Worming Advice 2018

13th March 2018

1) There is widespread irresolvable resistance to ALL equine wormers

2) No new wormers are becoming available in the foreseeable future

3) Generalised advice to a group or whole yard of horses is no longer valid. It is very important horses are treated individually according to faecal egg count results to prevent over-worming

4) NEVER overdose your horse. ‘A full tube’ is irresponsible worming as this will cause a potentially untreatable parasite resistance. You must weigh your horse with a tape or use the clinic weigh scales and dose accurately.

5) To obtain an accurate faecal result, collect several faecal balls from different fresh piles and mush together in a bag prior to submitting

6) Faecal egg counting does not assess tapeworm or encysted redworm levels. These must be treated in late autumn with moxidectin and praziquantel (Equest Pramox). AVOID USING MOXIDECTIN AT ANY OTHER TIME OF YEAR AS IT IS OUR LAST EFFECTIVE DRUG FOR ENCYSTED REDWORM AND IS ALREADY DEMONSTRATING RESISTANCE

7) Foals (<6.5 months)
Immediately after birth foals are at greatest risk of receiving worm from their mothers. Mares should therefore be wormed towards the end of pregnancy (see point 10). Foals should not be wormed until 6 weeks of age. We then advise giving the foal a wormer containing fenbendazole (Panacur) or ivermectin.


8) Weanlings, yearlings, 2, 3, & 4 year olds
Worming should be maintained regularly throughout the year alternating annually between ivermectin, moxidectin and pyrantel. Young horses are most at risk from high worm levels so should be treated regularly.

9) Lactating mares
We recommend lactating mares should not be wormed until at least 2 weeks after giving birth. We then advise giving a moxidectin or ivermectin based wormer repeatedly while the foal is at foot. The timing of this wormer depends on which wormer was last given during the pregnancy, i.e. 13 weeks after last moxidectin wormer, 8 weeks after last ivermectin wormer.

10) Pregnant mares
It is important to maintain a worm free status in the pregnant mare as she can pass on worm larvae to the foal soon after birth. We therefore recommend monitoring worm egg levels (WEC) as for adult horses (above) and giving a moxidectin or ivermectin wormer within the last month of pregnancy.