Worming How Often?

Discussion in 'Horse Management' started by Yarraman, Dec 16, 2009.

  1. Yarraman

    Yarraman Well-known Member

    Just a bit of feedback on how often people worm as I have had so many differing opinions on this. Because I agist where there is a large amount of horse turnover I was told that we should be worming every six weeks.

    Another opinion is three months.

    And do you need to rotate wormer brands or is that just a myth:confused:
  2. dayna

    dayna Well-known Member

    We worm Zophia every 6 weeks and rotate the brands. Zophia is agisted as well so I have a very strict worming schedule as paddocks are swapped regularly so horses do not develop a dependence on their current neighbour and you do not know the histories of the other horses that come and go at an agistment centre.
  3. Cornflower

    Cornflower Well-known Member

    I do mine every 3 months. I used to worm every 6 weeks, but then read that you don't need to do it that often due to the worm life cycle (can't remember exactly) so i changed to 3 months. The less often i have to put chemicals into my horse's body, the better. And yeah, i rotate, but not every time. I do it every now and then.
    And i rarely use wormers that have boticides, as i have been told that these are can cause digestive upsets as it is a very harsh chemical.
    And i don't have a problem with bot flies anyway, so don't see a point worming for it every time, especially if it's something that's very harsh.
  4. kp

    kp Well-known Member

    My young horses are done every 6 weeks. New horses are wormed once and then again in three weeks. If concerned about a heavy parasite load they are wormed with panacur every day for a week. They are then wormed between 6 weeks and three months. When rotating wormers I don't rotate brands, but drugs. Usually between mectins and fenbendazole.
  5. Double Helix

    Double Helix Well-known Member

    Mine are done every 3 months but I am not on agistment and have a pretty strict paddock management regime.

    You should rotate wormers (different active chemical not just different brand, eg. Equimax = Abamectin to Strategy T or Eqinox = oxfendazol) each year. So use a "mectin" wormer one year (Note: some like Equimec do not control tapeworm) then switch to a different chemical wormer such as Strategy T for the following year. The non-mectin wormers generally do not control for bots and some do not control for tapeworm (Strategy T does tapeworm but Equinox & Oximinth don't) so in the year that you are using these you can use a wormer that does bots and tapeworm (ie. contains praziquantel) once or twice during the year to break the bot cycle & control tapeworm (eg. late May & late August).

    If you switch between wormers too often that is when resistance develops.
  6. MyShadowfax

    MyShadowfax Well-known Member

    Shadow is wormed every 6 weeks and I do rotate, but not every time.
  7. Wendycam1

    Wendycam1 Well-known Member

    According to Virbac you should worm every 6-8 weeks and only rotate with a different chemical every second year.
  8. Anna E

    Anna E Guest

    Mine are done at varying intervals depending on the time of year rather than every 6 weeks because:
    1. I have a low stocking rate (3 horses, 100 acres!)
    2. I can rotate horses through paddocks, either resting some, or cleaning them up with sheep or cropping.
    The 2 factors above really affect the worm challenge your horse will be facing.
    So I wormed every 8 weeks through the autumn/winter/spring as they were confined to 10 acres - the rest was in crop. This weekend they will go out on the 100 acres so I wormed them last week, then that will be it until April when they have to come into the small paddock again. The stubble paddock can be considered "clean" as it has been cropped, and in hot summer weather larval challenge from grazing is very low to non existent, so I give the wormers a rest.
    While it is certainly true that horses at high stocking rates like in agistment centres horses need regular (6 weekly) worming, others may not need to be done so often. Where it can be done less often, it should be, as development of resistance to the drenches is certainly a possibility. If in doubt, faecal worm egg counts can be done.
    Switching between drench groups too often does NOT cause resistance, but rotation does not slow down the development of resistance much either (it hasn't in sheep, and there's no reason horse worms whould be any different). Whenever a drench is given to any animal, some of the worms in their gut at the time may have resistance to that drench (it's part of normal genetic variation). If they are then in a situation where no reinfection occurs from the pasture, those resistant worms get to reproduce without any competition, and the next time the animal is drenched it has more resistant worms. This is how drench resistance got to be so bad in sheep - they were routinely drenched every summer and then put onto stubbles, which because they had been cropped for year had no larvae on them. The ONLY worm reproduction that then took place over the summer was of the resistant worms that had managed to survive in the gut.
    If you drench in winter, as soon as the animal starts to graze again it is rechallenged by larvae from the pasture, and the resistant worms in the gut are therefore competed with by new infections.
    If you live in an area where the paddocks are essentially crispy dry all summer I would give serious consideration to NOT worming in summer, or worming less often. Where there is green feed all year round there will be no summer period where reinfection is not occurring. The risk of development of resistance is then much less.
    Maybe monitor them with faecal egg counts over a summer to see what is happening. Certainly if you have one farm pony who runs with the ram mob in the back paddock he does not need worming every 6 weeks!
  9. ZaZa

    ZaZa Guest

    Mine are wormed every 3 months. I worm at the change of every season (I find it easier to remember when to do it if I wok on the 1st week of Spring, 1st week of summer etc :) ). But my horses aren't at an agistment centre.

