BISCUIT

Biscuit is a five year-old spayed female Cocker Spaniel. She is owned by an elderly who spoils her and Biscuit eats a lot of "people food." Biscuit weighs 47 pounds.

Biscuit is brought to your clinic in a great deal of distress one morning. She had been vomiting since the previous night but her owner wanted to avoid the cost of emergency treatment so she waited until your office was open.

Biscuit's temperature is 41C, her respiration is rapid (30) and shallow, and her abdomen is taut and somewhat distended. Her sclerae are congested and her capillary refill time is increased. She yelps when you palpate her abdomen and is obviously in a great deal of pain.

You ask the owner if anything she did might have made her dog sick, specifically if she had given the dog anything to eat the previous evening that was unusual. She says that she gave the dog the fatty scraps of a ham she was preparing, and that Biscuit liked the scraps so much that she gave her a second helping.

You begin fluid therapy to rehydrate the dog and order radiographs of the abdomen. These indicate marked swelling of the pancreas and fluid accumulation in the mesentery around it. You decide to start analgesia and order her NPO, keeping Biscuit in your clinic for a couple of days' observation.

DIAGNOSIS

Biscuit has acute pancreatitis. This is inflammation of the pancreas, either due to infection or to dietary indiscretion. In this case, the cause was due to the dog's eating an big greasy pile of ham cuttings. The exact cause of pancreatitis from overindulgence in fat is unknown, but the principal mechanism is ischemic damage to the pancreas itself, particularly to the acinar cells. The acinar cells are responsible for elaborating several digestive enzymes, key among them being lipase and amylase, the enzymes that digest fat and carbohydrates.

In acute pancreatitis, the acinar cells become ischemic and die, thereby releasing large amounts of lipase and amylase into the pancreatic parenchyma. This causes immediate and massive damage to the pancreas, since the enzymes start to autodigest the parenchymal tissue. The result is predictable: intense local inflammation and necrosis, with subsequent edema, hemorrhage, and tissue devitalization. This leads to acute necrosis of the pancreas which in turn releases more enzymes into the abdomen. The course of inflammation and necrosis quickly spreads to the surrounding mesentery fat and other local tissues.

The basis of treatment for these cases is fluid therapy to restore tissue perfusion, overcome dehydration, and to help flush out the accumulated toxins from tissue necrosis. In some instances antiemetics can be given once perfusion has been reestablished. Mild acute inflammation should resolve within a few days and food should be withheld during that time. Sequela of the event may include diminished pancreatic function and adhesions of the mesenteric membranes to the bowel or body wall. Dystrophic calcfication is another common finding.

HISTOPATHOLOGY

 

A diagnosis of acute pancreatitis is typically made by reviewing the history and observing the clinical signs. The typical signalment for a pancreatitis patient is an older, obese, female canine with a history of dietary indiscretion; clinical signs include acute vomiting, dehydration, distended and painful abdomen, and possibly diarrhea. The diagnosis can be strengthened by testing serum levels of lipase and amylase, because in the pancreatitis patient they will be elevated.

Here's what an inflamed pancreas looks like, up close and personal. This is a low-magnification image, and you can see regions of hemorrhage at lower left; some fat necrosis at upper right, and a pretty good deal of fibrosis—proliferation of collagen in the septations of the organ, i.e., scarring—that testify to the organ's attempts to heal itself, and that this case is of fairly long standing. Leakage of digestive enzymes into the general parenchyma of the organ causes inflammation and widespread tissue damage, often snowballing to a disastrous level. In dogs acute pancreatitis is usually the result of "dietary indigestion." My sister-in-law's Jack Russell Terrorist ate an entire can of bacon grease and ended up in ICU for a week. She was lucky: if it had been any worse she'd have died, and many dogs do.

It wasn't necessary in this case to have taken one to make this diagnosis, but a biopsy of mesenteric fat from Biscuit's duodenopancreatic ligament would have shown the appearance you see here at low power and higher magnification. Many adipocytes are irregular in form and stain a light pink, indicative of severe irritation and necrosis in reaction to the lipases released from the inflamed pancreas.

This image (right) shows fairly normal adipocytes at the top left, and a region of necrotic adipocytes at center. Notice how the dead cells appear to have thicker membranes and appear crimpled and contracted. The pink color comes from proteinaceous and fatty debris. The blue-staining regions are the result of stain artifact caused by the abnormal ionic and pH conditions in the inflamed areas. At left is a close-up view of necrotic adipocytes, which have retained their general shape; but their normally clear cytoplasm has been replaced by amphophilic debris. This fat necrosis is a special case of the coagulative pattern. In the image above right, the interstitium has been thickened by edema and cellular inflammatory infiltrates.

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