When a dog presents with severe acute or chronic gastrointestinal upset, it can be difficult to pinpoint the exact cause of the distress. Symptoms associated with gastrointestinal issues include vomiting, diarrhea, loss of appetite and abdominal distention. To try and diagnose the ailment, x-rays and blood tests will be used. If these methods do not provide ample information, a biopsy may be needed.

Biopsies require affected tissue in the stomach or intestines to be collected and examined at a laboratory. Once the tissue is seen at a microscopic level, determining the cause of the problem becomes more likely. There are different ways to collect gastrointestinal biopsies. Endoscopy, using a long tube with a camera, can be used to visualize the gastrointestinal tract and collect shallow tissue samples. A full-thickness incisional biopsy can be harvested surgically and provides the veterinarian with the most information. A percutaneous (through the skin) biopsy may also be taken using the aid of ultrasonic imaging. An ACVS board-certified veterinary surgeon should be used for this diagnostic process.

Before a biopsy is taken, an ultrasound or x-ray will be needed to locate the inflamed area and any growths in the stomach or intestines. Blood work will be used prior to the biopsy harvest to help determine if the dog is healthy enough to receive general anesthesia. The dog will be required to fast for some time prior to the procedure, to limit complications with the anesthesia and to leave the stomach and intestines as empty as possible. If an incisional biopsy is being performed, the area of entrance on the abdomen will be shaved and disinfected. An  IV will be placed to administer the sedative.

For a full-thickness biopsy, an incision must be made in the dog's abdomen. Once the affected area of the stomach or intestines has been located, it will be secured using stay sutures. The tissue or growths can then be removed using scissors, a scalpel, or a Keyes biopsy punch. This tissue will be placed in an airtight container​ and sent to a laboratory for histopathological examination. The stay sutures can then be removed and the incision closed and sewn shut using regular sutures. 

If the biopsies are being taken endoscopically, the endoscopic tube will be inserted through the mouth and down the esophagus for stomach biopsies, and through the rectum and up the bowels for intestinal biopsies. Surface tissue may then be clipped off and removed from the body for evaluation. Percutaneous biopsies may be taken using a long needle inserted through the skin into the affected stomach or intestinal tissue. Ultrasonic imaging is used to guide the needle to the correct location.

The effectiveness of a gastrointestinal biopsy depends on the type of biopsy being performed. While incisional, full-thickness biopsies are more invasive, they generally yield much better results from the amount of tissue harvested. Incisional biopsies are tolerated quite well by most dogs. 

Endoscopic biopsies are more limited in their use, only identifying issues above the mucosa of the intestines. These biopsies are effective for identifying foreign objects, strictures, swelling or scars in the stomach or intestines. Percutaneous biopsies, while minimally invasive, only carry a 69% accuracy rate. All of these procedures may be paired with fecal evaluation.

The dog will need to be closely monitored as the general anesthesia wears off to ensure all vital functions resume properly. All tissue samples that were collected will be sent off for examination at a lab. If there was an incision made, an Elizabethan collar will be recommended to keep the dog from licking or biting at its surgical wound. A follow-up appointment will be needed one week after the biopsy to discuss the results from the lab. Depending on the ailment, a treatment plan will be constructed and initiated. Some health problems such as cancer will require ongoing care.

The cost of a biopsy can range from $1,000 to $2,000. This is due to the fact that general anesthesia is used for the procedure, and a skilled surgeon is required for proper tissue harvesting. The blood work alone may cost up to $100, and radiographs generally cost up to $150. If an MRI is used, this can increase the total cost by approximately $1,000. Ultrasonic imaging can be priced around $300. All of these costs combined make biopsies a more expensive diagnostic measure. It should be noted that further costs will be incurred in the actual treatment of the animal.

Complications resulting from gastrointestinal biopsies are very rare. The use of general anesthesia always brings serious health risks, especially in animals who are older or who already suffer from other problems. If a full-thickness biopsy is performed, the incision site may open or become infected. A very small number of dogs who undergo these biopsies develop septic peritonitis, which can be life threatening. The biopsy site from the stomach or intestines may also leak into the abdomen if not closed correctly.

Many different issues can lead to a gastrointestinal biopsy being needed. Cancers of the gastrointestinal tract may be genetically inherited or can develop due to environmental exposure. It is always important to request your dog's family health history when obtaining the animal. This can help identify certain issues to watch for as the dog ages. 

A foreign body lodged inside a dog that is not seen on an x-ray may lead to a biopsy surgery. To prevent blockages caused by foreign objects, do not allow your dog to chew on sticks, broken toys or any other non-food items. Keeping a dog's stress levels down may prevent certain inflammatory responses in the animal that leading to gastrointestinal upset.