Lecture 19: Basic Approach to Tx of Poisoned Animals 2

When should you NOT induce vomiting?

DO NOT induce vomiting if the patient:

• Is a horse, ruminant, rodent, rabbit, reptile, bird

• Is not FULLY alert and FULLY conscious

• Has any significant respiratory compromise

• Has abnormal pharyngeal reflexes

• Is seizuring or has imminent risk of seizures

• Has already vomited multiple times

• Has ingested substance with rapid onset of action

Why should vomiting not be induced if the patient has ingested a caustic/corrosive agent or the toxin ingested was mixed with something like broken glass?

re-exposure to the esophagus, pharynx, or mouth will cause additional injury

What conditions warrant caution when considering emesis?

• seizure condition

• serious heart disease

• megaesophagus

• recent abdominal or chest sx or trauma

How long after toxin ingestion does emesis become futile?

IT DEPENDS ON:

• Consistency and amount of material in stomach

• Caloric density of stomach contents

• Fat content of stomach contents

• Intragastric pressure

• The toxin ingested

How long does gastric emptying of liquids take?

starts within 15-45 minutes, complete within 1-4 hours

Solids are retained in stomach until _________.

almost liquid

What is the general rule of thumb for emesis regarding time?

• the sooner the better

• < 30 mins post-ingestion is best

• up to 2 hours reasonable

• > 4 hours can be questionable

True or false: emesis will completely empty stomach and remove all toxin.

false

What is the major risk from emesis?

aspiration

What is the best emetic for at home use?

3% hydrogen peroxide

What is the mechanism of action of hydrogen peroxide?

• irritate pharyngeal and gastric mucosa

• must be fizzy to work

What are the risks of hydrogen peroxide emesis?

• aspiration and lung injury

• can cause mucosal erosions

If the hydrogen peroxide emesis does not work, what can be done?

repeat 1-2x if no effect within 10-15 minutes

What emesis methods should NOT be used?

• Table salt

• Liquid dishwashing detergent

• Copper sulfate

• Dry mustard powder

• Manual pharyngeal stimulation

Why should syrup of ipecac not be used?

Horrible taste, cardiotoxic, CNS depressant, prolonged vomiting, diarrhea, other risks

What are examples of pharmaceutical emetics?

apomorphine, ropinirole xylazine

What is the MOA of apomorphine as an emetic?

IV admin preferred → stimulates dopaminergic receptors in CRTZ in dogs

What is the MOA of xylazine as an emetic?

activates alpha1-receptors in CRTZ (works well in cats)

What is the most common administration method of apomorphine?

place tablet or portion of tablet under eyelid in the conjunctival sac or can dissolve in solution and place drops in conjunctival sac → flush out remainder of drug once vomiting occurs

What drug is a dopamine D2 aagonist and used as an emetic?

repinirole

What should be considered if decontamination is necessary, but emesis is unsafe?

gastric lavage

Do not perform gastric lavage if:

• The toxin ingested is caustic, corrosive

• The toxin ingested is a volatile hydrocarbon

• An increased risk of gastric perforation exists

• If sharp objects are in the stomach

• If emesis can be carried out safely!

Gastric lavage is indicated over emesis if:

• The patient has altered mental status

• The patient has respiratory compromise

• Emesis is unsuccessful or unlikely to be so

What species require an endotracheal tube in place for gastric lavage and which do not?

small animals required, horses and ruminants do not need anesthesia and endotracheal tube

True or false: there are many more risks with lavage than emesis and it is not as effective.

true

What is the major complications with gastric lavage in small animals?

• aspiration

• damage to GI tract

• fluid and electrolyte imbalances

What is the technique for rumen lavage?

• animal not anesthetized, performed in standing animal (avoid chute if possible)

• using a mouth gag, place large tube into rumen

• easiest if have a source of running water

When should gastrotomy or rumenotomy be considered?

• if large items or imbedded items in stomach/rumen

• if emesis or lavage not safe or unlikely to be effective

When is endoscopic removal in horses or small animals recommended?

• if discrete item or imbedded item in stomach

• if emesis or lavage not safe or unlikely to be effective

What is used for whole bowel irrigation?

polyethylene glycol: large amount given via stomach tube → volume forces IG contents through intestines quickly; used for massive overdoses of sustained release drugs or toxins poorly bound by AC

What product is used more in large animals to form insoluble compounds in GI tract to decrease absorption?

oral chelators