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Lumps and Bumps
By Dr. Francesca Matthews
Lumps on our pets are common. Nearly every pet will develop a lump of some sort in its lifetime. Some of these lumps are benign and of no consequence to your pet, others are benign but annoy your pet so much that removal is required and others are of much more significance and can require extensive surgery and maybe even chemotherapy.
There is one thing about lumps that you must remember, as much as you would like it to be the case, vets do not have microscopic eyes so cannot definitively diagnose a lump and whether it is benign or malignant by looking at it and feeling it. Diagnostic tests are required.
In most cases, provided the pet is amenable to it, the lump is in or just under the skin and the lump it not too near something like an eye, it is possible for your veterinarian to take a sample of cells from a lump. This is called a fine needle aspirate.
The fine needle aspirate will then be examined. Sometimes we will have a look in-house but usually these are sent away to a veterinary diagnostic laboratory. The veterinary pathologists at the laboratory will look at the cells under a microscope and look at key features of the cells which tell them what type of cells they are and whether the lump is benign or malignant. 90% of fine needle aspirates will deliver an accurate result which then allows good management of the lump.
Image source wikimedia commons
It's benign ...
In cases where a benign tumour is diagnosed, such as a lipoma, these may be removed or more commonly accurately measured and monitored for changes in size, shape, consistency and so on, at regular veterinary follow ups. It is possible for benign lumps to change to further fine needle aspirates in the event of changes, or at least once a year are recommended.
We will record the size of the lump each time we see it in your pet's notes and we may even take a photograph too, if the lump is visible from the outside. This allows good comparison at future visits.
It's malignant ...
For malignant tumours, the results of the fine needle aspirate allow the us to make good surgical decisions as to how wide the margins on the lump need to be to ensure complete removal.
In a number of lumps, especially mast cell tumours, wide margins are required to actually remove all the malignant cells. Without a fine needle aspirate first to gain this knowledge, it may result in the requirement for a second surgery to go back and remove adequate margins.
Prior to removal, a thorough examination of your pet will be required and is likely to include blood tests and possibly x-rays of the chest, which is a common place for secondary tumours to appear (i.e. other places the tumour may spread to).
The lump has been removed, what next?
Once a tumour has been removed, it is essential that you give permission for the veterinarian to send the lump off to the laboratory for full and definitive diagnosis. The histopathology will not only allow the laboratory to confirm the diagnosis and be able to say definitely whether the entire lump was removed, but by looking at the margins microscopically will also help with completing the picture so that decisions can be made on whether any further treatment is necessary.
All pets should continue to be monitored for the return of the lump or development of additional lumps and if this occurs they should revisit the veterinary clinic as soon as possible.
Another important thing to note is that even if a lump has been diagnosed as a lipoma previously, if it changes in size, shape or consistency, a further fine needle aspirate should be performed to ensure that lipoma is still the correct diagnosis.
Other types of skin lumps (other than tumours)
We’ve mentioned benign and malignant tumours here, but it is also important to realise that lumps can be other things too. Some examples include: sebaceous gland cysts, warts (or papillomas) and pustules (or pimples as they are called in the human world). Surgical removal may be a solution for some of these, but in other cases medical therapy such as antibiotics is appropriate. For very small warts, liquid nitrogen treatment (just like in humans) may be the treatment of choice.
Should you have any questions or concerns about a lump your dog has, please don't hesitate to give us a call.