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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

PRUSSIC ACID POISONING

Prussic acid toxicity, also known as cyanide poisoning, occurs usually within 15 minutes of the goats' ingesting the toxic plant material. Symptoms include excessive salivating or frothing at the mouth and an increased respiratory rate. Ruminants are more susceptible to prussic acid (cyanide) poisoning than non-ruminant species, probably because the rumen releases larger quantities of hydrocyanic acid.

Mouth breathing develops within five to fifteen minutes. The heartbeat is rapid and weak. Muscle twitching occurs quickly and spasms precede death. Mucous membranes are bright red, indicating a lack of oxygen transfer throughout the body that is necessary for continued survival. Death from respiratory paralysis comes during severe convulsions. The heart continues to beat for several minutes after struggling ceases and breathing stops. Blood often passes from the nostrils and mouth near the time of death.

This entire process seldom takes longer than 30 to 45 minutes. If animals survive for more than two hours after the onset of signs of this illness, a high percentage of them will recover.

Intravenous administration of sodium nitrite in a 20% solution is the treatment for prussic acid poisoning. Because of the importance of speed in treating cases of cyanide toxicity, sodium nitrite and sodium thiosulfate are usually administered together. Some success has occurred by using oral preparations of sodium thiosulfate.

If you think that the goat's problem is prussic acid/cyanide poisoning, call your vet immediately. This is not something you are likely able to handle yourself.

Cyanide-containing plants include Gregg's catclaw, acacia, catclaw acacia, devil's catclaw, mountain mahogany, iris, blue flag, common flax, western choke cherry, pine cherry, wild red cherry, bird cherry, fire cherry, wild black cherry, apple, Johnson grass*, sudan grass*, common sorghum*, poison suckleya, white clover, arrow grass, goose grass, sour grass, pod grass, maize, corn*. The plants indicated by an asterisk (*) are most commonly encountered by goat breeders in my part of the United States (Texas). Several of these crops are used as hay or grain feed.

Prussic acid poisoning can and does occur in crops which have NEVER been fertilized.

NOTE: You can reduce the risk of prussic acid/cyanide toxicity by feeding commercially-prepared sacked goat feed before turning animals out to graze. Do NOT ever feed wet or moldy hay or grain to goats. Wet grain must be thrown out, but wet bales of hay can be broken and aired out until thoroughly dry, then used as goat feed, IF the bales are lightly wet and all mold and mildew has disappeared.

Suzanne W. Gasparotto, Onion Creek Ranch, Texas 8.1.22