FIVE POINTS OF ANIMAL HEALTH EVALUATION: NEUROLOGICAL HEALTH

By Jose Valles, MS, Production Animal Consultation

In previous issues of Protein Producers, we talked about a five-point animal health evaluation that I like to implement when working with animal caregivers in the area of pen riding in feedyards. This evaluation not only consists of detecting cattle that may need medical attention but also helps promote animal health in the lame ness, digestive, respiratory, neurological, and mental categories. In prior issues, we discussed lameness, digestive, and respiratory health; in this article, we will address the most common neurological issues.

When we enter a pen of cattle, it is important to take a few seconds to look over the entire group of cattle to observe their behavior and identify any obvious cases that may need immediate attention. As we move through the pen, it is crucial that we get all cattle up and ask them to move a reasonable distance or time that will allow us to make a careful evaluation to identify any possible neurological disorders. The distance or time the animal is asked to be in motion should be sufficient to identify symptoms such as improper head tilting, improper balance when in movement, circling, seizures, and in some cases, aggressive behavior.

Some of the most common neurological diseases found in feedlot cattle include listeriosis, thromboembolic meningoencephalitis (TEME), polioencephalomalacia (PEM), and nervous coccidiosis.

Listeriosis is a zoonotic infectious disease caused by Listeria monocytogenes, a gram-positive bacterium that can survive with or without oxygen in a wide range of temperatures. Both soil and the gastrointestinal tracts of mammals serve as reservoirs for the bacterium, and transmission occurs when cattle ingest vegetation or feedstuffs that have been contaminated via soil or feces. Listeriosis in feedlots most commonly occurs during the winter and spring months. Spoiled silage has a higher pH level, creating an environment conducive to replication of L. monocytogenes. Listeriosis outbreaks can occur 10 days or more after such silage is fed to cattle. Encephalitis or meningoencephalitis is the most common form of listeriosis seen in cattle and can affect cattle of any age. Lesions on the brain stem cause dysfunction of nerve nuclei, leading to clinical signs including anorexia, depression, disorientation, salivation, and facial paralysis often on one side affecting the ear, eyelid, lip, and muzzle. An affected animal may drive itself to a corner of the pen, lean against the fence or another stationary object, or move in a circular pattern, turning toward the affected side. When the animal eats, it may accumulate feed inside the cheek of the affected side since the muscles used for chewing are paralyzed. Severely affected cattle will fall and become nonambulatory. Listeria can also cause abortion and septicemia in cattle.

Another neurological disease seen in feedlot operations is thromboembolic meningoencephalitis (TEME). TEME affects cattle ages 6 months to 2 years and is caused by Histophilus somni, a gram-negative bacterium that can also cause respiratory disease, arthritis, and abortion in cattle. H. somni enters the body via the respiratory system, then migrates to affect the nervous system. The onset of TEME is often rapid, resulting in acute death. In cases with slower progression, affected animals can present stiffness, abnormal posture, lameness, and posterior incoordination or weakness. Affected animals may become non-ambulatory and depressed or comatose. Other clinical signs of TEME include fever, ataxia, opisthotonos, strabismus, nystagmus, blindness, hyperesthesia, and periodic convulsions.

Polioencephalomalacia (PEM) is another common neurological disease in feedlot cattle. Adult cattle are less likely to be affected than younger cattle. Thiamine deficiency and sulfur toxicity are the two most probable causes of PEM in feedlot operations. PEM can also be caused by lead poisoning, sodium toxicity, and water deficiency. Feedlot cattle are at higher risk for PEM caused by sulfur toxicity due to their exposure to higher levels of sulfur in the high concentration diets that they are generally fed. They are also at risk for PEM caused by thiamine deficiency because thiamine produced by rumen microbes can be reduced as a result of highconcentrate feed consumption. PEM can produce acute or subacute effects. In acute cases of PEM, affected animals can present blindness, tonic-clonic seizures, recumbency, and coma. In subacute cases, clinical signs can include separation from other animals, anorexia, ear and face spasms, elevated head position, cortical blindness, dorsomedial strabismus, ataxia, hypermetria, opisthotonos, head pressing, and grinding of teeth.

