Moose was a pretty sorry sight when he ambled through the waiting room door with his owner Mr Brown. His left eye was held tightly closed and a watery discharge matted the whole of the left side of his face. When he tried to open it to greet Sharon the receptionist, who was usually a very reliable source of treats, the swelling and redness was clear for all to see. Mr Brown was at a loss to explain quite what had happened.
A couple of days ago, Moose had returned from his usual walk with a slightly weepy eye. But Mr B didn’t think much of it. The next day, the eye was a bit sticky, but again, assuming it was just a touch of conjunctivitis, or a reaction to the ever-increasing amount of building dust in the house from the never-ending extension, he bathed it with some cool water and let Moose get on with his favourite activity – snoozing. But this morning, he knew Moose needed help. Ao after a call to his local vets, where Moose, being an elderly Boxer, was a long-standing and frequent visitor, an appointment was made to see Jonathon.
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Vet Jonathon carefully examined Moose’s eye, using an ophthalmoscope and fluorescein eye drops to determine quite what the problem was. Unfortunately, it wasn’t a case of a simple conjunctivitis. Moose had a corneal ulcer.
Corneal ulcers in dogs
A corneal ulcer is like a wound on the surface of the eye; often occurring due to trauma or an underlying ocular condition, and can be incredibly painful. The cornea is the surface or curve of the eye and is made up of three main layers. The outermost layer is the epithelium, the middle layer is the stroma, and the deepest layer is called Descemet’s membrane. Altogether, these layers equate to just 0.5mm in depth.
When damage occurs to the cornea, these layers are disrupted
In most cases, the ulcer is superficial and only affects the outermost epithelium layer. Some ulcers can be deeper, going into the stroma, or even worse, leaving only Descemet’s membrane intact. In the worst cases, this delicate membrane is also damaged, and the eye will actually burst.
An ophthalmoscope is used to determine if there is any sign of internal problems with the eye such as a cataract, infection or haemorrhage. The bright light it emits can also be used to check the nerve reflexes of the eye; ensuring that the pupil constricts in bright light and dilates in dim light.
The green fluorescein dye we use will not stick to healthy cornea, but in areas where this has been damaged, it will stain the corneal stroma green. The ulcer can be seen with a bright light, but will become even more clear under a blue light. This technique will allow the vet to establish how big and how deep the ulcer is; and therefore be able to determine the best treatment method.
Good news…and bad news…
The fluorescein dye had shown up a circular ulcer on Moose’s eye around 1cm in diameter. Thankfully there was no sign that the ulcer had gone any deeper than the most superficial layer. And the internal structures and function of Moose’s eye appeared intact. However, Jonathon had a note of caution for Mr Brown – eye ulcers in Boxers can be notoriously troublesome to heal. So, after providing some antibiotic drops to keep infection at bay, and some pain relief drops to be added to his food, Jonathon arranged to recheck Moose in five days.
How eye ulcers heal
One of the obvious key features of the cornea is how clear and transparent it is, allowing an unimpeded view of the world. But to achieve this means that there cannot be any blood vessels present. When the skin is damaged, because of the vast network of tiny capillaries carrying blood to the tissues, the blood vessels can immediately begin to deliver the cells and nutrients needed to heal that wound. With a corneal ulcer, the blood vessels must actually grow across the surface of the cornea, (a process known as neovascularisation) in order to help to heal the injury.
New corneal cells will also migrate across the ulcer from the edges to cover the deficit. This process takes time, but in most dogs, an uncomplicated corneal ulcer will heal within 5-7 days. In some dogs, especially middle aged to older dogs of breeds such as Boxers, Jack Russell Terriers and Staffordshire Bull Terriers, healing frequently stalls. This can lead to a condition known as Spontaneous Chronic Corneal Epithelial Deficit, or SCCED.
The exact cause of SCCED is unknown
However, it is often linked to a problem in the cornea. This means that the new epithelial cells don’t stick down correctly when migrating across the ulcer. This results in the edges not adhering; and therefore failing to provide the scaffold for further new cells to move over and heal the ulcer.
In order for these ulcers to improve, these under-run edges need to be removed, or debrided.
If you’re squeamish, look away…
Five days later, Moose returned for his check up with Jonathon. Mr Brown had succeeded in applying the eye drops three times a day. And Moose had been happily taking his pain relief as long as it came with a fairly hefty dose of chicken breast. Moose seemed more comfortable and was holding his eye open a little more. But on staining the cornea, Jonathon could see those tell tale loose edges around the ulcer, which hadn’t got any smaller. This meant that further intervention was going to be necessary.
Jonathon explained to Mr Brown that the ulcer needed to be debrided and a grid keratotomy performed. As he went through the procedure and outlined the potential risks, Mr Brown started to look distinctly uncomfortable, not having a particularly strong stomach for all things medical, especially anything to do with eyes. He hastily signed the consent form and handed over Moose’s lead.
Mr Brown’s reaction was not unusual in Jonathon’s experience. But actually, the procedure is fairly straightforward, quick to perform and highly effective at healing these stubborn ulcers.
Debridement of the ulcer followed by a grid keratectomy
Firstly, Jonathon applied some local anaesthetic drops to Moose’s eye and gave him ten minutes to allow them to take full effect. He then used a sterile cotton bud to gently wipe over the surface of the eye and remove the loose edges of epithelium – this is the debridement. Next, using a (very) steady hand, Jonathon used a fine needle to physically scratch an extremely shallow grid across the ulcer; this helps to stimulate the healing process again. Finally, he carefully placed a contact lens which would act like a bandage and provide some comfort for Moose.
In some cases, due to the temperament of the patient, sedation may be required. Having a needle so close to the eyeball obviously comes with some fairly major risks of further damage if the dog were to suddenly move. Many vets will now also use a diamond burr to gently debride the ulcer and encourage healing.
Moose, being Moose, was quite happy to sit and take the attention. And soon afterwards was tucking into a hearty lunch. Jonathon advised Mr Brown to continue with all the medication for now and he would see him back for regular checks to ensure the eye was now healing as it should.
Within three weeks, Moose’s eye was back to normal; though it was hard to tell sometimes as for most of the day it was closed as he enjoyed yet another nap. Mr Brown could also sleep soundly, knowing that the initial consultation, operation and all subsequent check-ups, along with the medication were covered on his insurance and that should the treatment have failed and referral to a specialist been required, he wouldn’t have had to hesitate to give his faithful companion the best chance.