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