Delphinium Poisoning in Dogs

There are more than 80 different types of delphinium in North America and all plants in the Ranunculaceae family contain diterpene alkaloids. Some of these plants can grow to over six feet tall and have blue flowers. These alkaloids in the plant prevent the nerves from traveling from the brain to the muscles, which causes weakness and even paralysis. This can also cause symptoms such as excessive salivation (drooling), heart rhythm irregularities, constipation, organ failure, and death.

The concentration of the alkaloids in the plant can vary greatly from the size to the age of the plant. Because of this, the symptoms can be varied as well, although any amount of diterpene alkaloids create a neuromuscular block that can be dangerous if not treated right away. If you think your dog may have eaten a delphinium, you should take your dog to the veterinarian or animal hospital immediately, even if there are no symptoms yet. Bring a part or a photo of the plant with you to show the veterinarian for easier diagnosis.

The delphinium, more commonly called larkspur, is a beautiful and tall flowering plant with toxic amounts of diterpene alkaloids that can cause serious neuromuscular effects in dogs, other animals, and even humans. In fact, just two milligrams of the plant is enough to kill an adult human. The amount of toxic chemicals change as the plant grows, losing some of its toxicity as it grows. However, if ingested, your dog may develop symptoms as mild as constipation or as serious as cardiac failure and death. The alkaloids in the delphinium are nerve blockers that block the receptors in the muscles, including the heart, which can be fatal if enough of the plant is consumed.

The symptoms will vary depending on the amount of delphinium your dog has consumed, but the effects are always due to the diterpene alkaloids found mainly in the shoots and the new leaves. The main symptoms of delphinium poisoning are neuromuscular blocks and can cause these side effects: 

• Abdominal pain
• Abnormal heart rhythms
• Bloating may occur
• Cardiac failure
• Cardiac or respiratory arrest
• Colic
• Constipation
• Death from respiratory paralysis
• Diarrhea
• Dehydration
• Anxiousness
• Dark urine
• Dry gums
• Lack of urination
• Licking lips
• Skin does not bounce back when pinched
• Drooling
• Excitement and physical exercise increase symptoms
• Gastroenteritis
• Heart and lung failure
• Increased salivation
• Labored breathing
• Minimal gross lesions (bloat and pulmonary congestion)
• Muscle tremors
• Muscular twitching
• Muscular weakness
• Nausea and vomiting may occur
• Nervousness
• Neuromuscular paralysis
• Rapid and irregular heartbeat
• Recumbency
• Respiratory failure
• Salivation
• Seizures
• Staggering gait
• Stiffness
• Sudden falling
• Tremors
• Weakness

• The cause of poisoning is the ingestion of diterpene alkaloids in any part of a delphinium plant
• These alkaloids in the plant prevent the nerves from traveling from the brain to the muscles
• Diterpene alkaloids that can cause serious neuromuscular effects in dogs, other animals, and even humans

Your dog will most often be obviously unhealthy after eating the delphinium plant, however and the veterinarian will go ahead with the physical examination. This will include your dog’s body weight, temperature, reflexes, heart rate, respiration, breath sounds, blood pressure, pulse oximetry (oxygen level in the blood), oral and optical examination. You will be expected to give the veterinarian all the information you can about your dog’s medical history, like vaccination records, strange behavior, unusual appetite, how often you let him out in the yard or take him to the dog park, illnesses, and recent injuries.

Your veterinarian will perform some laboratory tests that are essential to diagnosis by ruling out any underlying illnesses or injury. Some of these tests are urinalysis, complete blood count (CBC), blood gases, biochemistry profile, glucose test, blood urea nitrogen (BUN), liver enzymes, and a fecal examination. The veterinarian may also need to get some images of your dog’s abdomen by using digital radiographs (x-rays) and CT scans. If these are inconclusive and your veterinarian needs more details, an ultrasound and MRI will be performed.

Once the veterinarian rules out other illnesses or injury and is positive the cause is delphinium, he will start your dog on IV fluids and oxygen therapy. Fluids will be replenished and your dog will be admitted to the hospital and given the antidote, physostigmine, which is an inhibitor that helps stop the muscles from absorbing any more of the poison. The veterinarian may want to keep your dog overnight for observation in case he goes into respiratory arrest.

After you bring your dog home, the veterinarian will probably give you a diet plan to follow that includes foods low in fat and oil. This is important to follow and you should ask your veterinarian right away. He will expect you to keep your dog on cage rest for a few days to aid in recovery. Be sure to follow up with your veterinarian if you have any questions or concerns.