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Coffee husks should not be used as bedding for horses, because of the risk of poisoning, researchers warn.

In Brazil, coffee husks are abundant as a by-product of the coffee industry. The husks are often recycled for use as animal bedding.

Now research carried out by Diego José Delfiol and colleagues has found that coffee husks pose a risk of poisoning when used as bedding or as feed for horses.

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Written by Mark Andrews Published online 24.01.12

The work, carried out at the of Veterinary Medicine and Animal Science - Univ Estadual Paulista (UNESP), Botucatu, São Paulo, Brazil, was prompted by reports that horses had become intoxicated after eating coffee husks used as bedding.

Six clinically-normal quarter horse mares were recruited to the study. They were observed continually, and examined clinically every 12 hours. They were kept in individual stalls and fed a diet of free access hay. Each horse was offered 2kg coffee husks. Every 12 hours any remaining husks were taken away and weighed and fresh husks were given. This continued until the horses started to show signs of toxicity, at which stage no further husks were given.

The researchers noted that the horses were not very interested in eating coffee husks during the first hours after they were supplied. However, after ingesting the husks for the first time, the animals generally preferred them to hay.

The study, published in BMC Veterinary Research, lists the most evident toxic signs as excitability, restlessness, involuntary muscle tremors, chewing movements and constant tremors of the lips and tongue, excessive sweating and increased respiration and heart rates.

The authors report that, on average, toxic signs appeared 56 hours after exposure to the coffee husks. However, heart rates and respiratory rates rose 36 hours after access to husks, and only returned to normal 60 hours after removal of the husks.

All six horses showed signs of toxicity. The signs resolved once the coffee husks were removed, taking between 12-40 hours to wear off. No treatment was necessary.

The researchers excluded other possible causes of toxicity by checking there were no insecticides or fungal toxins in the husks. Analysis of samples of coffee husk found the concentration of caffeine concentration to be 0.9%.

They compared blood and urine taken from the horses before,and 56 hours after, exposure to the husks. They found significant differences between the before and after samples in the concentrations of caffeine in both urine and blood. to the pre-exposure caffeine levels, those found 56 hours later, when clinical signs appeared, were, on average, 3,966 times greater in the plasma and 1,300 times greater in the urine.

The researchers conclude that the high concentration of caffeine in the coffee husks make them toxic to horses. They warn that coffee husks should not be used as food or bedding material for horses

For more details see:

Equine poisoning by coffee husk (Coffea arabica L.)
Diego José Z Delfiol, JP Oliveira-Filho, FL Casalecchi, T Kievitsbosch, C Alberto Hussni, F Riet-Correa, JP Araujo Jr and AS Borges

BMC Veterinary Research 2012, 8:4

doi:10.1186/1746-6148-8-4