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Cataracts in Dogs

What are Cataracts in Dogs?

Cataracts in dogs refer to an abnormality where the lens of the eye becomes cloudy or opaque, hindering the passage of light and affecting vision. Normally, the lens should be clear, enabling clear vision by transmitting light to the retina. Cataracts can vary in size and severity, ranging from minor impairments to significant vision loss.

To identify cataracts in dogs, one can observe whitish discoloration on the pupils of one or both eyes. Cataracts are categorized based on various factors including the dog’s age at onset (congenital, juvenile, or senile), location within the eye, causes, shape, and degree of opacity.

The severity of cataracts can be further classified into different stages:

  • Incipient cataracts are small and may require magnification for diagnosis, covering less than 15% of the lens and causing minimal vision loss. Surgery is rarely recommended at this stage.
  • Immature cataracts cover more than 15% and up to 99% of the lens, often with multiple layers or areas affected. Visual deficits are usually mild, but significant vision loss may occur if the cataracts cover 75% of the lens.
  • Mature cataracts cover the entire lens, obscuring the retina during examination. Visual deficits are significant, often leading to blindness or near-blindness. Surgery is typically recommended at this stage if other health conditions are under control.
  • Hyper-mature cataracts are characterized by the shrinking of the lens and the appearance of a wrinkled lens capsule. This stage is often accompanied by inflammation within the eye.

The impact of cataracts on vision depends on factors such as the extent of lens involvement, whether one or both eyes are affected, and the progression of the condition. Cataracts covering less than 30% of the lens or affecting only one eye may not cause significant vision loss. However, when the opacity covers around 60% of the lens, vision loss becomes apparent, and complete opacity can lead to blindness in the affected eye. The progression of cataracts varies based on the type of cataract, the breed of the dog, and other risk factors.

Hereditary cataracts are frequently observed in young dogs aged between 1 and 5 years old. The following breeds are particularly prone to hereditary cataracts:

  • American Staffordshire Terrier
  • American Cocker Spaniel
  • French Bulldog
  • Labrador Retriever
  • Miniature Poodle
  • Miniature Schnauzer
  • Boston Terrier
  • Siberian Husky
  • Yorkshire Terrier
  • Welsh Springer Spaniel

Cataracts that dissolve naturally without treatment are known as cataract dissolution. They can lead to severe inflammation within the eye. As the cataract completely obstructs light from entering the eye through the lens, it impairs your dog’s vision. While the condition is still treatable with surgery, if left untreated, it may progress to glaucoma.

Glaucoma occurs when the fluid in your dog’s eye fails to drain properly, resulting in a painful increase in eye pressure. While not all untreated cataracts evolve into glaucoma, dogs with glaucoma often aren’t suitable candidates for cataract removal surgery. Although medical and surgical treatments are available for glaucoma, it generally carries a poor prognosis for maintaining long-term vision.

Symptoms

Signs of cataracts in dogs can vary depending on the age and severity of the condition. Puppies afflicted with complete juvenile cataracts may exhibit poor vision and may bump into objects. A noticeable white spot may appear in the middle of the pupil.

If you observe changes in the color or clarity of your dog’s eyes, or if puppies display signs of discomfort such as squinting or scratching at their eyes, it’s crucial to promptly consult a veterinarian. Additionally, any signs of illness warrant immediate veterinary attention.

Cataracts impair a dog’s vision, with symptoms corresponding to the extent of vision loss. Initially, cataracts may start small, akin to a pinpoint, and gradually expand to cover the entire lens, resulting in blindness. Dogs with less than 30% lens opacity may exhibit minimal to no symptoms, despite the presence of visible lesions on the eye.

Rapidly developing cataracts, such as those associated with diabetes mellitus, can cause disorientation or confusion in dogs. Inflammation linked to cataracts can induce pain and potentially lead to glaucoma, which exacerbates discomfort. The body’s response to perceived foreign substances on the lens contributes to the discomfort associated with cataracts. In cases where diabetes mellitus triggers cataracts, increased thirst and urination, changes in appetite, weight loss, eye lesions, and vision impairment may also be observed in affected dogs.

Causes

The primary cause of cataracts in dogs is often hereditary or genetic factors. Additionally, cataracts frequently develop in dogs as a complication of diabetes mellitus. Less common causes include:

  • Aging
  • Trauma, such as electric shock
  • Inflammation of the eye’s uvea (uveitis)
  • Low blood calcium levels (hypocalcemia or hypoparathyroidism)
  • Nutritional deficiencies, particularly linked to insufficient amino acids like Tryptophan during the puppy’s development when fed commercial milk-replacer supplements
  • Exposure to UV light, radiation, or toxic substances, akin to the most common cause of cataracts in humans

Cataracts that arise secondary to diabetes mellitus are increasingly observed in dogs. Elevated blood glucose levels lead to the accumulation of sugars within the lens of the eye, resulting in rapid cataract development that may rupture the lens capsule. When cataracts stem from diabetes mellitus, modifying the dog’s diet and insulin regimen can potentially slow the progression of the condition. In cases where the cataract has advanced significantly, surgical intervention may be considered as an option.

