Larkspur Poisoning in Dogs

There are more than 80 different types of larkspur 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 flowers in various hues. The alkaloids in the larkspur prevent your dog’s nerves from traveling to the muscles from the brain, producing weakness and paralysis. Alkaloids can also cause side effects like constipation, heart rhythm abnormalities, organ damage, drooling, and even death. The concentration of the alkaloids in the plant varies 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 can create a neuromuscular block that is dangerous if not treated right away. If you think your dog consumed any part or amount of larkspur, you should take your dog to the veterinarian or animal hospital immediately, even if there are no visible signs.

The 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 humans. In fact, just two milligrams of the plant are enough to kill an adult. The amount of toxic chemicals changes as the plant matures, losing some of its toxins as it grows. However, if eaten, your dog may develop mild symptoms like constipation or some as serious as cardiac failure and death. The alkaloids in the larkspur 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 throughout the plant, but is most prevalent in the new plants. Signs of larkspur poisoning are varied, but all are caused by diterpenoid alkaloids, which produce cardiac and neuromuscular dysfunction. The most common symptoms reported are:

• 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 twitching and weakness
• 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

 Types

The larkspur (delphinium) comes in over 300 varieties, which are all toxic to animals and humans. A few are listed here:

• Delphinium alabamicum: Alabama larkspur
• Delphinium alpestre: Colorado larkspur
• Delphinium californicum: California larkspur
• Delphinium carolinianum: Carolina larkspur
• Delphinium chamissonis: Chamisso's larkspur
• Delphinium glareosum: Olympic larkspur
• Delphinium glaucum: Sierra larkspur
• Delphinium grandiflorum: Siberian larkspur
• Delphinium gypsophilum: Pinoche Creek larkspur
• Delphinium hansenii: Eldorado larkspur
• Delphinium hutchinsoniae: Monterey larkspur
• Delphinium madrense: Sierra Madre larkspur
• Delphinium novomexicanum: White Mountain larkspur
• Delphinium parryi: San Bernardino larkspur
• Delphinium purpusii: Kern County larkspur
• Delphinium recurvatum: Byron larkspur
• Delphinium scopulorum: Rocky Mountain larkspur
• Delphinium sutherlandii: Sutherland's larkspur
• Delphinium trolliifolium: Columbian larkspur
• Delphinium wootonii: Organ Mountain larkspur

Larkspur poisoning is caused by the diterpene alkaloids in the plant, which affects the cardiac, digestive, and neuromuscular systems. Ingestion of the plant affects the brain, heart, organs, and bodily systems. The effects that will be caused depend on the concentration of the toxins and the amount consumed by your pet.

Bring a portion of the plant your dog ate to show the veterinarian if you can to help with diagnosis. The veterinarian will examine your dog’s overall health and then check body temperature, weight, reflexes, respirations, blood pressure, oxygen level, heart rate, coat, and skin condition. Tell the veterinarian as much as you can about your dog, including health conditions, injuries, behavior changes, vaccination record, and any symptoms you have seen, if any.

Some tests will be performed to verify larkspur poisoning and rule out other illness or disease. These tests will include glucose test, biochemistry profile, blood gases, complete blood count (CBC), blood urea nitrogen (BUN), urinalysis, fecal examination, and liver enzymes. The veterinarian may also need to get some abdominal x-rays. If these are inconclusive and your veterinarian needs more details, an MRI, CT scan, or ultrasound may be performed.

Once the veterinarian rules out other illnesses or injury and is positive the cause is larkspur poisoning, they will start intravenous (IV) fluids and oxygen therapy. In many cases, the veterinarian can give physostigmine, which is a well-known antidote for larkspur poisoning commonly used on people. This medication is an inhibitor that can control the absorption of toxins that may still be in your dog’s body. absorbing any more of the poison. The veterinarian will likely keep your dog overnight for observation and to administer supportive measures if necessary.

Once they let your dog go home, you should continue with all medications, care, and diet instructions. You will be expected to bring your dog back within a week or two for follow-up blood tests. Call your veterinarian if you have any concerns about the rate of recovery of your pet.