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

http://www.youtube.com/watch?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 drugshelp 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

stoolcathartic: 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 endingsBulk 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

Apomorphinestimulates 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

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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 Drugsused for treating constipation, chronic hairballs or used after surgery to increase GI motility

Enzyme Supplementing Drugsused 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 Prophylaxisattention should be given to the

oral cavity in any gastrointestinal condition.