What is Neck Threadworm?
If you read through any moxidectin or ivermectin based wormer packet you will find a long list of parasites written on the pack. No doubt, you will find the words Onchocerca cervicalis inscribed neatly towards the end. In lay man’s term, Onchocerca cervicalis is known as neck tthreadworm. Neck threadworm is as long as a ruler; yes it’s that long and surprisingly, it’s secret to habitat is the nuchal ligament of a horse. Neck threadworm runs through the length of the neck, covering from the poll to the withers with its flat ligament part attached to the cervical vertebrae.
Neck threadworm is a parasitic filarial worm that produces many hundreds of larva in its lifetime which is said to be ten years. The larvae are deposited in the horse’s skin, around the chest, shoulders, head, mane and tail, and the mid line of the belly. The adult worm finds its resting place in the nuchal ligament of the horse.
Neck threadworm affects almost, if not all horses. Though it affects most horses, neck threadworm doesn’t pose a risk for all horses. This is to say that neck threadworms are not a problem for all horses but for those that react badly to their microscopic larvae. This reaction is known as Onchocerciasis. Horses that are affected by this condition experience itching around the chest, neck, head, underside of the belly and the shoulders. This is why horse owners jump to the conclusion that their horses suffer from sweet itch when they observe these symptoms.
Much attention isn’t given to neck threadworms by horse owners because they are assumed to be itch and because they do not live in the intestine. Sadly, this problem is on a rampage as most horses are affected and it’s quite unfortunate for horses who are kept in warmer and humid climates as they are more prone to it.
The Culicoides fly is the biting insect that carries this parasite and that’s why neck threadworm is often confused with sweet itch or Queensland itch.
DOES YOUR HORSE HAVE NECK THREADWORMS OR SWEET ITCH?
Since neck threadworms are often confused with sweet itch, it’s important to identify which is affecting your horse so you can take the right treatment measures.
If your horse is experiencing itching;
- It could be that your horse is suffering from sweet itch or whatever it is called in your area and is just reacting to the saliva of the insect.
It could be that your horse has neck threadworm and that has affected his immune system and increased his sensitivity to fly bites. In this case, neck threadworm has triggered sweet itch as a secondary response.
It could be that your horse has neck threadworms considering that he is rubbing the base of it’s mane, along the mane, down the ventral line that is under the belly, under the chest and around the face and neck.
HOW TO IDENTIFY NECK THREADWORMS IN YOUR HORSE
Identifying neck threadworms can be somewhat confusing for horse owners considering that other parasites cause itching and skin lesions.
Horse owners are familiar with the widely known summer sores caused by Habronema.
In this case, flies lay their larvae on open cuts which then remain open until the cut is washed and larvae are removed. This condition is easy to tell as infected cuts oozes out bloody fluids.
This isn’t the case with neck threadworms.
Besides sweet itch, neck threadworm is also confused with Threadworm.
Threadworm is caused by the parasite Strongyloides westeri which infects foals. The clinical signs of these other parasitic infections are somewhat clear – this begs the question, how do horse owners identify neck threadworms in horses?
Studies show that neck threadworms have a distinct life cycle and it’s presentation depends on the horse.
It might come off as itching in the underside of the neck in a horse A or come off as itching the front of the withers in horse B. Even so, a horse that has never experienced itching before may start itching his face furiously.
All these are early signs of neck threadworms and are usually recognized by the owner only that they are confused as sweet itch.
Other signs of neck threadworms to look out for include weeping spots, a scaly crest at the mane as a result of rubbing, and small lumps that form on the horse’s face and neck and along the underside.
Then check the base of the man just outside the withers as that’s the focal point of neck threadworms.
Also you can consult a veterinarian to collect a simple skin biopsy from any affected area. The skin biopsy is now left in warm saline and the presence of Microfilariae can be checked with microscope.
WHAT ARE THE TREATED OPTIONS?
Medicated Shampoo and Neem Oil Skin Lotion to the rescue! Neem Oil Shampoo and Neem Oil have been proven to relieve the symptoms.
A Neem Oil Skin Lotion works by stopping cycle of the larva thereby reducing the itching and leaving the affected area unappetizing to the culicoides. This promotes healing in the skin.
Experts strongly advise that horse owners deal with the neck threadworm internally by using ivermectin wormer.
After all, you will find neck threadworm on the packet of ivermectin
Ensure you consult your veterinarian to advise the recommended dosage and frequency of usage. Most veterinarians recommend the use of injectable ivermectin.
While the adult neck threadworm that lives in the nuchal ligament cannot be killed, the larvae can be killed. This is why it’s crucial for you to look out for the early signs so you can begin treatment before the larvae grow into adults.