Coccidiosis is a parasitic disease affecting cattle. In cattle, it is caused by coccidia, which are protozoan parasites, of the genus Eimeria. Species E. alabamensis, E. auburnensis, E. bovis, and E. zuernii are most commonly associated with clinical disease. While coccidiosis often presents as a digestive disease affecting the intestinal tract of cattle, some cattle present with neurological symptoms (nervous coccidiosis), most commonly in winter. Clinical signs of nervous coccidiosis include incoordination, loss of balance, muscle twitches, hyperesthesia, tonic-clonic seizures, and nystagmus. Handling or other stressors may induce seizures, and the animal may recover and act normally after a seizure.

When evaluating cattle for neurological diseases, it is important to know recent history. It is very important to properly move all cattle within the pen as cattle with early stages of neurological disease can be difficult to identify. Note-taking is essential when pulling a sick animal from a pen as this will help guide the doctoring crew to a better case definition to provide proper treatment and follow up. It is very important to wear gloves when making contact with or evaluating chute-side cattle that present clinical signs of neurological disease because some neurological diseases are zoonotic and can be a risk to human safety.

Resources

• Constable PD. Listeriosis in Animals. Merck Veterinary Manual. October 2022.

https://www.merckvetmanual.com/generalizedconditions/listeriosis/listeriosis-in-animals https://tvmdl.tamu.edu/2020/09/14/bovinethrombotic-meningoncephalitis/ https://www.iowabeefcenter.org/bch/TEME.pdf

• Sheppard G, de la Concha-Bermejilla A. Bovine Thrombotic Meningocephalitis. September 2020. Texas A&M Veterinary Medical Diagnostic Laboratory.

• Lincoln SD. TEME in Feeder Cattle. Extension Beef Cattle Resource Committee, Beef Cattle Handbook BCH-3515.

• Lévy, M. Polioencephalomalacia in Ruminants. October 2022. https://www.merckvetmanual.com/ nervous-system/polioencephalomalacia/polioencephalomalacia-in-ruminants https://vetmed.iastate.edu/vdpam/research/disease-topics/toxicology/sulfur-toxicity

• Sulfur Toxicity. Iowa State University College of Veterinary Medicine. Department of Veterinary Diagnostic & Production Animal Medicine.

• Richards C, Step DL, Giedt EJ. Coccidiosis Treatment and Prevention in Cattle. October 2016. Oklahoma Cooperative Extension Service VTMD9129. https://extension.okstate.edu/factsheets/coccidiosis-treatment-and-prevention-incattle.html

• Andrews, A. Coccidiosis of Cattle. October 2022. https://www.merckvetmanual.com/digestivesystem/coccidiosis/coccidiosis-of-cattle

• Hauptmeier LD. Nervous Coccidiosis in Calves. April 1997. Iowa Beef Center. https://www.iowabeefcenter.org/Health/nervousc occidiosis.pdf

Jose Valles graduated with his Master of Biomedical Sciences from Kansas State University in 2013. He was born in the state of Durango in Mexico. He spent his childhood in both Durango and in southwest Kansas. In Mexico, his family has been dedicated to a cow-calf operation and the farming of dry beans, corn, and oats. After high school, Jose decided to further his education at the university level and has since lived in the U.S. He attended Seward County Community College in Liberal, Kansas, and during that time worked at the Liberal Animal Hospital. Jose transferred to Kansas State University through the Developing Scholars Program and Bridges to the Future Program. While attending Kansas State University, Jose worked at the Beef Cattle Institute from 2007 to 2013. After graduating from Kansas State University in 2013, Jose joined the PAC team, then later that year married his girlfriend Areli, and moved to Kearney, Nebraska. Jose enjoys spending time with his beautiful wife Areli and his sons Matteo and Antonio. He also enjoys riding a good horse, horse races, and grilling steaks.

This article has been translated to Spanish on page 50.