The digestive tract plays a role of bringing life sustaining elements into the body and taking waste products out of it.

Flow of material occurs by peristalsis. A wavelike motion of longitudinal and circular muscle fibers. Another process is segmentation..periodic repeating intestinal constrictions

v=o18UycWRsaA Peristalsis

Regulation of the actions is controlled by the autonomic nervous system. This consists of the

Sympathetic branch

Parasympathetic branch

Parasympathetic stimulation increases intestinal motility, increases secretions and relaxes sphincters

Cholinergic drugs stimulate these actions Anticholinergic drugs inhibit these actions

Gastrointestinal drugs help maintain the unobstructed and regulated flow of food into the body and waste products out of the body

Types of Gastrointestinal drugs

Saliva Stopping : Antisialogues

These drugs can be administered I.V, I.M or SQ, and are often given secondary to anesthetic use. These anticholinergic drugs block the effects of acetylcholine (a neuro transmitter) at parasympathetic nerve endings

These drugs are used to control: * hypersalivation *vomiting *diarrhea *excessive gastric secretions

Glycopyrrolate (Robinul)

Atropine

Diarrhea Stopping Drugs: Diarrhea is not a disease, but a sign of an underlying problem and can cause excessive fluid loss and a decrease in the uptake of nutrients.

Antidiarrheals decrease peristalsis allowing fluid absorption from the intestinal contents. These include: *anticholinergics *protectants *adsorbents *narcotic analgesics

Anticholinergics *used to treat tenesmus these drugs should be used with caution as motility may already be decreased.

Protectants/Adsorbents *coat the inflamed intestinal tract with a protective layer *binding bacteria, digestive enzymes and or toxins to protect the mucosa

Narcotic (Opiate related drugs) *decrease intestinal secretions and flow of feces, increasing segmental contractions resulting in increased intestinal absorption

Probiotics

*seed the gastrointestinal tract with beneficial bacteria. Some forms of diarrhea are caused by the disruption of normal bacteria flora

Metronidazole is an antibiotic that is effective against anaerobic bacteria and may be used to regulate intestinal bacteria and help return the stool to normal consistency

Stool Loosening

laxative: loosens bowel contents and encourages evacuation of stool cathartic: harsher laxative resulting in watery stool and abdominal cramping purgative: harsher cathartic.

Types of laxatives: *osmotic *stimulant *bulk forming *emollients (stool softener)

Osmotic: Include salts or saline, lactulose and glycerin. These salts pull water into the colon and increase the water content in the feces.

Stimulant laxatives increase peristalsis by chemically irritating sensory nerve endings Bulk forming laxatives consists of natural fibrous substances that absorb water into intestinal tract, increase fecal bulk stimulate peristalsis resulting in large soft stool production

Emollients are stool softeners, lubricants, and fecal wetting agents. These drugs are not absorbed systemically and have few side effects

Antiemetic Drugs

The act of vomiting is controlled by the vomiting center in the medulla of the brain. Acetylcholine is the neurotransmitter for the vomiting center.

This center gets input from pathways including *equilibrium changes *pain *fear *intracranial pressure changes *vagus nerve stimulation *activity in chemoreceptor trigger zone (CRTZ)

Dopamine is the neurotransmitter for the CRTZ and stimulation of the CRTZ results in dopamine release and stimulation of the vomiting center.

Types of antiemetics *Phenothiazine derivatives: inhibit dopamine in CRTZ.

Antihistamines: block input from the vestibular system to the CRTZ

Anticholinergics block acetylcholine which decreases intestinal motility. HOWEVER these drugs also decrease gastric emptying and may in fact increase the tendency to vomit

Procainamide derivatives block the CRTZ and speed gastric emptying. Do not use in obstructed animals due to the stimulation of gastric motility

Vomit Producing Drugs: Emetics used in the tx of poisonings and drug overdoses. Check with poison control prior to administering emetics

Remember… horses, cattle sheep and goats are unable to vomit

Apomorphine stimulates dopamine receptors in the CRTZ. Given SQ, IM or topically in the conjunctival sac

Xylazine (Rompun) induces vomiting in cats as a side effect of its use as a sedative =

Ipecac syrup, salt and hydrogen peroxide are also commonly used to induce vomiting. Activated charcoal may be given to reduce absorption of toxins when vomiting is contraindicated

Ulcer stopping Drugs

Antiulcer drugs: prevent the formation of ulcers Antiactids: promote ulcer healing Histamine-2: prevent acid reflux by reducing gastric acid secretion.

Antifoaming Drugs. Used in ruminants who are subject to acute frothy bloat. The rumen distends with gas that mixes with fluid to form a froth which can asphyxiate the animal

Motility Enhancing Drugs used for treating constipation, chronic hairballs or used after surgery to increase GI motility

Enzyme Supplementing Drugs used in cases of Pancreatic Enzyme Insufficiency (PEI) Care should be taken when handling this drug, it can be irritating to skin and to nasal passages

Dental Prophylaxis attention should be given to the oral cavity in any gastrointestinal condition.