Retinal Diseases in Dogs : Main Causes, Symptoms and Treatments

 

the dog is looking at the sky

 





Retinal diseases are a category of disorders that affect the normal structure and function of the retina. Common types include retinal detachment, diabetic retinopathy, macular degeneration, retinitis pigmentosa, and so on. If not treated promptly or properly, it may also lead to inflammation and subsequent cataract. The etiologies are diverse, such as genetic factors, vascular diseases, inflammatory diseases, ocular trauma, age factors, etc., which can all trigger them. Patients often experience symptoms such as vision loss, visual field defects, metamorphopsia, and night blindness. Diagnosis can be achieved by means of examination procedures such as visual acuity test, intraocular pressure measurement, fundus examination, optical coherence tomography, fluorescein fundus angiography, and other relevant methods. Treatment modalities differ in accordance with the specific condition and cause, encompassing drug treatment, laser treatment, surgical treatment, and gene treatment which remains in the research phase.

 

 

 

I. The Factors Causing Retinal Diseases in Dogs

 

 

i. Genetic Factors



1.Gene Defects: Certain breeds of dogs are predisposed to retinal diseases due to specific genetic defects, increasing their risk from birth. For example, some shepherd dogs may carry gene defects related to retinitis pigmentosa, causing abnormalities in the development or function maintenance of their retinal cells, and subsequently triggering the diseases.

 


2.Genetic Susceptibility: Some dogs are genetically susceptible to certain retinal diseases. Even without clear causative genes, their genetic backgrounds may make them more prone to developing retinal diseases when exposed to external factors.



ii.Nutritional Factors



1.Vitamin Deficiency: Vitamin A is crucial for the retinal health of dogs. A deficiency of vitamin A can affect the synthesis of rhodopsin in the retina, leading to retinal dysfunctions such as night blindness. In addition, a lack of antioxidant vitamins like vitamin E and C will make retinal cells more vulnerable to oxidative damage, increasing the incidence of retinal diseases.

 


2.Mineral Imbalance: Minerals like zinc and selenium have significant functions in the physiological operations of the retina in dogs. Zinc participates in the synthesis and metabolism of various enzymes in the retina. A deficiency of zinc may result in abnormal retinal functions. Selenium is a key component of the antioxidant defense system. It works in synergy with vitamin E to protect retinal cells from free radical damage. A lack of selenium will weaken this protective mechanism and trigger retinal diseases.

 


iii.Infectious Factors



1.Viral Infections: After being infected by viruses such as canine distemper virus and canine infectious hepatitis virus, dogs will not only experience systemic symptoms but also often suffer from ocular invasions, resulting in retinal inflammations and other pathological changes. These viruses can directly infect retinal tissues or indirectly cause retinal damage by triggering the body's immune responses.

 


2.Bacterial Infections: When bacteria including staphylococci and streptococci invade ocular tissues and are not promptly managed, the inflammation can extend to the retina, thereby inducing retinal diseases. The toxins produced by bacteria and the mediators released during the inflammatory reaction will damage retinal cells and blood vessels, affecting the normal function of the retina.

 


Fungal Infections: When common fungi such as Aspergillus and Candida infect the eyes, they may also affect the retina. Fungal infections are often highly resistant to treatment, posing significant challenges and frequently leading to chronic inflammation and damage to retinal tissue.

 



iv.Immune Factors



1.Autoimmune Diseases: When the immune system of a dog malfunctions and mistakenly attacks its own retinal tissue as if it were a foreign antigen, autoimmune retinal diseases can be triggered. Systemic autoimmune diseases such as rheumatoid arthritis may also affect the eyes of dogs, leading to retinal inflammations and other pathological changes.

 


2.Immune-Mediated Diseases: Certain immune-mediated diseases can lead to retinal vasculitis in dogs, disrupting the blood flow to the retina. This, in turn, leads to retinal ischemia and hypoxia, triggering retinal lesions. These diseases are typically linked to an imbalance in the body's immune regulation, causing the immune system to mistakenly attack the retinal blood vessels.

 

v. Traumatic Factors



1.Direct Ocular Trauma: During play or fighting activities, dogs might sustain external ocular injuries such as impacts, scratches, and bites. These can directly impair the retinal tissue and lead to pathological conditions like retinal hemorrhage and detachment. In addition, some accidents, such as car crashes and falls from heights, can also lead to severe ocular trauma and subsequently trigger retinal diseases.

 


2.Surgical Trauma: Ocular surgeries such as cataract surgery and glaucoma surgery may, Improper postoperative care or complications such as infections during surgery can lead to retinal inflammation or other forms of damage. The manipulation and stimulation of the ocular tissues during the surgery may affect the normal physiological environment of the retina, creating conditions for the occurrence of diseases.

 

 

 

 

II. Common Types of Retinal Diseases

the dog is lying

 


1.Retinal Detachment:

 

 

It refers to the separation of the neurosensory retina from the retinal pigment epithelium, which can be classified into three types: rhegmatogenous, tractional, and exudative. Rhegmatogenous retinal detachment is mostly caused by the formation of retinal holes, through which liquefied vitreous enters the subretinal space. Tractional retinal detachment is commonly seen in proliferative vitreoretinopathy such as diabetic retinopathy, resulting from the traction of the retina by fibrovascular tissue proliferation. Exudative retinal detachment is caused by subretinal fluid accumulation, which can be due to various reasons such as inflammation and tumors.

