What are primary GI causes of vomiting? (7)
dietary-related (intolerance/allergy, indiscretion), drugs, parasites, "bilious vomiting", foreign body, gastritis/ulcers, obstruction, neoplasia
What diagnostic tests can be done to identify primary GI causes of vomiting? (6)
- history (indiscretion, duration)
- radiographs/contrast studies (foreign body, obstruction, neoplasia)
- fecal exam (parasites)
- endoscopy (mucosal biopsy)
- therapeutic trial (exclusion)
What are systemic diseases that commonly cause secondary vomiting? (6)
pancreatitis, renal failure, liver disease, hypoadrenocorticism, hyperthyroidism, diabetic ketoacidosis, others
What diagnostic tests can be done to identify systemic diseases causing secondary vomiting? (6)
- CBC/Chem, urinalysis (liver and renal values, DKA, Addison's)
- PLI (pancreatitis)
- ACTH stim (Addison's)
- tT4 (hyperthyroidism)
In what cases should further workup always be performed, as opposed to conservative management of vomiting?
fever, lethargy, depression, weakness, dehydration, palpable abdominal abnormalities, pain, history of possible foreign body exposure, chronic vomiting, persists for 2-3 days, lack of appetite, organomegaly, vomiting/defecating blood, icterus, PU/PD
What electrolyte abnormalities are common with frequent or profuse vomiting? (3)
hypokalemia, hyponatremia, hypochloremia
What is the most likely cause of hypochloremic metabolic alkalosis in a vomiting dog or cat?
pyloric or proximal small bowel obstruction
Describe symptomatic treatment of vomiting. (3 steps)
- restrict food for 12-24 hours, offering small amounts of water or ice frequently
- if no vomiting after 24 hours, offer small amount bland, digestible, fat-restricted food (boiled chicken, rice, cottage cheese)
- gradually reintroduce normal food after 3-4 days
What is the mechanism of action of Ondansetron?
5HT3 serotonergenic antagonist at CRTZ and vagal afferent neurons
What is the brand name of Ondansetron, and when is it indicated?
Zofran; vomiting associated with chemotherapy, parvovirus, pancreatitis, or non-responsive to other antiemetics
What are contraindications and adverse effects of Ondansetron?
- contraindications- none
- adverse effects- sedation, lip licking, head shaking
What is the mechanism of action of Maropitant?
neurokinin-1 receptors antagonist, blocking SubstanceP from binding in the vomiting center
What is the brand name of Maropitant, and when is it indicated?
Cerenia; broad spectrum antiemetic, pancreatitis, motion sickness
What are contraindications and adverse effects of Maropitant?
- Contraindications- lower dose in hepatic dysfunction, not in pups <8 weeks
- Adverse effects- BM hypoplasia in pups <8 weeks old
What is the mechanism of action of Mirtazapine?
non-selective serotonin antagonist and alpha2-adrenergic blocker, acting in CRTZ and vagal afferent neurons
What is the brand name of Mirtazapine, and when is it indicated?
Remeron; cats that need antiemetic and appetite stimulation therapy
What are contraindications and adverse effects of Mirtazapine?
- Contraindications- decrease dose in liver and renal disease
- Adverse effects- vocalization, agitation, restlessness, tremors, hypersalivation, lethargy, vomiting, ataxia
What is the mechanism of action of Phenothiazine derivatives?
alpha 1 and 2 antagonists; inhibit CRTZ at low doses; depress vomiting center at high doses
What are indications for Phenothiazine derivatives?
What are contraindications and adverse effects of Phenothiazine derivatives?
- Contraindications- none
- Adverse effects- hypotension, sedation
What are indications for antiemetic therapy?
symptomatic control of vomiting (short-term), control of perfuse vomiting, motion sickness
What are the central and peripheral mechanism for action of Metaclopramide? Why doesn't it work centrally in cats?
- Central: antidopaminergic in the CRTZ
- Peripheral: stimulates GI motility
- Cats do not have as many dopamine receptors in the CRTZ as dogs, so it doesn't really work centrally for them.
How do antihistamines work as antiemetics, and when are they used?
act at CRTZ (H1 histaminergic antagonists); only used to control vomiting caused by vestibular disease or motion sickness
What should you rule out before pursuing primary GI disorders as the cause of vomiting?
rule out systemic diseases first
At what point of the vomiting reflex would the ideal antiemetic work?