Caring for Pets with Lumps

By Dr Joanna De Klerk

Finding a lump or bump on your pet can be worrying. Naturally, all the worst-case scenarios run through your mind. But the good news is there are many causes of lumps and bumps on your furry friend, many of which are nothing to worry about.

Ultimately, all lumps and bumps should be checked out by a vet as many of them will need treatment of some sort, or maybe even surgical removal. But it’s important not to worry too much, as non-harmful lumps are more common than the nasty ones.

Lumps can occur in any pet, but in this article we’ll look at lumps in dogs and cats.

What is a Lump?

A lump is a raised swelling on your animal. It can be found anywhere on the body, and its location often gives a big clue as to what it is. Lumps be caused by tumours, warts, swollen lymph nodes, infections, bites and foreign bodies. As you can see, there are many different causes, so there’s no need to immediately jump to the conclusion that your pet’s days are numbered when you find a lump.

It’s always a good idea to get a lump checked out earlier than later, as many types of lumps have a better treatment outcome the earlier they are attended to. It’s sometimes difficult to tell what a lump is and how serious it is, from looking alone. So, on the rare occasion it might be something that needs urgent treatment, your furry friend will have the best prognosis the sooner they get seen by your vet.

How Do You Tell if a Lump is Cancerous?

In short, it’s not always easy to tell if a lump is cancerous. Sometimes it’s not even easy to tell whether a lump is a tumour. But if it is a tumour, they are broadly defined into two categories; benign and malignant (cancerous). 

Defining a lump into one of the two categories is not always easy, as some benign lumps can look and act like malignant ones, and vice versa. Which is why it is always important not to be complacent about lumps. However, as a general rule the following applies:

Benign lumps are USUALLY:

  • Slow growing
  • Well circumscribed (i.e. spherical)
  • Covered in hair
  • Not painful or ulcerated
  • Mobile and not attached to underlying structures

Malignant lumps are USUALLY:

  • Fast growing
  • Diffuse or irregular in shape
  • Bald
  • Painful or ulcerated
  • Fixated to underlying structures such as muscle or bone

But the only definitive way to tell the difference is by histopathology, which is when a veterinary pathologist looks at some cells of the lump which have been removed by your vet. This can either be done by removing the lump entirely or inserting a needle and extracting some cells. The latter method is called a fine needle aspirate (FNA). The benefit of an FNA is that it is quick and simple and doesn’t require an anaesthetic. However, sometimes it is inconclusive and needs to be repeated, or your furry friend has to have surgery to get a better sample.

Most Common Causes of Lumps on Dogs

The five most common causes of lumps on dogs are:

  1. Lipomas: Lipomas are benign tumours originating from fat cells. They are more common in overweight, older dogs; however, some dog breeds are predisposed to them. They are essentially giant balls of fat. Some will remain relatively small, no bigger than a grape, whereas others will grow to the size of a grapefruit or bigger! The good news is, no matter how big they are, they are usually just cosmetic. The exceptions are the ones which grow in areas which restrict movement or catch and become traumatised. These ones need to be removed, but most are fine to monitor.
  2. Mast Cell Tumours (MCT): Mast cell tumours are the main exception to the rules differentiating benign and malignant tumours. They can be very nasty, yet often look benign. They are made from a type of white blood cell called a mast cell, which normally plays a role in allergies and inflammation. They release a lot of histamine if manipulated, and therefore you might see the lump vary in size, depending on the histamine-related inflammation. Occasionally they can also be itchy for your dog. Boxers, Labradors, Beagles and Schnauzers commonly develop MCTs, but they can appear on any breed of dog.
  3. Skin Tags: Skin tags are benign fibrous growths which extend off of the skin’s surface, usually from a stalk. It’s often the case that dogs get more than one, and they can pop up anywhere on the body. Large-breed dogs are more likely to develop them, although any dog might be affected. The good news is that even though they can be unsightly, they are harmless.
  4. Histiocytomas: Histiocytomas can look like cancer, so it’s important to get them checked out. They are hairless red bumps which develop on the legs of young dogs. They can be removed, but they sometimes go away by themselves.
  5. Warts (Papillomas): Warts have a cauliflower-like appearance, and can range from tiny to large, and grow individually or in clusters. Unlike most lumps, they are spread by a virus and are contagious between dogs. Most warts don’t cause a problem if they grow on the body, but when they are on the face, eyelids, mouth, feet or genitals, they can cause an annoyance to your dog.