 

2.Diabetic Retinopathy:

 

 It is one of the common microvascular complications of diabetes. Long-term hyperglycemia can damage the microvessels of the retina, leading to retinal ischemia and hypoxia, and then causing a series of pathological changes, such as the formation of microaneurysms, hemorrhages, exudates, and neovascularization, which seriously affect vision and can even lead to blindness.

 


3.Macular Degeneration:

 

 

It predominantly impacts the macular region of the retina, which undertakes the function of central vision. It can be divided into two types: dry and wet. Dry macular degeneration is mostly age-related, mainly manifested as the gradual degeneration and atrophy of retinal cells in the macular area. Wet macular degeneration is due to the abnormal growth of choroidal neovascularization beneath the macular area, resulting in hemorrhage, exudation, and edema. It progresses rapidly and causes more severe damage to vision.

 


4.Retinitis Pigmentosa:

 

 

It is a group of hereditary retinal degenerative diseases, mainly characterized by progressive night blindness, visual field constriction, and bone spicule-like pigmentation of the retina. Its pathogenesis is related to the dysfunction and gradual apoptosis of retinal photoreceptor cells and pigment epithelial cells. As the disease progresses, vision gradually declines and can eventually lead to blindness.

 

 

 

 


III. Symptoms of Retinal Diseases

the black dog is smiling and putting out its tongue

 



i.Decreased Vision

 



1.Progressive Visual Impairment: Dogs may gradually have difficulty seeing objects either in the distance or up close, and become less sensitive to their surroundings. For example, a dog that could easily catch a toy thrown by its owner before may often miss it after getting sick, and may even make significant errors in judging the position of the toy.


2.Sudden Blindness: When certain acute retinal diseases occur, dogs may suddenly lose their vision. They will be cautious when moving, reluctant to move forward, and easily bump into furniture or other obstacles. They will also no longer respond  to changes in light.

 

ii.Visual Field Defects

 



1.Narrowing of Peripheral Visual Field: The visual field range of dogs may gradually become narrower, and they can only see objects directly in front of them, being unable to detect objects on the side or behind. When an object appears at the edge of their visual field, the dog may not react until the object enters the visual field directly in front of them.

2.Hemianopia: Some retinal diseases may cause dogs to have hemianopia symptoms, that is, they can only see part of the visual field while being unable to perceive the other half. For example, a lesion on the left retina may cause a loss of the right visual field in the dog. When the owner approaches from the right side, the dog may not notice in time.

 


iii.Night Blindness

 

 


1.Poor Night Vision: Dogs with retinal diseases will have a significantly decreased vision at night or in dim environments, and it will be difficult for them to see the surrounding objects and environment. When taking a walk at night, the dog may be more cautious than usual, walk more slowly, or even be reluctant to move, and will be more sensitive and vigilant to the surrounding sounds and movements.

 


iv.Pupil Abnormalities

 

 


1.Dilation or Constriction of Pupils: Retinal diseases may affect the light reflex of the dog's pupils, causing abnormal dilation or constriction of the pupils. Normally, a dog's pupils adjust to light intensity, but illness can impair this function, leading to a slow or absent pupillary light reflex.

 

 

2.Irregular Pupil Shape: Certain retinal diseases may also cause a change in the shape of the dog's pupils, which will no longer be round but show irregular deformations such as oval or pear-shaped.

 


v.Changes in the Appearance of the Eyes

 



1.Retinal Hemorrhage: Severe retinal diseases may lead to retinal hemorrhage. At this time, red or dark red spots or patches can be observed inside the dog's eyes, making the eyes look bloodshot.

 


2.Retinal Detachment: When retinal detachment occurs, there may be some changes in the appearance of the dog's eyes. For example, there may be a slight bulge or depression on the surface of the eyeball, accompanied by symptoms such as redness, swelling, and pain in the eyes. The dog may blink frequently, rub its eyes, or show signs of eye discomfort.





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Noora 8 in 1 contains vitamin E and vitamin C, and Selenium, good for vision health for you pets. .

Advantages: Specifically designed for dogs, this supplement provides comprehensive health support, including for joints, muscles, cardiovascular health, skin, gut, vision and immune system.


Appearance/Taste: This product is available in chewable tablets that have a chicken liver taste to make it more appealing for dogs.


