Intestinal Biopsy in Dogs

Intestinal biopsy is a technique used to help diagnose the cause of long-term vomiting or diarrhea. It involves harvesting a small sample of the intestinal wall, which is then preserved, and sent to a laboratory where the cell types are identified. 

Typically full-thickness intestinal biopsies are collected during a laparotomy procedure, in which the dog's abdomen is surgically opened to allow inspection of the internal organs. When intestinal biopsy goes well and heals uneventfully, it gives a definitive diagnosis in many cases. Unfortunately, healing doesn't always go smoothly and complications can occur, the most serious being peritonitis (infection within the abdominal cavity) due to leakage from the biopsy site.

The dog is prepped for surgery with intravenous fluids, pain relief, and antibiotics. The patient is given a general anesthetic and their abdomen shaved and scrubbed ready for surgery. 

The surgeon makes a surgical incision through the body wall. They systematically inspect all the organs in the abdomen, and every inch of the gut whilst being alert for abnormalities. The surgeon then selects which parts of the intestine to biopsy that are most likely to yield interesting pathology, for the histologist to analyse. 

A small, full thickness tissue is removed and the hole in the bowel wall repaired with absorbable sutures. The biopsy site is checked for leaks, and then the abdomen closed. 

In the immediate postoperative period, the dog is maintained on intravenous fluids and given pain relief. Once the dog is fully awake and eating unaided, the supportive fluids can be withdrawn. 

Intestinal biopsy is an effective way of getting answers about bowel related disease. The method that yields most information is a full-thickness biopsy obtained via surgery. However, at specialist centers a partial thickness biopsy can be obtained via endoscopy. The latter has its uses, but can miss evidence of disease if pathology is located in the deeper layers of the gut wall. 

After surgery, the dog is encouraged to eat within 24 hours. A low fat, easy-to-digest food is ideal. Most patients are able to go home the day after surgery, provided the clinician has no concerns about leakage from the biopsy site and the dog is eating. 

The dog has a follow-up appointment one to two days later, where blood may be taken to check for signs of leakage. If all is well, the dog is maintained on a bland, easy-to-digest diet until the skin sutures are removed at the ten day point. 

During the recovery period, the dog must rest and not partake in any vigorous exercise. They must also leave the abdominal incision alone and not lick at the wound, which may mean wearing a cone. Once the biopsy results are back, the clinician can then prescribe a treatment course to address the underlying problem that meant biopsy was needed. If this involves immunosuppressive drugs then these are not started until after the bowel has fully healed (because they can interfere with healing), at around two weeks out. 

Bowel biopsy is commonly undertaken in first opinion practice. The cost of anesthetic and harvesting the samples is often $800 upwards, with $1,300 being the lower threshold when other procedures are undertaken at the same time, such as removing a foreign body. 

Ironically, obtaining an endoscopic intestinal biopsy, although less invasive, is unlikely to be any cheaper because the equipment itself is costly.

Intestinal biopsy is often reserved as a procedure undertaken when all other diagnostic avenues have been explored. Whilst the information gained is very useful, there is a risk of complications. Chief of these is wound breakdown in the bowel wall, leading to spillage of gut contents into the abdomen, and peritonitis. 

The risk can be reduced (but not completely eliminated) with good surgical technique, so the owner needs to be aware of the life-threatening consequences should the worst happen. This may then necessitate repeat abdominal surgery to flush out the abdomen and repair the hole in the gut wall. 

Intestinal biopsy is a diagnostic process and one only pursued when other avenues have been explored. Thus before proceeding, the clinician must have a strong argument that bowel biopsy with the associated risks is going to be beneficial to the patient.