Identification and treatment of encysted small redworms

Cyathostomins (small redworms) are one of the most common and harmful parasitic worms that live in horses and the time to identify and treat the larval stages (larval Cyathostominosis) these worms is between December and February.

During the winter, the larvae hibernate in the gut wall where they encyst (top image) and typically reactivate when the weather warms in the spring. At that time, they migrate out from the intestine walls, simultaneously and in considerable numbers, causing severe intestinal wall damage. The results of this mass emergence can cause sudden weight loss, abnormal blood conditions, diarrhoea, colic and even sudden death.

Encysted small redworm symptoms are not always easy to detect and the larval stage can’t be identified by worm egg counts, as the encysted worms are immature and not producing eggs. Horses that are badly affected with an encysted redworm burden may look bloated or overweight due to the inflammation.

Our laboratory offers a blood serology test for identifying encysted small redworms and can be used in combination with tapeworm testing during the late autumn/winter months. Based on your horse’s blood test results, it may not be necessary to use a wormer at all, thus reducing the potential for anthelmintic resistance. If a particular type of worm is identified by the laboratory tests, your vet will recommend the most appropriate treatment to target the specific worm type found, and risk levels.

Treatment in winter can be combined with worming for small redworms and all other roundworms, including pinworms, bots and all three types of tapeworm by giving Equest Pramox (moxidectin and praziquantel combined). If horses have been blood tested for encysted small redworms and tapeworms and have returned a negative result, this may not be necessary. Discuss this with your vet on an individual basis for each horse.

With increasing levels of resistance to anthelmintics (‘de-wormers’), a targeted and responsible worming protocol is very important to protect your horse or pony against internal parasites. Rossdales offers two options - our Standard Worm Control package and an Enhanced Worm Control package - to make worming your horse as convenient and cost effective as possible, and to give you peace of mind. Please speak to one of our vets if you require further advice.