The Canine Eye
Image Credit: Wiki
Dogs have a complete visual field of 250 degrees. They can see well at night and also have good depth perception. A dog’s eye is spherical, and is set in bony sockets which is protected by a layer of fat. The canine eye is placed in the front of the face which allows for a dog’s field of vision to overlap. The frontal placement also allows for a dog to judge depth and notice detail in his environment.
Cornea, Retina, Iris, Sclera, Conjunctiva & Pupil
The cornea is the transparent outer coating of the eye. Covering the cornea is the sclera, which is a white area of connective tissue. This supports the eyeball. Covering the sclera is the conjunctiva, a pinkish membrane. This contains the blood vessels and nerve endings. The pupil is the central opening of the iris. This is where light enters the back part of the eye. The iris is right behind the cornea. This is circular and pigmented and widens and narrows so as to regulate the amount of light that enters the eye. The iris also gives the eye its color. The retina contains plenty of rod cells to detect light. It also has a lesser amount of cone cells that allows the eye to distinguish color. The retina converts incoming light rays into electrical impulses and sends them to the brain through the optic nerve. The brain then translates all the electrical impulses into visual images.
Eyelids, Tears & Third Membrane
The eyelids support the front of a dog’s eye. All dogs have a third eyelid called the nictitating membrane. This is found at the corner of the eye. This membrane usually stays retracted, although it sometimes covers the eye for protection if need be. In this case the eye will look as if it has rolled back into the dog’s head. Tears keep the cornea moist and also make immune substances to help fight infections.
Proptosis in Dogs
This occurs when the eyeball is partially or entirely out of its orbit.
Dog Breeds Most Prone
All dog breeds that have protruding eyes with short muzzles and noses. These dogs have flat and wide skull shapes, and are known as brachycephalic dogs.
What To Do If Your Dog’s Eye Becomes Displaced
Your dog needs to visit the emergency vet RIGHT AWAY.
Apply a saline solution to a sterile gauze and cover the eye so that the eye does not dry up. You can apply a contact lens solution to the gauze.
Call your vet prior to leaving to let them know that you’re arriving and explain your situation. That said, they will be ready for your dog.
Keep in mind that your dog will be in terrible pain and under stress.
Symptoms of Eye Proptosis in Dogs
One or both eyes are out of the orbit
The eye is bloody and bulging
Eye tissue is swollen and red
Torn or severed eye muscle or ligaments
Cornea is misty colored
Your dog cannot blink or close his eye(s)
Pupils are constricted
Dog may be in shock and have other injuries
How is Eye Proptosis Caused in Dogs?
Another larger dog may have applied pressure to the dog’s skull while playing or fighting
Dog was injured by a car
Dog was hit
Dog accidentally crashes into something
Choking by use of the choke collar
How Vets Diagnose Proptosis
If you’re visiting a new veterinary clinic in an emergency situation, let them know which medications your dog is currently on and what health conditions he may have.
Your dog will need to be stabilized and assessed by the veterinarian on call.
An IV will most likely be administered and your dog will undergo skull and chest X-rays together with a complete blood count. The vet will also do a serum chemistry panel. All these tests will help to show the condition of the injured dog like how much blood he’s lost, as well as organ function.
After all this is done, your vet will do an ophthalmic evaluation.
What Happens During Treatment?
If your dog has torn extra ocular torn eye muscles or optic nerve muscles, your vet will suggest enucleation of the eye. In this case, the eyeball is removed and the outer parts of the eyelids are sutured closed.
Nonetheless, if your vet feels that your dog may have a chance to see again, he will suggest re-attaching the globe and performing a temporary tarsorrhaphy. In this case the eyelids will be partially stitched together for around three weeks. This is done to protect the cornea. All these procedures are done under general anesthesia.
Most dogs that have undergone enucleation of their eye have a fair chance of good recovery. Nonetheless, even after having had this surgery, proptosis can happen once again. Your dog will be put on pain meds and antibiotics. You will have to bring in for follow- up visits. It is vital that all post- op instructions are followed.
Dogs that have undergone tarsorrhaphy will be prescribed topical and oral antibiotics, atropine, pain meds and atropine. The use of an E-collar will help to prevent your dog from hurting himself.
Long Term Prognosis
20-40% of dogs will regain their vision.
Proptosis may occur again.
Complications such as blindness, corneal ulceration, keratitis and glaucoma may occur after surgery.
Follow-up visits are of vital importance so that your dog’s progress can be monitored.
It is highly recommended to carry pet insurance since this type of surgery can be costly.
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