Insulinoma with diabetes mellitus!
This is just the most unbelievable story I’ve come across in some time. This 11 y.o. dog presented with episodic collapse. After a thorough work-up it transpired that she was sometimes hypoglycaemic and an insulin assay confirmed that levels were way above what would be expected at the time of hypoglycaemia. She was treated with prednisolone and dietary modifications and the frequency of collapses greatly decreased. So far so good.
The prognosis for dogs with insulinoma is surprisingly reasonable (I hesitate to say good because it does usually catch up with them eventually) but they often be managed with good quality of life for months or even years. Palliative surgical resection of pancreatic lesions and identifiable metastases improves survival.
We performed an ultrasonographic exam of her abdomen and were satisfied to locate a hypoechoic mass in the right lobe of the pancreas, plus an enlarged pancreaticl ymph node immediately cranial to the duodenal flexure. That’s a good start because they can be difficult to find -even with CT.
The only concern here is that the rest of the pancreatic right lobe also looks abnormal. There are mottled areas of increased echogenicity which suggest chronic pancreatitis:
So, feeling a little uneasy about this, we had a long discussion about the potential risk and benefits of surgery given that there might be more going on than just the insulinoma. It emerged during this discussion that the patient had, curiously, stopped collapsing at all over the preceding few weeks, and furthermore was now a bit poorly and possibly drinking more. Blood biochemistry revealed a glucose of 30 and this hyperglycaemia was subsequently shown to be persistent. A pancreatic lipase result was consistent with pancreatitis.
There are various unanswered questions at this point. The most likely scenario seems to be that chronic pancreatitis has caused enough damage to prevent insulin production -a not infrequent sequel to pancreatitis in dogs without an insulinoma. Investigations continue.
