NITRATE/NITRITE POISONING

Few plants normally have high nitrate content, but drought increases nitrate concentration in them. Plants have the ability to accumulate large quantities of nitrates which are toxic to goats and other ruminants. Toxic levels of nitrate are found in common pasture grasses and plants during periods of rapid growth, particularly when warm rains follow a very dry summer. Since soluble sugars are low at this time, nitrite accumulates in the rumen by slowing up the rate of metabolism to ammonia.

Crops grown on summer-fallow land often have a higher concentration of nitrates than land which is in continuous production, since the latter conditions result in absorption of nitrates as the crops grow.

Nitrate poisoning usually occurs within several days after the plants or hay has been moistened by rain, snow, or excessive dampness. Plants containing more than 1.5% dry weight potassium nitrate are lethal to goats.

The amount and type of fertilizer used on a field, as well as soil type, influences nitrate accumulation.

Nitrate-accumulating plants and grasses include pigweed, redroot, oatgrass, goosefoots, lamb's-quarter, Canada thistle, jimsonweed, barnyard grass, cockspur, bursage, silver leaf, poverty weed, white ragweed, wild sunflower, fireweed, cheeseweed, sweet clover, smartweed, Russian thistle, Johnson grass*, oats*, beets, rape, soybean, flax, alfalfa*, rye, sudan grass*, wheat* and corn*. The asterisked (*) products are often used to feed goats in Texas and other parts of the United States.

Deaths have also resulted from animals consuming water from shallow wells in certain areas of the Great Plains. An increase in the concentration of nitrates in stock tanks above that of the well water's nitrate level occurs, often during freezing weather, by ground-water's being contaminated from heavily-fertilized soil or by barnyard runoff.

Signs of nitrate/nitrite poisoning appear suddenly. Difficulty in breathing is usually the first sign. Mouth breathing, weak and rapid heartbeat, low body temperature, extreme apprehension, anxious behavior, muscular weakness, and foaming at the mouth are symptomatic of this illness. The blood is brown colored because of the presence of methemoglobin; methemoglobin cannot bind oxygen, which means that it cannot carry oxygen to tissues. Death usually occurs within three to four hours; in extreme cases, the goat dies in convulsions within an hour.

Goats who survive nitrate poisoning may have continuing health problems associated with this toxic reaction. Respiratory distress in the form of labored, heavy breathing and occurrences of interstitial pneumonia often happen. For those goats who recover from nitrate poisoning, it takes about 10-14 days, but pregnant females usually abort following recovery.

The most sensitive and reliable simple test for nitrites is the dephenylamine blue (DPB) test. Treatment for the illness is best accomplished by the administration of a 2% solution of methylene blue, which through a series of chemical reactions, allows the toxic methemoglobin to be converted to hemoglobin. A vet is needed for these procedures, which can be combined with the oral introduction of mineral oil to protect irritated mucous membranes. Stimulants usually don't help.

Goats fed rations containing grain (processed sack goat feed) can survive higher level of nitrates than animals maintained on pasture alone. The soluble carbohydrates in processed grain feed permits metabolism of nitrates without harming the goats.

Both prussic acid poisoning and nitrate/nitrite toxicity have several items in common. First, symptoms are remarkably similar and overlapping, with few exceptions, making diagnosis by a veterinarian essential. Secondly, producers should feed dry roughage (grass hay - NO silage) and supplement their goats with a formulated pelleted goat ration. Breeders who insist on making their animals survive without supplements are destined to lose goats to these problems.

Suzanne W. Gasparotto, Onion Creek Ranch, Texas 8.1.22

The author, Suzanne Gasparotto, hereby grants to local goat publications and club newsletters, permission to reprint articles published on the Onion Creek Ranch website under these conditions: THE ARTICLE MUST BE REPRODUCED IN ITS ENTIRETY AND THE AUTHOR'S NAME, ADDRESS, AND CONTACT INFORMATION MUST BE INCLUDED AT THE BEGINNING OF THE REPRINT. We would appreciate notification from any clubs or publications when the articles are used. (A copy of the newsletter or publication would also be a welcome addition to our growing library of goat related information!)

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