VCA Animal Hospitals

Buffy Coat Examination for Mast Cells

What is the buffy coat?

"The buffy coat is simply a concentration of all the white blood cells... in a sample of blood"

Blood consists of millions of cells suspended in a liquid called plasma. These cells include red blood cells (whichbuffy_coat_examination-1 carry oxygen), white blood cells (which fight infection), and platelets (which help with clotting). Examining red blood cells is easy because there are so many of them; thousands of red blood cells can be seen in a single drop of blood. By comparison, white blood cells are present in very small numbers, and examining them is more difficult.

The fastest way to examine large numbers of white blood cells is to look at a buffy coat smear. The buffy coat is simply a concentration of all the white blood cells and platelets in a sample of blood. To prepare a buffy coat, a special machine spins the blood sample in a small circle at very high speed in a process called centrifugation (much like a spinning ride at an amusement park). This causes the blood to separate into three parts: a large bottom layer of red blood cells, a large top layer of clear plasma, and a narrow middle band that contains all the white blood cells and platelets. This band just happens to be creamy white to buff-colored, and as a result it is called the buffy layer or "buffy coat". The buffy coat material is collected and spread on a glass slide where it is examined under the microscope.

Why examine the buffy coat?

The main reason to examine a buffy coat is to look for abnormal white blood cells that are circulating in the blood stream. The most important cell to look for in a buffy coat is called a mast cell.

What are mast cells, and what does it mean if mast cells are found in the buffy coat?

buffy_coat_examination-2Mast cells are a specific type of white blood cell. They play an important role in allergies and related conditions. In healthy pets mast cells are found almost exclusively in body tissues and only very rarely in the blood stream. Mast cells can become neoplastic (neoplasia means "new growth" or tumor), and when they do, they form a mass or growth called a mast cell tumor. These growths may develop in the skin or in an internal organ, and they can be benign or malignant (cancerous).

If a mast cell tumor is highly malignant it may spread through the body, enter the bone marrow, and ultimately appear in the blood stream. This widespread distribution of malignant mast cells through the body is called systemic mastocytosis. The simplest way to detect this condition is to examine a buffy coat smear.

If a pet has been diagnosed with a mast cell tumor, it is important to do a buffy coat examination before surgically removing the growth. Knowing ahead of time whether or not mast cells are present in the buffy coat may help the veterinarian predict what will happen after the growth is removed. The chances for a good outcome are much better if the buffy coat is negative, which suggests the tumor has not spread. The presence of large numbers of mast cells in the buffy coat usually indicates that systemic mastocytosis is present. This is a worrisome finding since the condition is difficult to cure and can be fatal. However, there are medications that can help to control the disease and prolong the life of the pet.

If the buffy coat examination is negative, what then?

"A negative buffy coat examination is good news, but it is not a guarantee..."

A negative buffy coat examination is good news, but it is not a guarantee that the mast cell tumor has not spread. Your veterinarian may want to do further testing, and may suggest sampling lymph nodes (lymph glands) or bone marrow to see if the tumor has spread. Alternatively, your veterinarian may suggest doing a series of buffy coat examinations at regular intervals to monitor the pet for systemic mastocytosis.

What sample is needed?

A simple blood sample is all that is needed for a buffy coat examination.

Related Tags

buffy, cells, mast, examination, mastocytosis, tumor, cell, sample, smear, white, negative, examine, encouraging, marrow, bone, centrifuge, spun, centrifugation, amusement, platelets, concentration, layer, veterinarian, park, spinning, important, simply, growth, guarantee, surgery, alternatively, prolong, fatal, medication, suppress, disease, elect, invasive,

Looking to learn more?

We also offer free, instant access to over 1,500 related articles on your pet's health including preventive medicine, common and not so common diseases, and even informative case studies. We encourage you to read any of these popular articles below or search our extensive pet health library.

Most Popular Articles

About our approach to exceptional pet health care

At VCA Animal Hospitals, our veterinarians take you and your pet's health seriously. With over 600 hospitals and 1,800 fully qualified, dedicated and compassionate veterinarians, we strive to give your pet the very best in medical care. We understand your pet is an extension of you, and appreciate the opportunity to share in providing exceptional pet care and quality of life.

* Free initial health exam for new clients only. Not to be combined with any other offer. Not good toward boarding, grooming, prescription and non-prescription medication, and retail items. Not good toward emergency and/or specialty veterinary services. Coupon good for up to two pets (dogs or cats only) per household. Redeemable only at a general practice VCA Animal Hospital. For pet owners who are aged 18 and older.

If you are a new client, you can get a free first exam* on your first visit.

Free First Exam

Get to know us by visiting one of our neighborhood hospitals.

Locate a Hospital

General Practice

We have over 540 animal hospitals in 41 states that are staffed by more than 2,000 fully qualified, dedicated and compassionate veterinarians, with more than 200 being board-certified specialists. The nationwide VCA family of general practice hospitals give your pet the very best in medical care, providing a full range of general medical and surgical services as well as specialized treatments*: Wellness, Spay/neuter, Advanced diagnostic services (MRI/CT Scan), Internal medicine, Oncology, Ophthalmology, Dermatology, Cardiology, Neurology, Boarding, Grooming

*services may vary by location.

Our family of pet hospitals stands out by delivering the greatest resources in order provide the highest quality care available for your pets. By maintaining the highest standards of pet health care available anywhere, we emphasize prevention as well as healing. We provide continuing education programs to our doctors and staff and promote the open exchange of professional knowledge and expertise. And finally, we have established a consistent program of procedures and techniques, proven to be the most effective in keeping pets healthy.

Find a VCA General Care Animal Hospital near you:


See all VCA Animal Hospitals >


Specialty Care

Sometimes sick or injured pets need the care of a veterinary medical specialist. When that happens, VCA specialty hospitals work closely with the general practitioner veterinarians who refer cases to us in order to provide seamless veterinary care to your pet. When your pet is facing any kind of serious illness or injury, our specialty referral hospitals will provide the compassionate and expert care your beloved pet needs.

Our goal is to make sure that when you and your pet are in need that you have access to board certified specialists who are up to date on the very latest developments in their field. In our state of the art hospitals, our specialists also have access to the most sophisticated diagnostic and treatment tools and techniques from ultrasonography and endoscopy to CAT scans and even MRI.

We have twenty-eight specialty hospitals across the US so there may be one near you. Our specialized services include: cardiology, critical care, dentistry, dermatology, internal medicine, neurology, oncology, ophthalmology, radiology and surgery.

Find a VCA Specialty Care Animal Hospital near you:


See all VCA Animal Hospitals >


Emergency Care

In case of emergency, please call us immediately. If it is after hours, check with a local animal hospital emergency clinic.