Diagnosis

When you notice a cloudiness in one or both of your dog’s eyes, it’s imperative to promptly schedule an examination with your veterinarian. During the examination, your vet will inquire about your dog’s medical history, previous health issues, and the onset of symptoms. A comprehensive physical examination, focusing on the eyes and surrounding structures, will be conducted. Initial diagnostic tests such as complete blood count, serum biochemistry profile, and urinalysis typically yield no abnormalities unless concurrent conditions like diabetes mellitus or hypocalcemia are present.

During the initial eye assessment, your vet will employ various tests to diagnose cataracts and establish a baseline for monitoring your dog’s condition over time. Dilating your dog’s eyes may be necessary to examine the cataract’s outer edge and the eye’s posterior region if feasible. It’s important to differentiate cataracts from other lens imperfections in young dogs and from the normal age-related increase in nuclear density, known as nuclear sclerosis, in older animals. Diagnostic tests may include:

  • Slit lamp biomicroscopy: A specialized light is directed into the dog’s eye, enabling direct examination of the lens.
  • Schirmer tear test: A small filter paper is inserted beneath the dog’s lower eyelid to measure tear production by assessing moisture content.
  • Fluorescein stain: Ocular stains, typically neon orange or yellow, are used to assess the cornea’s surface integrity, detecting scratches or foreign materials.
  • Tonometry: After numbing the eye surface with drops, a small device is used to measure intraocular pressure by tapping the eye’s surface.

If your vet is unable to perform these tests or if abnormalities are detected, you may be referred to a board-certified veterinary ophthalmologist in your vicinity.

If cataract surgery is deemed necessary based on the eye condition and cataract appearance, further tests will be conducted to assess retinal health. Some cataracts are associated with retinal function loss or detachment. Pre-operative tests to evaluate the retina may include an electroretinogram (ERG) and ocular ultrasound to measure retinal cell electrical responses. These tests typically require sedation and can take several hours. If retinal function is compromised, even after cataract removal, your dog’s vision may be affected, and in such cases, cataract surgery may not be recommended.

Treatment

Currently, there are no medical treatments available to reduce or eliminate cataracts in dogs. Surgery remains the sole option. Ongoing research explores the efficacy of certain topical eye medications, such as topical aldose reductase inhibitors (ARI eye drops), which have shown promise in treating cataracts induced by diabetes mellitus.

To optimize the chances of restoring vision post-surgery, both the eyes and overall health of the dog are carefully assessed. This assessment is crucial to ensure that any underlying conditions, like skin or dental diseases, are adequately managed before proceeding with cataract surgery.

As cataracts are progressive, timely surgical intervention is recommended if deemed necessary. Pre-operative medications are administered several days to weeks before surgery to control any inflammation associated with the cataracts. Reported long-term success rates following uncomplicated cataract surgery in dogs range from 85% to 90%.

Phacoemulsification is the contemporary surgical method used to remove diseased lenses in cataract treatment. This procedure involves using an ultrasonic probe to emulsify, or liquefy, the eye’s lens. After removal, fluids are replaced with a balanced salt solution. During surgery, a corrective or artificial lens resembling a contact lens may be implanted onto the eye, ensuring a permanent attachment.

Living and Management

Following cataract surgery, dogs typically spend one night in the hospital. They are required to wear an Elizabethan collar or inflatable cone to prevent them from scratching their eyes. Owners will receive instructions to administer eye drops to their dogs at least two to four times daily at home.

Cataract surgery necessitates a lifelong commitment from the owner. For owners opting to treat immature cataracts, initiating their dog on a regimen of multiple anti-inflammatory eye drops upon diagnosis is essential. These eye drops will likely remain a part of the dog’s daily routine for the rest of their life.

The rate of cataract progression varies depending on factors such as the underlying cause, the cataract’s location, and the dog’s age. Cataract surgery for dogs with diabetes mellitus demonstrates comparable success rates to those with hereditary cataracts.

Prevention

As most instances of cataracts in dogs are hereditary, there are limited preventative measures pet owners can take. However, maintaining a high-quality diet for your dog, rich in omega-3 fatty acids, can support overall eye health. Consult your veterinarian to explore supplement options that may offer the greatest benefits.

It’s important to monitor your dog’s exposure to UV rays to help prevent cataracts. Providing ample shade outdoors and considering protective goggles like Rex Specs, especially in areas with high UV exposure, can help shield your dog’s eyes from harmful rays.

Cataracts in Dogs FAQs

Can cataracts in dogs be removed?

Cataracts in dogs are typically removed surgically using a method called phacoemulsification, which boasts an 85–90% success rate.

Can cataracts in dogs be treated?

Currently, there are no medical therapies to reduce or cure cataracts in dogs. Surgical intervention is the only permanent solution capable of restoring your dog’s vision.

Can dogs live comfortably with cataracts?

No, untreated cataracts can lead to deep inflammation within the eye and may result in glaucoma, both of which are extremely painful conditions for dogs.

What are immature cataracts in dogs?

Immature cataracts in dogs encompass 15–99% of the lens, often affecting multiple layers or areas. Despite the presence of these cataracts, the retina remains visible during examination, and visual impairments are usually mild. However, significant vision loss may occur if the cataracts cover 75% or more of the lens, although the impact varies among dogs.

Do dogs become blind because of cataracts?

Without proper treatment, most cataracts will eventually cause complete blindness in the affected eye(s).

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