Black Walnut Toxicosis

Black Walnut Toxicosis



Basic Information image



Definition




• Black walnut trees are large (50–100 feet) deciduous forest trees often planted as ornamentals.


• The demand for black walnut lumber has increased, and the wood shavings are sold for animal bedding. Shavings that contain even a small percentage of black walnut can cause laminitis when used as bedding for horses. Colic and respiratory distress have been reported in horses after they have chewed on black walnut bark.



Synonym(s)


Walnut family, including English walnut, butternuts, hickories, and pecans



Epidemiology



Species, Age, Sex


Foals and yearling horses are often unaffected or recover quickly.



Risk Factors




• Horses that are bedded on more than 5% to 20% walnut shavings may develop laminitis (Figures 1 and 2).


• Not all black walnut trees have naturally occurring toxicity.


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FIGURE 1 Pine and spruce wood shavings (right) and walnut wood shavings (left).


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FIGURE 2 Pine shavings contaminated with walnut wood shavings.



Geography and Seasonality


Black walnut (Juglans nigra) is a common hardwood species that ranges from the Great Plains to the east coast of North America. The species has been widely planted outside of its natural range and can be found all over North America. Laminitis may occur any time of the year, whenever walnut bedding is used.



Associated Conditions and Disorders


Consumption of the shavings or bark may cause laminitis as well as mild colic. Horses on pasture may show mild respiratory signs from chewing on bark, pollen, or fallen leaves.



Clinical Presentation



Disease Forms/Subtypes




• Laminitis


• Limb edema


• Respiratory distress


• Colic



History, Chief Complaint




• History of new bedding material introduced with dark-colored shavings.


• Horses (often several animals in a stable) with clinical signs of laminitis.


• Signs usually develop within 8 to 18 hours of contact.


• Affected horses become unwilling to move or have their feet picked up, are often depressed, and may have limb edema.



Physical Exam Findings




• Laminitis


• Edema of the legs (“stocking up”)


• Anorexia and depression


• Increased heart rate, respiratory rate, body temperature, and coronary band and hoof temperature


• Pounding digital pulse

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Jul 24, 2016 | Posted by in SMALL ANIMAL | Comments Off on Black Walnut Toxicosis

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