Exam 2 Flashcards
(131 cards)
Vomiting (Emesis)
- Forceful ejection of stomach contents through the mouth
- Protective mechanism to remove harmful substances from body
- Initiated by activation of the emetic center
Can be generated by impulses caused by-
- Pain, excitement, fear— cerebral cortex
- Disturbances inner ear (vestibular apparatus)- CRTZ
- Drugs-CRTZ
- Metabolic Conditions- CRTZ
- Irritation peripheral receptors
GI DRUGS
- Emetics
- Anti-emetics
- Anti-ulcer
- Diarrhea stopping
- Stool loosening
- Saliva stopping
- Motility enhancing
- Foam stopping
- Enzyme supplements
Regulation of GI System
SNS stimulation:
- decrease intestinal motility and tone
- decreases intestinal secretions
- Inhibits relaxation of sphincters
- Sympathomimetic or anticholinergic drugs cause similar actions
PSNS stimulation:
- increase motility and tone
- increases secretions
- stimulates relaxation of sphincters
- Cholinergic or parasympathomimetic drugs cause similar actions
What animals do NOT vomit?
Horses, rabbits, and rodents
What can vomiting lead to?
It can lead to electrolyte disturbances, hypokalemia, and dehydration
What are emetics used for?
Used to induce vomiting
-for animals that have ingested toxins
(must first weigh risk of aspirating stomach contents into lungs versus potential benefits of induced vomiting)
Administer within 2-4 hours
How is an emetic classified?
Classified according to site of action
- Centrally Acting- act on CRTZ
- Peripherally Acting- act on peripheral receptors
Centrally Acting Emetic Drugs:
- Apomorphine
- Xylazine
Peripherally Acting Emetic Drug:
3% Hydrogen Peroxide
What is Apomorphine?
A centrally acting emetic drug
(it is a morphine derivative)
USE: induce emesis in dogs
Side Effects: protracted vomiting, depression
Given by IV or IM injection OR tablets placed in conjunctival sac (poorly absorbed from GIT)
-It stimulates dopamine receptors in CRTZ (cats have fewer receptors)
What is Xylazine?
It is a centrally acting emetic
-Stimulates Alpha2 receptors in both CRTZ and emetic center in cats
DRUG OF CHOICE FOR INDUCING EMESIS IN CATS
-Within minutes of injecting can be reversed with yohimbine
What is 3% Hydrogen Peroxide used for?
-peripherally/locally acting emetic
Can cause direct irritation of oropharynx and gastric lining
Administer within 5-10 minutes
Side Effects: aspiration, severe gastritis, and ulceration in cats
MUST USE 3% NOT 10%
What do Antimetics do?
Prevent or decrease vomiting
-phenothiazine derivatives
Phenothiazine Derivative Drugs
- Acepromazine (PromAce)
- Chlorpromazine (Thorazine)
- Prochlorpromazine (Compazine)
phenothiazine Derivatives
Antimetics
Centrally Acting– block dopamine receptors in CRTZ and emetic center
Lowers the seizure threshold so contraindicated in epileptic animals
USES: motion sickness in dogs and cats
Side Effects: hypotension, sedation
Antihistamines
Block input from vestibular system to CRTZ
USES: to control vomiting due to motion sickness, vaccine reactions, or inner ear problems
Side Effects: Sedation
Antihistamine Drugs
Dimenhydrinate (Dramamine)
Diphenhydramine (Benadryl)
Procainamide derivative
Act centrally-block CRTZ
Act peripherally-speed gastric emptying, increase sphincter tone, increase force of contractions
USES: antimetic especially for chemotherapy, kidney failure, and viral gastroenteritis
Side Effects: behavioral/CNS disorders
Procainamide derivative Drug
Metoclopramide (Reglan)
NK-1 receptor antagonist
USES: prevention and treatment of acute vomiting; prevention vomiting due to motion sickness
Side Effects: pain and swelling at injection site, diarrhea, anorexia
NK-1 receptor antagonist Drug:
Maropitant (Cerenia) – prevention and treatment of acute vomiting
Injectable solution: dogs/cats
Oral Tablets: Dogs
What do Antiulcer Drugs do?
– they prevent formation of ulcers.
What are Ulcers?
erosions of mucosa and are named according to site: gastric ulcer, duodenal ucler, esophageal ulcer etc.
Signs: anorexia, melena, hematemesis, abdominal pain
H2 Receptor Antagonists (antiulcer)
USES: treats or prevents ulcers by reducing acid due to blocking H2 receptors of parietal cells in stomach by histamine.
Side Effects: diarrhea, inhibit liver enzymes and alter rate metabolism