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Abscess or Cancer?

Species: Dog
Breed: Shih tzu
Age: 8-11 years
My 8 year old shih tzu had raptured disks surgery five months ago. He was on wheel chair but he was getting better even walking without wheels last few weeks. Never problem urinating or having poo. He was happy and in no pain as I know him for 8 years . Now last Thursday suddenly he felt bad. Heavy breathing and problem defecating . Could not eat at all. His vet checked him and he had 104 temperature and when we checked inside his anus there was large quite hard mass on the left side maybe one inch inside. Friday he had tests done and biopsy at specialist. The answer was malignant tumor. We supposed have our options discussed on Monday and on Sunday night he started vomiting coffee colored liquid and black tar like was coming from his anus. On web I learned that it may be caused by internal bleeding. He still has not eaten anything and could not lift himself up. Then he urinated under him. On Monday when we got to the clinic he was in bad shape. The doctor said that he needs to be stabilized or he dies. He has been there since Monday. Now I learned from doctor that his anal sack was also infected and raptured. Today I was told that his bladder failed. Now is it possible that all this was caused by anal sack infection and not cancer? Could they misdiagnose and the mass inside was just anal sack? Now they said that the cancerous location raptured. Is it possible that all it was anal sack/ gland all along and because it was not picked up it raptured Sunday night causing internal bleeding? I am being talked to put him down and I am realistic I know that prognosis for this cancer are poor but it is hard to believe that happy and healthy dog who had all blood checked for any potential problems just four weeks ago and was declared healthy, suddenly had cancer without any signs that basically started this whole situation last Thursday and by Monday he is on a death bed? Can tumor get infected also and rapture? Can such tumor be not discovered with all blood work being done? He is now on antibiotics and liquid in the hospital. He still has black tar like stuff coming from his anus. I was told that only when he is stabilized I can be told of options for cancer remedy which are poor. They said they could stabilize him and now they suggesting to let him go even before he is stabilized???.
What is your thought on all this?
I appreciate honest opinion
Thank you


Online vet, Dr. Marie

Dr. Marie replied:

Oh, this is a difficult situation. The biggest problem with veterinary medicine is that we often have to make really hard decisions based on tests that are not always completely accurate.

I think the most important thing for us to know in this situation is how certain the pathologist is on the diagnosis of cancer. It's not always black and white. So, if the histology report is very certain that this is an anal sac cancer, then this really pushes me towards the decision to euthanize. A tumor certainly can rupture and become infected.

I have seen a lot of anal sac infections and I can't say that I have ever seen one make a dog sick enough to need stabilization or else he is in danger of dying. This really does sound like there is something very serious going on.

The coffee colored vomit and black tar are very suspicious for internal bleeding, but we can't say 100% if this is the case. If it is though, this is a bad sign.

When you say his bladder has failed, I'm wondering if you mean perhaps his kidneys? Kidney failure would be another sign that this is likely to be a fatal condition. We don't really see bladder failure...but we could see that the bladder is blocked by a tumor perhaps. This would be bad as well.

Most cancers are not detectable on blood work. If this is a cancer then there likely was no test that could have been done to pick it up prior to it causing obvious problems.

The decisions you have to make here are really hard though. Everything really looks like this is cancer. And if this is the case, then in my opinion, euthanasia is the best option. While many cancers are treatable, it sounds like this would be extremely hard and maybe not possible to cure.

But, there still is a small possibility that this is not cancer. Again, I would be wanting to know from the vet how certain the pathologist is on the diagnosis of cancer.

So, let's say that the diagnosis is uncertain and you want to go ahead with treatment. The risk here is that you could end up spending a large amount of money just to end up making a decision for euthanasia. And, if this happens, in hindsight, you would probably be sad that your dog had to suffer through extra days of pain and discomfort for naught. Still, I do think that there is a small chance that this could be all related to an anal sac infection. A very small chance.

The other factor that could help in your decision making is how he is responding to treatment. If things are not improving despite being on antibiotics then this is a bad sign as well.

In cases like this the best advice that I can give is to trust your vet's advice. They have your dog's best interest in mind and really should be able to advise you well.

I hope things do work out ok.

Dr. Marie


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Disclaimer: Although Dr. Marie is a qualified veterinarian, the information found on this site is not meant to replace the advice of your own veterinarian. AskAVetQuestion.com and Dr. Marie do not accept any responsibility for any loss, damage, injury, death, or disease which may arise from reliance on information contained on this site. Do not use information found on this site for diagnosing or treating your pet. Anything you read here is for information only.

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Dr. MarieDr. Marie is a veterinarian who practices in a busy animal hospital in Ottawa, Ontario. She created Ask A Vet Question as a resource for good, accurate veterinary advice online. Dr. Marie treats dogs, cats, hamsters, guinea pigs, and rats. She has been a vet since 1999.

Is an online vet visit just as good as a trip to your veterinarian? No! But, many times, asking an online veterinarian a question can help save you money. While Dr. Marie can't officially diagnose your pet or prescribe medications, she can often advise you on whether a vet visit is necessary. You can also ask Dr. Marie for a second opinion on your pet's condition.