I just noticed that no other expert had answered your question. I apologize for this oversight. When a dog's eye starts becoming a bit cloudy, owners sometimes say it is turning blue. Blue eyes can be a sign of Infectious canine hepatitis which is a disease of the liver and other organs caused by the adenovirus type 1. It is spread in urine and nasal discharge. Dogs who recover can shed the virus for up to 9 months in their urine. Symptoms are sore throat, coughing and sometimes pneumonia. It can also affect the eyes, liver and kidneys and may give the eyes a bluish cloudy cast. As the liver and kidney’s fail you may notice seizures, increased thirst, diarrhea and vomiting. Treatment for canine hepatitis is supportive such as IV’s and antibiotics, etc to treat the symptoms. Most puppy shots and boosters provide protection against this.
If it is cloudiness giving it the appearance of turning blue, then your dog may have glaucoma or Anterior Uveitis or a corneal ulcer or cataracts. Symptoms of Glaucoma include conjucntivits (red eye), discharge from the eye, light sensativity, possible swollen eye. As the condition worsens and pressure increases, the pupil can dilate and the cornea becomes cloudy. It is important to diagnose this early to save the dog’s sight in the eye. Depending upon the underlying cause for the Glaucoma, the other eye could also be at danger as well. Treatment depends upon identifying the underlying cause for the increased pressure in the eye. You can read more about this here;
Symptoms of Anterior Uveitis are similar and include redness, tearing, squinting in bright light, small or uneven pupil, cloudy appearance to the eye and a unevenly colored iris. Treatment for this condition may be topical or oral medication depending on the cause. You can read more about this here:
A corneal ulcer may also be to blame and may be caused by injury, eyelashes scratching the eye and has similar symptoms to those of glaucoma and anterior uveitis. The third eyelid frequently covers the eye so sometimes the eye is not able to be seen. You can read about this here:
You can read up on Cataracts here:
The following site goes over reasons for cloudiness of the eye.
As you have seen, this could be an emergency situation depending on the severity of the condition. I would have my dog seen as soon as possible to avoid further damage to the eye.
Hope this information is helpful to you.