As always, talk to your vet if you suspect you have a goat with a serious illness! This site is not intended to be a substitute for a vet or for further research and accurate diagnosis.
WHAT CAUSES THIS DISEASE: This disease is caused by the round worm Parelaphostrongylus tenuis (more commonly known as “brain worm”; “meningeal worm” or “P. tenuis”). P. tenuis normally lives in the sinuses and brain case of white tail deer. The adult worm will lay eggs, which migrate in the blood stream to the lungs. Here the eggs hatch into larvae, which travel up the lungs to be swallowed by the deer into the digestive tract. The larvae then leave the deer in the mucous coat of the deer fecal pellet. This mucus is then fed on by snails and slugs. After a period of time in these intermediate hosts the larvae becomes infective. When a snail or slug is accidentally consumed by a goat the larvae penetrate the intestinal wall and travel to the spinal cord. However, instead of traveling to the brain as the parasite does in its natural host the white tailed deer, the parasites become lodged in the spinal column of the goat.
In deer the infection is relatively silent, though some minor neurological symptoms are rarely seen. Other species are not so lucky. If P tenuis is consumed by a goat, (or sheep/elk/moose/black tailed deer/caribou/mule deer), P. tenuis damages the nervous system, eventually resulting in the death of the animal.
SYMPTOMS: Usually only 1 or 2 goats in a herd are ill at any one time and cases may appear sporadically. There may be some genetic resistance to infection that can be passed on to offspring. My personal experience of the disease is that the goat looks like it has a dislocated hip. Check to make sure it isn’t a dislocated hip! The goat presents in the early stages as unstable when walking, with way too much movement in the hind end. Otherwise the goat will act normally. Once you’ve seen this once you’ll remember it forever because this off balance walk is very distinctive. As the goat gets worse it may start to fall over occasionally, then lose use of its hind end, with greater and greater paralysis occurring. Eventually the goat may be very weak, down, paralyzed, and unable to even sit up on its sternum on its own, (in the normal “chewing cud” position). Severe paralysis may result in loss of blood flow and the need to amputate legs, (yes, I have seen this happen in person). Sometimes chewing of the skin and signs of severe itch may be present, but I’ve never actually seen this happen in person.
TREATMENT: Get the goat started on treatment BEFORE it is down, paralyzed, or leg dragging. As ivermectin cannot pass into the spinal cord its use is considered ineffective (though treatment with ivermectin does seem to help anecdotally). Use Safeguard (10% Fenbendazole) orally for 5 days at 1 1/3 cc per 10lbs of body weight. This kills the worms by crossing into the spinal column. Along with Safeguard, use dexamethasone injectable at 1/2 cc per 10lbs of bodyweight for the first 3 days and 1/4 cc dexamethasone for 2 days. This controls the inflammation caused by the worms dying in the spinal column. Inflammation in nervous tissue is bad and can further damage the spinal column! If you can’t get Dex, or your doe is in the last month of pregnancy oral banamine (flunixin meglumine) can be substituted at a rate of 1cc per 100lb bodyweight. Injection of a B vitamin complex may be beneficial, (my goat mentor always had me do that but I have no data on the effectiveness). No treatment can repair the nerve damage that the worm is causing, but it can save the goat from death. There has been some interest in producing a P tenuis vaccine, but this does not yet exist. Necrotic paralyzed legs may need to be amputated to save a severely infected animal.
PREVENTION: P tenuis is a common sporadic killer of goats in boggy northern states, (like New York), with massive deer populations. However, the worm has been reported in most of the northeast, midwest, and southeastern United States as well as in southeastern Canada. Pastures that stay moist and are conducive to the survival of snails will be prone to producing infected goats. I once visited a meat goat producer in New York who had two pastures. One was well drained, the other prone to bogginess. When grazing goats on the well drained pasture no P tenuis symptoms were seen. As soon as the goats got on the boggy pasture, though, someone would turn up staggering around and obviously infected!
Raising pack goats on dry well drained pasture, fencing them out of slug/snail habitat, and using species such as ducks that may consume snails as a cross grazing species can help remove p tenuis from the goat environment. Use of ivermectin to prevent infection is also possible, but contributes to undesirable dewormer resistance.
WHY THIS MATTERS TO PACK GOAT ENTHUSIASTS:
This disease damages the rear legs’ nervous system, (and possibly does worse). Dogo was infected with this disease and nearly died from it. When she recovered she was unable to walk straight and would fall off wooden boardwalks a lot because her sense of balance was ruined. After several months of intensive hiking, (without a pack on), she regained her sense of balance and now walks normally, (though some what stiffly when tired on her rear legs). However, her balance is still slightly off, making it hard for her to cross water on logs and prone to falling painfully on her back if she starts crow hopping when running.
She is also limited on the number of times she can be bred, (3 kiddings max after infection), because if she continues to breed her legs will eventually give out from the strain and she’ll have to be put down. She is always hiked when pregnant to keep her nerves and muscles in good shape to insure she has a trouble free kidding, and this seems to help a lot. She was bred for her last kidding in Fall 2015 and will be retained as a hiking only goat for the remainder of the time she plans to spend getting into trouble on this earth. * As an update, she is doing much better than other producers with p. tenuis infected goats have reported. Therefore, she will be bred in Fall 2016. We’ll see how this goes…I might be lining myself up for a huge vet bill.
Most of all though, I realized quickly that Dogo would be perfectly able to hike, but unable to pack. She was infected as a yearling, and she was able to hike with a lightly loaded soft sided pack, but the wooden pack proved to be too much weight and pressure on her loins (the area of the back where the stomach joins the rear hips). The wooden pack would cause her even over relatively short hikes (2-3 miles) to progressively lose the ability to stand up and walk on her rear legs. Removal of the pack would cause her to slowly regain use of her rear legs over about half a mile. So obviously today she hikes and trains other young goats, but she will never be a pack goat.
IN SUM: If you want to pack your goats don’t keep them on boggy pastures with lots of snails and white tail deer present, or you may spend 4 years raising an animal that you won’t be able to pack.