Page 1216 - Veterinary Toxicology, Basic and Clinical Principles, 3rd Edition

Prevention and Treatment of Poisoning Chapter | 82 1147

VetBooks.ir the total calculated dose of activated charcoal is mixed dosing of other oral medications since the charcoal can
also bind them.
with 50 200 mL of warm tap water to make a slurry
(Rosendale, 2002). In horses and ruminants, each gram of
Administration of activated charcoal carries a signifi-
activated charcoal powder is mixed with 5 mL of water cant risk of aspiration. If the patient does aspirate the
(Plumb, 2015). In symptomatic small animal patients and charcoal, the prognosis is poor. Hence proper placement
large animals, the activated charcoal liquid or prepared of the stomach tube and a protected airway is a must in
slurry is administered via stomach tube (Bailey and symptomatic patients. The patient may also experience
Garland, 1992). Small animals receiving activated char- constipation and black bowel movements, making it diffi-
coal via stomach tube should be sedated and have a cult to determine if melena is present. If the activated
cuffed endotracheal tube in place to prevent aspiration. In charcoal sits within the GIT for a significant period of
small animal patients where no clinical effects are pres- time, it may release the compound it has adsorbed, lead-
ent, activated charcoal can be given orally with a large ing to systemic absorption and recurrence of the clinical
syringe or can be mixed with a small amount of canned signs. It is for this reason that activated charcoal is fre-
food or chicken broth and offered to the patient quently administered with a cathartic. In fact, many com-
(Rosendale, 2002). Some patients, especially dogs, will mercially available preparations do contain a cathartic,
voluntarily ingest the mixture. Many birds will regurgitate such as sorbitol.
a portion of the activated charcoal dose given, and some Another possible adverse effect of activated charcoal
dogs and cats will vomit after administration. administration is the development of hypernatremia. In
Repeated doses of activated charcoal may be indicated humans, hypernatremia has been reported primarily in
in some instances, such as cases where toxicants undergo children when multiple doses of a charcoal sorbitol mix-
enterohepatic recirculation. The first step in this process ture were administered. The hypernatremia is attributed to
involves the toxicant being carried to the liver by either a water shift from the intracellular and extracellular
the portal vein after absorption from the GIT or via the spaces into the GIT as a result of the osmotic pull of the
systemic circulation. Once in the liver, the toxicant then sorbitol cathartic (Allerton and Strom, 1991). The
enters the bile and is excreted into the GIT where it is ASPCA Animal Poison Control Center (APCC) has also
again available for absorption. Many toxicants are known received reports of elevated serum sodium following acti-
to undergo this type of recycling, including ibuprofen, vated charcoal administration in dogs. Hypernatremia
marijuana and digoxin. seems to be more often reported in small dogs receiving
When repeated doses are indicated, half the original multiple doses of activated charcoal, but it has also been
dose should be given at 4 8 h intervals, often for 2 3 reported in large dogs and in cases receiving only a single
days (Peterson, 2006). It is important to mention that with dose. Furthermore, unlike the human reports, hypernatre-
medications that are excreted in the bile, activated char- mia has also been noted in cases where no cathartic was
coal can be of benefit regardless of the route the medica- present in the charcoal product given (Ball, 2014).
tion was administered. Thus, if a patient received an Perhaps one of the other components of the product is
overdose of injectable ivermectin subcutaneously, acti- also osmotically active. In these cases, the APCC has
vated charcoal will still be a very valuable decontamina- found that administration of a warm water enema is very
tion option. The ivermectin molecules will be carried to effective at lowering the serum sodium and easing the
the GIT by the bile. resultant central nervous system effects (Ball, 2014).
The use of activated charcoal does carry some risks
and it does not bind all compounds equally. Some che-
micals that are not effectively adsorbed include: ethanol, Cathartics
methanol, fertilizer, fluoride, petroleum distillates, most Cathartics enhance elimination of substances, including
heavy metals, iodides, nitrates, nitrites, sodium chloride activated charcoal, by promoting their movement through
and chlorate. Activated charcoal should not be given to the GIT. Since activated charcoal only binds to toxicants
animals that have ingested caustic materials since it is by weak chemical forces, without cathartics, the bound
unlikely to bind them, it can be additionally irritating to toxicant can eventually be released and reabsorbed
the mucosal surfaces and make visualization of oral and (Rosendale, 2002). When used with activated charcoal,
esophageal burns difficult (Buck and Bratich, 1986). If the cathartic should be given immediately following or
ethylene glycol testing will be performed, activated char- mixed with the charcoal. Cathartics are contraindicated if
coal should be administered after blood is collected, the animal has diarrhea, is dehydrated, if ileus is present,
since propylene glycol found in many formulations can or if intestinal obstruction or perforation are possible
cause afalsepositiveonsomeof these tests. (Peterson, 2006).
Additionally, the timing of the activated charcoal admin- There are bulk, osmotic, and lubricant cathartics.
istration should be taken into account when deciding on The most commonly used bulk cathartic is psyllium