Size: 2.5 grams each tablet, 50 tablets in each bottle, a total of 125g (4.41 )

Dvantages: Noora Daily Multi is a comprehensive health supplement designed to complement today's dog diets by providing 21 essential nutrients. It supports overall health maintenance and well-being in dogs of all ages, ensuring they receive a balanced intake of vital vitamins and minerals.  Appearance/Taste: The supplement comes in a vegetable flavor, which is appealing to dogs and encourages consumption.  Size: Each chew is formulated to be 3.5 grams, making it a manageable size for dogs to chew comfortably.  Quantity: 60 chews in each bottle, a total of 210 g (7.41 oz).  Ingredients:  Vitamin A: 1000 IU, essential for maintaining healthy vision, immune function, and skin health. Vitamin D3: 100 IU, aids in calcium absorption and bone health, supporting the skeletal system. Vitamin E: 15 IU, acts as an antioxidant, protecting cells from damage and supporting the immune system. Thiamine (Vitamin B1): 0.2 mg, important for energy production and nervous system function. Riboflavin (Vitamin B2): 1 mg, contributes to cellular function and energy metabolism. Pantothenic Acid: 4 mg, necessary for the synthesis of hormones and the production of energy. Niacin: 5 mg, supports energy production and healthy skin. Pyridoxine (Vitamin B6): 0.4 mg, important for amino acid metabolism and nervous system health. Folic Acid: 0.08 mg, essential for DNA synthesis and cell division. Vitamin B12: 0.008 mg, important for red blood cell formation and neurological function. Ascorbic Acid (Vitamin C): 25 mg, acts as an antioxidant and supports immune health. Functions: These vitamins, along with a blend of other nutrients like minerals and antioxidants, work together to support the immune system, promote healthy skin and coat, and maintain overall health in dogs. The feeding directions are tailored to the dog's weight, ensuring appropriate supplementation based on individual needs.


Noora Daily Multi contains vitamin A vitamin C and vitamin E, good for vision health

Dvantages: Noora Daily Multi is a comprehensive health supplement designed to complement today's dog diets by providing 21 essential nutrients. It supports overall health maintenance and well-being in dogs of all ages, ensuring they receive a balanced intake of vital vitamins and minerals.

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IV.How to Treat Retinal Diseases in Dogs

 

the dog is lying on the ground

 


i.Medication Treatment

 



1.Anti-inflammatory Drugs: Veterinarians typically treat retinal diseases caused by inflammation, whether infectious or immune-mediated, with anti-inflammatory medications. Commonly used ones are glucocorticoids, such as prednisone, dexamethasone, etc., which can be administered orally, as eye drops, or by injection to reduce the inflammatory response of the retina. In addition, non-steroidal anti-inflammatory drugs, such as diclofenac sodium eye drops, can also be used to relieve ocular inflammation and pain, with relatively fewer side effects.

 


2.Anti-infective Drugs: For retinal diseases caused by bacterial, viral, or fungal infections, corresponding anti-infective drugs are required. For example, antibiotics are used for bacterial infections, antiviral drugs for viral infections, and antifungal drugs for fungal infections, etc., to eliminate pathogens, control the infection, and prevent the disease from further deteriorating.

 


3.Neurotrophic Drugs: To promote the repair and functional recovery of retinal nerve cells, some neurotrophic drugs can be used, such as B vitamins, mecobalamin, etc. These drugs can provide the necessary nutrients for nerve cells, help maintain the normal metabolism and function of nerve cells, and improve the recovery ability of the retina.

 


4.Antioxidants: Given the role of oxidative stress in retinal diseases, the use of antioxidants may help reduce damage to retinal cells. Common antioxidants include vitamin C, vitamin E, lutein, taurine, etc. They can neutralize free radicals, reduce oxidative damage, and protect retinal cells from further harm.


ii.Laser Treatment

 



1.Retinal Photocoagulation: For some retinal vascular diseases, such as diabetic retinopathy and retinal vein occlusion, retinal photocoagulation is a commonly used treatment method. Through the thermal effect of the laser, the abnormal blood vessels in the retina are sealed or atrophied, reducing vascular leakage and the formation of new blood vessels, thereby preventing the occurrence of complications such as retinal hemorrhage, edema, and detachment, and protecting the function of the retina.

 


2.Photodynamic Therapy: Photodynamic therapy is mainly used to treat diseases such as wet macular degeneration. In this method, a special photosensitizer is first injected into the dog's body, and then the retinal lesion site is irradiated with a laser of a specific wavelength. Under the action of the laser, the photosensitizer will generate active substances such as singlet oxygen, which will destroy the abnormal blood vessels at the lesion site, thus achieving the purpose of treatment while causing relatively little damage to the surrounding normal tissue.

 


iii. Surgical Treatment

 


1.Vitreous Surgery: When retinal diseases are accompanied by severe complications such as vitreous opacity, hemorrhage, and retinal detachment, vitreous surgery may be required. This surgery removes the cloudy or diseased vitreous, relieves the traction of the vitreous on the retina, enables the retina to return to its normal position, and creates favorable conditions for the repair of the retina.

 


2.Retinal Reattachment Surgery: For dogs with retinal detachment, retinal reattachment surgery is one of the main treatment methods. Surgical methods include scleral buckling and vitreous cutting combined with retinal reattachment surgery. Surgical procedures aim to reattach the detached retina to the eye's wall, thereby restoring its normal structure and function.

 


3.Cataract Surgery: If retinal diseases are accompanied by cataracts, and the cataracts seriously affect vision and the observation and treatment of retinal diseases, cataract surgery can be considered. Cataract surgery removes the clouded lens, restoring eye clarity and providing an optimal environment for subsequent retinal disease treatment and vision recovery.