Complications on unabsorbable suture materials are not widespead in the countries where absorbable suture material or tissue sealing with electrocautery or Ligasure devices are used. But it’s still seen as a consequence of using unabsorbable multifilament suture material. It is considered, that such reactions arise because of lack of sterility during the surgery, and bacteria forming biofilms on the sutures as a result. As a reaction from the body granulomas form around the sutures and lately they might cause formation of fistulas. The most common surgeries when we can see such complications are bitch spays.
Periods of time, when fistula(s) form can be quite different. From my personal experience it can happen a cuople of weeks after the surgery, but it also happens as late as several years after spaying. The longest period in my practice was 10 years after the surgery.
The clinical appearance is usually typical: owners notice fistula(s) on the abdomen or lateral parts of the pet with exudate or pus. Rarely it can be just a painful skin inflammation on the flank without actually a fistula there. A lot of dogs demonstrate unwillingness to run and jump without any obvious lameness. Another clinical sign can be pollakiuria in the cases when granuloma forms around the uterus stump.
The tentative diagnosis can be made via clinical appearance. But in all the cases it’s mandatory to perform an ultrasound of the abdomen in order to check all the possible granulomas, that can be asymptomatic. The areas of interest during the ultrasound are caudal poles of the kidneys and uterus stump. It’s quite important to check whether the ureters are involved in the granulomas, as it makes the case much more complicated. CT can be much more useful in checking the organ involvement and planning the surgery.
The СBСs are usually unremarcable or with signs of inflammation. In cases where granulomas have formed around the ureters the patient can show signs of azotemia (post-renal) and we will see high urea and creatinine in biochemistry panel.
The only possible option to treat the patient is surgical removal of the granulomas with the suture material inside or just the suture material from the ventral body wall. The therapeutic approach: using antimicrobials, flushing and draining the fistulas can help for some period of time, but then the problem will arise again.
The surgical approach to such cases is always the same: remove all the sutures from the body wall (often with a part of it in case of severe inflammation and thickening) and remove all the sutures and granulomas from the abdomen via middle-line laparotomy. Nevertheless, a lot of such surgeries are quite complicated because granulomas tend to be firmly connected with kidneys and it’s mandatory to remove them without injury of the kidneys. Another problem can be to free the ureter from the granuloma without breaking it or sometimes you have to reimplant them to the bladder or partly resect. It can be quite tricky to remove the granuloma from the uterus stump as they tend to be firmly connected with the dorsal part of the bladder. Sometimes other organs can be involved like omentum and intestines that leads to partial resection.
In severe cases you can observe hydronephrosis because of the mechanical compression of the ureter, and in such cases the kidney must be removed.
After removing granulomas it’s important to check whether all the suture material has been removed, and to flush and suture the peritoneum. The actual absesses around the sutures are quite rare.
After closing the abdomen don’t forget to check and flush and maybe drain if nessesary all the fistulas. If you have removed all the implants, the fistulas will resolve in about a week.
The prognisis in such cases depends on how much all the other organs (kidneys, ureters, bladder) are involved in granulomas, so it can vary from excellent to grave.