Bighorns Captured and Treated for Pink Eye

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Arizona Game and Fish Department personnel captured and treated 22 desert bighorn sheep in the Ironwood Forest National Monument last week to protect the animals from a disease outbreak that can cause blindness if not treated.

Game and Fish Department biologists also plan to identify and treat any additional infected bighorns that are found during the next month or so.

Biologists say 13 of the captured bighorn sheep had the bacterial infection, which is often referred to as pink eye. Bighorns don’t necessarily die directly from the disease. Bighorns inhabit areas with steep cliffs, where blind animals can easily die falling. Blind bighorns are also easy prey for mountain lions.

The captured animals were given antibiotics to help them recover from the bacterial infection. Eighteen of the captured bighorns were fitted with radio telemetry collars so biologists can monitor them. The other four were fitted with ear tags.

The department, assisted by University of Arizona graduate students and the Desert Bighorn Sheep Society, will be conducting weekly helicopter flights to locate and treat other bighorns that might become infected. Wildlife officials say ASARCO, which operates the Silver Bell Mine, is also assisting by monitoring bighorns in the mine area.

Game and Fish Department wildlife experts say that based on what they saw during the capture operation, it appears the disease outbreak is concentrated around the main portion of the Silver Bell Mountains, which are located in the Ironwood Forest National Monument.

Jim deVos, a wildlife diseases expert with Arizona Game and Fish, says the bacterial infection in question, chlamydial conjunctivitis (kluh MID ee uhl kuhn juhnk tiv EYE tis), causes the animals’ corneas to turn white, thus blinding it. “The bacteria can be spread from flies landing on the eye of an infected animal and then landing on the eye of another animal. The spread of this disease can happen rapidly. It takes only a week or two for the blindness to set in,” says deVos.

This outbreak of pink eye occurred three weeks after approximately 4,800 domestic goats were brought onto state lands on a grazing lease by a private firm. While biologists cannot definitely link the goats to the disease outbreak in bighorns, deVos says the circumstances suggest a connection. "It is well known that domestic sheep readily transfer diseases to bighorn”, he says. “The goat-bighorn disease connection is not as well established, but goats can carry many diseases that have caused bighorn sheep die-offs.”

In conjunction with the capture and treatment effort, the Bureau of Land Management Tucson Field Office has organized the removal of domestic goats trespassing onto the Ironwood Forest National Monument.

Game and Fish biologists say the bighorn sheep population in the Silver Bell Mountains is biologically and historically significant because it is the last naturally occurring bighorn population in the central part of Arizona and dates back to the Pleistocene era. The Silver Bell Mountains are located approximately 30 miles northwest of Tucson.