NORFOLK, Va. (WVEC) -- Diallo, the 5-year-old watusi at the Virginia Zoo who had a heavy horn was euthanized this week.

In August, Diallo was overproducing mucus in one of his horns causing a weight difference between his two horns. At the time of the diagnosis, he didn't have any pain.

The Zoo's veterinarians made several attempts to treat Diallo's condition, but were ultimately unsuccessful.

He was given Mucinex® daily to help with the mucus breakdown, and weights were applied to the unaffected horn to help counteract the weight on the affected horn, but this was unsuccessful.

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The veterinarian staff also contacted other institutions that have experienced this same issue with their cattle. Unfortunately, no permanent solution was found.

His Keepers noticed him rubbing the bottom of his horn on surfaces around his exhibit causing damage to his horn. At this point, Diallo's welfare was in question and the decision was made to euthanize him.

There is still one watusi at the Virginia Zoo, Gamba, who has shown no signs of a heavy horn.

The Zoo is exploring the possibility of getting more watusi in the future.