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Gastrointestinal decontamination

ISSN 2398-2950

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Synonym(s): Gut decontamination; Gastric decontamination

Introduction

  • Should be considered in all acute cases of toxin ingestion. The aims are to:
    • Remove the ingested substance from the stomach and
    • Reduce absorption of ingested substance that has passed beyond the stomach.

Techniques

Emesis

  • Will only retrieve material from the stomach.
  • Generally only worthwhile within 1-2 hours of ingestion.
  • Efficacy declines the longer the time between ingestion and emesis.
  • Induction of emesis in cats can be challenging.
  • A number of substances can be used for induction of emesis:
    • Apomorphine is the emetic of choice in dogs.  It is generally not used in cats because it can cause behavioral changes and hypermania.
    • Alpha-2 adrenergic agonists (eg xylazine Xylazine, medetomidine Medetomidine are used in cats. Vomiting is an adverse (and therefore unreliable) effect of these drugs. Sedation is common and can be reversed with atipamezole Atipamezole.
    • Sodium carbonate (washing soda) crystals are an effective emetic in dogs and cats. Washing soda must not be confused with caustic soda (sodium hydroxide) which can cause severe tissue burns.
      • Dosage:  There is no standard dose but usually a large crystal in a medium to large breed dog and a small crystal in a small dog or cat is sufficient.
    • Hydrogen peroxide 3% is used in dogs but it can cause local tissue damage with hematemesis and gastritis, particularly with overdosing in dogs or usage in cats.
      • Dosage 1-5 ml/kg in dogs.

Gastric lavage

  • Gastric lavage will only retrieve material from the stomach.  It is generally used in potentially severe cases of poisoning, particularly where there is rapid onset of signs and emesis is contraindicated Gastric lavage

Absorbents

  • Activated charcoal is the most commonly used absorbent; it can be given as a single dose or in repeated doses Charcoal activated

Cathartics

  • Used to increase the movement of substances, including absorbents, through the gut.  
    • Bulk laxatives can be used to reduce transit time of foreign bodies, eg coins, batteries. 
    • Osmotic laxatives such as lactulose Lactulose can also be used.  
    • Saline (eg magnesium sulphate) or saccharide cathartics (eg sorbitol) are sometimes given after activated charcoal to enhance elimination Charcoal activated
    • Cathartics alone are ineffective as a method of gut decontamination.

Whole bowel irrigation

  • Used in human medicine as a method of gut decontamination, but rarely used in the management of poisoning in veterinary medicine Bowel cleansing solutions

Contraindications and cautions

Emesis

  • Induction of vomiting Emesis induction is contraindicated:
    • If the animal:
      • Is very drowsy or unconscious
      • Is fitting
      • Has reduced cough reflex.
    • If the substance ingested:
      • Is likely to cause rapid onset of drowsiness or seizures
      • Contains paraffin, petroleum products or other oily or volatile organic products which could be aspirated into the lungs
      • Contains detergent compounds, which could be aspirated into the lungs
      •  Is a strong acid or alkali, which could cause further damage to the esophagus if regurgitated.
  • The following should never be used as emetics. They are obsolete and potentially dangerous.
    • Salt (sodium chloride) - risk of hypernatremia Hypernatremia.
    • Mustard - unreliable.
    • Copper sulphate - risk of toxicity. 
  • Syrup of ipecac (ipecacuanha) 7% was widely used in the past but is now not routinely recommended.  It is relatively ineffective and has a bitter taste.

Absorbents

  • Activated charcoal does not adsorb or should not be given for the following substances:
    • Alcohols (eg ethanol, methanol) and glycols (eg ethylene glycol)
    • Metals (eg lead, iron, zinc)
    • Paraffin, petroleum products or other oily or volatile organic products
    • Acids and alkalis
    • Detergents.

Cathartics

  • Should not be used in animals with:
    • Dehydration
    • Diarrhea
    • Gastrointestinal obstruction or perforation
    • Hypotension
    • Electrolyte abnormalities.
  • Electrolyte monitoring is required in animals receiving multiple doses of cathartics.
  • Mineral oil (liquid paraffin) is generally not recommended because of the risk of aspiration.

Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Chyka P A, Seger D, Krenzelok E P et al (2005) Position Paper: Single-Dose Activated Charcoal. Clinical Toxicology 43 (2), 61-87 PubMed.

Other sources of information

  • Peterson M E, Talcott P A (eds) (2013) Small Animal Toxicology, 3rd edition. St Louis, Missouri: Elsevier Saunders.
  • Osweiler G D, Hovda L R, Brutlag A G, Lee J A (eds) (2011) Blackwells Five Minute Veterinary Consult Clinical Companion Small Animal Toxicology. Ames Iowa: Blackwell Publishing Ltd.
  • Veterinary Poisons Information Service, Mary Sheridan House, 13 St Thomas Street, London SE1 9RY. Tel number 020 7188 0600 (admin); Fax number +44(0)207 294 7561; Email: info@vpisglobal.com; Website: www.vpisuk.co.uk