Chemotherapy in dogs is normally given at doses that are as high as possible. This is to try to rid the body of as many cancer cells as we can, although some dogs will have occasional side effects related to the use of conventional chemotherapy.
For this reason, there is interest in using lower doses of chemotherapy to simply try to control spread of the disease, and perhaps increase lifespan, while also reducing the odds of side effects.
Canine hemagiosarcoma is a tough cancer. This cancer grows from the walls of blood vessels, and is often found in the spleen, although sometimes can occur in the liver, heart, eye, skin, and other sites in the body. Hemangiosarcoma in the dog tends to resist the effects of chemotherapy generally, although there are chemo protocols that exist to try to increase lifespan. These usually contain the drug doxorubicin.
However, the use of high doses of doxorubucin for dogs with hemangiosarcoma may only increase life span by a few months, in comparison to dogs who did not receive chemotherapy at all. Additionally, there are occasional cases where doxorubicin may injure the heart, as well as other side effects.
Recently, a new protocol has been developed that does not use high dose doxorubicin, and has some real promise for dogs with this disease. The strategy is called metronomic chemotherapy, which is covered in The Dog Cancer Survival Guide in detail. However, the short story is this: metronomic chemo uses low doses of chemo, given at home (pills or capsules), which are meant to help the immune system and lessen the growth of blood vessels that aid cancer growth. Although these beneficial effects can also be seen with the use of certain botanicals, the research for these pharmaceuticals in dogs is strong.
A paper came out in 2011 which looked the effects of a cocktail of 3 different oral medications (cyclophosphamide, piroxicam, and etoposide) on hemangiosarcoma in the dog. The amazing thing was that these dogs could be medicated at home, instead of requiring an IV infusion in the veterinary hospital. The side effect rates were low. And the results were better than the normal protocol using doxorbucin. The disease-free interval (the time where there are no more signs of the disease) using the low dose protocol was 178 days, compared to 126 days on the traditional doxorubicin protocol!
It is true that there were not many dogs in the study, but nonetheless, this is a very encouraging result, and can be an option for guardians who are coping with hemangiosarcoma dog cancer.
I hope this helps,