Angiosarcoma in Cats: Symptoms, Causes, and Treatments Explained by a Veterinarian

Hemangiosarcoma is a malignant tumor that originates in the blood vessels. It mainly occurs in organs such as the skin, liver, and intestines. Although it is a rare tumor in cats, it can cause internal bleeding, and in some cases, it may have already metastasized by the time it is discovered.

In this article, we will provide a detailed explanation of feline hemangiosarcoma.

What is Feline Hemangiosarcoma?

Definition of Hemangiosarcoma

Hemangiosarcoma is a malignant tumor that arises from vascular endothelial cells, which are the cells lining the innermost part of the blood vessels where they come into contact with blood. While it is a common tumor in dogs, it is quite rare in cats. Hemangiosarcoma can occur anywhere there are blood vessels, but it is primarily categorized into the cutaneous type, which occurs in the skin or subcutaneously, and the visceral type, which occurs in organs such as the liver, intestines, or spleen.

Incidence and Trends by Breed and Age

The occurrence of hemangiosarcoma in cats is rare, affecting about 2 in every 100 cats. There is no specific breed predisposed to the condition, but it tends to be observed in senior cats aged 8 years or older. However, it can occur even in younger cats.

Main Symptoms of Feline Hemangiosarcoma

Symptoms of Cutaneous Hemangiosarcoma

The cutaneous type, which develops in or under the skin, presents as red-purple masses on the skin. These masses tend to grow larger over time.

Symptoms of Visceral Hemangiosarcoma

Visceral hemangiosarcoma occurs in organs such as the liver, intestines, abdominal lymph nodes, and spleen. It is prone to bleeding, and may be discovered due to intra-abdominal hemorrhage. Anemia and a decreased platelet count resulting from bleeding may also be observed. As the mass grows inside the abdomen, symptoms such as lethargy, loss of appetite, vomiting, and difficulty breathing can occur.

Progression and Severity of Symptoms

The cutaneous type is considered less aggressive than the visceral type. In the case of the cutaneous type, if the mass is noticed and surgically removed, long-term survival is possible. The visceral type tends to metastasize or develop multiple lesions. In many cases of the visceral type, metastasis has already begun by the time treatment starts, and even with treatment, the life expectancy is generally around six months.

Causes of Feline Hemangiosarcoma

The exact cause of hemangiosarcoma is unknown. In dogs, it is thought that genetics may be involved due to its high incidence in certain breeds, but this is not known for cats. Since there have been reports of hemangiosarcoma associated with foreign bodies in cats, it is possible that ultraviolet light or trauma could be contributing factors.

Diagnosis and Treatment of Feline Hemangiosarcoma

Diagnostic Methods

Because masses on the skin can be felt, pet owners may notice them immediately. However, the visceral type grows inside the abdomen, so it is often only noticed after symptoms appear.

Physical examination is used to check not only for masses but also for swollen lymph nodes. We also check for oral mucosal pallor or subcutaneous hemorrhaging (purpura) as signs of anemia or blood clotting abnormalities.

Imaging tests such as X-rays and ultrasounds are crucial for hemangiosarcoma. These tests are used to determine the location of the mass, the presence of metastasis, and whether there is any intra-abdominal bleeding.

If a mass is identified, a biopsy is required. However, fine-needle aspiration is often inconclusive for hemangiosarcoma, necessitating an actual surgical removal of the mass for pathological examination.

Treatment

Surgery is the first-line treatment for hemangiosarcoma. While the cutaneous type can sometimes lead to long-term survival through surgical excision, the visceral type often involves metastatic disease identified post-surgery, requiring the additional use of chemotherapy.

If the animal's physical condition has deteriorated prior to surgery, it is necessary to first improve their overall systemic state.

Post-Treatment Follow-up

Long-term survival is possible for cutaneous hemangiosarcoma if it is thoroughly excised, but there is a risk of recurrence if it has spread deep into the skin.

For the visceral type, it is a fast-progressing malignancy, and even with tumor removal and chemotherapy, patients often pass away within six months. Metastasis or recurrence is typically observed within a few months. Whether the type is cutaneous or visceral, regular check-ups are essential even after treatment has concluded.

Prevention and Early Detection of Feline Hemangiosarcoma

Importance of Regular Health Checks and Massage

If it is a cutaneous hemangiosarcoma, you may notice a lump on the skin. Therefore, brushing or massaging your cat's entire body while interacting with them is recommended.

Unfortunately, the visceral type is difficult to detect early, and owners often only visit the vet after symptoms appear. While annual health check-ups are desirable, the fast progression of hemangiosarcoma can make it difficult to catch even with yearly screenings. Because hemangiosarcoma is more common in the senior years, health check-ups every six months are recommended.

Daily Life Precautions (UV Protection, Trauma Prevention, etc.)

There is no way to prevent hemangiosarcoma as the cause is unknown. However, since UV exposure is considered a cause of skin cancer in humans, it is probably best to avoid extreme UV exposure.

Prompt Response and Veterinary Consultation Upon Noticing Abnormalities

If hemangiosarcoma is not addressed promptly, metastasis may begin. In the case of the visceral type, it can lead to shock due to bleeding or clotting issues. At that stage, your cat will be lethargic, unable to move, and their mouth or tongue will appear pale, which you will likely notice. This is a life-threatening emergency, so please find a hospital that can provide immediate care. In the stages leading up to this, symptoms such as loss of appetite may appear. It is important to visit a veterinary clinic even for minor changes.

Summary

Although feline hemangiosarcoma is a rare malignant tumor, it can be discovered due to intra-abdominal hemorrhage. Because hemangiosarcoma progresses rapidly, it is difficult to detect early, especially in the visceral type. If you notice even the slightest abnormality, please visit a veterinary clinic immediately. Additionally, senior cats should undergo health check-ups every six months.