Samantha Taylor, FAB Resident at Bristol University, reports on another of the cases she sees on referral - this time the shock of blindness to a seemingly healthy cat

MOSSCHOPS, a neutered male Persian cross, had been a healthy cat, apart from the odd episode of cystitis during his 10 years. So when his owners noticed he had lost a little weight and wasn't quite himself they wondered if his bladder was uncomfortable. A check up at the vets didn't reveal anything worrying, so it came as quite a shock when they returned home one day to find Mosschops distressed and bumping into things. He was rushed to the vets who identified that he was completely blind, although they could see no obvious damage to his eyes.  Mosschops was referred to a veterinary ophthalmologist who confirmed that Mosschops could not see anything at all and his pupils did not respond to light. Examination of the back of Mosschops' eyes showed that his optic discs(the collection of nerves that carry the visual information to the brain) were swollen. This appearance is consistent with a condition called optic neuritis which can have many underlying causes. Mosschops was referred to us at The Feline Centre at Bristol University for further investigation.

When Mosschops, pictured, arrived at The Feline Centre he was disorientated and confused. He bumped into objects in the consultation room, his pupils were dilated and did not respond to light. He was also quite thin. He resented having his head touched and seemed quiet and withdrawn. Routine blood and urine tests showed no abnormalities and Mosschops' blood pressure was normal. Tests for infectious diseases were negative. As Mosschops was an older cat we were concerned that he could have an abnormality such as a tumour in his brain causing optic neuritis. An MRI scan of his brain showed that all was normal. We took a sample of fluid from around his brain and laboratory tests showed again that there was nothing abnormal. We treated Mosschops with pain killers as he showed signs of a severe headache. He was also treated with medication to reduce the inflammation in the optic discs. For the next week, Mosschops stayed with us and he showed signs of feeling more comfortable — his appetite even returned. He was sent home and two weeks later Mosschops returned to the hospital. Although his optic discs were a lot less swollen and he was allowing his owners to stroke him and touch his head, unfortunately he remained blind. He had gained weight which was a good sign.

Mosschops' retina showing cupping of the optic disc which is now non-functional

After one month of treatment, despite the hope that his sight might return, he remained totally blind. However, he had gained 0.5 kg in weight and was a bright and happy cat. His owners reported he was behaving normally and had learnt where everything was in the house and they were careful not to move the furniture or his food bowl. They were even taking Mosschops outside on a harness so he could get some fresh air and a walk around the garden. Examination of his optic discs revealed that there was no longer any swelling but the discs were small. It looked as though the inflammation had resolved but this had left little functioning tissue behind. The medication was reduced and withdrawn over the next month. We never found out what had triggered Mosschops' optic neuritis but were happy that he was no longer in pain and was adjusting to his vision loss. Two months after Mosschops' visit to The Feline Centre he was back to his normal weight and a happy, contented cat. He still can't see but is enjoying his life, his walks around the garden and is back to his old self again!

Adjusting to loss of sight
Cats are very good at adjusting to slow progressive loss of sight and owners may not notice any change in their cat's behaviour, apart from lethargy and perhaps reduced food intake. They compensate by using their other senses of hearing, smell and touch (using whiskers to prevent bumping into objects). However, sudden loss of sight is obviously distressing for a cat. They may bump into objects in the house or garden or appear withdrawn and where they feel safe.

Caring for a blind cat has challenges. Affected cats will adjust well but certain changes will make their lives a lot happier. Furniture should be kept in the same position and resources (food, water, litter trays) made easily accessible. Care should be taken to avoid noisy approaches and any children should be told to move slowly, quietly and be careful not to frighten the cat who cannot see them coming. Blind cats may be able to go outside, but only into an enclosed garden as they may otherwise lose their way or be vulnerable to attack by other cats or dogs.

July 2009