Laurel Poisoning in Dogs

Laurels are a small genus of flowering shrub in the heather family with lanceolate leaves and clusters of white, pink, or purple flowers that resemble the blooms on the rhododendron plant. Laurel plants are known scientifically as the kalmia genus and all parts of these shrubs contain the potent neurotoxins called grayanotoxins. These toxins can disrupt the ability of the cells of the body to return to their normal state after excitation. Ingested grayanotoxins can interfere with normal skeletal and nerve functionality as well as hinder the action of the heart muscle. If your pet has eaten any part of a laurel shrub, contact your veterinarian immediately.

The flowering shrub laurel contains a powerful neurotoxin called grayanotoxin which can disturb the proper function of the body’s cell membranes. Laurel poisoning should be treated as an emergency.

Symptoms usually begin within just a few hours after ingestion. Just a few leaves from most varieties of laurel plant can instigate the following symptoms of poisoning:

• Abdominal pain
• Abnormal heart rate  
• Abnormal heart rhythms
• Coma
• Depression
• Diarrhea
• Excessive drooling
• Hypotension
• Lethargy
• Loss of appetite
• Low blood pressure
• Muscle weakness
• Perspiration
• Rapid, shallow breathing
• Seizures
• Temporary blindness
• Tremors        
• Vomiting
• Weakness

Types 

Kalmia latifolia - This variety goes by the names mountain laurel, calico-bush, and spoonwood. Due to its method of pollen dispersal, the kalmia latifolia flower is capable of throwing its pollen up to 15 centimeters away. 

Kalmia angustifolia - Also known as sheep laurel and lambkill, this shrub grows wild throughout the eastern portion of North America and produce bright pink clusters of flowers in the summer. 

Kalmia Carolina - This type of laurel is also referred to as the Carolina laurel and the Carolina wicky. It is found in the warmer southern regions and has pink blooms. 

Kalmia microphylla - The bog laurel is a short laurel, usually under eight inches tall and is found in boggy and wet environments throughout the western half of North America. 

Kalmia cuneata - An endangered variety of laurel known as white wicky, this shrub has attractive cream colored flowers with a red band.

The toxicity of the laurel lies in the neurotoxin that it contains, called grayanotoxin. The toxin is located in the leaves, petals and even pollen of the laurel plant. The grayanotoxin produced in the laurel plant has chemical properties that closely resemble turpentine, and this causes some burning in the mouth when it is chewed. Once inside the body this organic compound binds to the sodium channels in the host’s cell membranes, disrupting the natural electrical current present in the cells preventing them from returning to their normal state. This reaction leaves the cells in a permanently excited state.

If you see your pet consuming any part of the laurel shrub, identification is often sufficient information for a primary diagnosis of poisoning. A sample of the plant that your dog consumed will help to confirm the identity of the plant, and your veterinarian will likely  order a biochemistry profile, complete blood count, and urinalysis at this time, as well performing as a full physical examination. 

If the ingestion of the laurel plant was not witnessed, your veterinarian would take particular note of any opportunistic eating (such as dietary indiscretions like sampling garbage) that was suspected or observed, in addition to data regarding concurrent supplements or prescriptions that are being administered to your dog, in order to reveal toxins or drug interactions that may be at the root of the symptoms. Plant material found in the vomit or stools of the dog will assist in an accurate diagnosis as well. Supportive treatment will often start before a definitive diagnosis is made due to the severity of the symptoms.

Preliminary treatment will depend on the length of time since the flower was ingested and if any symptoms have already become apparent. In most cases of laurel poisoning, your dog will be admitted to the veterinary hospital for treatment right away. If the laurel plant was consumed recently and if no symptoms are showing as of yet, vomiting will be induced as soon as possible to prevent the absorption of the toxins into the bloodstream. Activated charcoal will also be will be dispensed to your dog in an attempt to soak up as much of the grayanotoxin as possible.

If the exposure was more than an hour or so before treatment, the attending veterinarian might choose to perform a gastric irrigation under general anesthetic to remove as much toxin from the patient’s digestive system as possible. Once the poison has been eliminated from the gastrointestinal system, supportive treatments will begin, including IV fluids to prevent dehydration and combinations of electrolytes and sugars to adjust for any imbalances. Respiratory support may be required, and atropine may also be needed if your canine’s heart rate drops below 40-50 beats per minute.

Recovery from mild laurel poisoning is usually within about 24 hours. Larger doses, extended time before diagnosis, or extreme reactions to the toxin may extend the recovery time. Plenty of fresh water should be available for the recovering patient, and extra bathroom breaks should be planned for as both the toxins and the medications make their way through your dog’s digestive system. 

Dogs that are recovering from anesthesia for gastric irrigation may have coordination difficulties when they first get home, and they are often confused and disoriented as well. Isolation from children and from other pets is generally advised until the medication has a chance to fully clear from your companion’s system. Your veterinarian may recommend more frequent monitoring of your pet’s blood chemistry levels in the future, particularly in relation to kidney and liver functionality or impairment.