What Causes Cloudy Eyes in Dogs?

Before explaining why a dog's eyes are cloudy, we should understand the structure and function of canine eyes. While there are many similarities with the human eye, there are some fundamental differences.

Dogs have something called a nictitating membrane, also known as a ‘third eyelid’. This is located in the inner corner of the eye and is not usually visible. When the third eyelid does become visible, it is usually the sign of something wrong. Infection, presence of a foreign body or an underlying pathology may be the cause, but a trip to the vet is the best way to diagnose the problem.

In terms of visual acuity, a dog is myopic and unable to register as many colors as humans. As we stated in the introduction, they are able to see in places with less light and have a broader field of vision. Their ability to see depends on the amount of cone cells and rod cells present in their eyes^[1], working better in well-lit and poorly lit environments. If you want to know more, we have this article on what colors a dog can see to help you out.

When there is a problem with our dog's eye or eyes, we need to look out for some particular signs and symptoms. If there is an ocular problem with our dog we may observe:

• Pain
• Lachrymation (eye discharge)
• Photophobia (sensitivity to light)
• Protrusion or inflammation of the nictitating membrane
• Eye hard or soft to the touch
• Sunken eye
• Bulging eye
• Inflammation of the eyelids
• Cloudiness or opacity

If your dog shows any or a combination of these symptoms, we should seek veterinary assistance. Some eye disease can be treatable, but if they are not reached in time can progress rapidly and result in permanent loss of vision. This is why we need to be so careful with any changes to our dog's well-being. Some breeds are more prone to eye problems than others. Brachycephalic dogs often have eyes which bulge, predisposing them to disease.

In the following sections we go into the possible reasons why my dog has a cloudy eye, including causes, symptoms and possible treatments.

If the third eyelid extends over the surface of the eye, it can give the impression that the eyeball has turned around in its socket. The eyes may look practically white and blank. Paresis is a general term for weakness in voluntary movement. When applied to the eyeball, it can make the eye move back into the head involuntarily. In these cases, the whiteness of the eye is not cloudiness, but the sclera (the white part of the eye). This abnormal movement of the eyeball may be exophthalmos, i.e. the change of the eye's orbit.

Some dogs are born with this disorder meaning that the cause is a genetic one. However, the presence of an underlying pathology may be the root cause. These causes could be:

• An eye infection
• Muscle issues
• Damage to the cranial nerves
• Trauma incurred by an injury
• Toxic shock from an animal bite
• Horner's syndrome
• Carcinoma^[2]

Genetic causes may not provide much of a issue for the dog. The issues may be more cosmetic and they may be able to enjoy an otherwise happy life. When the cause is pathological, it is this problem which needs to be diagnosed and treated by a vet.

Keratitis is the inflammation of the cornea and is most often accompanied by pain and redness in the eye. Additionally, the dog's eyes will weep, causing the dog to rub them or try to scratch them due to the irritation. A protrusion of the nictitating membrane may also be concurrent. It can be a very stressful situation for the dog, so immediate action is required.

There are several types of keratitis in dogs, not all of which will result in cloudiness appearing in the eye. If we see either a black spot or whiteness of the eye, lack of treatment can lead to blindness. Some cases are not as severe and may present milder irritation. There are main types of keratitis which may cause cloudiness in the eye:

• Ulcerative keratitis: the epithelial layer of the eye is affected by the corneal infection. They may recur, but should be treated by antibiotics.
  
  
• Acanthamoeba keratitis: this is a condition where amoebae (singular cell organisms) invade the cornea and cause inflammation. It is relatively rare, but advanced cases will make the cornea turn a milky white color.

The corneal ulcers will cause the eye around the corner to become bloodshot, but advanced cases may cause the whole eye to change color. It is important not to ignore these symptoms and determine the difference between these and another ocular conditions. Mixed-breed dogs are less likely to develop the disease than purebred dogs such as the Pug^[3].

Perhaps the best known cause of cloudiness or white milkiness of a dog's eye is cataracts. This condition involves the loss of transparency in the lens, resulting in an opaque appearance and loss of vision. The affected lens turns white giving the appearance of a film or white coating over the eyes, almost like wearing white contact lenses. +

There are different types of cataracts and a dog's breed may affect their disposition towards them. Breeds with genetic proclivity to cataracts include the Cocker Spaniel, the Fox Terrier, the Poodle, the Golden Retriever, the Labrador Retriever and the different types of Schnauzer. Juvenile cataracts in dogs usually occurs below the age of five, but it is possible to be born with them.