    It's not necesary to change to a wormer with a different active constituent every time you worm.
    From the Newcastle Equine Centre.....

    In order to minimise the development of resistance it is important to choose a
    highly effective wormer; “Equimax” (abamectin) is said to treat all equine
    worms as well as tapeworms, and has so far had no reported cases of
    resistance2. Using wormers that combine classes of drugs has been
    recommended to slow the development of resistance2. For example, the
    combination of oxfendazole and pyrantel (“Strategy-T”) is said to be highly
    efficient against small strongyles that are resistant to benzimidazoles alone. It is
    recommended to choose a wormer that controls tapeworms2, such as abamectin
    or one that includes praziquantel or pyrantel.
    An example worming program would be to use a drench containing abamectin
    (eg “Equimax”) for 12 months and then change to oxfendazole/pyrantel (eg
    “Strategy-T”), which contains two drugs from different classes to abamectin2.
  10. Ghost

    Ghost Banned

    article from The Horse online magazine..
  11. Jonty3

    Jonty3 Guest

    If you think about it worming your horse with one active for 12 months is well and truely less effective than rotating everytime as you are building resistance in those worms.....when you change active ingredients everytime you are diluting resistance!

    Make sence?
    Last edited by a moderator: Dec 18, 2009
  12. ZaZa

    ZaZa Guest

    And there are schools of thought that think the other way Jonty.

    The Naturevet site recommends changing after about 9 months (generally over winter), the Newcastle Equine Centre say 12 months and from Virbac -

    3. Rotate Worming Drug Classes On An Annual Basis

    A slow (yearly) rotation of worming drug classes has been suggested as a means of slowing the development of resistant worms in sheep, goats and horses. However, it is very important that you rotate to a different chemical family, not to another product within the same family eg. there is no advantage in rotating from one “mectin” wormer to another “mectin”. Table 1 shows which brands of worming product belong to which chemical class

    My horses are healthy and don't carry a worm burden so I think 'll stick with what I'm doing :)
  13. SexyRitzy

    SexyRitzy Well-known Member

    Mine gets done every 6 to 8 weeks.. He at an agistment and they get rotated to different paddocks every few weeks so i fugre go on the safe side.

    As to what wormer i use..... which ever one happens to be on special :eek: tends to be a different one every 6 to 8 weeks then
  14. beagle

    beagle Well-known Member

    I personally think worming is overdone on the whole.
    I worm mine onto fresh paddocks probably 3-4 times per year.
    In situations where fresh paddocks can't be utilised,resistance is particularly encouraged by using the same family of wormers every 6-8 weeks ie mectins vs non-mectins.It's difficult in agistment centres I imagine to "spell" a paddock for 12 weeks but correct me if I'm wrong.
    The info that ZaZa provided is imo good,but I'll change paddocks & change family of wormer for my horses every time. Usually Equimax then Strat T or Oximinth Plus.
    People really should be careful to check that they are rotating wormers properly,whichever time frame they use.
  15. Jonty3

    Jonty3 Guest

    It also depends on were the horse is kept (location) wetter areas have higher worm burdens the same as sheep.....

    Each to there own, however vets are seeing more and more horses with worms come in and owners are unsure about the whole worming thing or just dont do it, I congratulate those who are doing it weather it be correct or slightly off the mark!
  16. Leti loves Elmo

    Leti loves Elmo Well-known Member

    Mine get done every 6 weeks. I would think at a big place 3 months is kinda to long. I'd def be doing 6-8 weeks atleast. Yeah i change my wormer's everytime as they build up immune to them. don't just change the wormer by the way make sure you look at the ingredients. A lot of them have the same stuff **)
  17. Ren

    Ren Well-known Member

    mine are wormed every 6 weeks at the same time as the others in the paddock
  18. Clerrt

    Clerrt Well-known Member

    You can never know - fecal egg counts don't turn up many parasite species.

    Parasites affect the whole horse - from the digestive system, like we are all familiar with, to the lungs, liver, other organs and many blood vessels and nerves.

    You should worm regularly (every 8 weeks) - especially with young horses who havent built up resistance to some parasites like ascarids, who can cause permanent damage to the lungs and liver of your horse. This damage can cause hemorrhaging in the lungs and all kinds of nasty things. When they're older - its not as a big a worry, but its still a worry.

    The reason we need to worm captive horses is because horses and parasites have learnt to co-exist in harsh environments where they have evolved. We interrupt the horses lifestyle by confining it; horses are naturally nomads who will travel miles every day in search of resources. They pass parasites and eggs, of which some species can survive dormant in the harsh conditions of deserts like northern africa where many of today's modern horses developed. These parasites survive on the ground sometimes after the manure has broken down!! We confine them to paddocks where they are forced to graze around their manure, and constantly re-infest themselves with parasites. Some parasites have synced their lifecycles so effectively with the horse that they don't even need to leave the horses body to reproduce. They take a short time to do much damage.

    BUT i suppose its the owners choice

    *edit* changing product regularly is a must - make sure the active ingredients are different (Mectins, Benzimidazoles,Tetahydropyrimidines, and more lol)
    Last edited: Dec 24, 2009

Share This Page