Browsing tag: blindness

Ask a Vet Online – ‘I have a border collie he has progressive retinal atrophy and now he has a cateract, is there anything that can be done for him?’

Question from Anne Wood

I have a border collie 5 years old. Hes a very frightened dog but he is completly blind in 1 eye and partly blind in the other the vet told me it was progressive retinal atrophy and now he has a cateract on top of his blind eye, is there anything that can be done for him please and thank you for taking the time to read this.

Answer from Shanika Online Vet

Hi Anne, thank you for your question regarding your dog’s eyes and behaviour.

So what is progressive retinal atrophy (PRA)?

As the name suggests it is a condition where there is gradual degeneration of the retina (layer lining the back of the eye). PRA is usually an inherited condition and sadly there is no cure for it, however on the positive side it rarely causes pain.  There is no treatment for PRA at present, there have been some trials of using antioxidants to slow down the degenerative process but the results of this are as of yet inconclusive.

Cataracts are a common finding along with PRA; a cataract is cloudiness in the lens of the eye. The loss of vision caused by the PRA itself means that cataract surgery is rarely advised as there will not be much improvement to vision as a result of the surgery.

How would I know that my dog has PRA and how is it diagnosed?

Owners usually notice a loss of vision in the pet, most noticeable in low light conditions, their pets pupils may appear more dilated with an increased glow/shine (tapetal reflex) from the back of the eye.

A diagnosis is usually made when your vet or ophthalmologist examines your dog’s eyes and notices the damage to the retina.

What can I do for my dog with PRA?

Sadly there is no treatment for PRA itself but as it is a painless condition then it is more a case of trying to help your dog to adjust to his gradual loss of vision. Generally the other senses smell, hearing, touch and taste increase to try and compensate for the one that is deteriorating.

You can take steps to make your home environment easier for your dog with poor or no vision to get around. Keep large pieces of furniture in the same place, use stair gates to block off dangerous areas, when out and about use lots of vocal and physical clues to let your dog know where you are and to provide reassurance.

Dogs are incredibly resilient animals and adjust very well to changes especially when they are gradual. I hope that this answer has helped you to understand a little bit about PRA and how both you and your dog can still lead a happy life together.

Shanika Winters MRCVS

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Why cats go blind.

Blind cat showing dilated pupils

Blind cat showing dilated pupils

One of the most common causes of sudden blindness in an elderly cat is due to high blood pressure (hypertension). The increased pressure pushes the light sensitive layer (retina) away from the back of the eye and this can happen literally overnight.

The affected cat will have very widely dilated pupils even in bright sunlight and there might be some blood visible when looking into the eyes. They will appear to be disorientated, bump into things and might vocalise excessively.

Monitoring a cat's blood pressure

Monitoring a cat's blood pressure

The usual cause of raised blood pressure in cats is an excess of thyroid hormone (hyperthyroid) but it can also be due to kidney disease or diabetes. This is why it’s important for the vet to take blood tests to decide which condition to treat.

We monitor cats’ blood pressure in a similar way to human doctors by inflating a cuff just above the paw on a front leg but we listen for blood flow with an ultrasonic probe rather than a stethoscope. Some cats are calmer if the cuff is placed around the tail base. A few readings are usually taken to make sure that the blood pressure has not been raised through stress.

blood pressure kit

Blood Pressure Monitor

Drugs are very successful in bringing a cat’s blood pressure down to normal but the blindness is usually permanent. Cats are extremely adaptable when it comes to finding their way around the house and finding their food but they are not safe to allow outside due to all the dangers out there.

There are a number of other causes of blindness but these generally come on more slowly:

Glaucoma is the same condition as people get where there is an increased pressure within the cat’s eye. This is usually seen as a very angry painful eye and the white of the eye appears red due to the many new blood vessels. Drops can control the condition if caught early enough but if it reaches the stage where the eye is visibly swollen or ulcerated, then removal of the eye (enucleation) will usually be suggested. Glaucoma can be found in just one eye or both.

Cataracts are much less common in cats than dogs and would be seen as a misty or pearly lens. Tests would be required to rule out diabetes which can be a cause.

Tumours within the cat’s eye are occasionally discovered when the eyes are examined with an ophthalmoscope. Loss of vision would be slow to develop in these cases and often in only one eye initially.

If you have a pedigree cat (particularly an Abyssinian) who starts to slowly lose vision early in life, there is a possibility of Progressive Retinal Atrophy (PRA) which is a genetic disease, very similar to the condition in some pedigree dogs. There is no treatment but the cat usually has time to adapt to the slow loss of vision.

Something we hardly ever see these days is Taurine (an amino acid) Deficiency. Modern complete diets have all the taurine a cat needs but it is just possible that a cat fed exclusively on tinned tuna could develop slow onset blindness due to this deficiency. If caught early enough, the loss of vision can be stopped or even reversed.

Most cats adapt very well to blindness and go on to enjoy a good quality of life. Some adapt so well that it would be hard for a casual observer to know they were blind.

If you are worried about any problems with your cat’s eyes, please contact your vet or use our interactive Cat Symptom Guide to help you decide what to do next.

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