Sudden Acquired Retinal Degeneration (SARD) is often labelled as an autoimmune disease. Let me walk you through why this can not be the case. It’s a simple concept.
Point #1: SARD dogs CAN regain vision
Despite the often-repeated mantra that blindness is permanent in SARD, reports have surfaced for years demonstrating that SARD dogs can regain vision. My own website began documenting these cases in 2006. Dr. Grozdanic (Iowa State University) demonstrated this in 2007. And if you get veterinary ophthalmologists into a private conversation, many will admit that they have witnessed some reversal of blindness during their career.
Blind dogs can see after new ISU treatment*
Note the phrasing is this article: “… reverse blindness and restore sight to dogs diagnosed with SARDS.”
*Also note: these dogs are often prescribed long-term daily prednisone, which acts as a cortisol replacement.
Point #2: In autoimmune disease, retinal cells are destroyed which causes blindness
Pay attention to the sequence of events in autoimmune disease:
A) The body initiates an autoimmune attack
B) Retinal cells are destroyed
C) Blindness follows
Therefore, in total blindness, all retinal cells have been destroyed. That’s the theory.
Note: In humans with autoimmune retinal diseases, the vision loss is not as sudden as in SARD. Treatment for human autoimmune retinal disease is geared toward reducing destruction of remaining retinal cells — remaining cells and REMAINING VISION.
Point #3: Retinal cells do not regenerate
Now IF the autoimmune theory was true for SARD, and retinal cells were destroyed prior to the vision loss, then in order for these dogs to regain vision — which some obviously do — these dogs would have to produce new retinal cells.
Therein lies the problem. Mammals can not regenerate retinal cells. Only fish and reptiles can do this, not dogs.
Point #4: Based on the theory of autoimmune disease, SARD cannot be autoimmune
If autoimmune retinal disease destroys cells then they cannot regain vision. Since we know that these dogs can regain vision, SARD is not likely to be an autoimmune disease. SARD is some other type of disease process such as a seizure of the retina.
Excitotoxicity (a seizure that causes cell death) was proposed as a mechanism in SARD over 30 years ago. (1,2) I have long suspected this is why some dogs also lose their sense of smell, and some even their sense of hearing. As with the retina, olfactory and auditory nerve function seems to experience seizure activity.
In contrast to the autoimmune theory, this excitotoxicity (seizure) theory suggests that:
A) Retinal cells have a seizure
B) Visual function is lost suddenly
C) If the seizure is halted some retinal cells can regain function
D) If the seizure remains unchecked retinal cells are destroyed (apoptosis)
Note the difference in the sequence of events between the autoimmune theory and the excitotoxicity theory. In the excitotoxicity theory, cell destruction occurs at the very end of the sequence. And this explains why there is a window of opportunity to restore some retinal activity and vision. The cells are NOT dead at the start of the disease process, they are just having a seizure.
A few additional points
Some may say that autoimmunity has “been proven” because researchers have found immune system cells primed for retinal tissue. The presence of immune system activity is not necessarily the cause of SARD, but rather the result.
Apoptosis was reported as a mechanism of retinal cell destruction in SARD more than 25 years ago. (3) Apoptosis is a cellular self-destruct method. It is not an inflammatory reaction nor autoimmune destruction. The cells turn themselves inside out.
Researchers in both veterinary and human medicine have reported that once retinal cells do this, the immune system reacts to the cell proteins previously contained within the cell and now exposed to the rest of the body. Researchers question whether immune cells associated with SARD are the result of retinal destruction rather than a causative factor. (4,5)
Furthermore, excitotoxicity (seizure) is frequently initiated by a natural chemical called glutamate. Glutamate has been reported to increase the number of circulating immune system cells. (6)
And finally, the autoimmune theory provides no explanation for the considerable hormone dysfunction these dogs experience.
IN REVIEW
The autoimmune theory suggests that retinal cells are destroyed resulting in blindness. In order to regain vision after autoimmune destruction, dogs would have to regenerate retinal cells. But no mammal can do this. So autoimmune disease is an unlikely cause of SARD.
Retinal seizure activity appears to disrupt communication with the visual cortex of the brain. Vision is suddenly lost. If the seizure continues unchecked, retinal cells are THEN destroyed. But before then, there are things that can be done to help these dogs. Correct the hormones. Protect the retina. Stop the seizure.
Look to a holistic veterinarian or a general practice veterinarian with whom you have a good working relationship. They will be the most helpful in getting your dog treated.
I hope this helps you and your dog.
Best,
Caroline
1. Riis RC. EM observations of a SARD case (abstract). 21st Annual Meeting of the American College of Veterinary Ophthalmologists 1990; 21: 112–113.
2. Abrams KL, Dreyer EB. Excitotoxicity in canine sudden acquired retinal degeneration. Investigative Ophthalmology and Visual Science 1993; 34(Suppl): 3297.
3. Miller PE, Galbreath EJ, Kehren JC, Steinberg H, Dubielzig RR. Photoreceptor cell death by apoptosis in dogs with Sudden Acquired Retinal Degeneration syndrome (abstract). American Journal of Veterinary Research 1998; 59: 149-152.
4. Braus BK, Hauck SM, Amann B, Heinrich C, Fritsche J, Kostlin R, Deeg CA. Neuron-specific enolase antibodies in patients with sudden acquired retinal degeneration syndrome (abstract). Veterinary Immunology and Immunopathology 2008; 124: 177-183.
5. Berger RP, Pierce MC, Wisniewski SR, Adelson PD, Clark RS, Ruppel RA, Kochanek PM. Neuron-specific enolase and S100B in cerebrospinal fluid after severe traumatic brain injury in infants and children (abstract).Pediatrics 2002; 109: E31.
6. Levite, Mia. Glutamate, T cells and multiple sclerosis. Journal of Neural Transmission 2017; 124(7): 775-798.