6 Possible Reasons for That Thick Red Vein in Your Dogs Eye

Have you ever looked in the mirror and noticed that one of your eyes has a thick red vein? It’s terrifying, isn’t it? Things can get particularly scary if more red veins appear all over the eye and even start showing up on the other. You may even think that you’re dying. 

So imagine if you suddenly noticed a thick red vein in your dog’s eyes – still terrifying, right? That’s why it’s important to understand these red veins. Fortunately, this is what we’re going to talk about today. 

In this post, we are going to delve deeper into the reasons why your dog would develop a thick red vein in its eye. We will also discuss what you can do about this. Ultimately, this post has been designed to not only arm you with helpful information but also put your mind at ease. 

6 Reasons Why Your Dog’s Eye Might Have a Thick Red Vein

The most common reasons for your dog’s eye to have a thick red vein are:

Dry eye

As its name suggests, this condition is characterized by dryness of the eye. The lack of moisture usually makes the layer covering the eye (the tear film) malfunction. This is dangerous because this film is what protects your dog’s eye and provides it with moisture and nutrients. 

Dry eye can be caused by eye/eyelid defects or an autoimmune condition that makes your dog’s body attack its tear glands. Interestingly, dry eye is mostly an inherited and lifelong condition – fortunately, you can easily use eye drops to manage it. The dog breeds that commonly get dry eye are schnauzers, bulldogs, Lhasa apso, and cocker spaniels.


Uveitis is a condition that makes the middle layer of your dog’s eye inflamed. It can make your dog’s eye swell and its blood vessels grow in an attempt to heal the area. 

Increased blood flow to the area can even create a bloody spot in the corner of your dog’s eye. Common causes of uveitis are injury, trauma, cataracts, cancer, autoimmune diseases


This is a common dog condition that is characterized by inflammation of the area’s mucus membranes. It can also cause thick red veins in the eye and swelling. While conjunctivitis usually affects both of your dog’s eyes, it can only affect one sometimes. 

Common causes of conjunctivitis are infections, parasites, allergies, and tick-related diseases.


This common dog condition is primarily caused by increased pressure in the eye. For the most part, it is inherited. However, it can be related to other diseases like uveitis, tumors, and lens damage. 

Glaucoma can lead to a thick red vein appearing in your dog’s eye and overall redness in it. In acute cases, it can also cause squinting, lethargy, loss of appetite, intense pain, and blue cornea tint. Glaucoma can either show up suddenly or slowly develop over time. 

Lens Luxation

Lens Luxation is a term describing the displacement or dislocation of an eye’s lens – this can either be forward or backward. This is serious because of the big role the lens plays in your dog’s ability to see. It is located behind the iris and focuses light rays before sending them to the retina. 

Common causes of lens luxation are glaucoma, uveitis, injuries, and genetic disorders. Lens luxation usually makes your dog’s eye inflamed, red, and swollen. Sometimes, you can even see the displaced lens moving around in your dog’s eye. 

Corneal ulcer

The cornea is the clear lens that is on top of your dog’s eye. When an empty body enters the eye or scratches it, an ulcer can develop – this is what is referred to as a corneal ulcer. Other causes of corneal ulcers are eye and eyelid conditions like dry eye.

The most dangerous thing about corneal ulcers is that they can easily lead to infections. Beyond that, corneal ulcers on their own can cause inflammation, redness, and swelling. To make the situation better, though, the eye’s blood vessels grow and supply more nutrients to the area. 

When corneal ulcers remain untreated, they can even cause eye discharge, lethargy, and loss of appetite.

What Can I Do About My Dog’s Eye Vein?

When you notice that your dog has a thick red vein in its eye, there are 2 main things you can do. These are:

Take Your Dog to The Vet

The safest and most common course of action when it comes to dealing with thick red veins in your dog’s eye is going to the vet immediately. While this condition by itself may not warrant immediate medical intervention, it does when accompanied by other more alarming symptoms. One of the biggest signs that it’s time to see the vet is severe redness and swelling. 

So if you notice that your dog’s eye is bulging out or its white area is completely red, take it to the vet immediately. Another sign that you need to consult a vet is when your dog’s eye is closed 24/7. This indicates that the eye is too swollen and/or painful for your dog to open. 

It’s also important to seek medical intervention when you know that your dog injured their eye, even when the injury is minor. This is also a great move if you notice that your dog is disoriented, in chronic pain, or is consistently acting out of character. You should also take your dog to see a professional if you notice that the red vein in its eye has gotten too thick.

Keep in mind that these veins get thicker and thicker as the eye pressure increases. So if you ignore their growth, you may wake up one day and find out that these vessels have burst because of excessive pressure. Although this is rare, it’s not impossible. 

Wait for A Little While and See

If your dog doesn’t exhibit any of the alarming symptoms we have discussed in the previous section, you can wait and see if the red vein will resolve on its own. However, don’t wait too long – eyes are usually pretty sensitive. Ultimately, it’s still advisable to talk to your vet and book an appointment with them if the situation doesn’t seem to be getting better within 24 hours. 

Even if your dog isn’t in dire condition, seeing a vet will at least put your mind at ease. Whatever you do, though, don’t try to treat your dog’s eye vein or any other of their eye issues at home. The eyes are a sensitive part of your dog’s body and should not be interfered with by anyone other than a vet. 


No matter how you look at it, seeing a thick red vein in your dog’s eye is a bad sign. At the very least, it could indicate that your dog has allergies or dry eye – at worst, it could be a sign of glaucoma, lens luxation, or a corneal ulcer. So if this condition persists, escalates, or is accompanied by other alarming symptoms, go to the vet immediately. They are the only ones who can effectively diagnose and treat your dog. 


  • Brad

    Hi I'm Brad, the founder of bulldogpapa.com. Having been a vet of 6 years I work alongside our team to provide valuable insight into your dog's health. I have a frenchie myself named Senzu who is my pride and joy!