Principles of Therapy of GI Disease

See also Systemic Pharmacotherapeutics of the Digestive System and see The Ruminant Digestive System.

Although eliminating the cause of the disease is the primary objective, the major part of treatment is supportive and symptomatic, aimed at relieving pain, correcting abnormalities, and allowing healing to occur.

Elimination of the primary cause may involve antimicrobials, coccidiostats, antifungal agents, anthelmintics, antidotes for poisons, or surgical correction of displacements.

Correction of excessive or depressed motility appears rational, but often the nature and degree of abnormal motility are uncertain; in addition, available drugs may not give consistent results. There is little clinical evidence to recommend the routine use of anticholinergic or opioid drugs to slow intestinal transit. Slowing intestinal transit may be counterproductive to the defense mechanism of diarrhea, which acts to evacuate harmful organisms and their toxins. In general, anticholinergic drugs probably are justified only for short-term symptomatic relief of pain and tenesmus associated with inflammatory diseases of the colon and rectum. In some disorders of gastric or colonic motility, prokinetic drugs (eg, metoclopramide, erythromycin) may be useful.

Replacement of fluid and electrolytes is necessary when dehydration and electrolyte and acid-base imbalance occur as in diarrhea, persistent vomiting, intestinal obstruction, or torsion of the stomach(s), in which large amounts of fluid and electrolytes are sequestered.

Relief of distention medically by stomach tube (as in bloat in ruminants) or surgically (as in acute intestinal obstruction, or in torsion of the abomasum in ruminants or of the stomach in monogastric animals) may be required. The GI tract may become distended with gas, fluid, or ingesta at any level due to physical or functional obstruction.

Relief of abdominal pain by administration of analgesics should be done when the pain is reflexly affecting other body systems (eg, cardiovascular collapse) or when it is causing the animal to injure itself because of rolling, kicking, or throwing itself. Animals treated with analgesics must be monitored regularly to ensure that the relief of pain does not provide a false sense of security; the lesion may be progressively worsening while the animal is under the influence of the analgesic.

Reconstitution of ruminal flora should be done in situations in which the ruminal flora may be seriously depleted (eg, in prolonged anorexia or acute indigestion). Transfaunation (ruminal fluid transfer; see Ruminal Fluid Transfer) involves oral administration of ruminal contents from a healthy animal that contains rumen bacteria and protozoa and volatile fatty acids.