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Meningeal Worm in Alpacas and How to Prevent it

Four White Alpacas In A Green Pasture Under A Blue Sky

Alpacas are hearty animals that can thrive in many environments, but there are a few health risks that caretakers need to be aware of in order to maintain a healthy herd. One potential threat to many alpaca herds is meningeal worm, which can cause serious issues and even death if left unguarded or untreated.

Meningeal worm is a parasite that affects the central nervous system (CNS) of alpacas. The larvae of this parasite are transmitted through ingestion – once transmitted, these larvae migrate through an alpaca’s body until they reach the spinal cord and brain area, where they can do a lot of damage. If left untreated, meningeal worm can cause neurological breakdown and even death in alpacas.

In this article, we will provide an overview of meningeal worm in alpacas and discuss what you can do to protect your alpacas from this often deadly parasite.

Where does meningeal worm come from?

Meningeal worm (Parelaphostrongylus tenuis) is a parasite that is commonly found in white-tailed deer. As the typical host, white-tailed deer can usually endure the parasite without showing many adverse reactions or signs of disease. However, when infected, alpacas and other camelids can easily develop a severe neurological disease that affects the central nervous system.

The meningeal worm parasite is often passed through a white-tailed deer’s feces and picked up by small snails and slugs. Alpacas commonly acquire the meningeal worm parasite when eating snails and slugs on pasture grasses. Meningeal worm, or m-worm, is quite difficult to control once it reaches an alpaca’s CNS, so it is important to protect your herd from this parasite and the damage it can cause.

A Slug in a Green Pasture

Statistically, alpacas infected with meningeal worm have a high mortality rate due to the damage the parasite causes to the CNS. Alpacas are at the greatest risk of contracting m-worm in areas of North America that house large populations of white-tailed deer (particularly on the East Coast), but this parasite can be found in a variety of environments.

How does meningeal worm affect alpacas?

When an alpaca ingests meningeal worm larvae, the larvae will penetrate the alpaca’s intestine tissue and begin its journey through the alpaca and toward its spinal cord. On average, it takes one of these little m-worm parasites around 30 days to reach the spinal cord of an alpaca.

The severity of symptoms caused by meningeal worm can vary widely from one alpaca to the next. Symptoms of m-worm in alpacas can include muscle weakness, loss of coordination, and paralysis. In some cases, the parasite can even cause death to an alpaca.

Although meningeal worm parasites can often destroy spinal tissue, they can also migrate to the brain and cause blindness, seizures, and abnormal behavior, among other symptoms. In order to prevent these unwanted problems, it is important to regularly check for signs of infection and to preventatively treat your alpacas for meningeal worm. Keeping your alpaca’s pastures clear of deer and slugs/snails as much as possible will help mitigate the risk of m-worm in your herd. You can do this by installing proper fencing around the pasture’s perimeter, and even placing a border of gravel along the outside of the pasture to discourage slugs/snails from entering the pasture.

How to spot meningeal worm symptoms in alpacas

Ideally, a good preventative treatment plan will protect your herd from falling ill from m-worm, but it is still important to know how to identify m-worm symptoms in case something slips through. Common signs that an alpaca has meningeal worm include difficulty standing, stiff or awkward mobility, weakness in the hind legs, and lethargy.

Meningeal worm can often be diagnosed based on shown symptoms, though it’s worth noting that m-worm symptoms can closely resemble the symptoms of other alpaca health issues such as spinal cord injuries, thiamine deficiencies, and more.

The earlier you can spot meningeal worm symptoms in an alpaca, the quicker you can begin treatment, and the better the chances will be for recovery. If caught early enough and treated appropriately, many alpacas can make a full recovery from meningeal worm damage. The longer the worm is allowed to live in the alpaca’s CNS, the more damage it can do. Even in many severe cases, partial recovery is possible, but there can be some lingering issues, such as stiffness, limping, and loss of sight.

A Group of Full-Fleeced Alpacas on a Farm

Unfortunately, many alpacas that develop symptoms from meningeal worm are not diagnosed early on. Alpacas are relatively good at hiding their illnesses because they are prey animals that are programmed to hide their weaknesses. So it’s essential to carefully observe your alpaca’s behaviors and mannerisms and to act fast if anything seems off.

