Surgical excision is the preferred method of treatment for benign glomus tumors.

Treatment includes chemotherapy and, where practical, removal of the tumor with the affected organ, such as with a splenectomy. Splenectomy alone gives an average survival time of 1–3 months. The addition of chemotherapy, primarily comprising the drug doxorubicin, alone or in combination with other drugs, can increase the average survival time to 2-4 months, or more.

A more favorable outcome has been demonstrated in recent research conducted at University of Pennsylvania Veterinary School, in dogs treated with a compound derived from the Coriolus versicolor (commonly known as "Turkey Tail") mushroom:

“We were shocked,” Cimino Brown said. “Prior to this, the longest reported median survival time of dogs with hemangiosarcoma of the spleen that underwent no further treatment was 86 days. We had dogs that lived beyond a year with nothing other than this mushroom as treatment.”There were not statistically significant differences in survival between the three dosage groups, though the longest survival time was highest in the 100 mg group, at 199 days, eclipsing the previously reported survival time.

The results were so surprising, in fact, that the researchers asked Penn Vet pathologists to recheck the dogs’ tissue biopsies to make sure that the dogs really had the disease.

“They reread the samples and said, yes, it’s really hemangiosarcoma,” Cimino Brown said.

Chemotherapy is available for treating hemangiosarcoma, but many owners opt not to pursue that treatment once their dog is diagnosed.

“It doesn’t hugely increase survival, it’s expensive and it means a lot of back and forth to the vet for the dog,” Cimino Brown said. “So you have to figure in quality of life.”

This treatment does not always work. So, one should always be prepared for their pet to have the same survival time as a dog who is untreated.

Visceral hemangiosarcoma is usually fatal even with treatment, and usually within weeks or, at best, months. In the skin, it can be cured in most cases with complete surgical removal as long as there is not visceral involvement.

Glomangiosarcoma is a low grade tumor of the soft tissue. They rarely metastasize, but metastases are possible. It is also known as "malignant glomus tumor". Positive staining for vimentin has been reported.

A glomus tumor (also known as a "solitary glomus tumor," "solid glomus tumor," or glomangioma) is a rare neoplasm arising from the glomus body and mainly found under the nail, on the fingertip or in the foot. They account for less than 2% of all soft tissue tumors. The majority of glomus tumors are benign, but they can also show malignant features. Glomus tumors were first described by Hoyer in 1877 while the first complete clinical description was given by Masson in 1924.

Histologically, glomus tumors are made up of an afferent arteriole, anastomotic vessel, and collecting venule. Glomus tumors are modified smooth muscle cells that control the thermoregulatory function of dermal glomus bodies. As stated above, these lesions should not be confused with paragangliomas, which were formerly also called glomus tumors in now-antiquated clinical usage. Glomus tumors do not arise from glomus cells, but paragangliomas do.

Familial glomangiomas have been associated with a variety of deletions in the GLMN (glomulin) gene, and are inherited in an autosomal dominant manner, with incomplete penetrance.

Hemangiosarcoma is a rapidly growing, highly invasive variety of cancer that occurs almost exclusively in dogs, and only rarely in cats, horses, mice, or humans. It is a sarcoma arising from the lining of blood vessels; that is, blood-filled channels and spaces are commonly observed microscopically. A frequent cause of death is the rupturing of this tumor, causing the patient to rapidly bleed to death.

The term "angiosarcoma", when used without a modifier, usually refers to hemangiosarcoma. However, glomangiosarcoma (8710/3) and lymphangiosarcoma (9170/3) are distinct conditions [in humans]. Hemangiosarcomas are commonly associated with toxic exposure to thorium dioxide (Thorotrast), vinyl chloride, and arsenic.