Conversely, acquired cataracts are linked to old age. Some eye diseases such as uveitis or progressive retinal atrophy may lead to cataracts as can more general conditions such as diabetes. They can lead to blindness, so treatment in the form of surgery may be required if the dog's quality of life is affected. Otherwise, treating the underlying problem is required. With diabetes, this will include changes to the diet, but a veterinary assessment is also required.

Glaucoma is caused by an increase in intraocular fluid in the eye. This can be caused by secondary causes such as pressure within the eye^[4]. Like cataracts, this can also derive from genetic predisposition. Equally, it can also be a secondary effect of another disease. Acute or chronic glaucoma can also develop. As the eyes need a lot of fluid to function and stay healthy, they need to synthesize it quickly. When a dog has glaucoma, the fluid is not drained away fast enough leading to a build up and a white cloudy appearance of the eyeballs.

Most commonly, glaucoma in dogs is treated by eye drops to control the intraocular fluid. Your vet will need to show how to properly apply them without harming the animal further. They can also be very stressed by the application, so you will need to create some positive reinforcement. If the problem is chronic or acute enough, surgery or even laser eye surgery may be implemented.

Intraocular fluid causes a dog's eye to be cloud, but other fluid can also affect their health. Learn more with our article on why dogs have blood in their eye.

The health of the cornea greatly affects the appearance of the eye and one hereditary disorder which causes cloudiness is corneal dystrophy. It is not one specific disease, but a range of disorders which lead to the white appearance in the eye. As a hereditary disease, your dog's eyes will not turn white suddenly. Rather, color and appearance changes will occur gradually. They will also be bilateral, i.e. affecting both eyes and not just the one.

The progression will affect the different layers of the cornea which are:

• Epithelium: the ‘film’ over the eye which we have mentioned before.
• Stroma: the connective structure of the cornea which can basically be described as the middle part.
• Endothelium: the deepest part of the cornea.

How cloudy the eye becomes will depend on how acutely the eye is affected. Many of the early stages may be asymptomatic, so your dog may not show signs even if the disease is progressing underneath. Eyedrops may be used to help once symptoms do occur, but there is no actual cure for the disease. It does not always result in loss of vision, but the only effective treatment would be a corneal transplant. This is not a treatment often carried out in veterinary medicine and vets are unlikely to recommend this procedure^[5].

This condition is similar to cataracts in that it affects the lens of the dog's eye, turning it a cloudy white. For this reason, the two conditions are often confused. Similarly, it is also related to advanced aging in the dog^[6]. In humans, it is known as nuclear sclerosis, but in veterinary medicine it is known as lenticular sclerosis. It is characterized by a blue grayish coloration of the eye, which can also look white and cloudy.

With lenticular sclerosis, light shone into the eye will reflect off the tapetum lucidum (the colorful membrane at the back of the eye). This does not occur with cataracts, being the main way to differentiate between the two. Unfortunately, there is no treatment for this disease, but it does not usually affect their vision acutely.

You may think your dog's eye will have become cloudy suddenly, but this is rarely the case. Whether it is due to an infection, contracted disease or hereditary genetic condition, it will usually start small and build up. This is why you need to regularly observe the condition of their eyes. Many dogs do not like it if you hold their gaze for too long, even if they have an otherwise good relationship with you. However, you can still have a look and they shouldn't feel too uncomfortable.

Sometimes cloudiness in an eye will come from an injury. Again, the cloudiness will not likely appear suddenly. Instead, the injury will lead to infection, hemorrhaging or similar damage. This is what will cause the change in appearance and color long term. As your dog may get an injury to the eye, you should include some sort of eye wash in your canine first aid kit.

If you see your dog has a cloudy eye, take them to the vet immediately. In our list of possible causes and disorders, the progression can be slow or rapid. If the latter is the case, we need to ensure effective diagnosis and treatment is carried out by a professional. Otherwise, temporary or permanent blindness can occur. You should not treat the condition yourself, especially not with medications designed for humans. Due to the eye's sensitivity, you could be the one doing damage and causing a loss of vision.

This article is purely informative. AnimalWised does not have the authority to prescribe any veterinary treatment or create a diagnosis. We invite you to take your pet to the veterinarian if they are suffering from any condition or pain.

If you want to read similar articles to What Causes Cloudy Eyes in Dogs?, we recommend you visit our Eye problems category.