Simple indigestion occurs most commonly in hand-fed cattle and is the result of cattle being fed an abnormal diet. Diagnosis is based on multiple animals having decreased appetite and forestomach motility, abnormal rumen pH, and an abnormal diet. Treatment focuses on feeding a typical ruminant diet.
Simple indigestion in ruminants is a minor disturbance in GI function that occurs most commonly in cattle and rarely in sheep and goats. It is a diagnosis of exclusion and is typically related to an abrupt change in the quality or quantity of the diet.
Etiology of Simple Indigestion in Ruminants
Almost any dietary factor that can alter the intraruminal environment can cause simple indigestion. Simple indigestion is common in hand-fed dairy and beef cattle because of variability in the quality and quantity of their feed. Dairy cattle may gorge excessive quantities of highly palatable feeds such as corn or grass silage; beef cattle may eat excessive quantities of relatively indigestible, poor-quality roughage during winter. During drought, cattle and sheep may be forced to eat large quantities of poor-quality straw, bedding, or grain. Simple indigestion can result from suddenly changing the feed, using spoiled or frozen feeds, introducing urea to a ration, turning cattle onto a lush cereal grain pasture, or introducing feedlot cattle to a high-level grain ration.
Simple indigestion is usually associated with a sudden change in the pH of the ruminal contents, such as a decrease in ruminal pH due to rapid fermentation of ingested carbohydrates or an increase in ruminal pH due to forestomach hypomotility and putrefaction of ingested feed. It can also result from accumulation of excessive quantities of relatively indigestible feed that may physically impair rumen function. Multiple animals in a group are usually simultaneously affected because simple indigestion has a nutritional basis, although severity of clinical signs can vary among animals.
Clinical Findings for Simple Indigestion in Ruminants
Clinical signs of simple indigestion depend on the type of animal affected and cause of the disorder. Overfeeding of silage causes anorexia and a moderate drop in milk production in dairy cattle. The rumen is usually full, firm, and doughy. Primary forestomach contractions are decreased in rate or absent, but secondary forestomach contractions may be present albeit usually decreased in strength. Temperature, pulse, and respiration rate are normal. The feces are normal to firm in consistency but reduced in amount. Recovery usually is spontaneous within 24–48 hours.
Simple indigestion due to excessive feeding of grain results in anorexia and ruminal hypomotility to atony (stasis). The rumen is not necessarily full and may contain excessive fluid. The feces are usually soft to watery and foul smelling. The mechanism for diarrhea formation is uncertain but is most likely due to increased luminal osmolality as a result of the rapid degradation of ingested carbohydrates. Affected animals are bright and alert and usually begin to eat within 24 hours. More severe digestive upset due to excessive feeding of grain is described as grain overload.
Diagnosis of Simple Indigestion in Ruminants
Decreased appetite and forestomach motility, and abnormal rumen pH, in multiple animals
Recent dietary change
Diagnosis of simple indigestion is based on a history of an abrupt change in the nature or amount of the diet, multiple animals in a group being affected, and most importantly exclusion of other causes of forestomach dysfunction. Ruminal fluid may have an abnormal pH (< 6 or >7), decrease in number and size of protozoa, or prolonged methylene blue reduction time (a measure of bacterial metabolic activity). For herds, simple indigestion should not be suspected if only one animal in a group is affected.
The systemic reaction and painful responses to deep palpation of the xiphoid in traumatic reticuloperitonitis are not seen. The history and the absence of ketonuria help eliminate clinical ketosis from consideration. The possibility of left displaced abomasum usually can be eliminated by simultaneous percussion and auscultation.
Vagal indigestion, abomasal volvulus, and cecocolic volvulus become more readily detectable as they progress. Grain overload is differentiated from simple indigestion by greater severity, lethargy, and pronounced decrease in the pH of the rumen contents to < 5.5.
Treatment of Simple Indigestion in Ruminants
Cessation of the abnormal diet
Feeding of a typical ruminant diet
Treatment of simple indigestion is aimed at correcting the suspected dietary factors. Spontaneous recovery is usual when animals are fed a typical ruminant diet, and additional treatment is usually not needed. Administration of warm water or saline (0.9% NaCl) solution (~20 L, orally [eg, as a drench or via stomach tube], once), followed by vigorous kneading of the rumen, may help restore rumen function in adult cattle (no withholding times established). Magnesium hydroxide (294 g of magnesium oxide salt in 4 L of water, PO, repeated as necessary) may be useful when excessive amounts of grain have been ingested, but magnesium hydroxide should only be administered to cattle documented to have low ruminal pH (< 6); otherwise, excessive forestomach and systemic alkalinization can result. Milk taken from animals during treatment and for 12 hours (1 milking) after the latest treatment must not be used for food.1 Purported rumenatorics (eg, nux vomica, tartar emetic, parasympathomimetics) are not recommended as ancillary treatments. Ginger may be effective as a rumenatoric, but additional studies are required. If too much urea ( see Nonprotein Nitrogen Poisoning) or protein has been ingested, vinegar (5% acetic acid) may be administered (2–6 L, PO, repeated as necessary2) to return rumen pH to the normal range. If the number or activity of ruminal microbes is reduced, ruminal fluid transfer (4–8 L, infused ruminally via stomach tube, once) from a healthy cow will help. Oral or IV administration of electrolyte solutions may be needed to correct electrolyte and acid-base abnormalities, particularly in dehydrated cattle.
References
Key Points
Simple indigestion affects multiple cattle in a herd being fed an abnormal diet.
Affected cattle have decreased appetite, reduced forestomach motility, and abnormal rumen fluid characteristics.
Treatment should focus on changing the diet.
For More Information
Fubini SL, Yeager AE, Divers TJ. Noninfectious diseases of the gastrointestinal tract. In: Divers TJ, Peek SF, eds. Rebhun's Diseases of Dairy Cattle. 3rd ed. Elsevier; 2018:168–248.
