Prostatic Biopsy in Dogs

Prostatic biopsy is used to diagnose diseases of the canine prostate gland. These conditions are most commonly diagnosed in sexually intact dogs, particularly those over five years old. However, some prostatic diseases can occur in dogs that have been neutered. Prior to biopsy, the veterinarian will conduct a physical examination of the prostate gland in addition to other diagnostic tests. There are a few approaches to prostatic biopsy. These include fine needle aspiration, ultrasound-guided needle biopsy, and excisional biopsy. The type of biopsy recommended will vary depending on the suspected underlying condition.

The procedure steps for various biopsy techniques are outlined below.

Fine Needle Aspiration

1. A small needle attached to an empty syringe is inserted into the prostate gland, either through the body wall or the rectal wall.
2. The veterinarian will draw prostatic cells into the needle by pulling back the syringe plunger. This suction is called aspiration.
3. This process may be repeated to obtain an adequate cell sample.
4. The cell sample is applied to a microscope slide and dried.
5. The veterinarian will apply a stain to the sample so the cells show up clearly under the microscope.
6. The sample is examined immediately, providing a tentative diagnosis.
7. Examination by a certified veterinary histologist is required to confirm the diagnosis. 

Ultrasound-Guided Needle Core Biopsy

The main difference between FNA and needle core biopsy is the size of the needle used and the use of ultrasound equipment. Needle biopsy requires sedation or anesthetization. This technique is used when a larger cell sample is required.

Excisional Biopsy

This technique is required if cancer is suspected. It is often performed during another therapeutic surgical procedure.

• General anesthesia or sedation is administered.
• The operative area is cleaned.
• Cysts and abscesses are typically removed before biopsy is performed.
• The surgeon will use a scalpel to excise a tissue sample from the prostate gland.
• This tissue sample is sent to a veterinary histologist to confirm the diagnosis.
• The dog may be hospitalized following surgery, depending on the procedure performed.

Prostatic biopsy is typically very effective in diagnosing prostatic conditions. Fine needle aspiration biopsy carries a success rate of 70% to 80%. When combined with excisional biopsy, the success rate increases to 89%. Fine needle biopsy is minimally invasive and rarely presents a false positive diagnosis. It also provides a tentative diagnosis quickly. Excisional biopsy allows for better visualization of the prostate gland, and is usually performed during a surgical procedure employed to evaluate and/or treat the condition. All cell or tissue samples collected must be analyzed by a veterinary histologist to confirm the diagnosis. The results typically take one to two days to come back.

Dogs will not need to recover from fine needle biopsy, since it is typically painless. For excisional biopsy, the recovery instructions will depend on the surgical procedure performed. Owners should follow their veterinarian’s recovery instructions carefully.  Sutures are removed within fourteen days of surgery. Exercise is typically restricted, and the dog may need to wear an Elizabethan cone to avoid contaminating the suture site. If bleeding, swelling, or discharge occurs near the incision site(s), owners should contact their veterinarian immediately. Follow-up appointments will be scheduled as needed to administer further treatment.

The cost of prostatic biopsy in dogs will vary based on standards of living, the type of biopsy performed, and additional diagnostic costs incurred. The price of prostatic biopsy, including the price of the vet visit and additional tests, ranges from $100 to $1,000.

Prostatic biopsy should not be performed in dogs with severe swelling, inflammation, or the presence of abscesses. Abscesses must be removed prior to prostatic biopsy. Additionally, for ultrasound-guided biopsy, the ultrasound gel must be removed before biopsy because it can contaminate the cell sample.

Prostatic biopsy typically carries little to no risk of complications. However, complications may include:

• Allergic reaction to sedative or anesthesia
• Inaccurate diagnosis
• Trauma to the body or rectal wall
• Infection

Some prostatic conditions, particularly BPH, are difficult to prevent because they affect a large percentage of dogs. Owners should consider neutering their intact dogs to decrease the risk of prostatic disease. Castration may cure certain prostatic conditions.