Categories: HAPPA Facts, Latest News373 words1.4 min read

Pinworm the Parasitic Problem.


November 19, 2015



The Pinworm (Oxyuris equi).  This problematic parasite was thought only to affect young equines but this seems not to be the case and horses and ponies of all ages up and down the country are feeling the effects of infestation.
These white/grey worms can measure up to 15cm and colonise in the rectum of infected horses. The key with pinworm is that they live and breed within the dorsal colon with only females passing through to the small colon and rectum to lay their eggs. This must be taken into careful consideration when treating horses with suspect pinworm.  Routine faecal egg counts also fail to pick up any traces of pin worm due to eggs being laid around the anus and not expelled in dung.
Pinworm can be passed from horse to horse though mutual grooming, ingestion of eggs which have fallen on to pasture/water/feed, contaminated fence posts/stables and through contaminated grooming kits/brushes.
The signs of infestation include – swishing and rubbing of the tail, yellow eggs around the anus, loss of appetite and even protrusion of worm from the horse’s anus – the female pin worm can lay up to 60,000 eggs per day and will come to the opening of the anus to lay her eggs. The biggest risk to equines is colic due to inflammation of the colon and caecum. Most signs are easily missed and most equine owners are unaware of the problem especially if routine worming and faecal egg counts are undertaken.
It is thought that due to wormer’s on the market being so good and so well absorbed by the front section of the gut that a sufficient amount of chemical is not reaching the hind gut where the pinworm resides. There is also the idea that there is a resistance to wormer being seen in several other species of worms and chemical wormers.
So what to do if you suspect pesky pinworm? Call your vet and they will put together a thorough treatment plan, it is also thought that the application of neem oil around the dock area kills eggs and acts as a barrier for preventing further eggs from sticking to the dock area.
Emma Finnigan
Senior Equine Care Officer