Surgical Approach to Skin and Subcutaneous Tumors in Small Animal Practice

Author: Donny Astor, VMD, DACVS-SA
 

As a board-certified veterinary surgeon, surgical oncology cases are a large part of what I see on a day to day basis. Understanding the surgical approach to these cases not only enhances our teamwork but can also significantly improve patient outcomes. Here, I’ll share insights on how we can effectively address tumors in our canine and feline patients from a surgeon’s perspective and how we can best collaborate on these often challenging cases.

Tumor Classification

Effective tumor management begins with understanding the types we commonly encounter:

1. 1. Benign Tumors:  While they may not always pose a health risk, surgical removal is sometimes recommended if they cause discomfort, restrict movement, if they rupture, or if the patient intentionally or unintentionally traumatizes them. Benign tumors typically exhibit well-defined margins, resulting in a lower chance of recurrence when excised.

2. 2. Malignant Tumors: Tumors such as mast cell tumors, soft tissue sarcomas, and carcinomas require a more comprehensive approach. Here, staging tests are very important before any procedure as they are crucial to formulate a successful treatment plan.  Considering what the appropriate surgical “dose” is for these tumors is a very important exercise before any procedure.

Diagnostic Essentials

An accurate diagnosis is fundamental for effective treatment. Key steps include:

• Comprehensive Physical Examination: This helps assess the tumor's size, location, whether there are enlarged lymph nodes, and any related clinical signs.

• Imaging Techniques: Radiographs, ultrasound, or CT scans may be indicated depending on tumor location and extent.  Diagnostic quality three view thoracic radiographs should be performed for screening prior to surgery for most malignant tumors.

• Cytology*: Fine-needle aspiration (FNA) is a vital tool for initial evaluation.  This is a quick and easy test and it is so helpful when we already have the results at the time of the initial surgery consultation.  While we do not always get an answer, we usually at least get some helpful information.  For example, if you get a hemorrhagic sample when aspirating a mass that was thought to be a lipoma, it should set off some red flags that the mass might be something more insidious.  Aspiration of draining lymph nodes is also very important, especially if we are dealing with tumors such as mast cell tumors.  It is very helpful to know prior to surgery if we may need to remove the draining lymph node.

I highly recommend this test before removal of almost any dermal or subcutaneous mass because it can be invaluable in preventing the situation where an “underdose” of surgery is performed when we think a mass is benign but it is not.  Usually, the best chance to get good outcomes for malignant tumors is the first surgery!

• Histopathology: Incisional biopsies are warranted especially if we do not get a diagnosis from our cytology.  Owners can be resistant to the idea of two procedures but they can be very helpful when determining a treatment plan when less invasive options have failed.

Surgical Strategy

When surgical intervention is necessary, several considerations come into play:

• Achieving Clean Margins: For malignant tumors, obtaining adequate margins (proper dose of surgery) is critical to minimize the risk of recurrence. This often requires careful surgical planning and may involve advanced techniques such as skin flaps or grafts if primary closure is not possible with standard techniques.  Unfortunately with most tumors, there are no clear guidelines for safe margins often leaving us to use our best clinical judgment.  Factors such as type of tumor, location of tumor, whether there is an accessible skin flap to use, and patient factors (age, behavior, and general health status) are all things I consider.

• Management of Expectations:  I consider this an essential part of my job as a veterinary surgeon.  It is very important to be open with the owner about possible complications and likelihood of achieving our surgical goals.  With large mass removals, tumors in difficult locations, and when we are using advanced techniques, complications can occur and the process is much smoother when owners have proper expectations from the start.

  • It is important to discuss potential outcomes with the owners as they should be aware before surgery if treatment modalities such as radiation therapy or chemotherapy may be recommended postoperatively.  They are costly and sometimes involved treatments that may be recommended after what is likely a costly surgery.  If the owner would not pursue them, it may change how we approach the case. 

  • For example, consider a situation where there is a soft tissue sarcoma on a patient’s leg and it is not amenable to wide resection. There may be two reasonable options in this situation.  One option would be to remove the mass and follow with radiation therapy to save the limb and reduce the risk of recurrence.  The other option would be amputation.  If the owner indicates that they would not pursue radiation therapy, this should be taken into consideration and amputation may be the more appropriate option.

Strengthening Collaboration

As veterinary surgeons, we value our partnership with primary care veterinarians. Here are ways we can enhance our collaboration:

• Coordinated Care Plans: We should work together to develop cohesive treatment plans that integrate surgical, medical, and supportive care for our patients.  If you have questions about a surgery you are undertaking, please reach out!

• Timely Referrals: Recognizing when a case requires surgical referral is crucial. Early referrals can improve outcomes for difficult masses.

Conclusion

In conclusion, effective tumor management in small animals requires a collaborative approach that combines diagnostics, surgical expertise, and strong communication. By working together, we can provide our patients with the best possible care and outcomes.

Thank you for your commitment to improving the health and well-being of our furry companions. I look forward to our continued collaboration in tackling these complex cases!