Nervous Coccidiosis: Curious Cold-Weather Livestock Condition

Coccidiosis is a common bacterial condition in livestock, but when cold weather hits, the illness can present odd neurological symptoms, too.

by Anna O'Brien
PHOTO: Kimberly/Adobe Stock

The winter is full of many livestock ills. Most have to do with feed, water, mud and muck. One infectious disease in cattle that occasionally throws a weird loop when it’s cold out, however, is the neurologic form of coccidiosis. Let’s take a closer look at this cold-weather conundrum.

All About Coccidiosis

Coccidiosis is a diarrheal disease in livestock caused by single-celled protozoa called coccidia. Different species of coccidia infect different hosts. There are specific coccidia for cattle, sheep, goats, camelids and poultry.

Coccidia are very common in the environment. When they are ingested, they invade the intestinal lining. The bacteria have a complex life cycle once situated in the gut. Suffice it to say, though, that after a few rounds of reproduction, they create pretty significant damage to the inside lining of the intestines.

Severe diarrhea and subsequent weight loss then occur. Infective spores (called oocysts) are shed in the manure, completing the cycle and contaminating the environment for other animals to then ingest them. This starts the whole process over again.

These oocysts are very hardy and can survive in the environment for a surprisingly (and frustratingly) long time.

Read more: Check out these tips for preventing coccidiosis and other illnesses in cattle.

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Cold-Weather Symptoms

Diarrhea is the most common clinical representation of coccidiosis and one that hobby farmers likely will encounter at some point in their animals. A drug called amprolium is frequently used to help treat and control a disease outbreak. However, when the weather gets cooler and calves are sent to feedlots, something odd can sometimes happen.

Newly arrived calves in a feedlot occasionally start to show neurologic signs, starting with incoordination, rigid legs and jerky eye movements. If this progresses without intervention, signs may progress to the inability to rise and seizures.

These signs are not limited to the winter, but the majority of cases show up in the colder months.

A Curious Condition

What’s weird about this condition, called nervous coccidiosis, is that animals with coccidiosis and neurological clinical signs don’t have any detectable brain lesions. In fact, researchers don’t really know why this neurological form occurs.

One theory is that the diarrhea associated with coccidiosis hastens the loss of electrolytes and a resultant imbalance of minerals such as magnesium and calcium then cause neurologic signs.

Other researchers suspect a toxin is to blame. Intriguingly, if serum from infected calves is injected into mice, the mice develop neurologic signs, too, despite not being directly infected with the coccidia.

Read more: Prepare cattle and yourself for cold winter temperatures.

What to Do

Treatment of coccidiosis (whether nervous or not) should be started quickly to prevent further spread to other animals and reduce clinical signs in those already infected. Amprolium can be given in the drinking water—read the directions on the label for proper dosing calculations.

Clinically dehydrated animals may also benefit from supportive care, such as IV fluids and supplemental electrolytes. Contact your veterinarian if you have an outbreak of diarrhea on your farm. Accurate diagnosis and prompt treatment can save animals from severe disease.

Prevention is always worth a pound of cure. Coccidiosis is no exception.

Since this is a disease associated with a contaminated environment, keeping the barn clean is one of the best ways to prevent severe coccidial infections. Avoid crowding animals in tight spaces for long periods of time, and clean manure-contaminated feed bunks.

Keep water troughs clean and regularly clean manure from aisles and other heavily used areas. This will help reduce the number of oocysts in the immediate area, which lessens infection pressure in the herd.

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