I have come across so many people that are really stuck in an old school way of handling worms and it really is creating a huge problem. Some people get quite defensive and upset when you try to explain this.
I have had people tell me their agistment requires them to worm every 2 months.
I have had people tell me they just look at the horse and say it looks wormy so it needs worming (and they do).
I have people say they use the same wormer every time or just change the brand.
None of these are effective and are adding to the huge problem that we are going to have to face.
So when you continually over worm you are just making the worms resistant. Those worms then go reproduce more resistant worms which the wormer's wont work on and in the end all we end up with is a whole lot of worms that are resistant.
☆ RESISTANCE ☆
Resistant parasites are those on which drugs are no longer effective. So what happens when we create these resistant worms to all our wormers? What happens when all wormer drug classes just dont work?
“Resistance develops because parasites are subject to natural selection, like all living things, and as we impose selection pressure on them by killing susceptible ones, it’s the ones that aren’t susceptible to the drug that reproduce. The more we worm, the more resistance we get.” (Dave Rendle, equine internal medicine specialist)
Yes for years people have been over worming and just rotating wormers but now we are forced to deal with the issue because we don’t have any more classes of drug to turn to.
The sad reality is even though a lot of people turn to vets to tell them the correct way of doing things I have heard and personally had vets tell me the wrong thing. Mind you there are a lot of vets that are aware and do give the right knowledge but there are some that just aren't up to date with the right data or procedures.
Should we just go along with bad worming policies from agistments? No we are just allowing this problem to get worse and then when its too late when no drugs work what do we do?
Speak up and try to inform them that their policies are outdated and that there is evidence it is creating a bigger problem. Encourage them to look into new worming strategies to help combat the problem.
Would I ever agist somewhere that enforces a policy that is adding to this issue? NO
My horses health comes first. Problem is the more people who ignore this issue and just keep on going the way they are aren't helping those of us trying to stop resistance becoming a bigger issue that it already is.
So educate yourselves on the up to date way of worming, share the knowledge with other horse owners. Speak to vets that know and give the right advice.
☆ FEC TESTS ☆
FEC (Fecal egg counts) are so important these days and yes when recommened to get them done I get all sorts of responses from:
"I cant be bothered poo watching because my horse will make me wait hours if he knows I'm watching"
"Its too complicated because I have several horses"
"I don't understand it so its a waste of time"
I could go on
FEC tests results determine whether your horse is a low, moderate, or high strongyle egg shedder.
Most vets will do FEC tests and even some feed stores offer the service. I myself pay $15 per test for each of my horses. Hunt around for a good price local to you and there are even some places that you can mail samples to (poor mailman having to smell that mail)
A fecal egg count measures the number of strongyle eggs your horse is passing in each gram of his manure. When you send a sample to your veterinarian or independent laboratory, you get back a number like 50 EPG (eggs per gram) or 500 EPG. This is called a quantitative test.
Now some have slightly varied advice on when to worm at what result. My own vet recommends any result that is 300 EPG or higher requires worming. Some maybe a little different that's ok.
When should you do an FEC test?
As some wormers last 12 weeks it is recommended to FEC every 3 months.
I do my FEC's on the 1st day of each season change. It makes it easy to remember. There are some different strategies but the important thing to remember is do not worm your horse if it does not need it.
☆ WORMING STRATEGY ☆
So the next thing to learn is about wormers themselves and which ones to use. Its not about swapping the brands which was a very old school way of each time you worm swap the brand of wormer....... This doesn't work as some wormers have the same active ingredients.
Active ingredients is what you need to look at, these are the different drug classes that worms are becoming resistant to
Using the same active ingredient every time you worm is just building a resistance or worming to often. Some active ingredients only target certain types of worms for example Praziquantel kills tape worms. Tapeworms only need to be wormed against once a year and best time for this is start of spring
Now this is a topic that I could spend another few hours writing up information about active ingredients and to be honest I am constantly reading about this subject to try keep myself up to date on the best worming strategy.
Also we have to remember that horses have different ranges of shedding worms, low, moderate or high shedders. Just because your paddock has a high shedder with a low shedder doesn’t mean the that they will both become high shedders. High shedders more often than not will need worming 3-4 times a year. Low shedders are usually once a year where moderate 2-3 times.
Out of the 10 horses at my agistment farm we only have 1 high shedder he most often comes back with an epg over 300 and needs worming. Most of the others only need worming once to twice a year.
While I will try do another post at some stage explaining more about active ingredients there is plenty of knowledge online to learn the different types and what they treat. But remember using the same one too much will build a resistance.
My worming strategy works well for us and I have worked with my vet to try perfect it. While there are several options for wormer's out there that have different combinations of active ingredients this is what I use (it may not be perfect but it gives you an idea).
● 1st September (Spring)
All horses wormed with Equest Plus Tape (Active ingredients are: Moxidectin and Praziquantel)
We don’t do an FEC test here as we need to do tape worm once a year and this is the best time. Equest plus tape covers all worms including bots.
● 1st December (Summer)
All horses have an FEC test done. Any above 300epg is wormed with Strategy T wormer (Active ingredients are: Oxfendazole and Pyrantel) . Those under 300epg do NOT get wormed.
● 1st March (Autumn)
All horses have an FEC test done. Any above 300epg is wormed. Now if the horse had Strategy T wormer at Dec 1st then they get Equimec (Active ingredients are: Ivermectin) any that missed worming Dec 1st get Strategy T wormer (Active ingredients are: Oxfendazole and Pyrantel).
