Why Did My Dog Die Suddenly?

It’s incredibly heart-breaking to lose a beloved dog suddenly and without warning. As a veterinarian with over 20 years of experience, I’ve talked with countless clients who lost a dog without even knowing they were sick. Hopefully, if this is what you’ve experienced, this article can provide you with some information and, hopefully, some peace as you deal with your grief.

This article will focus on unexpected causes of death in the dog. Many diseases, such as brain tumors and kidney disease, will have symptoms in the vast majority of cases that are seen prior to a dog dying.

Most Common Reasons Why Dogs Die Suddenly

Purdue University conducted a study over a decade ago where they performed necropsy (like an autopsy on a dog) to determine the cause of death in dogs that had died without warning. Their findings were consistent with what I’ve experienced in practice.

I’m not including trauma in this list because typically someone witnesses the dog being struck or injured and, while that’s heart-breaking, it doesn’t leave someone questioning why the dog died.

Most Common Reasons For Sudden Death:

  • Heart Abnormalities
  • Internal Hemorrhage Not Related To Trauma
  • Gastric Bloat/GDV
  • Ingested Toxin

There are some other potential causes of sudden death in dogs such as an embolism, but this is a fairly rare occurrence. Let’s focus on the most common causes.

Heart Abnormalities

The kind of heart problems that can lead to sudden death usually involve ones that involve arrhythmias (abnormal heart beat).

The most common types of arrhythmias occur in large-breed dogs with heart diseases such as dilated cardiomyopathy or boxer cardiomyopathy. There are, however, some smaller breeds of dogs that can be affected by a condition known as Atrioventricular block.

How would you know your dog has a condition that could cause an arrhythmia?

  • Regular checkups with your veterinarian can help to catch heart problems
  • Sometimes fainting spells (called syncope) can be a prelude to a sudden death
  • Another symptom can be exercise intolerance – your dog has always loved to play ball but now won’t even get up to play or plays very little compared to how it used to be

Internal Hemorrhage Unrelated To Trauma

By far, the most common reason a dog suddenly starts bleeding internally is cancer. We tend to see this mostly in larger breed dogs (bigger than 40 lbs) but it could happen at any size.

The most common cancer that causes bleeding is hemangiosarcoma. In simple terms, this is cancer of the blood vessels.

Hemangiosarcoma is typically found in one (or more) of the following locations:

  • Spleen
  • Liver
  • Heart

Are there symptoms of internal bleeding that you can catch? If a dog begins to bleed from a tumor in the abdomen, you will begin to see a sudden change in the size of that abdomen. Most people think their dog is bloated and certainly bloat and internal bleeding can be difficult for the average person to tell apart.

Bloat is described further below, but when you tap your finger on a bloated abdomen it will sound like a thump (think of a big drum). It will also seem fairly hard. When a dog’s abdomen fills with blood, the sound that your tapping makes is much more muted. They will also have what is called a “fluid wave.” This describes what it feels like when you push in one one side of the abdomen and feel the pressure radiate to the other side (has to be done while the dog is standing).

What If My Dog Has Bleeding Around The Heart?

Hemangiosarcoma (and there are a few other cancers) can also be found on the “base” of the heart. The base is where all the blood vessels congregate to bring blood in and out of the heart. If a tumor grows on one of these vessels, it will eventually weaken the vessel and can cause a quick accumulation of blood in the pericardial sac.

The pericardial sac is just what it sounds like – it’s a layer of tissue that holds the heart in place and separates it from the rest of the chest. If blood fills this sac, it begins to prevent the heart from expanding and contracting like normal. This will result in a decrease in blood flow out of the heart to vital organs such as the brain, kidneys, etc.

Dogs that have this happen to them will become weak either very suddenly or over the course of a day or so. They will have pale gums, likely be breathing faster than normal, have a rapid heartrate, but they won’t have the swollen abdomen usually associated with blood loss internally.

As a veterinarian, the other physical exam signs that I can usually detect is a muffled heart sound (the fluid preventing the normal heartbeat from being heard clearly)

Gastric Bloat/GDV

When a dog dies of bloat or GDV, it’s usually fairly obvious to the trained eye. The abdomen will be distended and it sounds almost hollow if you tap on the side. That’s the air trapped in the stomach creating that sound.

GDV, or gastric-dilatation-volvulus (stomach-swelling/bloating-twisting), is an often fatal condition that follows bloat. Think of how a full balloon twists and turns on it’s axis (where it’s tied). The stomach can do the same thing in the abdomen when bloated.

Ingested Toxin

Toxins rarely cause a quick death but it is possible. The vast majority of toxins that are ingested will cause symptoms such as vomiting, seizures, abnormal mentation, etc.

If you suspect toxin ingestion, discuss with your veterinary about doing a toxin screen post-mortem.

Can Dogs Have Heart Attacks?

Humans have heart attacks when their coronary arteries become blocked enough that the heart muscle can’t receive proper blood flow and stops working. Thankfully, dogs don’t live long enough to be able to develop the kind of plaque in their coronary arteries.

However, dogs can have a sudden heart stoppage due to an arrhythmia. Boxer cardiomyopathy and Dilative cardiomyopathy would be two examples of diseases that can cause arrhythmias to the point where the heart stops.

In some cases, a murmur or an occasional arrhythmia may be detectable by a veterinary during an exam. However, a thorough evaluation with a veterinary cardiologist is the best way to determine if a murmur or arrhythmia needs to be more seriously treated.

What Do I Do When I Find My Dog Suddenly Dead?

In the terrible situation in which you come upon your dog and it is truly gone, there are a few options as to what you can do next.

  • Some owners want to know exactly why their dog died (especially when there was no warning). These owners can contact their veterinarian or a emergency veterinary clinic near them to have a necropsy performed. In a necropsy, a veterinary will examine the dog both inside and outside looking for any abnormalities. This will involve opening both the abdomen and chest cavity to look at the individual organs (including inside the heart). If needed, biopsy samples can be submitted to a pathologist to check for toxins or microscopic abnormalities (such as a cancer diagnosis).
  • If this isn’t your wish, then your next options are either a home burial or cremation. Depending on where you live and the amount of land that you own, burial may be possible and legal.