• Bom Harris, DVM

Recognizing Neurologic Disease in Ruminants


Neurological diseases are diseases of the brain, spine and the nerves that connect them. A similar array of neurologic diseases affect cattle, sheep, goats and camelids and are often relatively common emergencies across species.


Listeriosis

Listeriosis is a bacterial infection of the brain in ruminants, but can also cause sepsis and abortion in many species, including humans. The neurologic form of Listeriosis is commonly called “circling disease” because severely affected individuals will circle constantly in one direction. The hallmark of this disease is one-sided neurologic symptoms, such as an eye or ear droop, head tilt to one side, or blindness in one eye.

The bacteria is picked up in the environment in soil, hay or silage. We typically do not see multiple animals in a herd affected at once. Treatment is a combination of antibiotics, anti-inflammatories and supportive care. Some affected animals respond very quickly to treatment, especially if caught early. Other cases are not responsive to treatment and may lead to euthanasia.


Polioencephalomalacia

Commonly called “polio,” this condition is caused by thiamine (vitamin B1) deficiency that leads to brain damage. Thiamine deficiency can be caused by excessive sulfur in feed or water, overdose with drugs such as amprolium (“Corid”) which inhibit thiamine uptake, or reduced thiamine production in the rumen, which can be caused by any upset to the gut flora. Blindness, inability to stand, and seizures are the most common symptoms, which can be rapidly progressive. However, early detection can lead to complete recovery in response to treatment with thiamine.


Meningeal worm

This parasite travels from the gut to the spinal cord of small ruminants and camelids and causes symptoms of weakness, stumbling and inability to stand. The primary host is the white-tail deer and it passes through slugs and snails as an intermediate host. Infection can occur in the brain as well, but this is less common. Treatment is with a combination of parasiticides, anti-inflammatories and supportive care. Damage may be irreversible even with treatment. This parasite is not known to affect cattle.


Rabies

Rabies must be considered in any animal with neurologic symptoms. The most common symptoms of rabies in cattle is persistent bellowing and straining. However, there are many other possible manifestations of rabies including: aggression, hypersalivation, weakness of the hindlimbs/inability to stand and seizures. Wear gloves and avoid contact with saliva until rabies has been ruled out when handling animals with neurologic disease. When there is a history of human exposure to saliva in an animal with rapidly progressing neurologic signs that lead to death, it is important to test for rabies so that post-exposure prophylaxis can be implemented in a timely manner. Rabies vaccination is recommended for small herds when there is significant human-to-animal contact to minimize risks to human safety.


Owners should be aware of the symptoms and distinguishing factors of neurologic disease. Early detection and intervention can greatly impact treatment success and overall prognosis.

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