What hemangiosarcoma is. In words that actually help.

This is the most common way HSA is discovered. Your dog may have been fine one moment and collapsed the next. At the emergency vet, they'll likely perform a FAST scan — a quick ultrasound to look for free fluid in the abdomen. If they find blood (hemoabdomen), a ruptured splenic mass is the leading suspect.

The ER team will work to stabilize your dog — IV fluids, possibly a blood transfusion — before discussing next steps. This is often when the word “hemangiosarcoma” is first mentioned as a possibility.

Abdominal ultrasound is the primary imaging tool. It can reveal masses on the spleen, liver, or other organs, and detect free fluid. However, ultrasound alone cannot confirm HSA — benign masses like hematomas can look identical. Your vet may say “consistent with hemangiosarcoma” but a definitive diagnosis requires a tissue sample.

PCV / Hematocritis the most critical number. It measures the percentage of red blood cells in your dog's blood. Normal is 35–55%. During a bleed, this drops rapidly. If your vet mentions a low PCV, it means your dog is losing blood internally.

Other markers your vet may check: platelet count (low platelets can indicate bleeding), coagulation panel (how well blood is clotting), and a general chemistry panel to assess organ function.

Chest X-rays are often the first step in staging — they check for visible lung metastasis. A CT scan provides more detailed imaging and may be recommended before surgery to understand the full picture. Not all clinics have CT capability; you may be referred to a specialist.

The only way to definitively confirm HSA is through histopathology — a pathologist examining tissue under a microscope. This usually happens after surgery (the removed spleen or mass is sent to the lab). This means you may not have a confirmed diagnosis before the decision to operate. Your vet is making a best-judgment call based on imaging and clinical presentation.

Sometimes HSA is found by accident — a mass noticed during an ultrasound for an unrelated issue, or a lump found during a routine exam. If this is how you got here, you may have more time to plan, but the emotional weight is just as heavy. The sections below will help you understand what comes next.

For splenic HSA, surgery usually means removing the entire spleen (splenectomy). Dogs do well without a spleen — most bounce back within 1–2 weeks. For cardiac HSA, a pericardiectomy may be performed to relieve pressure around the heart.

Surgery alone does not cure HSA. It removes the primary tumor, but micro-metastasis — tiny clusters of cancer cells too small to see on imaging — is assumed to already exist. Surgery is often the first step regardless of what treatment follows.

The standard post-surgical chemotherapy for HSA is Doxorubicin (Adriamycin), typically given every 2–3 weeks for 5–6 treatments. Each treatment is an IV infusion at your vet or oncologist's office.

Side effects in dogs are generally much milder than in humans. Some dogs experience temporary nausea, decreased appetite, or fatigue for 1–2 days after treatment. Severe side effects are uncommon. Doxorubicin does carry a cumulative cardiac toxicity risk, which is why there's a lifetime dose limit.

What to expect: chemo for dogs is not what chemo looks like for people. Most dogs maintain a good quality of life throughout treatment.

Metronomic chemo uses low-dose oral medications given daily at home — typically cyclophosphamide and a COX-2 inhibitor like piroxicam. It's less aggressive, has fewer side effects, and is significantly less expensive than IV chemo.

It works differently than standard chemo — rather than killing cancer cells directly, it targets the blood vessels that feed the tumor (anti-angiogenic effect). It's often used when standard chemo isn't an option, or as maintenance therapy.

Immunotherapy is a rapidly evolving field for canine HSA. Options include the ELIAS cancer immunotherapy vaccine and Torigen's autologous tumor vaccine. Your veterinary oncologist can tell you what's currently available and whether your dog might qualify.

Clinical trials at veterinary teaching hospitals sometimes offer cutting-edge treatments at reduced cost. Ask your oncologist about current trials, or check with your nearest veterinary university.

When treatment isn't pursued — by choice, by circumstance, or because the cancer is too advanced — the focus shifts to comfort and quality of life. This includes pain management, Yunnan Baiyao for bleeding control, diet optimization, and making every day as good as it can be.

Choosing comfort care is not giving up. It is a valid, loving choice that puts your dog's quality of life at the center.