Wednesday, October 9, 2013
There is a lot to update here as it's been a long week for us. Let be backtrack to 5 days ago, on Friday, October 4th. We brought Phoebe into the vet that day because she had been vomitting for 36 hours. She had vomited her breakfast up on Thursday and our dog walker found it when she came to walk her at lunch. That night, Michael fed her dinner and about an hour and a half later she vomited it all up, again. When she vomited her breakfast up on Friday morning, we brought her into the vet emergently. We were concerned that she might be experiencing some sort of intestinal obstruction/blockage. That was the impetus for bringing her to the vet.
We had noticed for a few weeks prior to this that Phoebe was having more urination accidents in the house. Specifically, in the evenings after her dinner, she no longer could make it for 4 hours after dinner until the bedtime walk. Every night, around 8 pm, she has been jumping up and needing to go pee suddenly and urgently. If we don't notice it in time, she pees the floor. We mentioned this to our vet because we had been going through a three week period wherein we were taking her off the Trilostane (the medication for her Cushing's disease). Our concern about the frequent urination was that it might have been a sign of her Cushing's disease coming back which would mean that we'd have to restart the medication.
Her doctor a full panel of bloodwork, an ACTH stim test (that measures her Cushing's disease), a urinalysis as well as an abdominal ultrasound on Phoebe. The good news was that her intestines looked fine and there was no obstruction. The bad news was that there was a 7 mm mass in her bladder. More specifically, it is in the trigone of the bladder. The trigone is a region of the bladder where tumors are particularly difficult to treat, rarely operable, and most often found in dogs. We waited a day for the blood and urine results. If they were normal, we would think that this was a all coming from the tumor. If they were abnormal, it might have indicated an occult Urinary Tract Infection (UTI). The vet was clear that many dogs with a subacute/occult UTI experience vomiting as a response to it. They administered an injection of Cerenia (anti-nausea medication) as well as an antibiotic to her to start treating the UTI empirically on Friday.
The next day, we got the results: totally normal blood work and urinalysis. Specifically, her ACTH stom test levels were normal which was great considering that she had been off the Trilostane for a few weeks. So it wasn't Cushing's disease. Her urinalysis showed no blood, no white blood cells, no castes, and no changes in the specific gravity. In other words, there was likely no infection here. This got us very concerned because the only positive finding, at this point, was the mass in her bladder.
Statistically speaking, when an older dog (older than 10 years of age) has a mass in the trigone of the bladder, it is most likely The transitional cell carcinoma (TCC) until proven otherwise. TC see is the most common of all bladder tumors in dogs. Sadly, it's extremely aggressive and metastatic. Knowing this and that Phoebe, at 15 and half years old and female had a mass in the trigone of her bladder, we rushed that very afternoon to meet with a surgeon about doing a possible biopsy to start treatment for this. TCC is very aggressive and must be treated very early and quickly have any positive results.
We met with Dr. Greenberg at Blue Pearl Veterinary Partners. He was very clear with us: the only way to know exactly what this is would be to take a biopsy of it. He was also very clear to say that, based on the location in the trigone of the bladder and considering the small size of a Chihuahua's bladder, it would be nearly impossible to take out the entire mass and a 1 cm margin is the standard for removing a tumor. He mentioned that we could do this via cytoscopy. Still, this would require anesthesia and the trauma of surgery: making an incision in her abdomen and going into the bladder to obtain a piece of this mass with no potential to eradicate or fully remove this mass. He also mentioned that there is a test for TCC that checks for antibodies made against these tumor cells that are shed into the bladder. The test, called V-BTA (bladder tumor antigen) is about 90% sensitive but only 78% specific. Though this test is associated with many false positives, there are few false-negatives. What that means in English is this; If your dog has a positive V –BTA test, she may or may not have TCC. But, if your dog has a negative V–BTA, then it's very likely that she does not have TCC.
We have been waiting for four days for the results of phoebes V-BTA test. In the meanwhile, we had made an appointment to take her to visit with an oncologist this afternoon. In fact, it's the same oncologist who took care of Chandler when he was fighting malignant melanoma, Dr Tim Rocha. Just hours before going to the appointment, we got the news that Phoebe's test was negative. In other words, her bladder tumor is most likely NOT TCC.
We just got home from our later afternoon visit with Dr. Rocha. There were a lot of questions. Do we treat this empirically as TCC or not? Do we reconsider doing something invasive to find out what the tumor is made of? Dr. Rocha pointed out that many benign tumors continue to grow in this region, the trigone of the bladder, and still effect the same changes and problems that the progression of TCC does, albeit without metastatic disease. In other words, even though this now likely to be a "benign" tumor, it's still most likely going to continue to grow, eventually overtaking her bladder, one or more of the ureters and causing her kidneys to fail.
Many of the medications used to treat bladder cancer in dogs are NSAIDS, nonsteroidal anti-inflammatory drugs. Specifically, older NSAIDS like Piroxicam have been shown to slow tumor progression in both TCC as well as many other benign bladder tumors. It would be a no-brainer that we should start her on it but Phoebe has bad a history with NSAIDs. After many years of being on many different medications, she is very sensitive to this class of drugs. As it stands, her renal function (as measured by a BUN/creatinine) has been chronically elevated for many years. More importantly, when she has taken any NSAID (even for just a few days) it has thrown her renal function way off and we usually end up taking her off the medication after a week or so. In a 15 1/2 year-old senior dog, everybody is reluctant to start her on this.
Many of the chemotherapy drugs that are platinum based are extremely harsh and toxic. Dr. Rocha strongly advised against using this in Phoebe, even if she were to have a documented TCC pathology. He feels that this is just too strong a class of drugs for her at her age and size. We agree.
There is a relatively newer chemotherapy drug called Palladia (toceranib phosphate). Palladia is the first FDA approved oral chemotherapeutic agent for cancer in dogs. Unfortunately, the only studies on Palladia have been in limited studies of mast cell tumors of the skin in dogs. That has not stopped veterinarians from using this to treat a wide array of different types of cancers, including TCC. The nice thing about an oral medication like this is that side effects, if encountered, tend to be quickly stopped and reversed. This is not the case with infused platinum based IV chemotherapy. Still, Palladia is a very expensive and unproven medication with respect to TCC. More importantly, there is no evidence to suggest that it is useful in treating benign bladder tumors which we now know is more likely to be what is growing in Phoebe's bladder.
Michael and I have spoken about this at some length and we are in complete agreement. Phoebe is approaching the end of her natural lifespan. Of course, we want her to be with us as long as is possible. We do not, however, wish to achieve longevity at the expense of her comfort and quality of life. It is for this reason that we are extremely reluctant to even consider and invasive surgical procedure to biopsy this mass. In reality, whether this is TCC or some other benign tumor, it will likely continue to grow. How fast it will grow, nobody can know. Having done the antigen test, we feel reasonably confident with the 90% chance that this is not TCC. That means that, since it is not TCC, there will most likely not be metastasis to other parts of her body. So really, what were looking at, is treating and containing the growth of a benign tumor non-surgically.
We are in agreement with Dr. Rocha as to our plan. We are going to wait four weeks, add no medication at this time, and then we will recheck her ultrasound and x-ray scans. If the tumor has grown or if there are any signs of metastasis, then we will weigh our options as to the risk of using an NSAID versus starting something like Palladia.
It might be wishful thinking but, knowing who Phoebe is: her history of surviving against the odds and outliving every statistical probability for each diagnosis she's ever been given, it would not surprise us in the least to see no tumor growth or even tumor regression in four weeks. For right now, we are going to enjoy every day with her and we will cross those bridges if and when we come to them.