Sudden vision loss
There are many causes of sudden vision loss in the dog. Vision requires 3 main areas to be working; the retina, the optic nerve (takes information from the eye to the brain) and the brain itself.
Sudden vision loss is devastating for patients and owners alike. Dogs definitely go through a period of depression where their normal enthusiasm is overtaken by fear and anxiety. Whilst it is important to realise your dog’s anxiety, it is important to encourage his or her normal behaviour. Initially smaller walks, at the same time of day can help. In addition allowing your dog to “take you” and allow them to sniff as much as possible. This stimulates their brain function and generates confidence. Continual dialogue with your pet also relieves stress.
What are the clinical signs of sudden vision loss?
Most dogs have no signs of eye pain like, redness, cloudiness, discharge or discomfort.
Some owners feel that their dog may have shown odd behaviour weeks before they went completely blind. Others indicate and change in eating and or drinking patterns and possibly weight gain.
Retina Optic Nerve Brain
POSSIBLE CAUSES
Hypertension – detachment GME GME
Immune mediated inflammation Immune-mediated inflammation Brain tumour
Infectious Infectious Stroke
SARDs
CLINICAL FINDINGS
Pupil light response variable Pupil light response absent Pupil light response normal
ERG abnormal to absent ERG normal ERG normal
Neurological exam normal Neurological exam variable Neurological exam abnormal
The above table is only a guide – various diseases can present with multiple signs.
Diagnostic Testing
1. Pupillary light response
2. Examination of the retina after pupillary dilation
3. General physical examination
4. Neurological examination
5. Blood pressure
6. Electroretinogram – ERG – tests the functional capacity of the retina.
7. Referral to a medicine specialist for possible CT/MRI.
Treatment of sudden vision loss
Treatment depends upon the primary causes. Often without extensive tests it is difficult to determine the exact cause. Since many of the causes of sudden vision loss are immune-mediated aggressive systemic steroids are used. It is important to note that high doses of oral steroids will suppress the immune and change the levels of certain cells in the blood. If blood tests are to be performed, this is best done before starting the steroids. As a result it is vital to watch your dog’s behaviour and contact us if you note any problems.
SARDs – Sudden acquired retinal degeneration syndrome
This often occurs in middle-aged female dogs in early Spring, although it can occur in all ages, breeds and sex. Owners often report an increase in thirst, eating and weight gain around the time of the weight loss. These symptoms are also seen in another condition called Cushing’s disease. Whilst testing can be done by your local veterinarian, many dogs do not have “true” Cushings, just Cushing's-like symptoms. Unfortunately there is currently no proven treatment for SARDs. Therapy is aimed at helping your pet adjust to and cope with blindness (please see "Living with a Blind Pet" handout).
Should you have any questions or concerns please contact us on 03 9545 0103.
There are many causes of sudden vision loss in the dog. Vision requires 3 main areas to be working; the retina, the optic nerve (takes information from the eye to the brain) and the brain itself.
Sudden vision loss is devastating for patients and owners alike. Dogs definitely go through a period of depression where their normal enthusiasm is overtaken by fear and anxiety. Whilst it is important to realise your dog’s anxiety, it is important to encourage his or her normal behaviour. Initially smaller walks, at the same time of day can help. In addition allowing your dog to “take you” and allow them to sniff as much as possible. This stimulates their brain function and generates confidence. Continual dialogue with your pet also relieves stress.
What are the clinical signs of sudden vision loss?
Most dogs have no signs of eye pain like, redness, cloudiness, discharge or discomfort.
Some owners feel that their dog may have shown odd behaviour weeks before they went completely blind. Others indicate and change in eating and or drinking patterns and possibly weight gain.
Retina Optic Nerve Brain
POSSIBLE CAUSES
Hypertension – detachment GME GME
Immune mediated inflammation Immune-mediated inflammation Brain tumour
Infectious Infectious Stroke
SARDs
CLINICAL FINDINGS
Pupil light response variable Pupil light response absent Pupil light response normal
ERG abnormal to absent ERG normal ERG normal
Neurological exam normal Neurological exam variable Neurological exam abnormal
The above table is only a guide – various diseases can present with multiple signs.
Diagnostic Testing
1. Pupillary light response
2. Examination of the retina after pupillary dilation
3. General physical examination
4. Neurological examination
5. Blood pressure
6. Electroretinogram – ERG – tests the functional capacity of the retina.
7. Referral to a medicine specialist for possible CT/MRI.
Treatment of sudden vision loss
Treatment depends upon the primary causes. Often without extensive tests it is difficult to determine the exact cause. Since many of the causes of sudden vision loss are immune-mediated aggressive systemic steroids are used. It is important to note that high doses of oral steroids will suppress the immune and change the levels of certain cells in the blood. If blood tests are to be performed, this is best done before starting the steroids. As a result it is vital to watch your dog’s behaviour and contact us if you note any problems.
SARDs – Sudden acquired retinal degeneration syndrome
This often occurs in middle-aged female dogs in early Spring, although it can occur in all ages, breeds and sex. Owners often report an increase in thirst, eating and weight gain around the time of the weight loss. These symptoms are also seen in another condition called Cushing’s disease. Whilst testing can be done by your local veterinarian, many dogs do not have “true” Cushings, just Cushing's-like symptoms. Unfortunately there is currently no proven treatment for SARDs. Therapy is aimed at helping your pet adjust to and cope with blindness (please see "Living with a Blind Pet" handout).
Should you have any questions or concerns please contact us on 03 9545 0103.