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Nonprotein Nitrogen (Urea) and Hyperammonemia Chapter | 79 1097

VetBooks.ir Lloyd, 1981) until the rumen fluid pH is ,8 ( i.e., rumen ruminants undergoing dietary supplementation with NPN.
Diagnosis is based on clinical signs and analysis of the
fluid pH should be clearly acidic on testing). Ideally, the
body tissues/fluids and feed for urea and ammonia levels.
rumen fluid pH should be periodically checked using pH
papers during acetic acid administration in order to evalu- Treatment includes oral administration of acetic acid
ate the effectiveness of this treatment. (vinegar) and symptomatic and supportive therapies.
The next treatment objective is to decrease the reac-
tion rate of rumen microflora urease by reducing the tem-
perature of the rumen contents. Following rumen REFERENCES
acidification, a large volume (5 10 gallons) of cold water
should be administered by intrarumen intubation. Davis, G.K., Roberts, H.F., 1959. Urea Toxicity in Cattle. Agricultural
Animals that respond to treatment often relapse and Experiment Station, Bulletin 611, Gainesville, FL.
repeat treatment (usually using about half the amounts of Dinning, J.S., Briggs, H.M., Gallup, W.D., Orr, H.W., Butler, R., 1948.
Effect of orally administered urea on the ammonia and urea concen-
acetic acid and cold water used in the first treatment) is
tration in the blood of cattle and sheep, with observations on blood
typically required (can be aided by periodic monitoring of
ammonia levels associated with symptoms of alkalosis. Am. J.
rumen pH after initial treatment). Recumbent and con-
Physiol. 153, 41 46.
vulsing animals generally respond poorly to treatment. Haliburton, J.C., Morgan, S.E., 1989. Nonprotein nitrogen-induced
Other nonspecific, supportive therapies may include ammonia toxicosis and ammoniated feed toxicity syndrome. Vet.
anticonvulsant therapy (e.g., phenobarbital, pentobarbital) Clin. North Am. Food Anim. Pract. 5 (2), 237 249.
and intravenous fluid therapy to correct fluid deficits and Hatch, R.C., 1977. Veterinary toxicology. In: Jones, L.M., Booth, L.F.
any elemental or electrolyte abnormalities. (Eds.), Veterinary Pharmacology and Therapeutics. The Iowa State
Animals that recover usually do not appear to suffer University Press, Ames, IA, pp. 1253 1259.
any recognizable long-term adverse effects, although Hintz, H.F., Lowe, J.E., Clifford, A.J., Visek, W.J., 1970. Ammonia
abortions can occur in pregnant animals. intoxication resulting from urea poisoning by ponies. J. Am. Vet.
Med. Assoc. 157, 963 966.
Lloyd, W.E., 1981. Urea and other nonprotein nitrogen sources.
AMMONIA (NH 3 ) GAS In: Howard, J.L. (Ed.), Current Veterinary Therapy. Food Animal
Practice. W.B. Saunders, Philadelphia, PA, pp. 393 396.
NPN poisonings resulting in hyperammonemia should not
Loosli, J.K., McDonald, I.W., 1968. Nonprotein Nitrogen in the
be confused with ammonia poisoning (covered in detail in
Nutrition of Ruminants. FAO Agricultural Studies No. 73. Food and
the chapter on toxic gases). Synonyms include ammonia Agriculture Organization of the United Nations, Rome.
gas, anhydrous ammonia and liquid ammonia. Livestock Lower, S., Fraser, S., 2016. All about acids and bases; and Acid-base equilibria
can be poisoned by ammonia, either through inhalation or and calculations (Chapters 9 and 21 (respectively)). In: Chem1 Virtual
ingestion, through its use as a fertilizer. As described pre- Textbook a reference text for General Chemistry. Ed. Lower S, Fraser S.
viously, ammonia (NH 3 ) readily dissolves in water to Simon. ,http://www.chem1.com/acad/webtext/virtualtextbook.html.
1
form the ammonium cation (NH ) and hydroxyl ions (accessed 31.10.16.).
4
2
(OH ). This results in typical alkali burns (i.e., dissolu- Osweiler, G.D., Carson, T.L., Buck, W.B., Van Gelder, G.A., 1985.
Urea and nonprotein nitrogen. Clinical and Diagnostic Veterinary
tion of tissue proteins). Anhydrous ammonia is colorless,
Toxicology. Kendall/Hunt Publishing Company, Dubuque, IA,
highly irritating, and causes corrosive injury to the
pp. 160 166.
mucous membranes of the eyes, lungs, and skin.
Word, J.D., Martin, L.C., Williams, D.L., et al., 1960. Urea toxicity stud-
Inhalation of ammonia can lead to severe bronchiolar and ies in the bovine. J. Anim. Sci. 29, 786 791.
alveolar edema, and airway destruction that can result in
respiratory failure and death. Dermal contact or oral expo-
sures lead to corrosive skin lesions and corrosive damage FURTHER READING
to the mucosal lining of the oral cavity, esophagus, and
stomach. NCBI. (National Center for Biotechnology Information). PubChem
Compound Database; CID 222. ,https://pubchem.ncbi.nlm.nih.gov/
CONCLUDING REMARKS compound/ammonia.. CID 223. ,https://pubchem.ncbi.nlm.nih.
gov/compound/ammonium. (accessed 31.10.16.).
AND FUTURE DIRECTIONS
All mammalian species are susceptible to urea/ammonia
poisoning, although poisoning most commonly occurs in