What is involved in a skin biopsy?
Most skin biopsies are performed on a suspicious skin growth or on an area of skin that has failed to respond to treatment.
In many cases, the area to be biopsied is numbed with a local anesthetic. In some cases, depending on the area involved or the nature of the patient, it may be necessary to give the patient a sedative or general anesthetic. Either the entire mass or a small section of skin is removed and submitted to a veterinary pathologist, who will perform a histopathology analysis (examine the tissues under a microscope).
The pathologist will attempt to determine the nature of the lesion, identify the type of cells and their relationship to each other, as well as any evidence of malignancy (presence of cancer cells). Most skin biopsies are very small and require few sutures (stitches). If you need to provide any home care to the biopsy site after your dog returns home, your veterinarian will explain this in detail.
Skin punch biopsies can be done using a local anesthetic block, sedation, or general anesthesia. This is dependent on the area to be sampled and the patientâs temperament. Allow enough time for the local anesthetic to take effect before starting the biopsy. Time to effect is based on the individual patient, and can vary, and potentially may take up to 5-10 minutes3. Some patients will still demonstrate sensation due to the pressure on the skin from the punch.
Christine Hackworth is a RVT in the Exotic and Dermatology sections of the Veterinary Health Center at the Kansas State College of Veterinary Medicine.
If bacterial and/or fungal cultures are to be performed on a skin biopsy, the area can be lightly prepped by aseptic technique to remove any normal skin flora that may contaminate the sample, prior to taking the punch biopsy. The skin sample is then placed in a COPAN EswabTM. These swabs can be used for aerobic, anaerobic, and fungal tests.
Multiple lesions (3-4 representative areas) can be submitted in one formalin jar, unless otherwise noted by a veterinarian. When submitting lesions of different appearances in the same formalin jar, it is helpful to designate the separate samples with suture or some marking of each sample. Designate on the submitting paperwork how they are marked and what the sample is. Otherwise different samples can also be sent in separate formalin jars and labeled accordingly. Punch biopsies donât need to be placed in a biopsy cassette.
Skin punch biopsy is a common diagnostic technique that can provide valuable information. Most skin biopsies are performed on a suspicious skin growth or on an area of skin that has failed to respond to treatment1. Depending on the size and severity of the lesion, the entire skin growth or a small section of skin can be removed and submitted to a veterinary pathologist, who will perform a histopathologic analysis.
How long will it take to get the results?
The sections of skin are sent to an external laboratory, where they are processed ready for the pathologist to examine. A full report back from the laboratory normally takes around 5-7 days.
A section of skin shown in cross section following removal by biopsy
As performing a skin biopsy is a minor surgical procedure, – there is normally very little aftercare. Drugs such as antibiotics and pain killers are not usually required. Depending on the sites affected and the stitch material used, it may be necessary to remove the stitches after around 10 days.
If you have any queries or concerns, please do not hesitate to contact us.
How to take Punch Biopsy in Dogs
When your dog has a mass (something unexpected in or on his body), one of the decisions you will need to make with your veterinarian is whether you should remove and test it, or test a piece of it first, and then remove it. Regardless of which option you choose, testing a piece of a mass is called a “biopsy.” 
How is a biopsy performed? A biopsy is performed by removing a small portion of the mass and sending it to a pathologist. A veterinary pathologist is a veterinary specialist who reads microscopic preparations (cells or tissue on a slide). A few specialty practices, and all veterinary schools, have a pathologist on staff. Most other practices will send the samples to an outside lab. Depending on the sample and the lab, you will typically receive results an average of 7-10 days after the procedure. A biopsy is performed under sedation or general anesthesia in most cases. Small samples can sometimes be collected after local anesthesia is used, e.g., a skin biopsy.Click here to learn about anesthesia safety and myths. Why might your veterinarian suggest that a mass be removed after a biopsy? Depending on the location of the mass, it may be challenging to safely remove (excise) it in its entirety. If a microscopic examination reveals that the mass is cancerous (malignant), your veterinarian will want to remove as much of it as possible — even if it means removing healthy tissues beyond the mass (in every direction). This can be difficult, if not impossible, in some areas where there is little extra skin (such as the foot or the leg) but it will be very important to keep the cancer from spreading. However, if the biopsy reveals that the mass is benign, then less healthy tissue needs to be removed. In this situation, the biopsy will change the invasiveness of the surgery. Why might your veterinarian suggest that a mass be removed before a biopsy? When a mass is small, it may not be much more invasive to remove it completely than to take a biopsy first. The smaller the mass, the easier it is to remove, meaning a less invasive surgery for your dog and a smaller bill for you. Delaying treatment by performing a biopsy first is not always ideal either. Even if a mass is benign, if its causing a blockage or mobility issues, it should be removed right away. In these cases, since a biopsy would not change the immediate treatment plan, it is reasonable, if not advisable, to go straight to surgery. For very aggressive masses, actively bleeding masses or rapidly declining patients, delaying treatment is again not recommended. Waiting 7-10 days for biopsy results could make the difference between life and death, or could cause additional suffering. Performing a biopsy and then removing it also means that your dog will be undergoing anesthesia twice in a short period of time. If your dog is healthy, the risk is minimal. But if your dog is sick, your veterinarian may decide it’s safer to opt for removal without a preliminary biopsy to minimize the potential of anesthetic complications. Performing a biopsy first and surgery later is also more costly. Click here to learn about pet insurance so that you are never put in a position where finances keep your pet from the best possible care. Pet biopsy decision tips
If you have any questions or concerns, you should always visit or call your veterinarian — they are your best resource to ensure the health and well-being of your pets.