Feline pancreatitis: underdiagnosed or overdiagnosed? (Proceedings)
For years, feline pancreatitis has been assumed to be a similar disease to that in dogs. As with so many other disorders, this group of disorders is different in the cat. Given that the term "pancreatitis" implies nothing more than inflammation of that organ, it is not surprising that each species may have a variety of etiologies. In a German retrospective study, the prevalence of pathologically significant lesions in dogs was found to be 1.5% and in cats, 1.3% of the specimens submitted. Indeed, there are papers reporting the incidence as high as 2.9 and 3.5% of necropsied cats. More recently (2007), in a retrospective study evaluating the prevalence and histopathologic features of pancreatitis in the pancreata of 115 cats presented for necropsy for any reason, the stunning finding of prevalence of histologic evidence of pancreatitis in all of these cats was 67% and, even more astounding is the finding of a 45% prevalence in cats who were apparently clinically normal at the time of death! [DeCock]
Human medicine classifies pancreatitis as acute or as chronic. Using a similar scoring system, the aforementioned study determined that in cats, acute pancreatitis (AP) consists of neutrophilic inflammatory changes with concurrent interstitial edema and mesenteric fat necrosis. In chronic pancreatitis (CP) fibrosis is more notable than is inflammation, and the inflammatory cell infiltrate favours lymphocytes along with some macrophages and eosinophils. Additionally, cystic dilation and changes in lobulation were seen in the chronic form of the disease. Unlike human CP, there were only minimal pancreatic duct changes in cats.
From a clinical standpoint, AP is a short term, disease, often completely reversible unless it is acute necrotizing disease, which is a completely different entity. Because chronic pancreatitis, the more common form of pancreatitis in cats, represents a long-term process and is associated with irreversible histopathological changes, primarily fibrosis it isn't curable; however, it can generally be controlled and is less fatal than acute necrotizing pancreatitis (ANP). Although unproven, there is some thought that CP may ↔ ANP in some cases. [Washabau]Both acute and chronic pancreatitis can be mild or severe, but acute cases tend to be more severe, and chronic cases milder. Mild pancreatitis generally results in minimal clinical signs, minimal necrosis, and low mortality.
In acute necrotizing pancreatitis, (ANP) extensive pancreatic necrosis and multiple organ involvement +/- organ failure are seen. Fortunately, because in cats this form is rare, severe multi-system complications are uncommon. The prognosis for acute necrotizing pancreatitis is poor. Other complications of pancreatitis may include fluid accumulation around the pancreas, infection of necrotic areas, pseudocysts, and abscesses.[Bailiff] [Coleman]
Histopathologic classification may help in designing appropriate therapeutic protocols for our patients. DeCock paper suggests one schema and is found online at: http://vet.sagepub.com/content/44/1/39.full.pdf+html. When you submit pancreatic biopsies be sure to get a good description from your pathologist.