canis - Articles
Plant poisoning: cyanide
Introduction
- A number of plants accumulate cyanogenic glycosides. These include:
- Pitted fruits such as peaches, cherries and almonds.
- Pome fruits such as apples and pears.
- Elderberry.
- Legumes such as clover and vetch.
- A variety of grasses.
- Of these, those of greatest risk to dogs would most likely be the pits or seeds of pitted or pome fruits, which dogs might eat out of curiosity. Rapid ingestion of a toxic dose is required to overcome detoxification processes.
- Cyanide poisoning may also result from ingestion of cyanide baits laid to kill pests. Poisoning with these baits may be accidental or malicious.
- Hydrogen cyanide can be released from certain synthetic materials during a house fire, but a dog that is distressed or comatose after it has been exposed to the smoke from a house fire should be treated with oxygen for carbon monoxide poisoning because this is more likely Smoke inhalation.
- Generally there is not time to treat for both poisonings and the treatment for hydrogen cyanide poisoning may counteract the efficacy of treatment for CO poisoning.
- Cyanide poisoning in pets is extremely uncommon.
Presenting signs
- Hyperpnea, convulsions and coma.
- Cherry-red blood and mucous membranes (may not be readily apparent).
Acute presentation
- Peracute onset with excitement, and tremors which may rapidly progress to convulsions.
Geographic incidence
- Poisoning from fruit pits or almonds could occur anywhere that the plants are grown or the fruit or nuts are purchased.
- Cyanide baits are used in New Zealand to kill Australian brushtail possums, and in the USA to poison coyotes.
Public health considerations
- People should be aware that apricot pits and peach pits can be toxic.
- Human toxicity and fatality has occurred from rapid ingestion of a large quantity of apple seeds and apricot seeds.
- Baits for pests should be placed where children cannot access them, and warning signs should be posted that cyanide baits are in the area.
Special risks
- If the dog has cyanide bait around the mouth, exercise extreme care to avoid exposure.
Pathogenesis
Etiology
- Cyanogenic glycosides or cyanide baits.
Pathophysiology
- Cyanide combines with iron in cytochrome oxidase, preventing terminal electron transfer and blocking cellular respiration. Oxyhemoglobin cannot release oxygen. Although the blood is highly oxygenated and therefore a characteristic bright red, oxygen delivery to the tissues is poor and the pet becomes severely hypoxic.
- Convulsions and death are due to cerebral hypoxia.
Timecourse
- Peracute to acute, typically less than 30-60 minutes.
Diagnosis
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Treatment
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Prevention
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Outcomes
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Further Reading
Publications
Refereed papers
-
Recent references from PubMed and VetMedResource.
Other sources of information
- Plumlee Konnie H (editor) (2004) Clinical Veterinary Toxicology. Mosby.
- Osweiler Gary D (1996) Toxicology. Williams and Wilkins.
Organisation(s)
- ASPCA Animal Poison Control Center: www.aspca.org/pet-care/animal-poison-control, telephone (888) 426-4435.
- Veterinary Poisons Information Service (VPIS); www.vpisglobal.com, telephone + 44 (0) 2073 055 055.