What is the treatment for a canine mast cell tumor? What are the side effects of Clavamox in dogs?

Original Question: Are there any other treatment options for dogs diagnosed with mast cell tumor other than chemotherapy and radiation? Also what are side effects from Aventiclav antibiotics? I believe my dog has had an allergic reaction but the vet I see has said that this isn't possible. - Felicia

Mar 5, 2018

Hi Felicia,

Sorry to hear that you’re dealing with this.

I’m going to assume that your dog is been diagnosed with a mast cell tumor. We don’t really call it a mast cell disease because these lesions show up as individual tumours and unfortunately they have the ability to spread depending on how aggressive they are. Whenever a mast cell tumor is confirmed, it’s ideal to act as fast as possible before it has the opportunity to spread internally or to another location.

The first thing we have to do is stage tumor. The way we do this is by collecting a needle aspirate of the tumor to confirm if it is indeed a mast cell tumor. We also start looking to see if it has already spread somewhere else, so we perform X-ray’s on the chest, perform routine bloodwork to see if any organs are affected, and possibly an abdominal ultrasound to see if it has spread to any of the organs there. We also often recommend a test called a buffy coat smear. This is where we take a blood sample and see if the mast cells are coursing around the bloodstream. By performing these tests we can adequately stage the tumor before we determine the best course of action to treat it.

Now it’s not lost on me that this sounds expensive. Your question is whether there is a treatment other than chemotherapy or radiation. There is, but I assume you already know what it is. It is to surgically remove the mast cell tumour right away. We always try to be as aggressive as possible with surgery and I recommend you watch my video addressing lumps and bumps in pets because I go over the key features of this whole process. There are some clients who don’t want to spend the money on staging the tumour and they just want to spend the money on removing the tumour that they can visibly see. Unfortunately, if that tumour has spread, we would be doing a great disservice to the dog by having him undergo surgery to remove a tumor when there’s more cancer that has spread.

More to your question, there is a medication that tends to have a positive effect on mass cell tumours and that is a steroid called Prednisone. I have often seen that Prednisone will shrink a mast cell tumour in dogs but some practitioners may not feel comfortable treating a disease so serious with such a simple treatment. Therefore, it’s best to take this information with a grain of salt and have a thorough discussion with your veterinarian about the pros and cons of each treatment as well as their costs and effectiveness.

Now back to your question regarding the side effects of Clavamox in dogs. Every single drug we ingest has side effects. If you look in the drug handbook about aspirin, there are dozens of alarming side effects that it can cause, yet most of us take it without considering the risks. I also see that owners are very quick to label symptoms as a bad reaction, or allergic reaction to an antibiotic. Any antibiotic we take can cause stomach irritation, which can lead to vomiting and or diarrhoea. I wouldn’t consider this a serious reaction or an allergic reaction. Sometimes it helps to give that antibiotic with food so it’s less irritating on the stomach. A serious reaction would be breaking out in hives, becoming extremely itchy, difficulty breathing, or more serious symptoms like that. So it really depends on how your dog reacted to determine if he is actually significantly sensitive to medication. At the very least, I would suggest that if you’re concerned, then request a different type of category of antibiotic to treat the infection that you’re trying to treat.

Hopefully this information was helpful.