A snow leopard cub born at Highland Wildlife Park in the Cairngorms has had to be put to sleep.

The Royal Zoological Society of Scotland (RZSS) said the four-month-old male cub had contracted coloboma, a "very painful" condition that causes vision problems.

Although surgery can help alleviate the pain in some cases, the conservation park took the "incredibly difficult decision" to euthanise the cub as it was suffering due to the seriousness of its condition.

The litter's two female cubs also have the eye defect, but not to the same degree. Park staff will continue to monitor their health.

On Friday, a RZSS spokesperson said: "Our thoughts are with everyone who works with the cubs."

Snow leopards are classed as vulnerable, with threats including declining prey populations, protection of livestock and an increasing demand for their bones in traditional Asian medicine.

The species has an estimated wild population of 2700.