Yes, all plants in the Delphinium genus, commonly known as Larkspur, are highly poisonous to dogs, cats, and horses. The entire plant contains toxic diterpenoid alkaloids, with the highest concentrations found in the new growth (young leaves) and the seeds. The primary toxins are methyllycaconitine (MLA) and delphinine, which are potent neurotoxins. These compounds function similarly to the toxins found in the closely related Aconitum (Monkshood) genus. They interfere with the normal function of the nervous system by blocking neurotransmitter receptors.
The alkaloids in Delphinium plants act as neuromuscular blockers. Upon ingestion, they bind to nicotinic acetylcholine receptors in the body, preventing the nervous system from sending signals to the muscles. This disruption leads to severe neurological and neuromuscular symptoms. The onset of symptoms is typically rapid, often occurring within just one to two hours after ingestion. Key symptoms to watch for in a pet include intense drooling (ptyalism), burning sensation in the mouth leading to pawing at the mouth, vomiting, diarrhea, weakness, and an unsteady gait (ataxia). In severe cases, the neuromuscular blockade can progress to paralysis, particularly of the muscles involved in respiration, which can be fatal due to asphyxiation.
The degree of poisoning is directly related to the amount of plant material ingested relative to the animal's body weight. This means that a small dog or cat is at a much greater risk of severe poisoning from consuming a small amount of the plant compared to a larger animal. However, due to the high potency of the alkaloids, even a small nibble can cause significant clinical signs in any pet. The seeds represent the greatest concentration of the toxin, making them the most dangerous part of the plant. It is crucial to note that all cultivated varieties (cultivars) and wild species of Delphinium possess these toxic compounds, so no variety is considered safe for pets.
If you suspect your pet has ingested any part of a Delphinium plant, it is a medical emergency. You should contact your veterinarian or an animal poison control center immediately. Do not wait for symptoms to appear. If possible, try to identify the plant and estimate how much was consumed. If the ingestion was very recent, a veterinarian may induce vomiting to prevent further absorption of the toxins, but this should only be done under professional guidance. Treatment is primarily supportive and may include administering activated charcoal to bind any remaining toxins in the gastrointestinal tract, intravenous fluids to support kidney function and prevent dehydration, and monitoring of vital signs. In cases with severe neuromuscular effects, respiratory support may be necessary.
The most effective way to protect pets is to prevent exposure entirely. If you have dogs or cats that spend time in your garden, it is safest to avoid planting Delphiniums. Consider replacing them with non-toxic alternatives such as Snapdragons (Antirrhinum), Roses, or Petunias. If you choose to keep Delphiniums in your garden, they must be placed in an area completely inaccessible to your pets, such as behind a secure fence. Consistently deadhead (remove) spent flower spikes before they can form seeds, the most toxic part, and promptly clean up any fallen leaves or petals to reduce the risk of accidental ingestion.
