PARASITES

Text | Shelley Wolhuter, Fircroft Stud

A STUD FARM'S PERSPECTIVE

In 2017, one of our fillies colicked. The colic was severe, and our local vet was on his way but 40km away. The filly was in immense pain and tried very hard to roll. Eventually, she collapsed, and we could not get her up again. Our mom grabbed a nearby feed sack and shook it violently and luckily, the filly got a fright and jumped up. We managed to keep her up and moving until our vet finally arrived. She eventually recovered from what turned out to be a gas colic.

We could not figure out what went wrong because she couldn’t have eaten anything strange, and nothing had changed in her routine.

NEXT STEPS

Our vet suggested we do a faecal egg count, which is when you collect a few balls of poop and send it to a lab to have the worm eggs inside the poop counted. This gives a clue as to how many worms might be inside your horse’s body. A few worms are quite normal for a horse (as gross as that is), but above a certain number, you need to take action by deworming your horse!

In our case, we were shocked to discover that our filly was riddled with ascarids (roundworms), despite our careful deworming schedule. At the time, we were following the outdated guidelines of routine deworming, where we dewormed our horses every few months as a routine. We weren’t checking if they had worms, just regularly deworming using different dewormers each time. Our foals were dewormed more often in this regime, as they are known to be more vulnerable to parasites, especially ascarids.

Our vet and his colleagues concluded that the colic was caused by the heavy worm burden and the damage the parasites had caused to her gut. In light of this, we dewormed her and retested her ten days later and found that the dewormer had barely worked. This was because the filly was carrying drug-resistant worms. Drug-resistant worms are worms that are partly immune to certain dewormers, so do not die when the dewormers are given. It was a big shock to us to discover that a filly on our farm had drug-resistant worms!

After this situation, we realised that we could no longer simply deworm our horses and trust that it had worked. We did some research on the best way to manage parasites and discovered Worm-Ex Lab, a lab that has taken a special interest in parasites and guidance on parasite control. Most vets have their ‘special interest’, such as surgery or lameness, but not many are too excited about parasites! It is therefore important to know when to call which vet!

LESSONS LEARNED

We have now been performing faecal egg counts for almost three years. We have learnt a lot of lessons in this time:

• The results of these tests are surprising every single time.

• Often, only 1 in 5 or less of our horses actually need deworming.

• Different horses can have high worm egg counts on each round of testing.

• There are no consistent symptoms of a heavy worm burden in healthy horses. Sometimes the most glossy, dappled horses have the highest worm egg count.

• Nothing on the outside of a horse can show how effective a dewormer is.

• Drug-resistant worms can come from another yard/stud/visiting horse.

• Young horses do not always need to be dewormed.

• Drug efficacy (effectiveness) can be highly individual to the horse or the yard.

Because of these surprising lessons, we are starkly aware of two simple truths:

1. If you want to know what is going on inside your horse, you have to look (test).

2. If you want to know whether a dewormer/treatment worked, you must do a reduction test. This is a retest within 10-14 days after deworming to see if the dewormer was effective. Luckily, retests tests are free with the Worm-Ex Lab within a 30-day window period.

TAKE HOME MESSAGE

This article hopes to show why it is important to stay up to date with the most effective ways to manage your horses. The world of horse care is always changing, and new information comes out all the time. Therefore, it is good to remember that we should always be willing to keep learning and growing for the sake of our horses.

WRITE TO US

Feel free to write to us with any questions you would like us to answer on parasites and worms in the upcoming issues! You can get in touch at lizzie@hqmagazine.co.za