Help! My Dog Has A Splenic Tumour

One of the most common tumours of dogs is haemangiosarcoma of the spleen. This is a malignant cancer of blood vessels found especially in large breeds like German Shepherds. But just because they’re common doesn’t mean that every lump on a dog’s spleen is malignant.

Many of these dogs can go on to lead a normal life with the right treatment. Others cannot be saved, and treatment could do more harm than good.

Here I’m going to help you decide what to do if a vet finds a mass in your dog’s spleen.

Signs Of Spleen Tumours

There are three ways your vet might diagnose a splenic mass:

  1. They might find it without any symptoms during a health check (vets routinely feel the spleen during a physical exam)
  2. The mass might rupture, leading to sudden collapse or a swollen abdomen secondary to internal bleeding
  3. A dog may start losing weight or become lethargic and the cause is found after investigation

The decision on whether to operate is often based on the chance of complete cure, which is only possible if the mass is benign. However, we don’t have any way to be 100% sure before surgery. All we can do is show you the odds based on your dog’s situation.

Splenic Masses: The Odds Of Malignancy

Here’s what we know:

  • Overall, half to two thirds of splenic masses are malignant depending on the study (I believe it to be 50%*)
  • Splenic masses found without symptoms are malignant only 30% of the time
  • If a mass has bled into the abdomen, the odds of malignancy are around 70%.
  • Small-breed dogs are more likely to have benign disease
  • A dog with signs of weight loss or poor appetite is likely to have late stage disease

Once your vet performs some tests, we can further finesse these odds:

  • Masses being found on the liver at the same time increase the chance of malignancy to at least 75% (especially if more than one)
  • The smaller the mass is when it causes symptoms, the worse it is
  • The presence of low blood platelets or nucleated red blood cells worsens the odds

If you have access to both blood tests and a good ultrasound examination, there is even an online tool designed to help you estimate the odds of malignancy. Find it here.

* Some studies have drawn their subjects from emergency services, which leads to a higher percentage of serious cases that in the general population

How Long Dogs Live With Splenic Tumours

The lifespan after diagnosis mainly depends on whether the mass is benign or malignant (cancerous). This is why an estimation of the odds of malignancy is so important.

  • If the mass is benign, surgical removal is mostly curative and lifespan is around normal
  • If the mass is malignant, survival times after surgery are typically less than 60 days

While there’s nothing wrong with a surgery that gives 1-2 months of good quality life, most people would not choose to operate if they knew, and that’s OK. These dogs are probably best kept comfortable and quiet until a humane decision is needed.

I’ve written before about how haemangiosarcoma is the disease often associated with so-called miracle cancer cures. Most of the time these cases will have had a benign lesion mistaken for a malignant one. This only goes to show how hard it is for everyone.

The reality is that you will never know with certainty before the spleen is removed, and it’s OK to base your decision on the little you have. No one should ever feel they have to operate. However, I hope I’ve given you a realistic guide for what to do if it happens to your dog.

Have something to add? Comments (if open) will appear within 24 hours.
By Andrew Spanner BVSc(Hons) MVetStud, a vet in Adelaide, Australia. Meet his team here. The information provided here is not intended to be used as a substitute for going to the vet. If your pet is unwell, please seek veterinary attention.

Some Light Reading!

Cleveland, M. J., & Casale, S. (2016). Incidence of malignancy and outcomes for dogs undergoing splenectomy for incidentally detected nonruptured splenic nodules or masses: 105 cases (2009–2013). Journal of the American Veterinary Medical Association, 248(11), 1267-1273

Eberle, N., Von Babo, V., Nolte, I., Baumgärtner, W., & Betz, D. (2012). Splenic masses in dogs. Part 1: Epidemiologic, clinical characteristics as well as histopathologic diagnosis in 249 cases (2000-2011). Tierarztliche Praxis. Ausgabe K, Kleintiere/Heimtiere, 40(4), 250-260

Mallinckrodt, M. J., & Gottfried, S. D. (2011). Mass-to-splenic volume ratio and splenic weight as a percentage of body weight in dogs with malignant and benign splenic masses: 65 cases (2007–2008). Journal of the American Veterinary Medical Association, 239(10), 1325-1327

Leyva, F. J., Loughin, C. A., Dewey, C. W., Marino, D. J., Akerman, M., & Lesser, M. L. (2018). Histopathologic characteristics of biopsies from dogs undergoing surgery with concurrent gross splenic and hepatic masses: 125 cases (2012–2016). BMC research notes, 11(1), 1-5.