How to prevent meningeal worm in alpacas

Since meningeal worm larvae take approximately 30 days to reach an alpaca’s spinal cord, it’s crucial to proactively treat your herd for possible infection. Once the meningeal worm parasite reaches an alpaca’s spinal cord, it’s more difficult to treat because the spinal cord and brain are protected by multiple layers of membranes known as meninges – the meninges form a blood-brain barrier (BBB), which helps form a roadblock to stop unwanted microorganisms from passing through. And while the BBB stops many unwanted bacteria and viruses from entering the central nervous system, it also stops many chemicals and drugs used to kill m-worm parasites.

Ivermectin and Dectomax for preventative meningeal worm treatment

Ivermectin and Dectomax are two of the most commonly used preventative treatments for meningeal worm. Both of these drugs will kill m-worm parasites, but neither of them can pass the blood-brain barrier, so doses must be administered every 30 days to eliminate any potential meningeal worm larvae in an alpaca’s system.

In other words, there is a 30-day window after ingestion when meningeal worm larvae can travel from an alpaca’s stomach to its spinal cord. When a proper dose of Ivermectin or Dectomax is given to an alpaca, it kills any meningeal worm larvae that the alpaca has acquired in the past 30 days – it does not protect them for the next 30 days.

Essentially, Ivermectin and Dectomax give the alpaca’s system a shock that will kill any meningeal worm larvae ingested in the past 30 days. The frequency of which this preventative treatment should be done is not determined by how long the drug stays in the alpaca’s system, but rather by how long it takes for the parasite to get to the meninges. Once the meningeal worm has passed through the blood-brain barrier, these drugs cannot reach it to kill the parasite.

Ivermectin vs Dectomax

Ivermectin is absorbed into an alpaca’s system quickly, reaching peak blood and tissue levels in about 24 hours and leaving the system in about two days. Ivermectin quickly kills the unwanted meningeal worm parasites and leaves the animal’s body almost as fast.

Dectomax, on the other hand, is a less potent drug than Ivermectin and is absorbed into an alpaca’s system much more slowly. Dectomax takes at least ten days to reach peak blood and tissue levels in an alpaca – and after peaking, Dectomax takes up to four weeks to completely leave an alpaca’s system.

Both Ivermectin and Dectomax can be effective in killing meningeal worm in alpacas, but Ivermectin is commonly thought to be the better of the two options. Ivermectin works faster than Dectomax; it’s also more powerful, and leaves the alpaca’s system faster.

Injectable Ivermectin For Alpacas

If you are located in an area that is known to have meningeal worm (usually geographical areas that hold a white-tail deer population), it’s best to administer Ivermectin to each alpaca once every 30 days. It’s recommended that Ivermectin should be given in doses of 1cc per 70lbs of an alpaca’s weight.

Treating alpacas with meningeal worm symptoms

Meningeal worm symptoms in alpacas are a serious cause for concern and should be addressed as soon as possible. If you suspect that an alpaca in your herd has m-worm, we recommend that you contact an experienced camelid veterinarian immediately. Meningeal worm treatment plans can vary depending on the alpaca and its overall condition. Effective treatments can often include some variation of Safeguard, Banamine, Thiamine, vitamin Es, and vitamin Bs.

Safeguard is a dewormer that is capable of passing through the blood-brain barrier and can sometimes kill meningeal worm parasites that are present in an alpaca’s CNS, which makes it a popular option for treating alpacas with m-worm symptoms.

When all is said and done, the best treatment for meningeal worm in alpacas is proactive prevention. But if you do find yourself with an alpaca in your herd that is showing signs of m-worm infection (limping in the back legs, loss of coordination, muscle weakness), contact an experienced camelid vet as soon as possible.

It’s important to speak to a knowledgeable veterinarian before beginning treatment for meningeal worm. An experienced large animal vet can prescribe the most effective treatment plan, ensuring that your alpaca is getting the care it needs.

An Alpaca That Has Recovered From Meningeal Worm


Meningeal worm is a serious problem for alpaca herds in many areas around the United States. And m-worm can have fatal consequences for alpacas if left untreated. By being prepared and aware of the signs and symptoms of meningeal worm in alpacas and taking steps to preventatively treat your herd, you’re well on your way to protecting your alpacas from this terrible parasite.

If you think your alpaca may be infected with meningeal worm, don't hesitate to contact your veterinarian for diagnosis and treatment recommendations.

The information in this blog is intended to educate readers on alpaca care topics. Nothing contained in the content should be considered or used as a substitute for veterinary medical diagnosis or advice.


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