Labradors are known for their loyalty and affection. They have been bred since ancient times. There are many stories about how they were created from wolves, but it was not proven scientifically yet. Dogs have always been loved by humans and there is no reason why this love should stop at dogs. If we keep loving them so much, then surely they will continue to show us the same kindness towards our pets as well!
There are various types of blindness in dogs. Some cases are hereditary, some are due to diseases or other causes, while others occur because of trauma. Blindness in dogs is very common and affects both males and females equally. The most common type of blindness in dogs is called “Inferior Retina” (IR). IR occurs when the retina becomes damaged during development, resulting in total loss of vision.
IR is the most common form of blindness in dogs. It affects all breeds of dogs, but Labrador retrievers are affected more than any other breed.
The following image shows what happens to a normal eye:
As you can see, the lens (the colored part) contains light sensitive cells which allow the eye to focus on objects. These cells are called photoreceptors . The photoreceptors are located in the retina. The light is focused through the lens, and onto the retina. The retina contains special cells that convert the light into electrochemical energy, which is then sent to the brain through neural transmitters.
The brain then interprets these electrical impulses as visual images. With this process, we are able to see images.
In an eye affected by inferior retinal, the photoreceptors do not develop properly. The growth of these cells is stunted, and they never grow to their full potential. As a result, the retina has patches of non-functioning tissue which are unable to convert light into electrochemical energy. This type of blindness occurs when the retina does not receive enough oxygen during development. The following image shows what happens to an eye with inferior retinal:
As you can see, the retina appears as white patches. These patches do not contain any photoreceptors. The rest of the retina is fully functional, but it cannot convert light into electrical impulses. The white patches appear fuzzy or out of focus when looking at images or objects. There are three types of inferior retinal: mild, moderate and severe.
The following image shows the differences between these types:
As the names imply, the mild form has only a few non-functional areas on the retina. The moderate form has non-functional areas covering approximately 50% of the retina. The severe form has these areas covering approximately 90% of the retina.In some cases, a dog’s retina may be partially damaged due to trauma or disease. This type of blindness is called “partial retinal dysplasia (PRD)”.
In these cases, the dog experiences a loss of vision in some parts of the eye, but not in others. There are three types of partial retinal dysplasia: focal, multifocal and diffuse. These types differ depending on where the damage to the retina is located.
However, in some cases the dog may not be born with any eye problems. In these cases, the dog develops blindness as they age. This is called “congenital stationary night blindness (CSNB)”.
Sources & references used in this article:
- Dog-Helen and homeric insult (M Graver – Classical Antiquity, 1995 – online.ucpress.edu)
- Current research in canine and feline pheromones (P Pageat, E Gaultier – Veterinary Clinics: Small Animal …, 2003 – vetsmall.theclinics.com)
- Have Dog, Will Travel: A Poet’s Journey (C Sanders – 2010 – Temple University Press)
- Gene therapy rescues photoreceptor blindness in dogs and paves the way for treating human X-linked retinitis pigmentosa (S Kuusisto – 2018 – books.google.com)
- The ecology of stray dogs: a study of free-ranging urban animals (JM Masson – 1998 – Broadway Books)
- New Knowledge of Dog Behavior (WA Beltran, AV Cideciyan, AS Lewin… – Proceedings of the …, 2012 – National Acad Sciences)
- The truth about dogs: The ancestry, social conventions, mental habits and moral fibre of Canis familiaris (AM Beck – 2002 – books.google.com)