Introduction

• A number of plants Poisonous plants: overview contain toxins with clinical effects similar to those caused by nicotine.
• Clinical signs include rapid onset of CNS excitement, with subsequent weakness and paralysis.
• Pet poisonings as a result of exposure to these plants are extremely rare.
• Note that some nicotine-containing smoking cessation products also contain xylitol Xylitol toxicity.

Pathogenesis

Etiology

• Nicotine is a pyridine alkaloid present in produced byNicotianasp and is also found in tobacco products for human use, eg cigarettes, cigars, tobacco leaf, snuff, chewing tobacco, smoking cessation or nicotine replacement products (lozenges, gums, patches, inhalators, nasal sprays, electronic cigarettes), etc.
• Nicotine and/or related pyridine or piperidine alkaloids produced by other plants in the genusNicotiana.
• Coniine, a piperidine alkaloid with similar mechanism of action and clinical signs to nicotine, is produced byConiumsp, eg poison hemlock.
• Lobeline and/or lobelidine, pyridine alkaloids with similar mechanism of action and clinical signs to nicotine, are produced by plants of the genusLobelia.
• Piperidine alkaloids are also synthesized by members of the genusLupinus. The predominant toxic alkaloids inLupinusspecies are quinolizidine alkaloids, but some species also produce piperidine alkaloids.
• Cytisine, a quinolizidine alkaloid which causes similar clinical signs to nicotine, and quinolizidine alkaloids chemically related to cytisine, are produced by plants of the generaLupinus,Laburnum Laburnum anagyroides, Cytisus,GymnocladusandThermopsis.
• Nicotine is used as an insecticide on plants, and is approved for this use on organic produce. Dogs may be exposed to commercial insecticides containing nicotine, particularly if they have access to the gardens or crops of advocates of organic produce.

Predisposing factors

• Nicotine has low bioavailability as it is subject to first pass metabolism and poorly absorbed from the stomach. Chewing tobacco products and possibly plant material is more likely to cause toxicity.
• Tobacco and smoking cessation products, particularly electronic cigarettes, are readily available online and dogs may chew material delivered through the letter or mail box.
• Access to tobacco or smoking cessation products, or access to cultivated plants containing pyridine, piperidine or quinolizidine alkaloids causing the clinical signs characteristic of nicotine poisoning.
• A number of plants (Lobelia, Cardinal flower, Eye-bright) of the genusLobeliaare cultivated.
• A number of plants of the genusLupinus(lupins, lupines) are cultivated.
• Laburnum anagyroides Laburnum anagyroides (laburnum, golden chain) is grown as an ornamental tree, as isGymnocladus dioicus(Kentucky coffee tree).
• Coniumsp (poison hemlock) andCytisus(Scotch broom) are common weeds in numerous areas.

Specific

• A tendency to chew tobacco products or growing plants.

Pathophysiology

• Best characterized for nicotine, but the pathophysiology is similar for all these toxins.
• Nicotine mimics acetylcholine, and therefore stimulates acetylcholine receptors at sympathetic and parasympathetic ganglia, neuromuscular junctions, and some synapses in the central nervous system.
• Ganglia are initially stimulated, followed by a persistent ganglionic and neuromuscular blockade.
• Positive inotropic and chronotropic effects on the myocardium lead to an increase in cardiac output and blood pressure.
• Stimulation of the adrenal medulla results in catecholamine release.
• Death is a result of respiratory failure from neuromuscular blockade Anesthesia: non-depolarizing neuromuscular blockade.

Timecourse

• Generally a rapid onset and progression; death may occur within minutes or hours of ingestion of a lethal dose.

Diagnosis

Treatment

Prevention

Outcomes