● 1st June ( Winter)
All horses have an FEC test done. Any above 300epg is wormed. Now if the horse had a Strategy T on Dec 1st and a Equimec on March 1st then they get an Ammo Red (Active ingredients are: Abamectin and Morantel tartrate).
Then back to Spring and the rotation starts again. Most horses on the property only receive 2 wormers a year.
So in my program
All horses get Equest plus tape at start of Spring
If they return a epg above 300 at any of the next FEC’s they next get Strategy T wormer. If in that 12 month period they get a 3rd FEC result of above 300epg then they get an Equimec wormer. If a 4th result above 300epg they get Ammo red.
So for any particular horse the order of wormers I use is
• Equest Plus Tape (Active ingredients are: Moxidectin and Praziquantel)
• Strategy T (Active ingredients are: Oxfendazole and Pyrantel)
• Equimec (Active ingredients are: Ivermectin)
• Ammo Red (Active ingredients are: Abamectin and Morantel tartrate)
Other than the Equest plus tape which is done start of spring the others are done in that order if they return an epg above 300.
I know it gets a bit confusing and feel free to ask questions its better to ask than not understand it, my example of my routine is just to show you all to take note of active ingredients. Don’t keep using the same one.
Make sure to FEC test it is vital to know if your horse needs worming or not. Do not just worm because someone says your horse looks wormy or because your agistment manager/owner tells you. Make sure you know if its required. Most often than not your horse won’t need worming which is never fun and it isn’t that pleasant on your horses body because remember these are drugs.
In some countries the problem is getting so bad that now wormers are vet prescribed only to try prevent this horrible problem that we are all going to be faced with if we don’t act and keep up to date with proper worming strategies.
I am sure there maybe better options to some of the wormers I use or fine tuning of my strategy. I don’t know all the wormers on the market but at least I am trying to learn and do my best.
☆ How to do an FEC test ☆
Watch and wait for your horse to go to the toilet, have a clean zip lock bag ready (turn inside out, grab manure and them turn right way and seal).
If you cant get it into vet or place of test straight away then make sure to refrigerate (might want to double bag or put in container so the smell doesnt attach itself to your other refrigerated items lol).
Most will ask for sample within 24 hours of you getting it. Make sure you physically see your horse go the toilet and take sample (1 nugget size) from the centre of the manure pile.
☆ Worming ☆
When worming your horse it is best to know your horses weight, you can get weight tapes to get a rough idea which most vets or horse shops sell. Make sure NOT to under dose your worming. Its best to go over by a little than to under dose as it wont be as effective.
At least if this post gets you thinking about how your go about your worming and makes you learn and look into it more then I have achieved what I set out to.
☆ DRUG CLASSES ☆
These are the main classes of deworming compounds (anthelmintics) used to control internal parasites in horses:
1. Benzimidazoles - Familiar examples of benzimidazoles are fenbendazole, oxibendazole and Oxfendazole. These continue to have good activity against Ascarids, but small strongyles are now mostly resistant to this class. Single doses are effective against larval and adult roundworms and multiple doses may be effective against encysted roundworms by encouraging the larvae to emerge. Benzimidazoles are relatively safe and unlikely to cause side effects.
2. Tetrahydropyrimidines – Pyrantels and Morantel are active against larval and adult roundworms. These drugs act at the junction between nerve cells and muscle cells, causing paralysis, and a more rapid kill of worms than the benzimidazoles. They do not penetrate the intestinal wall and so will not kill encysted strongyles. There is now significant resistance to pyrantel among strongyles. Pyrantel at very high dose may have activity against tapeworms but praziquantel is likely more effective. Pyrantel is generally very safe for all age classes of horse.
3. Mectins - macrocyclic lactones (ivermectin, moxidectin & abamectin) are potent at even low levels. They work by blocking nerve transmission and paralyzing worms.
They are effective against a wide range of nematodes, (round worms) but have no activity against trematodes or cestodes, (flukes and tapeworms). They are also active against some mites and lice and they kill bots very effectively.
4. Praziquantel - Praziquantel only kills tapeworms. Acts to disrupt the parasites outer membranes causing it to become more permeable to excessive glucose loss and to be more susceptible to the enzymes found in the gut.
It is currently marketed for horses only in combination pastes with either Ivermectin or Moxidectin. Praziquantel is probably also being overused, especially in regions that have very few tapeworms. It is recommended to only worm with Praziquantel once yearly to cover tape worms.
5. Organophosphates – Dichlorvos and Trichlorfon are active against bots. Inhibit the actions of acetylcholinesterase causing a spastic paralysis. The worms are then expelled from the gut by the normal peristaltic waves.
Different classes have different effectiveness against different types of parasites.
☆ BOTS ☆
Worming for bots when eggs are on your horses hair is not going to kill the eggs.
This is the time to remove eggs to prevent the issue of them being ingested by horses. Make sure to remove them away from their paddock and grass as they fall down and the horses pick them up when eating the grass.
You need to understand the life cycle of bots. We need to kill them when in the bot larvae stage which lasts for 10 months. The bots emerge in Summer so making sure the wormer used at start of spring has a Mectin in it will be effective.
Hence why I use Equest plus tape here.
Also having another Mectin based wormer in your worming strategy will help also hence why Ivermectin wormer is also in mine
The same problem occurs if you over worm. What happens when they are resistant to out wormers? We wont be able to stop infestations.
Mectin wormers such as Ivermectin, Moxidectin and Abamectin cover bots.
The spring worming will kill the bot larvae in the horses stomach. Worming them while bot eggs are on their hair is not effective.
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