Most Common Causes of Lumps on Cats

The five most common causes of lumps on cats are:

  1. Cat Bite Abscess: An abscess is a lump filled with pus which is usually caused by a bite or scratch from another cat when fighting. They are very painful and can cause your cat’s temperature to become quite high, resulting in her feeling lethargic and off her food. Your vet will want to lance and drain it, as well as provide antibiotics and anti-inflammatories.
  2. Fibrosarcoma: Fibrosarcomas are cancerous tumours. Cats often develop them at an injection site, and as a result, the most common place is between the shoulder blades where annual vaccines are injected. Fibrosarcomas are difficult to remove entirely at surgery, which means a relapse of the tumour is common within a year of surgery. Chemotherapy and radiation can improve survival times.
  3. Lymphoma: Lymphoma is a type of cancer of the white blood cells. It can cause tumours in the skin or it can spread internally. When it is internal, it usually spreads to the guts, resulting in chronic diarrhoea, or in the lymphatic system, resulting in swollen lymph nodes, which will feel like lumps.  
  4. Sebaceous Cysts: Sebaceous cysts are fluid filled lumps which arise from blocked oil glands. They can be mistaken for tumours, but they are nothing to worry about. Your vet can drain them, surgically remove them or they can be left alone and monitored. They don’t usually grow more than 1cm in diameter.
  5. Squamous Cell Carcinomas (SCC): SCCs are most common in white or light coloured cats and are triggered by excessive sun exposure. They aren’t always an obvious lump, and usually look like unresolving bumpy scabbing. The most common places they appear are on the ear tips and nose but they can also come up on the eyelids or lips. Surgery, and sometimes radiation therapy, is the treatment of choice and while your kitty might look a bit unusual without ear tips, it will save her life.  

Home Care for Lumps and Bumps

If your furry friend has a new lump or bump, or an old one which is changing, the first thing you should do is get it checked out by your vet. If it is nothing to worry about, and your vet advises to monitor it, there are several things you can do at home to care for your pet.

Start by taking a picture with a ruler for reference. Sometimes it’s difficult to notice subtle changes in a lump, but if you have a picture to refer back to, you are more likely to pick them up. Every month compare the lump to your last picture and then take a new one. If the lump has changed, your vet should be told.

If your pet has a lump which catches and bleeds occasionally, it’s worth having to hand some antiseptic wash and a dressing. Chlorhexidine solution can be diluted by adding a splash into a cup of cooled, boiled water. Then you can gently clean the lump daily with a cotton wool ball if there is an open wound. After cleaning, pat dry and place a clean, breathable, adhesive dressing over it, such as a Primapore. After a few days, it should be dry and scabbed over, and you no longer need to keep it clean and covered. If your furry friend wants to lick or scratch at it, you might need to put a buster collar on him.

Finally, if your vet has given you medication for your pet’s lump, such as antibiotics, or chemotherapy medication, make sure you give your pet accurate doses. This means if you need to give the tablets twice daily, try to make them 12 hours apart. You might like to make a chart which you tick off doses to ensure you don’t forget and miss a dose.

Take Home Message

There are many causes of lumps and bumps in dogs and cats. Some are benign, some are malignant, and some are not tumours at all. Therefore, always inform your vet if you notice a new lump on your pet, as an early diagnosis will ensure your furry friend gets the best treatment.