Night Blindness In Dogs: Causes, Symptoms, And Treatments

Night blindness in dogs, or Congenital Stationary Night Blindness (CSNB), is a condition that affects a dog's vision at night and can cause permanent and irreversible blindness. While this condition is not painful or dangerous, it can impact a dog's quality of life, especially in environments without artificial lighting. Interestingly, researchers have recently discovered a form of congenital night blindness in dogs, paving the way for potential gene therapy treatments for both canines and humans suffering from similar vision problems.

Congenital stationary night blindness (CSNB) is a form of night blindness that can affect dogs

Congenital stationary night blindness (CSNB) is a rare inherited eye disease that can affect dogs. It is a non-progressive retinal disorder that causes a slow degeneration of the retina, which is the part of the eye that collects visual information and communicates with the brain. CSNB is caused by a defect in the RPE65 gene, which results in a mutation in the retinal pigmentation of the eye. This leads to a dysfunction in the retina and causes lipids to accumulate in the retinal pigmentation, usually around the tapetum lucidum, which is the part of the eye that reflects light.

Dogs with CSNB will experience night blindness and may have some degree of visual impairment during the day. The condition can cause permanent and irreversible blindness, although this will vary from dog to dog. Some dogs with CSNB will experience very little impact on their vision and can lead relatively normal lives. The loss of night vision in affected dogs can be noticed as early as 5 weeks of age, while ophthalmologic changes may not be visible until the dog is 2-3 years old.

CSNB is inherited in an autosomal recessive manner in dogs. This means that a dog must receive two copies of the mutated gene (one from each parent) to develop the disease. If a dog only has one copy of the gene, they are considered a carrier and will not show symptoms but can still pass the gene to their offspring. When two carrier dogs mate, there is a 25% chance that their offspring will inherit the disease and a 50% chance that they will be carriers of the gene without symptoms.

There is currently no treatment for CSNB in dogs. However, researchers have recently developed a gene therapy that shows promise in restoring dim-light vision in dogs with the condition. This therapy involves a single injection of a normal version of the LRIT3 gene, which has been implicated in cases of CSNB in both dogs and humans. The treatment has been shown to have a lasting therapeutic effect of a year or longer and could potentially be used to treat CSNB in both dogs and humans in the future.

CSNB is caused by a mutation in the LRIT3 gene, which affects the retina and can lead to permanent blindness

Congenital stationary night blindness (CSNB) in dogs is caused by a mutation in the LRIT3 gene, which affects the retina and can lead to permanent blindness. CSNB is a rare, non-progressive retinal disorder that impairs a person or dog's ability to adapt to low-light situations due to faulty photoreceptor transmission. This results in night blindness and can cause varying degrees of visual impairment during the day.

The LRIT3 gene plays a crucial role in ensuring the proper functioning of the retina. Specifically, it is responsible for the localisation of a molecular channel protein, TRPM1, at the tip of a secondary layer of retinal neurons called ON bipolar cells. These cells are crucial for relaying visual signals from the retina to the brain. The mutation in the LRIT3 gene causes a deletion of one base pair, leading to a truncated protein that disrupts the normal function of the ON bipolar cells.

The impact of CSNB on dogs can vary, with some dogs experiencing minimal effects on their vision, while others may become completely blind. The condition is not painful or dangerous, and dogs with mild cases can lead relatively normal lives. However, it is important to note that CSNB is a genetic disorder that can be inherited if two dogs carrying the mutated gene mate and pass it on to their offspring.

Recently, researchers from the University of Pennsylvania, in collaboration with a team from Japan, have made significant progress in understanding and treating CSNB in dogs. They identified the LRIT3 gene mutation and are now working on developing a gene therapy approach to correct the mutation and restore vision. This involves targeting the ON bipolar cells, which presents a unique challenge due to their location in a less accessible layer of the retina.

There is currently no cure for CSNB in dogs, but gene therapy has shown promise in restoring dim-light vision

Night blindness in dogs, or congenital stationary night blindness (CSNB), is a recessively inherited retinal disorder that affects the Briard dog breed. Dogs with CSNB experience night blindness and have varying degrees of impaired vision during the day. Some dogs with the condition become completely blind, while others are minimally affected and can lead relatively normal lives.

