Common toxic winter plants

 Most horse owners are always on the lookout for potentially toxic plants in our pastures and around the barn and luckily MOST of the time our animals steer clear of anything dangerous.  However, in the winter when there is much less green to choose from, animals are much more likely to give a toxic plant a try.  Here are a few common plants that stay green through the fall and winter that can pose a hazard to your animals:

Azalea-These beautiful, native flowering bushes are a common fixture in North Carolina landscapes.  They are also unfortunately highly toxic to all species and stay green through the fall and winter.  This plant also seems to be palatable to animals and is sometimes sought out.  The leaves and the nectar of an azalea contain toxins called grayanotoxins and are cardiac glycosides. The toxins will obstruct the natural rhythm of the heart. This can cause arrhythmias and possible cardiac arrest.  Symptoms to watch for in azalea poisoning in horses includes:

• ·         Excessive salivation that is usually frothy and green
• ·         Slow or erratic heart rate
• ·         Loss of appetite
• ·         Cardiac arrhythmias 
• ·         Muscle weakness
• ·         Colic
• ·         Gastrointestinal disturbances
• ·         Diarrhea
• ·         Acute colitis
• ·         Tremors
• ·         Seizures 
• ·         Death

Yellow Jessamine- This flowering vine is also a native of North Carolina and is sometimes used in landscaping.  It can easily be found in the winter woods, as it is oftentimes the only thing that is green aside from evergreens.  The toxin found within the Carolina jessamine can lead to neurotoxicity in your horse.  This plant contains multiple alkaloids and is what causes the paralysis.  The most abundant alkaloids found in this plant include gelseminine, gelsemine, gelsevirine, gelsemoidine, gelsemicine, gelsenicine, and koumidine.  These toxins can be found in all parts of the plant but can be found in higher concentrations in the roots.  The alkaloids build up in the system and have a cumulative effect on the nervous system.  Scientists believe the alkaloid gelsemine, most commonly found in the flower and interfere with nerve transmission. Symptoms may include:

• ·         Ataxia 
• ·         Weakness 
• ·         Incoordination
• ·         Dilated pupils
• ·         Decreased body temperature
• ·         Weak pulse 
• ·         Muscle convulsions
• ·         Respiratory distress
• ·         Respiratory paralysis

Mistletoe-European mistletoe (Viscum album) as well as American mistletoe (Phoradendron serotinum) are both evergreen parasitic perennials with white or translucent berries that grow on the trunks and branches of deciduous trees. They are common holiday symbols sold frequently during the winter holiday season.  Symptoms of mistletoe poisoning include:

• ·         Colic
• ·         Behavioral Changes
• ·         Diarrhea
• ·         Low Blood Pressure
• ·         Convulsions

Red Maple- The red maple is another NC native and is very commonly used in landscapes due to its beautiful fall colors.   Fresh red maple leaves are not a concern and although this tree does lose its leaves every year, it is a health concern, specifically in the fall and early winter.  Leaves that are wilted either from a heavy frost or downed limbs due to a storm or pruning have toxic properties and become increasingly palatable.  The toxin in red maple leaves has never been identified, but after eating red maple leaves, horses develop severe anemia that results in pale to yellow mucous membranes and dark brown to red urine due to the hemoglobin being released when the horse's red blood cells are destroyed.  Other symptoms include:

• ·         Increased respiratory rate
• ·         Lethargy
• ·         Weakness
• ·         Depression

Yew- Although this plant is not native to NC it is commonly found in NC landscapes because of its unique look and evergreen properties.  Yew species contain a number of toxic alkaloids, the most toxic of which are taxine A and B. They are collectively referred to as "taxine" and mainly affect the heart. Horses are commonly poisoned by eating yews when they wander into an area around a house or barn that has yews planted in the landscaping. Livestock are accidentally poisoned when yew trimmings, or wreaths made of yew, are thrown onto manure piles or over a fence, where they are easily accessible to horses, cattle, sheep and/or goats.  Symptoms of yew poisoning include:

• ·         Death
• ·         Muscle trembling
• ·         Incoordination
• ·         Nervousness
• ·         Difficulty breathing
• ·         Slow heart rate
• ·         Vomiting
• ·         Diarrhea
• ·         Convulsions

If you suspect your horse has consumed any of these plants or any other potentially toxic species, contact your vet IMMEDIATELY. 

If you think you may have these or any other potentially toxic plants on your property but would like help identifying them contact your local extension agent.

References:

https://wagwalking.com/horse/condition/azalea-poisoning-

https://wagwalking.com/horse/condition/carolina-jessamine-poisoning

http://www.horsedvm.com/poisonous/mistletoe/

https://aaep.org/horsehealth/red-maple-poisoning

http://www.omafra.gov.on.ca/english/livestock/horses/facts/07-055.htm