Dogs of any age can be susceptible
to hemangiosarcomas - malignant tumors arising from blood vessels - but those
middle-aged and over 8 are especially vulnerable. The aggressively spreading
cancer may go undetected until the last stages, making it a silent killer.
Although they can be found almost anywhere in the body, about 80 percent of all
heman giosarcomas begin in the spleen, said John Berg, DVM, chair of the
Department of Clinical Sciences at the Cummings School of Veterinary Medicine
at Tufts University. The spleen, a large organ in the abdomen, stores blood,
among other functions. “Fewer hemangiosarcomas arise in the heart and fewer
still in other sites, such as the skin, “he said. “And although not directly
heritable, there appears to be a predisposition among purebreds - particularly large
breeds such as German Shepherds, Labradors and Golden Retrievers. “Surgery can
often cure the form of the disease affecting the skin. In that location, the
tumor often doesn’t metastasize, or spread, to distant sites. Otherwise,
hemangiosarcomas are rarely curable. As long as expectations are realistic,
however, temporary remissions are possible. “Many dogs recover quickly from
tumor removal surgery and, although they may only have a short time left, the
quality of life during this time can be excellent, “said Dr. Berg, a surgical specialist.
Because splenic hemangiosarcomas develop internally, they often give little warning
until they become quite advanced. The spleen may suddenly begin bleeding, and
blood may enter the abdomen. “A dog may exhibit sudden weakness or he may
collapse,”Dr. Berg said. “His gums look pale and his pulse is rapid. He is in
danger of going into shock or even dying. If this happens, consider it an
emergency and get your dog to a veterinarian.”
DISTENDED ABDOMEN
An alternate scenario occurs when
the tumor grows slowly within the spleen without bleeding. “The dog’s abdomen
may become quite distended,” said Dr. Berg. “The tumor may grow as large as a
basketball and weigh five pounds or more. Owners may not recognize the presence
of a tumor of this size because organs within body cavities, such as the liver,
lungs, kidney or spleen, have a lot of reserve capacity, and tumors within them
often must become very large before they make a dog feel ill. Also, tumors
within the body are difficult to see or feel until they are quite large.
“Understandably, dogs with such tumors may act “off, “exhibiting low energy and
reduced appetite. They may tire easily, and they may experience weakness, rapid
breathing and depression. In some instances, veterinarians find
hemangiosarcomas during a physical exam. Abdominal swelling may suggest the
disease in an older, large-breed dog. Bloody fluid aspirated from the abdomen
is even more suggestive. For hemangiosarcomas of the spleen and heart, the key
test is ultrasound, said Dr. Berg. “In splenic hemangiosarcoma, the image
shows a huge mass - the primary
tumor - attached to the spleen.”
It might also re- veal metastases to
the liver. Veterinarians take X-rays to rule out metastases to the lungs.
Without treatment, the average time from the tumor’s discovery until death of
affected dogs is under two months. Some dogs die suddenly after showing no
symptoms apparent to their owners. When an older, large-breed dog dies
suddenly, owners might consider an autopsy. A diagnosis of hemangiosarcoma can
prevent agonizing over possible reasons for the death of a beloved pet.
SPLEEN REMVAL
If no definitive evidence of
advanced metastases is found, veterinarians usually recommend a splenectomy -
removal of the spleen - for splenic hemangiosarcoma. Dogs tolerate this
relatively simple surgery well. Certain tumors involving the heart can also be
removed, although this surgery is more complex and entails a slightly longer
recovery period. “Removal of the spleen makes the dog feel normal again and
prevents sudden bleeding that the tumor might otherwise cause,” Dr. Berg said.
Virtually all dogs undergoing removal of heart or splenic hemangiosarcomas will
eventually die of metastatic disease. Their average lifespan with treatment is
four months; however, the added time is important to many owners. When the end
does approach, most dogs will develop signs such as sudden weakness, breathing
difficulty or poor appetite At that point, owners should consult their
veterinarian, and if advanced metastases of the tumor are confirmed, euthanasia
should be considered. Radiation therapy usually doesn’t play a role in the
treatment of hemangiosarcomas. And although chemotherapy may be given in an
effort to slow the growth of metastases, it’s not likely to cure the cancer,
Dr. Berg said. “If owners want to feel they’ve done everything possible and
perhaps obtain some more time for their dog, they may consider chemotherapy. However,
there are no definitive studies proving it prolongs survival times. “Because
the chemotherapy doses used in animals are lower than those used in people, dogs
receiving chemotherapy usually don’t experience severe side effects, he said. “The
expense may be a bigger factor in a dog owner’s decision whether to go with chemotherapy.”A
typical regimen of chemotherapy in a large breed dog may cost $1,000 to $3,000.Surgery
remains the cornerstone of treatment for splenic hemangiosarcoma. “For some owners,
the prospect a good quality of life for several months makes the surgery worthwhile,”
Dr. Berg said. “It may give a dog another spring, summer or fall, and hours and
hours of quality time with his owner.
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