• DVM360_Conference_Charlotte,NC_banner
  • ACVCACVC
  • DVM 360
  • Fetch DVM 360Fetch DVM 360
DVM 360
dvm360 | Veterinary News, Veterinarian Insights, Medicine, Pet Care
dvm360 | Veterinary News, Veterinarian Insights, Medicine, Pet Care
By Role
AssociatesOwnersPractice ManagerStudentsTechnicians
Subscriptions
dvm360 Newsletterdvm360 Magazine
News
All News
Association
Breaking News
Education
Equine
FDA
Law & Ethics
Market Trends
Medical
Politics
Products
Recalls
Regulatory
Media
dvm360 LIVE!™
Expert Interviews
The Vet Blast Podcast
Medical World News
Pet Connections
The Dilemma Live
Vet Perspectives™
Weekly Newscast
dvm360 Insights™
Publications
All Publications
dvm360
Firstline
Supplements
Vetted
Clinical
All Clinical
Anesthesia
Animal Welfare
Behavior
Cardiology
CBD in Pets
Dentistry
Dermatology
Diabetes
Emergency & Critical Care
Endocrinology
Equine Medicine
Exotic Animal Medicine
Feline Medicine
Gastroenterology
Imaging
Infectious Diseases
Integrative Medicine
Nutrition
Oncology
Ophthalmology
Orthopedics
Pain Management
Parasitology
Surgery
Toxicology
Urology & Nephrology
Virtual Care
Business
All Business
Business & Personal Finance
Hospital Design
Personnel Management
Practice Finances
Practice Operations
Wellbeing & Lifestyle
Continuing Education
Conferences
Conference Listing
Conference Proceedings
Upcoming dvm360 Conferences
Resources
CBD in Pets
CE Requirements by State
Contests
Partners
Spotlight Series
Team Meeting in a Box
Toolkit
Top Recommended Veterinary Products
Vet to Vet
Veterinary Heroes
  • Contact Us
  • Fetch DVM360 Conference
  • Terms and Conditions
  • Privacy
  • Do Not Sell My Information
  • About Us

© 2023 MJH Life Sciences and dvm360 | Veterinary News, Veterinarian Insights, Medicine, Pet Care. All rights reserved.

Advertisement
By Role
  • Associates
  • Owners
  • Practice Manager
  • Students
  • Technicians
Subscriptions
  • dvm360 Newsletter
  • dvm360 Magazine
  • Contact Us
  • Fetch DVM360 Conference
  • Terms and Conditions
  • Privacy
  • Do Not Sell My Information
  • About Us
  • MJHLS Brand Logo

© 2023 MJH Life Sciences™ and dvm360 | Veterinary News, Veterinarian Insights, Medicine, Pet Care. All rights reserved.

Diagnosing and Treating Cancer in Companion Animals

June 2, 2017
Laurie Anne Walden, DVM, ELS

What your clients want to know: What type of cancer does my pet have? How extensive is it? How can it be treated? A veterinary cancer expert outlines the basics.

In a forum last week at North Carolina State University, Steven Suter, VMD, MS, PhD, DACVIM (Oncology), shared tips for diagnosing and treating cancer in pets. He structured his talk around three basic questions: What is it? Where is it? And how can I get rid of it?

What Is It? Identifying the Tumor Type

In many cases, veterinarians can identify the cancer category (carcinoma, sarcoma, or round cell tumor) during the initial appointment, said Dr. Suter, who is director of the Canine/Feline Oncology Diagnostic Laboratory and medical director of the Canine Bone Marrow Transplant Unit at NC State.

Pinpointing the category is crucial because tumors in different classes behave differently with respect to metastasis and response to therapy.

Fine-Needle Aspiration

Fine-needle aspiration is a low-cost, low-risk, rapid method to identify tumor category (but not grade), he said. He discussed tips for obtaining fine-needle aspirates:

  • If an aspirate has low cellularity, try again with a larger needle, use suction if you did not use it on the first attempt, and be more aggressive (the procedure is rarely painful).
  • Evaluate only intact cells.
  • Be sure the sample accurately represents the mass.

