A small section of collagen membrane was implanted in eight-year-old Gemma's eye, to fill the wound where a tumour had been removed.

The material acted as a framework around which the animal's own tissues could grow. As new cells and blood vessels grew across the area, the engineered membrane dissolved away.

The pig-derived material has been used before in dogs, to replace bladder and abdominal walls. But this is a first for eye surgery affecting the cornea, the eye's transparent "front window".

The operation is reported in the Journal of Small Animal Practice.

Initial diagnosis

Gill Williamson, the dog's owner said: "We initially noticed a dark mark in the corner of Gemma's eye and didn't think much of it.

The membrane material can be cut to shape

" We did, however, take her to the vet and were terribly upset by the initial diagnosis when we were told that the only option was for Gemma to have her eye removed.

"She was actually on the table, ready to have the eye out when our local vet suggested a second opinion."

Gill took Gemma to see Gary Lewin from the Caldew Vet Group in Carlise, England.

The veterinary ophthalmologist suggested the new treatment.

Tissue engineering

It is yet another example of how engineered tissues are starting to revolutionise surgical techniques in both human and animal medicine.

Indeed, the US Food and Drug Administration have approved this new pig-derived tissue for clinical evaluation in certain human operations.

It is made from the sub-muscosa of pig intestines. The purified product actually comes in sheets that the vet can cut to size. Developed in the US and sold under the trade name Vet Biosist, the membrane is also proving its potential as a treatment for traumatic injuries to the eye, such as those caused by cat scratches and bites.