Gross Examination of Feces

The gross appearance of the feces of cattle is not only an indicator of disease of the digestive tract but can provide valuable clues for the differential diagnosis of disease elsewhere.


Amount

In adult cattle, the passage of ingesta through the digestive tract takes 1.5 to 4 days. Mature cattle generally pass some feces every 1.5 to 2 hours, amounting to a total of 30 to 50 kg/day in 10 to 24 portions.

A reduction in the bulk of feces can be caused by a decrease in feed or water intake or a retardation of the passage through the alimentary tract. In diarrhea, the feces are passed more frequently and in greater amounts than normal and contain a higher water content (>90%) than normal.


Absent or Scant Feces

Failure to pass any feces for 24 hours or more is abnormal, and the continued absence of feces may be caused by a physical intestinal obstruction. However, in many cases the intestine is not physically obstructed; instead, there is a functional obstruction. Diseases causing disturbances of motility of the rumen and abomasum often result in a relative absence of feces. Paralytic ileus of the intestines caused by peritonitis or idiopathic intestinal tympany also results in a marked reduction in feces, sometimes a complete absence, for up to 3 days. The marked reduction of feces that occurs in functional obstruction is a major source of diagnostic confusion because it resembles physical obstructions of the intestines.


Colour

The color of the feces is influenced by the nature of the feed, the concentration of bile in the feces, and the passage rate through the digestive tract. Calves reared on cows’ milk normally produce gold-yellow feces, which become pale brown when hay or straw is eaten. The feeding of milk substitutes adds a gray component to a varying degree.

The feces of adult cattle on green forage are dark olive-green, on a hay ration more brown-olive, and the ingestion of large amounts of grain produces gray-olive feces. Diarrheic feces tend to be paler than normal because of their higher water content and lower concentration of bile.

Blood in the feces may originate from the following locations:

• Hemorrhage into the abomasum: acute hemorrhage usually appears as black, tarry feces (melena); chronic hemorrhage as occult blood.
• Hemorrhagic enteritis of small intestines: the feces are uniformly dark red.
• Hemorrhagic enteritis of the large intestines: In the cecum or colon - blood appears evenly distributed throughout the feces (dysentery); In the rectum - blood appears as streaks or chunks of frank blood unevenly distributed throughout the feces (hematochezia).
• “Occult blood” is not visible grossly; the color of the feces may be normal or dark. Although a variety of commercially available fecal occult blood tests developed for humans have been adapted for use in ruminants.

Odor

Fresh bovine feces are not normally malodorous. Objectionable odors are usually caused by putrefaction or fermentation of ingesta, usually associated with inflammation. E.g. Feces in cattle with salmonellosis may be fetid.


Consistency

The consistency of the feces is dependent on the water content, the type of feed, and the length of time the ingesta has remained in the digestive tract. Normally, milk-fed calves excrete feces of a medium to firm porridgelike consistency. After transition to a plant diet, the first solid particles begin to appear. Normal bovine feces are of a medium porridge-like consistency. A moderate thickening leads to the passage of fecal disks of a more solid consistency, and severe dehydration causes the formation of firm balls of feces arranged in facets inside the rectum, the surfaces of which are dark and coated with mucus.

The feces of cows with left-side displacement of the abomasum are commonly pasty in appearance. Sticky and tenacious feces are commonly seen in obstruction of the fore-stomachs (vagus indigestion and chronic peritonitis).


Degree of Digestion

The proportion of poorly digested plant particles in the feces is dependent on the duration and adequacy of rumination and the rate of passage of ingesta through the fore-stomach and abomasum. The length of time the ingesta is in the postruminal digestive tract seems to have no appreciable influence on its digestion. Inadequate digestion indicates failure in rumination or accelerated passage of ingesta through the fore-stomach. Thus in some cattle with acute traumatic reticuloperitonitis, the feces may contain small walnut-sized chunks of undigested plant fibers that have escaped the cellulose digestive processes of the fore-stomachs.


Other Substances in the Feces

Mucus
The presence of excessive mucus on the surface of feces suggests increased transit time of the ingesta in the large intestine. The presence of a plug of mucus in the rectum is suggestive of a functional obstruction (paralytic ileus). In enteritis, large quantities of clear, watery mucus may be passed, which sometimes clot to form gelatinous masses.

Fibrin
In fibrinous enteritis, fibrin may be excreted in the form of long strands, which may mold into a print of the intestinal lumen (intestinal fibrinous casts).