Poisonous Plants
Common Poisonings in Small Animals
Barry Blakley, DVM, PhD
Western College of Veterinary Medicine
Introduction
Poisonings are often observed in small animals. In a typical clinical environment, approximately 4% of all cases involve poisonings. Poisonings may be accidental or malicious in nature. Frequently forensic or criminal investigation is required. It is important to identify both the cause of the poisoning and the source to successfully treat the animal and to prevent future poisonings. Based upon metabolic, biochemical or exposure differences, the types of poisonings seen in animal species are highly variable. Animals are dependent upon man. Husbandry conditions or exposure circumstances influence to some degree the types of toxicoses encountered. Animal behaviour may also influence the occurrence of poisonings. For example, cats tend to be very picky eaters whereas dogs are less particular. A food source containing strychnine may have a slightly bitter taste. Cats may detect the taste and refuse to eat the material whereas the dog gulps down the food and develops clinical manifestations. Consequently, most cases of strychnine poisoning are seen in dogs.
Animal poisonings are often true emergencies. Prompt medical intervention is critical. In many instances, treatment must begin prior to a thorough clinical examination in order to save the animals life. This initial treatment is strictly symptomatic in nature.
The treatment may be refined based upon the response or new clinical data. In many instances, the following treatments should be considered:
- activated charcoal orally
- emetics
- fluids intravenously
- wash the animal (dermal exposure)
- sedation
- oxygen
The selection of treatment options should be based upon the systems affected. In many instances the response to a specific medication provides useful insight. For example, a dog poisoned with an organophosphate insecticide should be given atropine. The response is virtually instantaneous. Administer with caution, an overdose of atropine may also be fatal.
Epidemiology of Small Animal Poisonings
A wide variety of animal poisonings can potentially occur. In Saskatchewan, a limited number of agents account for most of the reported cases.
- strychnine – 90%
- organophosphate/carbamate insecticides – 5%
- anticoagulant rodenticides – 1-2%
- Ethylene glycol - 1-2 %
- Other - 1-2 %
Strychnine and the various insecticides are extremely toxic and require immediate intervention. Many of the other agents, by the nature of their action or the relative potency are self limiting or require high or repeated doses to be fatal.
It is not possible to cover all agents and probable circumstances in great depth. The following list is an abbreviated summary.
Strychnine
Seen at all times of the year
| Symptoms | - extensor rigidity - death by suffocation |
| Treatment | - sedation - emetic in some instances |
Organphosphate / Carbamate Insecticides
Seen primarily in spring and summer
| Symptoms | - salivation - tremors - dyspnea |
| Treatment | - atropine - activated charcoal |
Anticoagulant Rodenticides (Warfarin, bromodiolone)
Many products in this group
Seen in the spring and summer
| Symptoms | - bleeding - shock |
| Treatment | - Vitamin K1 (Not Vitamin K3) - blood transfusion - fluids |
Ethylene Glycol
Seen primarily in the fall
| Symptoms | - depression (alcohol poisoning) - metabolic acidosis - renal failure |
| Treatment | - 4 – methylpyrazole (first 24 hours) - no effective treatment if renal failure present |
Household Products
Most soaps, disinfectants, etc cause irritation. The poisoning is self limiting if exposure stops.
Bleach
Seen throughout the year
| Symptoms | - salivation - vomiting, pain - dyspnea |
| Treatment | - antacids - prognosis poor |
Oils
aspiration pneumonia
difficult to treat
Plants
There are many plants that have the potential to cause poisonings. In most cases the syndrome is self limiting. The plant is irritating and the animal does not eat sufficient quantities to cause severe poisoning. Oxalate crystals are a common example of the irritation effects. Many plants have a distinct seasonal occurrence, often associated with Christmas or Easter. In many instances, the severity and frequency of poisoning with these plants is grossly overrated by the media. Many plants produce GIT upset and neurology disturbance. Without a detailed history, it is difficult to determine which plant is responsible.
Mistletoe
| Toxic principle | - a glycoprotein |
| Symptoms | - GIT upset, vomiting - hypotension - depression - seizures - self limiting |
| Treatment | - activated charcoal - fluids |
Poinsettia
Over rated as a problem, mildly toxic
| Toxic principle | - diterpene ester |
| Symptoms | - vomiting, diarrhea - salivation |
Dieffenbachia
| Toxic agent | - oxalate crystals - irritation |
| Symptoms | - salivation - vomiting, diarrhea - dyspnea |
| Treatment | - antihistamines - oral calcium |
Philodendron
Same as above
Lilies
Many different kinds. Some are highly toxic whereas others are relatively non-toxic. Treat as an emergency until proven to the contrary.
Lily-of-the valley
| Toxic principle | - cardiac glycoside |
| Symptoms | - vomiting - diarrhea - weakness, depression - elevated heart rate, heart block, arrhythmias |
| Treatment | - activated charcoal - digibind |
Easter Lily (cats very sensitive)
| Toxin unknown | |
| Symptoms | - vomiting - polyuria (renal damage) - weakness |
| Treatment | - activated charcoal - fluids and diuresis - prognosis fair |
Other Agents
| a. Mycotoxins | - source – composte - tremors - sedation - prognosis – good |
| b. Xylitol | - sugar free gum - weakness, ataxia, seizures - treatment – dextrose |
|
c. Drugs |
1. acetaminophen 2. NSIADS - GIT disturbance 3. Ivermectin |
| d. Grapes / Raisins |
- ingestion of large quantities |
|
e. Herbicides |
There are many chemicals in this group. Most are relatively non-toxic. Gastrointestinal disturbance is primary manifestation. Treatment is symptomic with a good prognosis.
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