Hello I am Dr. Joey. Thanks for trusting me to help you and your pet today. I am a licensed veterinarian with over 16 years of experience. I look forward to working with you.
Allergies are certainly a possibility but at their worst they lead to a conjunctivitis and secondary infection. A dog can, however, cause secondary injury to her own eyes by rubbing (scratches, ulcers). There are many other possible causes of what you seeing (keeping her eyes closed with some discharge) such as contact irritant (something got into her eyes and perhaps cause ulceration), intraocular problem (such as glaucoma or uveitis), eyelid issue (sometimes associated with allergies) and the list continues.
Over-the-counter and without an exam there is not a lot you can use. The only safe product would be a lubricating eye gel such as Celluvisc or Refresh which you can instill every 2 to 4 hours. It provides some lubrication but will not treat anything. You should not use anything else in the eye without an exam. So, the best next step for her is to take her to see her veterinarian for an exam and possibly some testing to know if this is due to corneal ulcers or intraocular problem. This is particularly important if the eye(s) look red or cloudy. IF we miss something like glaucoma which can come on very suddenly, then she could go blind, if not treated quickly.
However, if you feel her discharge and irritation is mild then you could flush her eyes with a sterile eye wash as made for people and then use the lubricating drops as mentioned above. If not improved or worsening in the next day then she must be seen.
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