Water Hemlock Poisoning in Dogs

The water hemlock is most prolific in moist areas around springs, streams, ditches and meadows. The entire plant is toxic with the most concentrated part being the tuberous roots. Ingestion of any part of the plant is very dangerous and will result in symptoms like drooling, abdominal pain, and convulsions. There are many recorded instances of poisoning in humans and animals; livestock such as cows and sheep are particularly prone to poisoning due to the presence of the plant in grazing areas. Instances of water hemlock poisoning are well recorded in cows, with death being noted within 15 minutes to two hours after symptoms appear. If you suspect that your dog may have ingested any part of the water hemlock, it must be considered a medical emergency. If possible, carefully take a portion of the plant with you as you head to the nearest veterinary hospital.

Water hemlock is a highly poisonous plant found in many areas of North America. Ingestion of even a small amount can be lethal to humans and animals. Thought to be the most poisonous range plant on the continent, exposure to the plant means a guarded prognosis.

Do not wait for symptoms to appear before taking action. The time between symptom onset and severe poisoning can be as little as a few minutes. Prompt aggressive treatment involving supportive measures is needed to save the life of your pet.

• Cardiac dysfunction
• Panting
• Muscle twitching
• Tremors, convulsions, and seizures
• Excessive salivation and frothing of the mouth
• Nervousness and frenzy
• Eye abnormalities (rolling back of eyes and dilated pupils)
• Abdominal pain
• Vomiting
• Stiff limbs
• Twisting of head and neck
• Coma
• Death

Types

The water hemlock is of the Cicuta family. It is much more lethal than the poison hemlock, which has a similar name but an entirely different form of toxicity. The water hemlock is also known by the following names.

• Poison parsley
• Poison parsnip
• Spotted parsley
• Spotted cowbane
• Cowbane

• Water hemlock is considered to be the most poisonous plant in North America
• The toxins contained in the plant are cicutoxin and cicutol
• Ingestion of just a few leaves is deadly
• Drinking of water contaminated by the plant may cause poisoning
• The central nervous system is affected
• Asphyxiation and cardiac collapse are caused by the water hemlock

Ingestion of the poison hemlock must be considered a medical emergency. The clinical signs of water hemlock poisoning are very evident within minutes to two hours at most after ingestion. In cases where poison hemlock is suspected to be responsible for a canine’s symptoms, supportive treatment will be started before diagnostic steps are taken as this is necessary in order to reduce the risk of death.

Once your pet is stabilized, the veterinarian may do blood tests and a urinalysis to determine the effects of the poison on the heart, brain, organs, and respiratory system among others. Ingestion of the roots, leaves, stems, and green seed heads will all have an effect on the health of your pet, and diagnostic testing will enable the veterinary team to analyze your pet’s condition throughout the treatment based on the baseline markers provided upon the first testing.

Unfortunately many cases of water hemlock poisoning do not make it to the treatment phase because the action of the poison is so rapid. However, there have been recorded cases of survival. The effect on your dog may be determined by the season of the year; the water hemlock does lose a bit of its toxicity as it matures but can still be lethal in any season. The health condition of your dog, his age, the length of time between ingestion and treatment, and the amount consumed are all factors related to the toxicity.

Treatment is mainly supportive as there is no antidote to water hemlock poisoning. Because stabilization is so crucial to treatment, medications to control seizures and convulsions will be administered early as will sedative measures and oxygen therapy. In addition, the elimination of the toxins from the body through emesis, gastric lavage accompanied by active charcoal, and intravenous fluids will be essential for recovery.

The prognosis for water hemlock poisoning is guarded at best. If early aggressive treatment was possible, the recovery time may still be lengthy. With water hemlock poisoning, the effects on the systems and organs of the body can be devastating. If your pet survives the ordeal, the veterinarian will release him from the hospital once his vitals and bodily functions return to normal. Your canine companion will need a quiet place to rest away from other family pets. He must be monitored carefully and the expectations placed on him should be minimal. If you have concerns about the recovery, contact your veterinarian without delay or hesitation.

In the future, avoid the area where the water hemlock is found. It is always wise to watch your dog carefully when he is in an area where noxious weeds, wild flowers, and unfamiliar cultivated plants can be found. Park activities should be monitored as well, as many of the plants found in public places and meadowlands both can be toxic to canines. If your dog is the type that likes to eat greenery and flowers, be sure to verify the toxicity of plants within your own garden space as well.