Marloe the three year old Labrador

Marloe’s saga started a few weeks ago, when Aisling noticed a strange looking area of skin on the underside of her neck. Marloe had previously worn a collar that had caused a bald patch to develop where it rubbed. This is something that happens commonly and it isn’t anything to worry about. Aisling had bought a new collar, and she had presumed that in time her fur would grow back in.
However, at the end of August, she noticed that the bald area was still there, and that if anything, it seemed more pronounced. The bald skin seemed thickened, as if it had filled with a small amount of fluid. It wasn’t painful at all, and Marloe was in her usual good form.
When something unusual on the skin is seen, it can be hard to know how much to worry about it at first. Energetic dogs like Marloe rush through undergrowth, roll around on beaches and charge through woodlands, so it’s not uncommon for them to suffer occasional bruises, abrasions and scrapes.
In the world of internet connectivity, people are as likely to send a WhatsApp or Facebook message to their vet as to make a phone call to ask a question. Aisling sent me a photo of the abnormal area to ask my opinion. My first impression was that it didn’t look like anything particularly unusual.  I suggested that Aisling should just monitor it carefully. If the fur hadn’t grown back after six weeks or so, it would be wise to check it out in more detail.

trip to the vet

As it happened, just two weeks later, Marloe suffered another crisis: she sliced the pad of one of her front toes while running on pebbles on the beach. She had to be admitted to our clinic for the day to have the pad sutured back together. While this was being done, I suggested that it might be wise to take the opportunity to take a simple biopsy from the thickened, balding area on her neck. I carried out a Fine Needle Biopsy, which is the simplest form of tissue sampling. A sharp needle (the same type that’s used to give injections) was pushed into the thickened area, and the contents of the needle were then squirted onto a microscope slide. This was then sent off to a specialist laboratory for processing.The laboratory team stained the slide, then examined it under a high powered microscope. I expected that they would only find benign cells, but it turned out that the underlying cause was something much more sinister after all. The thickened area was, in fact, a potentially malignant skin tumour, known as a Mast Cell Tumour.
Mast Cell Tumours are the most common type of malignant skin cancer seen in dogs. They are usually seen as lumps on the skin, and they are known as “the great pretenders” because they often resemble completely benign skin swellings, thickenings and nodules. Marloe was a classic example: there was nothing remotely sinister about the appearance of the skin thickening. In 99 out of 100 cases, the biopsy sample would have come back confirming that it was nothing to worry about. She just happened to be the one in a hundred dogs: a Mast Cell Tumour has the potential to become a serious, life threatening situation if it is not dealt with effectively.
Once I had the biopsy results, I knew there was only one possible cause of action: surgical removal of all of the strange looking bald area, with a wide margin of healthy tissue around it to ensure that no trace of mast cell tumour was left behind. This operation was carried out the next day, and the entire excised area was sent to the laboratory for full, detailed analysis.
The results arrived four days later: the Mast Cell Tumour was “low grade”, and the surgical margins were “clean” which meant that the tumour had definitely been completely cut out. This was great news: we now knew that it was very likely that the surgical excision that we had already done was enough to provide a complete cure.
If the lab result had come back as a “high grade” tumour, or if the surgical margins had been “dirty” (i.e. if cancer cells were present at the edges of the skin that had been excised),  there would have been a high risk of the cancer recurring or spreading to other parts of her body. She would have needed further surgery, chemotherapy and perhaps even radiation treatment. And even then, her prognosis would have been uncertain. When they are high grade and aggressive,  mast cell tumours can be amongst the trickiest cancers to treat in dogs.
It’s important that mast cell tumours are tackled promptly: if left alone, a low grade tumour may turn into a high grade one over time. This is why vets like to take simple biopsies from skin lumps of all shapes and sizes: this is the only way that a mast cell tumour can be diagnosed.
Marloe is a lucky dog: the tumour was removed so promptly that she’ll almost certainly make a rapid and full recovery. The wound has already healed, and her fur is growing back in.
Aisling is relieved that she had Marloe insured: the veterinary costs add up when biopsies and surgery is involved.
She’s hoping that this saga is now over: Marloe can go back to enjoying her busy life running through woods and on beaches.

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