If your dog is undergoing treatment for cancer or an immune system disease, your veterinary oncologist may recommend a chemotherapy treatment using a drug called cyclophosphamide (also known as cytoxan). Although cyclophosphamide is a beneficial anticancer drug, a small percentage of dogs may experience a side effect known as hemorrhagic cystitis, which literally means "bloody urine."
-
Function
-
Dogs with immune diseases or cancers such as osteosarcoma and lymphoma are often given the anticancer chemotherapy drug cyclophosphamide (cytoxan).
According to the veterinary professionals at Mar Vista Animal Medical Center in Los Angeles, CA, "Cyclophosphamide works by killing cells that are causing harm. It works by binding to DNA, and interfering with normal cell function. By disrupting cellular DNA, cyclophosphamide is able to kill the cell. Cells that divide rapidly (and thus replicate their DNA rapidly) are especially targeted by cyclophosphamide. This makes cyclophosphamide especially able to kill rapidly dividing cancer cells."
Cystitis as a Possible Side Effect
-
Depending on a dog's treatment protocol, cyclophosphamide will be given daily or a few times a week. While cyclophosphamide will help fight cancer, it is also a toxic drug that requires extreme care and vigilance when used for chemotherapy treatment.
Once cyclophosphamide enters a dog's system, it is quickly metabolized into a carcinogenic chemical called acrolein, which is excreted in the urine. If the acrolein stays in a dog's bladder for too long, a condition called cystitis can occur, resulting in inflammation and possible bladder infection. Signs of cystitis include straining while urinating and blood in the urine. Female dogs are more often affected than males.
Steps to Avoid Cystitis
-
If your dog is taking cytoxan, you can take the following steps to avoid cystitis: Always give cyclophosphamide in the morning. Make sure your dog drinks plenty of water; to encourage drinking, try adding low-sodium broths to his water or a small amount of a sports drink. Ice cubes are also a good way to get water into his system.
Ask your veterinarian to prescribe a diuretic like Lasix, which will encourage water intake and induce elimination. Take your dog outside to eliminate more often on days when cyclophosphamide is given. Inspect your dog's urine several times a week, by capturing it with a container. If the urine looks bloody or dark, she may have a bladder infection or cystitis. If you suspect your dog is experiencing side effects, stop the cyclophosphamide and call your veterinarian.
Treatment for Cystitis
-
"A small percentage of dogs affected by cystitis will need sedation and flushing of the bladder along with DMSO (dimethyl sulfoxide) or other anti-inflammatories," says Dr. Pam Wiltzius, a veterinarian in Puyallup, WA. In most instances, she adds, the cystitis will resolve once the cyclophosphamide is discontinued.
If a dog is diagnosed with cystitis, most veterinarians do not administer it again. Often a drug like CCNU (lomustine) or chlorambucil (leukeran) can be substituted.
Even if your dog doesn't show signs of cystitis, it is important to remain vigilant during and after treatment. Be sure to regularly inspect his urine, and have your dog undergo periodic urinalysis tests before and after undergoing cytoxan treatments.
-