote from the book ‘Research has shown that cyathostomes (small strongyles) have become more and more important as a cause of sickness and death in horses, and today are considered the main reason for worming horses.

If you want to save yourself from a huge vet bill, and your horse from all those injections – don’t put it off! Equest is available (often at discount prices) in many online stores and is sold by most saddlery stores/vets.

Why I Use Chemical Wormers
I would love to be able to worm my horses more naturally, and years ago I tried it that way, but their health was suffering due to the following issues I have with the place I live:
• Too small for the number of horses (15 on less than 40 acres).
• Not enough slaves to pick up poo all the time and land too steep for poo vacuum cleaners!
• Not enough paddocks to rotate around to let them rest for long enough.
• Neighbours who don't worm their horses for bots and so my horses get infected too.
• A wet climate which allows worms to spread easily (they travel in water and along grass that is covered in water droplets).
• Breeding young horses who are more susceptible to worm infestation so they need treatment more regularly until around 3 yrs.
• Natural wormers don't really work as my faecal egg counts showed.
• Previous problems with colic symptoms in various horses which I couldn't attribute to anything else.

Since reading Ann Nylands book I've come to realise that perhaps the only way you can get around using less chemical wormers is to have the opposite of all the situations I listed above, and/or use a long acting wormer like Equest.

Also, some horses are more likely to have a better immunity to worms so if you only had a couple of horses who lived together on a largish acreage then you might get away with worming naturally and keeping a check on their egg counts.
However, egg counts won't tell you if they have tapeworms or encysted strongyles that can stay in the gut wall for years, just waiting for the right conditions to hatch.

From a total of 280 votes – it looks like less than half the voters in a recent online poll knew what to treat encysted strongyles with (Moxidectin or Fenbendazole).

Results of the Poll by The Horse.com
Which of the following dewormers do you use to treat encysted small strongyles?
• Ivermectin: 35.57% (164)
• Moxidectin (e.g., Quest): 25.60% (118)
• Pyrantel Pamoate (e.g., Strongid): 19.09% (88)
• Fenbendazole (e.g., Panacur): 15.84% (73)
• Other: 3.90% (18)

Ivermectin will not touch encysted strongyles and there seems to be more branmds of wormer these days that contain Ivermectin (+ other chemicals) than there are alternatives.
To better understand worming and for a complete list of wormer brands with their chemical compounds, get Dr Ann Nylands book here.



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Cynthia Cooper -
Natural Horse World

46 Wattle Lea Lane, Golden Valley. Tasmania, 7304. Australia.

Ph. 0419 372279

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