My Golden Retriever’s CLL Diagnosis: Everything Dog Owners Need to Know About Chronic Lymphocytic Leukemia

No dog parent ever wants to hear that their dog has cancer. Recently, I faced this heartbreaking reality when my senior golden retriever, Koru Bear (KB), was diagnosed with Chronic Lymphocytic Leukemia (CLL).

After receiving this devastating news from his veterinarian, I immediately began researching CLL in dogs—a condition I was unfamiliar with. Most of the articles I read were difficult to understand, and some confused me even more because they were written in complex medical terms.

That’s why I decided to write this article. I gathered all the information I’ve learned (and confirmed it with AI). I want to explain CLL in an easy-to-understand way for fellow dog parents, especially if their dog has been diagnosed with CLL. In this post, I’ll also share KB’s CLL diagnostic journey in the hope that our experience can help other dog parents navigate their dog’s diagnosis.

What is CLL in Dogs?

CLL stands for Chronic Lymphocytic Leukemia. It is a type of blood cancer that affects white blood cells, specifically the dog’s lymphocytes.

What are Lymphocytes?

Lymphocytes are specialized white blood cells that play a crucial role in your dog’s immune system.

Here’s a simple example:
Think of your dog’s white blood cells like tennis balls:

Normal, healthy white blood cells are like good tennis balls:

• Bounces high when you throw it
• Your dog can catch it easily
• It does exactly what it’s supposed to do

In CLL, here’s what happens: Your dog’s body starts making way too many white blood cells – like having tons and tons of tennis balls in your yard.

But here’s a big problem: ALL these new white blood cells are non-functional – like flat, useless tennis balls that don’t bounce, and your dog can’t play with them.

So now your dog has:

• Way more white blood cells than normal (hundreds of tennis balls everywhere)
• But none of them work properly (your dog can’t play fetch anymore because all the balls are flat)
• The extra white blood cells are taking over (like having bad tennis balls taking over your yard)

The Simple Truth: It’s better to have 5 good tennis balls than 100 that don’t bounce. Same with your dog’s cells – fewer working cells are much better than many that can’t do their job.

In other words: In CLL, having MORE Lymphocytes (a type of white blood cell) actually makes your dog’s immune system WEAKER.

Normal dog lymphocyte counts:

900-4,700 cells per microliter (μL) of blood or lymphocytes in each tiny drop of blood

Dogs with CLL have:

A diagnostic threshold of 5,000-6,000 lymphocytes/μL, but treatment typically isn’t needed until counts exceed 60,000/μL or other clinical signs develop (every dog is different, especially depending on age)

2 Types of Lymphocytes

1. B cells
2. T cells (which include CD4 and CD8 T cells)

CLL in dogs is most often a T-cell disease, with CD8 T cells being the most frequent subtype.

2 Blood Tests: How to Determine if Your Dog Has CLL

1) CBC (Complete Blood Count) This is the first test your vet will ask for. Think of it like counting everything in your dog’s blood:

• How many red blood cells?
• How many white blood cells?
• How many lymphocytes specifically?

Typically, if there’s something suspicious in your dog’s blood count, a pathologist will review the results and make some recommendations.

2) Flow Cytometry This is a sophisticated test that analyzes each individual cell more closely. Think of it like giving each cell an ID check:

A pathologist will review the results, provide an assessment, and may recommend further testing.

Take Note: You have a right to ask your vet for copies of your dog’s blood test results.

Dog’s CLL Symptoms You Might Be Ignoring: 5 Most Common CLL Symptoms:

1. tiredness/lethargy
2. loss of appetite
3. weight loss
4. pale gums
5. bruising easily

Some dogs, like my golden retriever KB, did not exhibit visible symptoms and were only discovered to have elevated lymphocytes through a CBC test (which I’ll share more about later in this post).

CLL in Dogs is Rare and Slow Progressing

• CLL in dogs is considered a rare form of cancer, affecting only a small percentage of dogs. The most common dog breeds are Golden Retrievers, German Shepherds, Boxers, and English Bulldogs.
• Good News: It’s slow-progressive, which means it develops gradually over months or years.
• The slow progression allows dog parents time to monitor the condition and plan for treatment
• Many dogs maintain a good quality of life for extended periods
• Early detection through routine blood work is key since symptoms develop gradually

There’s No Cure for CLL — Only Treatment

• Unfortunately, there is No Cure for CLL in dogs
• Treatment helps manage the disease
• Main focus: control symptoms
• Ultimate goal: keep dogs comfortable and maintain quality of life

My Golden Retriever’s Chronic Lymphocytic Leukemia Diagnosis

Skin Ear Inflammation to Unexpected Blood Test
Weather changes affect my senior golden retriever KB’s right ear. There’s no ear infection; his skin just gets red and inflamed. So, I called the vet for a refill of an anti-inflammatory prescription. Since it had been 6 months since this medication was prescribed, a blood test (CBC) was required to ensure there were no other underlying conditions.