Advertisement

Inflammatory changes can look like neoplasia, he cautioned. Criteria for malignancy include anisocytosis, anisokaryosis, increased nucleus:cytoplasm ratio, high mitotic index, basophilic cytoplasm, and multiple or prominent nucleoli. He described cytology characteristics of tumors of different categories:

  • Carcinomas: These tumors are epithelial in origin, so the cells tend to clump together on the slide. Anal sac adenocarcinoma cells have minimal anisokaryosis and almost no cytoplasm. Squamous cell carcinoma cells may have nuclei, unlike normal squamous epithelial cells.
  • Sarcomas: Aspirates of these mesenchymal-origin tumors typically include more blood and fewer nucleated cells than aspirates of the other tumor types. Osteosarcoma yields cells with very eccentric (off-center) nuclei.
  • Round cell tumors: These tumors “love to give up their cells,” he said. High-grade lymphosarcoma aspirates may include lymphoglandular bodies (small blebs of cytoplasm outside cells) and cells with a thin rim of basophilic cytoplasm.

Biopsy

Biopsy is the diagnostic gold standard, said Dr. Suter. Biopsy tips include the following:

  • Do not use Penrose drains; they increase the risk for tumor seeding.
  • When submitting samples, avoid cauterizing the margins, use proper fixation, and provide an appropriate case history.
  • Request a microscopic description on the pathology submission form so the report will include the mitotic index.

Where Is It? Staging the Cancer

Cancer staging is costly but is the only way to determine the tumor burden and uncover concurrent diseases (including other cancers), said Dr. Suter. Clients should understand the reasons for staging before deciding whether to pursue it. Staging includes the following:

  • Complete blood count and biochemistry profile
  • Urinalysis
  • Aspiration of regional lymph nodes
  • Thoracic radiographs
  • Abdominal ultrasound
  • Advanced imaging if indicated and if finances allow

Sarcomas tend to metastasize hematogenously, he said, so thoracic radiographs are crucial for staging these cancers. Carcinomas spread through lymphatics, so fine-needle aspiration of lymph nodes is necessary; be aware that some cancers skip nodes or spread to contralateral nodes. Round cell tumors are systemic and can metastasize to any location.

How Can I Get Rid of It? Cancer Treatments

Dr. Suter gave a broad overview of the 3 treatment modalities available for companion animals: surgery, irradiation, and chemotherapy/immunotherapy. In general, he said, surgery and irradiation are used for local control and chemotherapy is used for systemic control.

Surgery

The best way to remove a solid tumor that is visible to the eye is by surgical excision, he said. For cancer that has not metastasized, surgery can be curative if the margins are large enough. Dr. Suter made the following points:

  • Do not “shell out” a tumor; tumor capsules are composed of compressed cancer cells.
  • Remove as much normal tissue as possible to still allow wound closure.
  • Ideal margins are greater than 1 cm; margins less than 5 mm are concerning.
  • Obtain very large margins with feline injection-site sarcomas and high-grade mast cell tumors.

Irradiation

Irradiation can be either definitive (curative) or palliative. Curative irradiation targets microscopic disease; high-dose stereotactic radiation can also be used as definitive treatment. Palliative radiation is designed to slow or stop tumor growth and can also be used to control osteosarcoma pain, he said.

Chemotherapy

Chemotherapy is used as the primary treatment for hematologic cancers and also to control metastasis of solid tumors. The main goal in veterinary medicine is maintaining a good quality of life; to avoid toxicity, therefore, doses are lower and protocols are less intense than in human medicine. For this reason, the cure rate with chemotherapy is very low, he said, although chemotherapy does extend lifespan with some types of cancer.

Conclusion

Dr. Suter concluded by observing that the role of the veterinarian is to advise the client, who will then decide how aggressively to pursue staging and treatment. “Our job is not to get them to make a [particular] decision,” he said. “Our job is to present the options and let them make the decision.” In general, more aggressive treatment will prolong life. However, pet owners also take into account cost and the pet’s age, so he does not frame the options as right or wrong.

Dr. Laurie Anne Walden received her doctorate in veterinary medicine from North Carolina State University. After an internship in small animal medicine and surgery at Auburn University, she returned to North Carolina, where she has been in small animal primary care practice for over 20 years. Dr. Walden is also a board-certified editor in the life sciences and owner of Walden Medical Writing, LLC. She works as a full-time freelance medical writer and editor and continues to see patients a few days each month.


Advertisement

Latest News

New technology and products for veterinary genealogy

Reduce your veterinary teams’ stress with financial wellness

Cuban crocodiles receive surgery to extract foreign items

Purina Pro Plan Veterinary Diets joins forces with AVMF

View More Latest News
Advertisement