O’Byrne, K., & Hosgood, G. (2019). Splenic mass diagnosis in dogs undergoing splenectomy according to breed size. Veterinary Record, 184(20), 620-620

Stewart, S. D., Ehrhart, E. J., Davies, R., & Khanna, C. (2020). Prospective observational study of dogs with splenic mass rupture suggests potentially lower risk of malignancy and more favourable perioperative outcomes. Veterinary and comparative oncology, 18(4), 811-817

Wendelburg, K. M., Price, L. L., Burgess, K. E., Lyons, J. A., Lew, F. H., & Berg, J. (2015). Survival time of dogs with splenic hemangiosarcoma treated by splenectomy with or without adjuvant chemotherapy: 208 cases (2001–2012). Journal of the American Veterinary Medical Association, 247(4), 393-403

15 Replies to “Help! My Dog Has A Splenic Tumour”

  1. My 9 year old bulldog mix just had his spleen and a mass removed. His symptoms were loss of appetite. He was pink and his chest films were clear. No hemoabdomen. They sent it out for pathology and we should hear in about a week or so. My question is, do the masses look different to the eye and feel different? The surgeon mentioned the mass was “firm” and that seemed to indicate a poor outcome to her but she said best to see what pathology shows.

    1. Hi Lauren. I don’t think you can make any good judgements from the appearance of the mass itself. It is a good sign that no other ones were found though.

  2. Hi my 11 yr old Cairn terrier (male nuetred) was in the 2, 2/3 category of most likely benign mass (Dr Sue Ettinger “cancer vet” videos and readings) back in Feb 2023. A visit to the vet for suspected cruciate ligament damage was the catalyst for X-ray then ultrasound. Despite this local vet diagnosed hemangiosarcoma (HSA) of spleen based on x-ray and ultrasound. He called and said there’s a large mass on the spleen. I did quite a bit of reading over the next 2 hours when the vet said to come in to discuss. Armed with some very useful information I questioned how he knew it was HSA. Replied because it looks like it. Also said could do a fine needle aspiration which based on my reading was not recommended due to potential to induce a bleed of the mass of was HSA. Dissatisfied I sought a second opinion and long story short surgery revealed was not a splenic mass but a large and small tumour on the liver. Pathology result both benign hepatocellular hyperplasia. Nine months on I’m again waiting to hear from a vet re surgery outcomes. Same deal as above inadvertent discovery of masses on spleen when investigating potential UTI late last week. Pathology report from previous surgery did state “this dog may be predisposed to hyperplasia”. Let’s hope so. I did coincidentally find and read the Leyva et al. (2018) paper you have listed above and it gave me some hope re this latest incident. I love my wee Cairn, best friend. Thanks

  3. Hi Andrew. I found this article very helpful. Our girl had a large mass at discovery and had a malignant mammary gland removed in December. We are going to keep her comfortable as long as possible. I don’t want her to undergo a major surgery with the odds not in her favor. I really appreciate your perspective our vet hasn’t been super supportive.

  4. My 10 year old Aussie cattle dog went to emergency vet for what turns out to be mild pancreatitis. Blood tests all normal except mild pancreatitis and very mild elevated liver enzymes. All vital signs were good. The ex Ray showed a very tiny growth on the spleen. So small the doctor didn’t see it only the radiologist. ER vet in too much of a hurry to talk to me but said get an ultrasound. I don’t have a vet. I got her shots from mobile vet. Is there a rush and is ultrasound always necessary and will it tell me if cancer or benign when so tiny? I live in US. Any info you can provide would be appreciated. Thank you so much

    1. Hi Francisca. There is probably a reasonable urgency as (although I don’t have evidence of this) it is likely that as the tumour grows the chance of it spreading increases. In my opinion, all splenic tumours should be removed as soon as they are found. An ultrasound is necessary prior to surgery to ensure that the tumour is only in the spleen.

  5. My 8 year old Havanese had an episode of syncope on Friday, and has been diagnosed with a spleen tumor. He was given a transfusion, and his RBC’s are good, but platelets only improved from 31k-35k. Tomorrow I need to decide risky surgery or just take him home. Worse, there’s no way of confirming malignancy without surgery.

  6. Hi Andrew,
    Echoing Meke’s question, it’s my understanding that if a spleen mass is benign, it can still be dangerous if left in situ because it can rupture. Is this correct?
    Thank you

  7. Andrew, you write that if the mass is benign, surgical removal is mostly curative and lifespan is around normal. What if spleen w/non ruptured mass is not removed? Recognizing we have only “odds” to tell us the mass may be benign, if it is what is the potential lifespan? Is there a risk of rupture even if a mass is benign?

    1. Hi Meke. Vets aren’t much into gambling so this sort of information is not available. We usually only discover the nature of the tumour retrospectively so we can’t really say what would happen if it was left in situ.

  8. Hi Andrew. My dog died with splenic cancer 2month ago. He had speen removed but he didnt live long after surgery. I have been wondering what would have been the best for him.

  9. In a 30 pound dog how much do you think the spleen weighs? The with a mass that seems to be independent of other organs

    1. Hi Robyn. The spleen of dogs is much bigger than it is in humans. It’s hard to give you a size because it varies depending on whether it’s relaxed or contracted (it’s a blood storage organ). I would guess between one quarter and a whole kilogram.

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