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Cancer of the Blood Vessel Cells in Dogs

Hemangiopericytoma in Dogs

A hemangiopericytoma is a malignant vascular tumor that originates from pericyte cells, which are associated with blood vessels. The term “hemangio” pertains to blood vessels, while pericytes are a type of connective tissue cell.

Hemangiopericytoma affects the cells surrounding small blood vessels (capillaries) in subcutaneous tissue. Pericytes are initially non-specialized cells, originating from embryonic cells. Rather than assuming specific functions, they remain in their initial stage until required by the body. Pericytes’ primary function is to differentiate into various cell types as needed for tissue regeneration. However, in the case of hemangiopericytoma, pericytes undergo improper cell division, resulting in tumor formation instead of useful tissue.

While hemangiopericytoma typically does not metastasize widely, it steadily grows at its origin site. Over months to years, the tumor expands within its location, impacting nearby organs and potentially compromising their function. This situation can be critical when the tumor develops in the chest vicinity, near vital organs like the heart and lungs. Fortunately, successful treatment rates for this tumor are high, but intervention is necessary before it becomes unmanageable. Although relatively uncommon, metastasis occurs in approximately 20 percent of patients. In dogs, hemangiopericytoma is more prevalent in large breeds than in small breeds.

Symptoms and Types

  • A slow-growing mass may develop over weeks or months, typically observed on a limb.
  • In the case of a high-grade variant tumor, rapid growth may occur.
  • The mass can feel soft, fluctuant, or firm, commonly found on a limb, although occasionally present on the animal’s trunk.
  • A small, slowly growing bump or nodule may appear on the body, manifesting as an ulcer, sore, bald spot, or differently pigmented (colored) area.


The precise cause remains unknown.


To diagnose the condition, you’ll need to provide a comprehensive history of your dog’s health leading up to the appearance of symptoms. Following the collection of initial background information, your veterinarian will conduct a thorough physical examination, including routine laboratory tests such as a complete blood count, biochemistry profile, and urinalysis. Typically, the results of these tests fall within normal ranges.

A definitive diagnosis relies on the findings of a biopsy analysis. Your veterinarian will extract a tissue sample from the growing mass and examine it under a microscope to confirm the diagnosis and determine the tumor grade. Additionally, X-rays, computed tomography (CT) scans, or magnetic resonance imaging (MRI) scans may be conducted to assess the extent of local metastasis and the depth of tumor infiltration. These diagnostic studies are crucial for devising a treatment plan and ongoing therapy for your dog.


The primary treatment of choice remains early and aggressive surgical excision of the affected tissue, along with the removal of some surrounding normal tissue to maximize the chances of complete tumor removal. A skilled veterinary surgeon will perform the excision to ensure thorough removal of the tumor. The excised tissue will undergo evaluation by a veterinary pathologist.

Radiation therapy is generally highly effective for this type of tumor and may be recommended in conjunction with surgery. You and your veterinarian will collaborate to determine if a combination of surgery and radiation therapy is the optimal treatment approach for your dog.

Recurrence is common due to the high incidence of regrowth with this type of cellular tumor. Your veterinarian will conduct follow-up visits to monitor the area closely. If recurrence of the hemangiopericytoma occurs, your veterinarian will discuss treatment options with you to make the most suitable decision for your dog.

In some cases, amputation of the affected limb may be considered as it removes the entire affected area. Since this tumor typically remains localized and does not spread widely in the body, amputation can be an effective solution. Another approach involves repeated removal of the growth, possibly combined with radiotherapy, especially when complete removal of the mass is not feasible. However, the drawback is that each recurrence tends to become more invasive than the last, leading to deeper tissue infiltration.

Choosing to take no action may be appropriate, particularly for older dogs, as the tumor grows slowly and may not impact the animal’s health until it reaches a size that affects organs or limbs. However, this may not be advisable for younger dogs.

Living and Management

The overall survival duration significantly relies on the tumor’s characteristics and the extent of surgery and treatment aggressiveness. Dogs that undergo early and aggressive surgical tumor resection stand a chance of being cured. Due to the common recurrence of hemangiopericytoma, regular follow-up checkups or radiotherapy treatments are necessary. Your veterinarian will establish a schedule for progress evaluation visits.

Post-surgery, your veterinarian will prescribe pain medication to ensure your dog’s comfort. Use pain relievers cautiously, as pet overdoses are preventable accidents. Cage rest is advisable after surgery. Provide a quiet area away from household activity, active children, and other pets to aid your dog’s recovery. Placing food dishes close to your dog’s resting area promotes independence. Outdoor trips for relieving itself should be leisurely and nearby. Assist your dog as needed. If required, consult your veterinarian before setting up a temporary relief area indoors, as it may necessitate retraining your dog.

Avoid leaving the dog alone for extended periods. Affection aids recovery, and ensuring your dog doesn’t remain in the same position for too long is crucial. Following limb amputation, most dogs recover well and adapt to compensate for the lost limb.

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