One of the most common chemotherapy drugs used today is cyclophosphamide.
This medication can be given at home, as it comes as a pill that is given by mouth. It can also be given as an injection in the veterinary hospital.
One of the side effects that is seen in about 1 in 10 dogs on this drug involves the bladder. The signs you will see if your dog is experiencing this side effect include:
- urinating small amounts frequently
- straining to urinate
- posturing for a long time with little urine being produced
- blood in the urine
- having to go outside more frequently to urinate
These are all signs of bladder inflammation. When the bladder gets inflamed, our dogs feel like they need to go urinate more often. They also feel like they need to empty their bladder more, even when they have passed all the urine they have and their bladder is empty.
We make these assumptions about how they feel since this is what people experience when we have bladder inflammation, which happens with problems like bladder infection.
The reason a dog might get an inflamed bladder while taking cyclophosphamide is this drug can cause a condition called sterile hemorrhagic cystitis (SHC). This can be translated to mean “an inflamed bladder that bleeds without an infection.”
The reason this can happen is that dogs on the drug accumulate a by-product in their bladder called acrolein. This chemical is produced in the body when cyclophosphamide is broken down, and it collects in the urine.
Oncologists will often combine cyclophosphamide with medications like prednisone or prednisolone, which can decrease the odds of SHC. If diuretics are administered when the drug is given in the hospital, it can also lower the risks.
It is important to differentiate SHC from an actual bladder infection, which is also common in dogs with cancer receiving chemo. The signs you see with a bladder infection are identical to SHC, but antibiotics are used to treat an infection. They will do nothing for SHC however, which requires different steps.
So it is important to get your dog’s urine tested if you see these signs to find out if infection or SHC is the real culprit.
The Dog Cancer Survival Guide has a lot of information on how you can address possible side effects from chemotherapy in your dog if you would like more on important topics like this.
Dr. Demian Dressler is internationally recognized as “the dog cancer vet” because of his innovations in the field of dog cancer management, and the popularity of his blog here at Dog Cancer Blog. The owner of South Shore Veterinary Care, a full-service veterinary hospital in Maui, Hawaii, Dr. Dressler studied Animal Physiology and received a Bachelor of Science degree from the University of California at Davis before earning his Doctorate in Veterinary Medicine from Cornell University. After practicing at Killewald Animal Hospital in Amherst, New York, he returned to his home state, Hawaii, to practice at the East Honolulu Pet Hospital before heading home to Maui to open his own hospital. Dr. Dressler consults both dog lovers and veterinary professionals, and is sought after as a speaker on topics ranging from the links between lifestyle choices and disease, nutrition and cancer, and animal ethics. His television appearances include “Ask the Vet” segments on local news programs. He is the author of The Dog Cancer Survival Guide: Full Spectrum Treatments to Optimize Your Dog’s Life Quality and Longevity. He is a member of the American Veterinary Medical Association, the Hawaii Veterinary Medical Association, the American Association of Avian Veterinarians, the National Animal Supplement Council and CORE (Comparative Orthopedic Research Evaluation). He is also an advisory board member for Pacific Primate Sanctuary.