Poisonous Plants And Chemicals

One of the by-products of modern living is widespread use of poison in a variety of forms for the control of undesirable animals and insects. Few of the ever increasing cases of canine poisoning can be traced to human viciousness; rather, the majority come from rodenticides, insecticides, drugs or other chemicals which are handled carelessly by home users or sprayed for crop protection. Your dog can be poisoned by walking over chemical fertilizers and licking his pads or sniffing roach powder or chewing boards covered with lead-base paint or gobbling up some old pills or toxic food while nosing through a garbage bin. Blowfish discarded by fishermen along the Florida and Gulf coastlines, can be deadly, as can some types of mushrooms and plants.

If you see your dog stagger blindly into a wall or begin writhing and groaning in agony, if he looks aimless or in a near state of collapse, or he is vomiting or in convulsions, you had better consider the possibility of poisoning and act quickly. Check around for any poison container he might have gotten into: It will list the proper antidote and emergency treatment. There are so many different types of poison, some eat through the stomach and intestinal walls; others are absorbed into the system and affect the nerves; still others thin the blood or cause internal bleeding. Treatment for each is different, which makes is vitally important to find what type the dog consumed. Call your veterinarian and take the dog and container to him at once.

Universal Antidote

If you know your dog has been poisoned and have no idea of the type, the universal antidote is:

  • Pulverized charcoal - 2 parts
  • Magnesium oxide - 1 part
  • Tannic acid - 1 part

A heaping teaspoon of the above mixed in a glass of warm water is given, followed by mineral oil or other mild laxatives to keep the bowels open for several days.

In the treatment of poisons, prompt action is necessary. However, it is often impossible for the layman to diagnose the situation, which is why veterinary help must be sought quickly.

Plants Poisonous for Dogs


  • Castor Bean
  • Daffodil
  • Dieffenbachia (Dumb Cane)
  • Elephant Ear
  • Hyacinth
  • Narcissus
  • Rosary Pea
  • Autumn Crocus
  • Bleeding Heart
  • Foxglove
  • Iris
  • Larkspur
  • Lily-of-the-Valley
  • Monkshood
  • Star of Bethlehem


  • Rhubarb
  • Allium spp. (chives, garlic, onion)


>Water Hemlock


  • Buttercups
  • Jimson Weed (Thorn Apple)
  • Nightshade
  • Poison Hemlock
  • Black Locust
  • Elderberry
  • Oak trees
  • Wild and cultivated cherries


  • Jack-in-the-Pulpit
  • Mayapple
  • Mistletoe
  • Moonseed
  • Azaleas
  • Daphne
  • Golden Chain
  • Jasmine
  • Lantana Camara (Red Sage)
  • Laurels
  • Rhododendrons
  • Wisteria
  • Yew


Allium species which include wild and domesticated chives, onions, and garlic, contain n-propyl disulfide and other sulfur containing compounds that can interfere with glucose-6-phosphate dehydrogenase enzyme in red blood cells leading to oxydative damage. Oxidized hemoglobin precipitates to form Heinz bodies, which are subsequently removed from the spleen. This can result in anemia. Cats are the most sensitive domestic animal species to hemoglobin oxidation 3.

Rodenticide Poisoning

The common types of rodenticides (rodent control agents) include anticoagulant compounds such as cholecalciferol, bromethalin, strychnine, and zinc phosphide. The less common types include pyriminil, Red squill, thallium, arsenic, phosphorus, a-naphthyl-thiourea (ANTU), norbromide, barium, and sodium monofluoracetate (compound 1080). These substances interfere with normal blood clotting and cause uncontrolled bleeding in rats and mice which leads to death.

The anticoagulant rodenticide inhibits vitamin K 2,3-epoxide reductase enzyme and vitamin K quinone reductase enzyme in the liver, preventing the reduction of inactive vitamin K (vitamin K quinone). The result is the prevention of carboxylation of the calcium binding sites on clotting factors II, VII, IX, and X. The interference with vitamin K 2,3-epoxide reductase hinders the "recycling" of active vitamin K quinone and the decreases the vitamin K-dependent clotting factors II, VII, IX, and X which results in uncontrolled bleeding.

Clinical signs of rodenticide poisoning in dogs may not be seen for as long as 1 to 2 days after ingestion. These signs may include difficult and/or rapid breathing; spitting or coughing blood; bleeding from the nose and/or under skin; abdominal swelling, fever, lethargy, and lameness. On occasion, the onset of these signs is so quick as to find a dog dead. The sudden death may be caused by sudden catastrophic bleeding into the heart, lungs, abdomen, or brain.

Antifreeze Poisoning

Animals that have ingested antifreeze (propylene glycol) should be seen immediately by a veterinarian. Dogs that are not treated within hours of ingestion, die from kidney failure. Do not wait to see if signs develop and do not attempt to treat this at home 2.


  1. Wayne E. Wingfield, Marc R. Raffe. The veterinary ICU book
  2. Cody W. Faerber, Cody W. Faerber, DVM,S. Mario Durrant, DVM,Jane Fishman Leon, DVM, S. Mario Durrant. Canine Medicine and Disease Prevention
  3. Andreas Luch. Molecular, Clinical and Environmental Toxicology: Clinical Toxicology
  4. Poisonous Plants affecting Dogs

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