Lipoma in Dogs

Though a fatty tissue tumor is typically a mainly cosmetic issue, difficulties can arise for your pet if the tumor is located in an area of the throat (which can impede breathing). If a lipoma on a limb grows to be very large, this can cause discomfort for your dog as well, as he may find it difficult to get comfortable when walking or lying down. Tumors of fat (adipose tissue) tend to be found most often in female dogs that are overweight though any dog can be affected.

A benign fatty tissue tumor is also known as a lipoma. Fat cells form between the layers of the muscles and skin. Found in many locations on the canine body, lipomas are slow growing and a very common occurrence in dogs.

The usual adipose tissue tumor will be found by you as the owner, when petting your dog, or during a routine check up at the veterinary clinic. Of course, as this type of tumor can become very large, you may see it appear before you are even aware that it has been growing.

• These tumors are usually soft and smooth, often feeling rubbery
• They can usually move freely under the skin when touched
• Merging with local healthy tissue is common
• This benign mass is often round or oval, and well defined
• If the tumor moves into muscle, there can be swelling
• They are regularly seen on the neck, chest, trunk and legs but can also be found in other locations like the tongue
• Rarely, this type of tumor will appear behind the eye, in the abdomen, or around the head (causing serious secondary effects)

Types

Fatty tissue tumors are classified in two ways. Both types do not customarily mutate into malignant masses, but either form can be removed in order to maintain the health and safety of your beloved canine family member. Discuss with your vet if removal would be appropriate for your dog.

• Non-infiltrative
• These lipomas are easily removed
• Recurrence is not common
• Infiltrative
• This tumor has extended itself into adjacent muscle and tissue
• Recurrence happens frequently

It should be noted that a malignant lipoma (liposarcoma) is rare, but can happen.

In many cases, the exact known cause of the adipose tumor is not evident. There are some factors thought to be a cause for benign fatty tissue tumors.

• Hormones
• Sun exposure on the skin
• Chemical exposure in the environment
• It could be the beginning of a malignancy
• Viruses
• Genetics
• Predisposition has been documented in the following Breeds: Shetland Sheepdogs, Dachshunds, Cocker Spaniels, Weimaraners, Miniature Schnauzers, Labrador Retrievers, Doberman Pinschers, and mixed breeds

When you bring your canine companion to the veterinarian, be prepared for a full examination, and the possibility of further testing in order to receive a definitive diagnosis. The information you can provide in advance of the testing will be of great assistance to the veterinary team. Your veterinarian and her technicians may ask questions as they begin the examination.

• How long has the tumor been growing, to your knowledge?
• Does your pet show any pain when you touch the mass?
• What is his typical diet?
• Has his appetite been normal of late?
• Does he exhibit any difficulty when eating?
• What are his urinary and defecation habits like in recent days?
• Has his behavior changed at all?

Once your veterinarian has palpated your pet’s chest, limbs, and abdomen for tumors other than what you have been able to show her, she may suggest further testing.

• A needle aspirate will withdraw oily material and fat cells that will be examined under the microscope (cytology), in order to identify and confirm the fatty tissue tumor
• A punch biopsy or full excision biopsy may be necessary to examine tissue (histopathology) and rule out a malignant, cancerous tumor
• A radiograph, ultrasound, or computed tomography (CT) scan might be needed in addition, if the suspected tumor is thought to be in an area not easily reached during surgery, and to distinguish the tumor from normal fatty tissue
• Exploratory surgery could be recommended; for example, if the tumor is in the abdomen

If surgery is required to remove the lipoma, then a complete blood count, chemistry profile, and urine test will be done to review the general health of your pet, making assurances that surgery is viable.

The treatment protocol will have a few variables. The age of your dog, his present state of health, the type of tumor, the location, and the size all have a bearing on the procedure to follow. To be noted, for example, is the fact that if your dog is getting on in age and the tumor does not seem to be causing him distress and is indeed benign, the decision to leave well enough alone may her reached by you and your vet.

For our overweight canine family members who may need surgery, there is the possibility of the need to lose some excess weight first, so the veterinary surgeon can accurately distinguish the tumor from normal body fat. The surgeon will have the goal to excise the lump completely, and clearly defined tumor margins are necessary in order to achieve this.

During surgery, your much-loved dog will be carefully monitored. He will receive intravenous fluids and pain medication. While under the anesthesia, the observation of his blood pressure, body temperature, heart rate and rhythm, and oxygen levels will be of utmost importance.

Surgery tends to be curative and most lipomas do not recur. 

In the case of a simple (non-infiltrative) tumor, discharge from the hospital could be the same day. For a more invasive operation, overnight observation could be required.

Once home, your pet will need your diligent care. Pain medication and anti-inflammatories will be administered by you, with the direction of the veterinary team. Make sure your dog does not lick the wound. Your veterinarian will suggest an Elizabethan collar if she thinks it is needed. Monitor the incision for irritation or infection, and call the clinic if you have concerns about the healing process. Exercise will not be permitted for 3 weeks to a month after the surgery.

It should be noted that infiltrative tumors have been documented to return within a year in up to 30 percent of cases. Continued weight control is important, and may slow the regrowth possibility.