When something is going on with your dog’s eyes, it’s important to get to the root of what’s wrong as soon as possible to preserve vision and minimize pain and suffering. Dog eye allergies and infections are fairly common in dogs and often have similar symptoms. However, they require vastly different treatment. Are there ways pet parents and veterinarians can tell the difference between dog eye allergies vs. an infection?
In this article, you will learn to identify similarities and differences between dog eye allergies and eye infections in dogs. You will also learn what to do to help your dog, and when to go to the vet. Let’s dive in.
What Are Dog Eye Allergies?
A dog’s immune system exists to protect a dog’s body from foreign invaders, like bacteria and viruses. It does so by releasing chemical messengers that cause white blood cells and inflammatory proteins to gather around the invader, wall it off from the rest of the body, destroy it, and remove it.
When a dog mounts an inappropriately large immune response to otherwise harmless particles it is called an allergic response. Eye allergies in dogs are caused by an inappropriate, overly reactive immune system responding to allergenic particles such as pollen, mold, dust mites, cat dander, insect particles, and more.
The ocular immune system detects the foreign particle, thinks it is a foreign invader that needs an inflammatory response, and boom! You get itchy, red eyes and dog eye boogers.
Dog eye allergies, also called allergic dog conjunctivitis, usually only impact the conjunctiva, which is the pink tissue surrounding the eyeball and lining the inside of the eyelids.
What Is a Dog Eye Infection?
In contrast to dog eye allergies, if a dog has an infection in their eye, then the immune system does what it is supposed to do. It mounts an inflammatory response to eliminate the infection.
A dog’s eyes can be infected by several things, including bacteria, viruses such as herpes, several species of fungus, and eye worms. An ocular infection can occur in the conjunctiva, on the outside of the eyeball, or inside the eyeball. Where the infection is located determines what the condition is called. For example if the conjunctiva is infected it is called infectious conjunctivitis. If there is an infection inside the eye in structures of the uvea, it is called an infectious uveitis, and so on and so forth.
Dog Eye Allergies Vs. Infections: Symptom Similarities
The tricky thing about dog eye allergies vs. infections is that though they are caused by different things and require different types of treatment, both conditions can look the same. Furthermore, severe eye allergies can lead to eye infections. So, how do you know if your dog has an eye allergy or infection?
First, let’s talk about symptom similarities between eye infections and allergies in dogs. Both eye infections and allergies can:
- Occur abruptly. One day your dog’s eye(s) is fine, the next it is not.
- Cause red, itchy, swollen eyes, and dog eye irritation.
- Cause squinting and/or pawing at/rubbing the eye
- Cause clear or white dog eye discharge or runny eyes.
- Can affect both eyes.
How to Tell the Difference Between Eye Allergies and an Infection
Now that you know how dog eye allergies and infections can appear similar, let’s talk about how they can look different.
Dog Eye Allergies:
- Tend to happen at the same time each year and are recurrent if they are due to seasonal allergies. If they are due to a food allergy, then they happen after the dog eats the ingredient trigger.
- Tend to affect both eyes at the same time and cause swollen eyelids.
- Tends to happen more in dogs that already have seasonal allergies or food allergies. Affected dogs tend to have itchy skin and paws as well as itchy eyes.
- Respond well to treatment with antihistamines, prescription steroids, and/or rinsing the eye with sterile saline to remove any allergens. May also resolve on its own.
- Only produce white or clear dog eye boogers unless the allergy progresses to an infection (see below).
- Dogs are usually otherwise happy and healthy.
Dog Eye Infection:
- Can affect one or both eyes.
- In addition to white discharge, it also causes yellow green dog eye discharge.
- Is painful, especially if the infection spreads to the surface of the eye called the cornea.
- Affected dogs often act sick, painful, and may have a fever and low appetite.
- Doesn’t resolve with antihistamines or rinsing the eye with sterile saline. Steroids make the condition worse.
- Can cause dogs to be head shy (not wanting their head touched).
- Can lead to damage of the eyeball and blindness if not treated appropriately.
- Can cause the third eyelid to pop up.
- Can cause sensitivity to light.
- Is not associated with itchy skin or paws.
Diagnosing and Treating Dog Eye Problems
If you suspect that your dog has an eye infection or any type of eye problem, it is important to get them checked out and treated if necessary as soon as possible. While dog eye infections don’t typically lead to loss of an eyeball, they are painful, and there are several ocular diseases that mimic the signs of a dog eye infection that can cause blindness.
In order to preserve your dog’s vision, get them seen by a vet the same day or, if not possible, the next day. Some diseases like glaucoma can progress very quickly, are very painful, and can cause blindness.
A veterinarian will use a combination of tools to determine whether your dog has an eye infection, eye allergies, or another condition. They will examine your dog’s eye with their naked eye, and then they will use an ophthalmoscope as well as other equipment to examine the eye and surrounding structures more closely. They will look at the conjunctiva, the outside of the eyeball, and the inside of the eyeball.
In addition to an examination, a vet will often use a few other tests to determine the cause of the problem, including:
- Fluorescein eye stain (to check for corneal ulcers or scratches)
- Schirmer tear test (to check tear production)
- Tonometry (to check the pressure of the eye)
Additional diagnostic procedures may be ordered depending on what the vet finds with the initial testing. Additional testing can include:
- Cytology and culture to determine the type of infection
- Biopsy of any suspicious growths
- Blood or intradermal skin testing (allergy testing)
If your vet cannot get to the bottom of your dog’s eye problem or if they find a severe problem, they will likely refer you to a veterinary ophthalmologist for further care.
Treatment for Dog Eye Allergies Vs. Infections
Treatment for dog eye allergies depends on the severity of the problem. If it is mild, then your veterinarian will talk to you about rinsing the eye with saline and utilizing antihistamines. They may also show you how to protect your dog’s eyes with a lubricant.
If your dog eye allergies are severe, your veterinarian will talk to you about allergy testing and prescription medication to manage the problem. Eye allergies, for the most part, cannot be cured, but they can be managed.
Eye infections, on the other hand, can be cured. If the problem is a primary eye infection, then that will be treated with the appropriate antimicrobials. The only exception to this is eye infections caused by viruses, which can only be managed, not cured.
Oftentimes, dog eye infections are secondary to a primary problem, such as a tear deficiency or eyelid and eyelash abnormalities that irritate the eye. In these cases, the eye infection will resolve and not come back once the underlying disorder AND the infection are treated. Once properly treated, most eye infections will clear up in less than a week and your dog will be back to normal.
Don’t Turn a Blind Eye
Dog eye discharge and red dog eyes are relatively common complaints. Allergies, infections, and other diseases can affect the eyes, causing redness, irritation, and discomfort. In some cases, eye problems can lead to blindness if not treated promptly by a licensed veterinarian.
For the best outcomes, if you think your dog might have eye allergies or any other type of eye problem, consult with your veterinarian as soon as possible.
