If you don’t know what parathyroid tumors are, then you probably have a lot of questions. The good news is that most of them are benign, with only a very small percentage being malignant. Plus, they are highly treatable.
However, they can still cause some serious damage if left unchecked. In this guide, we’ll tell you everything you need to know about parathyroid tumors in dogs. But first, let’s talk about what a parathyroid gland is.
What Are Parathyroid Glands in Dogs?
Your dog has four tiny parathyroid glands in their neck, located right next to the thyroid gland. These little glands are essential for one thing: regulating calcium levels in the blood.
When calcium gets too low, the parathyroid glands secrete a hormone called the “parathyroid hormone” or PTH. This is a hormone that tells your dog’s body to increase calcium levels by getting it from the bones, increasing absorption in the intestines, and reducing loss in the urine.
So, when dogs develop an abnormal mass on one of these glands, that is essentially a parathyroid tumor. While it’s benign in most cases, the biggest problem with this is that the affected gland will continue to release PTH even if your dog’s calcium levels are high.
Parathyroid tumors in dogs are the most common cause of hyperparathyroidism.
Is Hypercalcemia a Problem?
Even then, excessively high calcium levels might not be that bad, right? Well, not exactly. Prolonged periods of heightened calcium levels can lead to several health issues. Namely:
Muscle weakness and tremors
Lethargy and fatigue
Increased thirst and urination
Loss of appetite
What Causes Parathyroid Tumors in Dogs?
The exact causes of these tumors aren’t fully understood, much like many different tumors and growths. Because the disease is quite rare in dogs, it can be hard to identify certain patterns and risk factors.
As of today, the most commonly cited cause is a combination of genetic factors and breed predisposition. Keeshonds are dogs that appear to have a genetic link to this disease. Other possible breeds that can develop this condition include German Shepherds and Labrador Retrievers.
How to Spot the Symptoms of Parathyroid Tumors in Dogs
One of the tricky things about a parathyroid tumor in dogs is that it often flies under the radar. Most dogs show no obvious signs at first, while others develop gradual symptoms that can be mistaken for old age and other diseases. These symptoms are usually tied to hypercalcemia.
Increased thirst. The high levels of calcium will interfere with the kidneys’ ability to concentrate urine, so your dog will compensate by drinking more water. You might notice empty water bowls more often.
Frequent urination. All that extra water your dog drinks has to go somewhere. This means more peeing all throughout the day and night. In some cases, dogs will have accidents indoors.
Loss of appetite. Hypercalcemia can also upset the stomach and make your dog lose its appetite. This is often one of the earliest signs many pet owners notice.
Vomiting or nausea. The high amounts of calcium in the body can often irritate the gastrointestinal tract, resulting in vomiting and nausea.
Lethargy or fatigue. Excess calcium levels can also affect a dog's energy levels, making them feel more sluggish and less interested in their regular activities.
Muscle weakness or tremors. While calcium is essential for maintaining muscle function, too much can cause muscle weakness, trembling, or stiffness.
Weight loss. A combination of reduced appetite, vomiting, and lethargy will result in overall weight loss.
Constipation. High calcium levels can reduce intestinal motility, potentially making it harder for dogs to pass stool.
How Do Vets Diagnose Parathyroid Tumors in Dogs?
General checkups can’t always detect the presence of a parathyroid tumor in dogs. The condition doesn’t have any significant external signs, making it harder to detect at a glance. However, if you notice any of the symptoms, your input will be helpful in the diagnostic process.
The main diagnostic method for detecting parathyroid tumors in dogs is through bloodwork. Blood tests, specifically blood chemistry panel, can check your dog’s overall body condition, with calcium levels as one of its markers.
If your dog’s calcium level is elevated (about 11.5 to 12 mg/dL), then our vets will run additional tests to figure out the cause. Hypercalcemia can stem from many different diseases, including:
Lymphoma
Chronic kidney disease
Ingestion of toxins or vitamin D overdose
This means that several tests will be conducted based on the observed symptoms, markers, and other indicators.
One additional test we use to diagnose parathyroid tumors in dogs after identifying increased calcium levels is parathyroid hormone testing. This tool assesses the function of the parathyroid glands, determining if they produce too much or too little.
It works by collecting a blood sample. This sample is tested through an immunoassay in a specialized laboratory. PTH levels will be measured along with calcium levels.
In the case of parathyroid tumors in dogs, these glands will produce too much. This means that high levels of PTH will be detected, strongly suggesting a parathyroid tumor.
Once we have detected high calcium and PTH levels, we can proceed to diagnostic imaging. We use ultrasounds of the neck to visualize the parathyroid glands. The affected gland will appear enlarged and have a distinct mass. If the tumor is hard to locate, we will use a CT scan.
What Are the Treatment Options for Parathyroid Tumors in Dogs?
Once a parathyroid tumor in your dog is diagnosed, we can proceed to treatment.
Parathyroidectomy
In most cases, surgery will be necessary. The main goal of the procedure is to remove the cause of your dog’s excess calcium levels, which is the tumor. An ultrasound is done to accurately locate the tumor before the surgery.
Our veterinary surgeons will create a small incision from which they can access the diseased parathyroid gland. The gland will then be removed, while the unaffected glands will be left intact. Most dogs only have one affected gland, and removing it will almost always resolve the issue.
After surgery, your dog’s PTH levels drop quickly. This means that your dog will be at risk of hypocalcemia, but this can be easily managed during post-op care. During recovery, we’ll constantly check on your dog’s calcium levels and provide calcium supplements as needed.
Ultrasound-Guided Ablation
Ultrasound-Guided Ablation is a minimally invasive procedure we can consider. Here, we inject ethanol into the enlarged parathyroid gland, destroying the abnormal tissue. We do this by using an ultrasound to see the tumor. After the procedure, your dog’s calcium levels will be monitored.
Prognosis and Recovery for Dogs With Parathyroid Tumors
The success rate for the procedures is high. Once the affected gland is removed, the body’s calcium levels will stabilize with the help of our vets. Most dogs go on to live full and healthy lives without the need for ongoing medication after the recovery process.
While recovery is usually smooth, close monitoring is important in the first week after treatment. The biggest concern we’ll look into is hypocalcemia, which can happen when the other glands haven’t continued to regulate calcium levels on their own.
“The key to keeping a dog healthy is by noticing the smallest changes.”
- Dr. Soheyl Simaei
Final Thoughts
While parathyroid tumors in dogs are uncommon, they are still a potential concern for our dogs. They don’t always show up with dramatic symptoms, but they can silently affect our dogs’ welfare and health. Through regular checkups, we can keep our best friends safe.
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