Swelling (Edema) in Dogs: What is the Swelling on My Dog?

Last time, we covered potential swelling causes that are so major that it might appear as sudden weight gain.

Typically, though, when talking about swelling, you’d imagine something much more localized, whether on the face, limbs, or anywhere else on the body. An example that most likely comes to mind is swelling due to a bug bite or sting.

Swelling (Edema) in Dogs

Insect bites and stings

Insect bites and stings are a common cause indeed.

Even with that, though, it does not mean you ought to automatically dismiss that as something trivial. On the contrary, you should be aware of any poisonous critters whose bite could seriously harm your dog, depending on where you live.

Most of the time, bug stings and bites are not an emergency. But if your dog is allergic, it can become one quickly if the swelling progresses to the throat or if your dog goes into anaphylactic shock. Do you know what signs you need to be watching for?

Even higher vigilance is needed when it comes to spiders, scorpions, or snakes. Do you know what venomous critters are crawling around in your area? Some are deadly in themselves, and even bites from relatively benign ones can result in massive infections. If you suspect your dog got bitten by a venomous spider or a snake, seek medical help immediately.

The swelling caused by an insect bite/sting is called urticarial or angioedema. It is a hypersensitivity (or allergic) reaction.

Dental issues

Besides insect bites/stings, a common cause of facial swelling is a tooth abscess.

While edema happens when small blood vessels leak fluid into tissues or body cavities, usually as part of the immune response, an abscess is filled with pus. Where there is pus, there is generally an infection. Besides fluid, it also contains white blood cells, dead tissue, and debris formed as the body fights invading organisms.

An abscess is more defined than a swelling, though further swelling can be around it. An abscess is painful to touch.


A hematoma is an accumulation of blood in places where it doesn’t belong, outside the blood vessels. A hematoma is usually caused by trauma leading to the rupture of blood vessels. For example, an ear hematoma is caused by trauma to blood vessels in the ear flap, commonly from excessive head shaking in response to an ear infection. Hematomas are generally painful.

Swollen lymph nodes

Lymph nodes are part of the immune system and can swell readily in response to local or systemic causes. For example, locally, in response to an infection or another inflammatory event. The scary part is that cancer, lymphoma, is one of the potential causes of lymph node swelling. Even more frightening, such swelling can look precisely like swelling from any other, less dangerous cause.

So how do you know what you’re looking at?

That’s the thing, isn’t it? For the most part, you don’t. And that’s leaving hard lumps and bumps aside.

Case in point, JD’s swelling above his eye. We figured it was a bug bite or sting when it happened the first time. I gave him some Benadryl, and it brought it down. Except it popped up again two days later, in the same place. And it wasn’t going away the second time around.

JD’s vet poked him and prodded. There was no dental issue. There was no eye issue. There was no evidence of a foreign body or infection around the eye. However, that same week they had two similar cases, both caused by a splinter in a soft palate with the infection finding its way out the best way it could, swelling up over the eye. “Does JD chew sticks,” they asked? Yes, sometimes he did.

JD got antibiotics, and the swelling went away. Two weeks later, this time, it returned. You can read the rest of the story here.

Whether it was the infection that made its way to places the antibiotics couldn’t deal with or whether it was cancer, it was JD’s undoing. My motto? You can never be paranoid enough, particularly if swelling isn’t behaving as expected.

Sometimes, things work out better than you’d expect to take some edge off. For example, when Jasmine’s neck lymph nodes swelled overnight enough to cause severe coughing, we feared lymphoma. Yet, after two days of therapeutic trial with antibiotics, she was back to normal.

Err on the side of caution

Even I don’t run to a vet with every bee sting. But when that happens, I have one foot out the door. I watch how large it gets, where it spreads to, whether there are any other concerning signs. I am less worried about a bee sting in the foot than in the face, but even that one could cause anaphylaxis with a bit of bad luck.

With any other swelling, particularly those that stay for more than a day, are painful or cause further trouble, I’m on my way to a vet. If I suspected a venomous bite, I’d be burning rubber.

Related articles:
Symptoms to Watch for in Your Dog: Sudden Weight Gain

Further reading:
Swelling in Dogs

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Jana Rade edited by Dr. Joanna Paul BSc BVSc

I am a graphic designer, dog health advocate, writer, and author. Jasmine, the Rottweiler of my life, was the largest female from her litter. We thought we were getting a healthy dog. Getting a puppy from a backyard breeder was our first mistake. Countless veterinary visits without a diagnosis or useful treatment later, I realized that I had to take Jasmine's health care in my own hands. I learned the hard way that merely seeing a vet is not always enough. There is more to finding a good vet than finding the closest clinic down the street. And, sadly, there is more to advocating for your dog's health than visiting a veterinarian. It should be enough, but it often is not. With Jasmine, it took five years to get a diagnosis. Unfortunately, other problems had snowballed for that in the meantime. Jasmine's health challenges became a crash course in understanding dog health issues and how to go about getting a proper diagnosis and treatment. I had to learn, and I had to learn fast. Helping others through my challenges and experience has become my mission and Jasmine's legacy. I now try to help people how to recognize and understand signs of illness in their dogs, how to work with their veterinarian, and when to seek a second opinion. My goal is to save others the steep curve of having to learn things the hard way as I did. That is the mission behind my blog and behind my writing. That is why I wrote Symptoms to Watch for in Your Dog, which has turned out being an award-winning guide to dog owners. What I'm trying to share encompasses 20 years of experience. Dr. Joanna Paul BSc BVSc is our wonderful sponsor and has been kind to edit and fact-check my important articles.

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