There is currently no cure for CSNB in dogs. However, recent advancements in gene therapy have shown promise in restoring dim-light vision in canines with this condition. In 2015, researchers from the University of Pennsylvania's School of Veterinary Medicine discovered that dogs could develop a form of inherited night blindness similar to a non-progressive retinal disorder in humans. Four years later, in 2019, the same team identified the gene responsible for CSNB: LRIT3. They found that a mutation involving a deletion of one base pair truncates the resulting protein.

In a recent breakthrough, the team has developed a gene therapy that successfully restores night vision in dogs with CSNB. The therapy involves injecting a normal version of the LRIT3 gene into the retina, targeting a group of cells deep in the retina called ON bipolar cells. This approach has shown promising results in adult dogs aged between one and three years, with improved night vision lasting a year or longer. The success of this gene therapy in dogs offers hope for treating similar conditions in humans, as the same LRIT3 gene has been implicated in certain cases of CSNB in people.

While the gene therapy has demonstrated functional recovery in dogs, there is room for improvement. In the treated dogs, the healthy copy of the LRIT3 gene was only expressed in up to 30% of the ON bipolar cells. Researchers plan to build on this success by increasing the uptake of the healthy gene and exploring the possibility of using the human version of the LRIT3 gene in future trials.

Dogs with CSNB experience poor vision in low-light conditions but typically have normal vision during the day

Night blindness in dogs, or congenital stationary night blindness (CSNB), is a rare condition that affects dogs' vision in low-light conditions. While CSNB impairs dogs' night vision, their daytime vision is typically normal.

Dogs with CSNB experience poor vision in low-light environments but generally have normal vision during the day. This condition is characterised by a dysfunction in the transmission of signals between the retina's photoreceptor cells and bipolar cells. While CSNB can lead to varying degrees of visual impairment, some dogs with the condition may experience minimal impact on their daily lives.

The severity of CSNB can vary among affected dogs. While some dogs may only have mild night vision issues, others can progress to complete blindness. Puppies with night blindness often appear normal during the day but may bump into walls and other objects at night. As the disease advances, their day vision can also deteriorate, leading to total blindness.

CSNB is caused by a mutation in the LRIT3 gene, which plays a crucial role in retinal function. This mutation affects the function of ON bipolar cells, a group of cells located deep in the retina. Researchers have successfully developed a gene therapy that targets these cells, restoring night vision in dogs with CSNB. This breakthrough offers hope for treating similar conditions in both dogs and humans.

It is important to note that CSNB is typically inherited, and dogs with the condition should be removed from breeding programs to prevent passing on the defective gene. Additionally, there are other causes of blindness in dogs, such as progressive retinal atrophy (PRA), which can also lead to night blindness and complete loss of vision over time.

CSNB is inherited in an autosomal recessive manner, meaning a dog must inherit two copies of the defective gene to show symptoms

Congenital stationary night blindness (CSNB) is a rare, inherited eye condition that affects dogs, causing progressive degeneration of the retina. CSNB is inherited in an autosomal recessive manner, which means that a dog must inherit two copies of the defective gene, one from each parent, to exhibit symptoms of the disease.

In autosomal recessive inheritance, variants occur in both copies of the gene in each cell. The parents of a dog with an autosomal recessive condition, such as CSNB, can carry one copy of the altered gene without showing any signs or symptoms of the condition. This is because they only have one copy of the defective gene and can still produce a functioning copy of the gene. However, when two carrier dogs mate, there is a 25% chance that their offspring will inherit the disease and a 50% chance that the offspring will be carriers of the gene without symptoms.

Genetic testing of the RPE65 gene can determine whether a dog is a carrier of CSNB. Reliable genetic testing is crucial for determining breeding practices. Since symptoms may not appear until adulthood, it is recommended to perform genetic testing before breeding. To prevent the birth of affected puppies, breeding between known carriers is not advised.

CSNB causes a loss of night vision in affected dogs as early as 5 weeks of age, while ophthalmologic changes may not be visible until the dogs are 2-3 years old. Light brown patches form on the surface of the retina, increasing in size and number over time until the entire retina is affected. Affected dogs may be hesitant to move in low light, and eventually, they may also lose their day vision.

While there is currently no cure for CSNB in dogs, researchers have made significant progress in developing gene therapy to treat the condition. A single injection of gene therapy containing a normal version of the LRIT3 gene has been shown to restore night vision in dogs with CSNB. This breakthrough offers hope for treating similar conditions in both dogs and humans.

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