My Experience with Meningeal Worm in Goats

Although we love dearly our ability to browse our goats over such a varied bit of land, this style of keeping brings it’s own issues. Meningeal Worm is something I’ve unfortunately become very familiar with.

Meningeal worm (Parelaphostrongulus tenuis) is a parasite that live in the brain and spine of whitetail deer. When the eggs are shed, they are often picked up by snails and slugs, which are then ingested by ruminants such as goats, llamas, and sheep.

This can cause some serious issues, as the parasite gets “lost,” potentially causing hind end lameness and even paralyzation.

My first experiences with Meningeal worm (henceforth referred to as MW) were confusing, because there was almost no information on the parasites, nor the strange symptoms we were experiencing. In the beginning, I actually thought I was looking at two diseases – one that caused hind end lameness, and one that caused skin lesions.

It started that very first year the rains really returned. We had been in a drought for so long, I think a lot of us forget just how green and wet it can get. As slugs and snails thrive in the wet, and whitetail deer are everywhere, it’s simply the perfect environment to pick up MW infection – though I didn’t know it at the time.

The skin lesions were the true start of my quest. Some of the goats – almost exclusively La Manchas – began to present with awful raw patches of skin. They started as small bare spots, but within a day would be bloody and raw, as if the goat had scraped it ferociously against something. Sometimes the lesions would grow larger, sometimes they would remain small. The vast majority were located on the upper parts of the body, most commonly on the neck. There have been instances of the lesions appearing on the head, shoulders, spine, rump, but rarely below the middle of the goat. After a few days, the lesions healed, and the hair grows back eventually, leaving no trace.

  

I assumed it was a fungal infection to start with – perhaps rain rot or ringworm, though it didn’t exactly fit any of those ailments. When treatments had no effect, I did a skin scraping to look for mites and found nothing. I was left scratching my head in puzzlement over the issue, and the problem was left unsolved.

As the season progressed, the skin issues continued, but appeared to have no long term effect on the goats. They’d rub themselves raw, then it would heal with no issues. No one lost their appetite, ran a fever, or became lethargic. I sent the pictures to several fellow goat owners, and even posted them on a couple forums, with no solid diagnosis.

However, at the same time, I began to have issues with hind end lameness. Several La Mancha does started to drag a hind leg or have trouble standing. A promising young Nigerian Doe had trouble getting up one day, and by the next, was completely paralyzed in the hind end, and could only drag herself about. This I could diagnose – surely MW. While researching MW I never once came across a description of the skin lesions, until Onion Creek Tennessee Meat Goats updated their own MW article, which included the following:

“You should suspect Meningeal Worm disease if the goat displays bare patches of hide from quarter to palm size (generally on the flank or near the front leg), a bloody hole chewed in the hide, neurologic signs or any problem involving the spinal cord, from hind leg dragging to inability to get up.”

It suddenly all made more sense, and I immediately launched into treatment not just for the lame goats, but the ones exhibiting skin. We use extremely high doses of fenbenzadole – 10x the normal dose at least, over several days (minimum five) depending on severity. If the animal is showing neurological symptoms, I include a dose of banamine to act as an anti-inflammatory.

Closer inspection of the lesions made it painfully clear it was MW causing these issues – the parasite exits the skin once it becomes lost, and underneath the hair, one can often find “track marks” and holes where it has done so.

  

No one else had described these lesions anywhere, and even a parasite specialist from Texas A&M during a small ruminants veterinary conference had no idea about them, asking us to bring some examples this year if possible. When I tried to bring it up during a goat meeting (that I no longer attend) I was promptly shut down (the rude way in which I was dismissed is one of the reasons I no longer attend, actually). I admit to feeling some vindication when Caroline Lawson wrote an article for the Dairy Goat Journal recently that also described the lesions – the first time since the Onion Creek article that I have seen someone other than myself report these issues in conjunction with MW.

Many claim that monthly doses of Ivermectin injectable will act as a preventative, but after trying this method for a season, I was forced to conclude it was not effective for our herd. It’s interesting to note that while both breeds we run can exhibit the hind end lameness, it’s almost exclusively the La Mancha that develop the skin lesions, while the Nigerian Dwarf have only two recorded cases of minor sores. Yet the Nigerian Dwarf are much more likely to go completely down in the hind end and become paralyzed, and also do not respond as well to treatment.

Most of the goats treated recovered, though not always 100%. One Nigerian Dwarf doe who had a minor case continues to show some permanent lameness, but it has not inhibited her ability to produce kids or keep up with the herd. Several La Mancha who have had varying degrees of infestation have recovered completely with no sign. A Nigerian Dwarf buck that lost complete control over his hind end recovered through intense treatment and therapy, but can no longer breed due to the weakness of his hind leg still.

And unfortunately, three goats – two Nigerian Dwarf does and a La Mancha buck – never recovered the use of their hind legs and were humanely euthanized.

Thankfully, this issue is rarely seen among penned goats, but unfortunately it’s one of the risks we personally run here with our style of keeping. There are positives and negatives to any way of keeping, and Meningeal worm remains our largest enemy running our goats the way we do. It’s a risk that, in the end, we have chosen to accept in order to continue to reap the immense benefits of free browsing. The life of a goat owner is never easy, and we all must decide what is best for ourselves and our own animals. Thankfully, the past few years have made me nearly an expert on this parasite, and I hope that this post will help someone else understand what they’re dealing with some day.