Blood Test Shows Elevated Lymphocytes
After two days, I received a call from KB’s vet, who informed me that his lymphocyte count (white cells) was high, also a clinical pathologist reviewed the test results (which she did not expect). She asked to bring KB for a physical check-up and a follow-up blood test. KB’s physical check-up was good; no alarming swollen lymph nodes. He had his blood taken for another CBC test.

2nd CBC Same Elevated Lymphocytes
Unfortunately, the second CBC result showed the same elevated lymphocyte count of 10,000+. KB’s vet also consulted with an oncologist and was told it’s an early stage of CLL, and at this time, no treatment is needed.

3rd Test: Flow Cytometry Test
To confirm, we opted for another type of blood test: flow cytometry. The test results showed an increase in CD8 T cells (lymphocyte T cells), which could indicate a developing cancer like T-cell leukemia. Also, almost three out of four (74%) of these white blood cells had little granules (tiny dots) inside them, which isn’t typical. To confirm the diagnosis, the pathologist suggested further testing – a PARR assay or Ehrlichia tests.

4th test: Ehrlichia Test
KB’s vet provided us with some hope that it might be just an infection. If it were, it could be treated immediately, and his lymphocyte count should go back to normal.

As suggested by the pathologist, we had KB tested for Ehrlichia – a test that checks if your dog has been exposed to a disease called Ehrlichiosis (a tick-borne disease).

I was hopeful, but unfortunately, the result came back negative, and KB’s vet confirmed that we have enough evidence that KB has CLL.

Final Diagnosis: Early stage of CLL (Chronic Lymphocytic Leukemia)
As I mentioned, since we caught it early, no treatment is needed. Why? The oncologist explained that starting treatment too soon could actually cause more harm by making cancer cells resistant to medication and destroying KB’s healthy cells, which would leave him at risk for infections. This is actually the best approach for early-stage CLL.

Currently, KB is on a “Watch and Wait” approach: We will be monitoring his lymphocyte count and will only start medication when he actually needs it. We are going to focus on what matters most and cherish every single moment with him.

Other FAQ’s about CLL in Dogs

1. At what age is CLL most common in dogs?
CLL in dogs is most commonly diagnosed in older dogs, typically around 10–12 years of age. It’s considered a disease of senior dogs, though it can occasionally appear in dogs as young as 7–8 years old.

2. What causes CLL in dogs?
The exact cause is unknown, but it may involve genetics, age, or changes in the immune system.

3. Is CLL painful for dogs?
CLL itself isn’t usually painful, but it can cause discomfort through related symptoms

4. Does diet or lifestyle affect CLL?
A healthy diet, exercise within comfort levels, and stress reduction can support overall health, but they don’t cure CLL.

5. Is CLL contagious?
CLL is NOT contagious – it cannot be transmitted from one dog to another through sharing water, food bowls, or any other contact.

My Final Thoughts: CLL in Dogs

Receiving a CLL diagnosis for my senior dog was devastating and completely unexpected. However, I’m grateful we caught it early, especially since KB will be turning 9 this November. I know that with this diagnosis and his age, he’ll need extra attention and careful monitoring, but I’m committed to ensuring he maintains the best quality of life possible.

As a concerned dog parent, I understand the heartache and confusion that comes with receiving an unfamiliar diagnosis or wanting to learn more about your dog’s condition. I hope this simplified article about CLL in dogs helps fellow dog parents understand this diagnosis and provides useful guidance. If you’ve experienced CLL with your dog, I’d love to connect.

Although there is no cure for CLL in dogs, there is still hope. Through early detection and a “watch and wait” approach, we can provide our dogs with the best possible care while cherishing every moment together.

Whether you have questions, want to share your dog’s CLL experience, or know additional information I should include, please leave a comment below. I’ll continue documenting KB’s journey and sharing what I learn about CLL in dogs because educating myself and fellow dog parents about this disease helps us celebrate the love and joy our dogs bring to our lives.