Toxicology of a bovine paraplegic syndrome

A clinical entity named 'bovine paraplegic syndrome' ('síndrome parapléjico de los bovinos') has spread alarmingly in the cattle-growing areas of the central and eastern plains of Venezuela. It is estimated that four million cattle are bred in the area where the disease occurs. The mortality ranges from 5 to 25% of the animals at risk, mostly pregnant or lactating cows. The principal characteristic of the bovine paraplegic syndrome is ventral or sternal decubitus, in animals that make vain efforts to stand when stimulated. The diagnosis is established when all other possible causes (e.g. paralytic rabies, botulism and blood parasites such as Anaplasma marginal, Babesia bovis, B. bigemina, and Trypanosoma vivax) have been ruled out clinically and by laboratory tests. Death always occurs, usually after a few days, and there is no known treatment. In this work, we describe results that show the presence of a toxin in the cattle suffering from, or liable to suffer from the syndrome. The toxin is produced by ruminal bacteria. In squid giant axons under voltage clamp conditions, the toxin blocks the sodium current. We detected the toxin analytically by absorbance measurements at 340 nm after reacting with picrylsulfonic acid. We obtained a good separation of the toxin with isocratic high pressure liquid chromatography, using 40% methanol in water on phenylborasil columns.