Low dose dopamine protects against hemorrhagic pancreatitis in cats

ACVIM consensus statement on pancreatitis in cats

Background

Pancreatitis in cats, although commonly diagnosed, still presents many diagnostic and management challenges.

Objective

To summarize the current literature as it relates to etiology, pathogenesis, diagnosis, and management of pancreatitis in cats and to arrive at clinically relevant suggestions for veterinary clinicians that are based on evidence, and where such evidence is lacking, based on consensus of experts in the field.

Animals

None.

Methods

A panel of 8 experts in the field (5 internists, 1 radiologist, 1 clinical pathologist, and 1 anatomic pathologist), with support from a librarian, was formed to assess and summarize evidence in the peer reviewed literature and complement it with consensus clinical recommendations.

Results

There was little literature on the etiology and pathogenesis of spontaneous pancreatitis in cats, but there was much in the literature about the disease in humans, along with some experimental evidence in cats and nonfeline species. Most evidence was in the area of diagnosis of pancreatitis in cats, which was summarized carefully. In contrast, there was little evidence on the management of pancreatitis in cats.

Conclusions and Clinical Importance

Pancreatitis is amenable to antemortem diagnosis by integrating all clinical and diagnostic information available, and recognizing that acute pancreatitis is far easier to diagnose than chronic pancreatitis. Although both forms of pancreatitis can be managed successfully in many cats, management measures are far less clearly defined for chronic pancreatitis.

Diagnosis of pancreatitis in dogs and cats

Pancreatitis is the most common disorder of the exocrine pancreas in both dogs and cats. Ante-mortem diagnosis of canine and feline pancreatitis can be challenging. The clinical picture of dogs and cats with pancreatitis varies greatly (from very mild to severe or even fatal) and is characterised by non-specific findings. Complete blood count, serum biochemistry profile and urinalysis should always be performed in dogs and cats suspected of having pancreatitis, although findings are not-specific for pancreatitis. Serum amylase and lipase activities and trypsin-like immunoreactivity (TLI) concentrations have no or only limited clinical value for the diagnosis of pancreatitis in either dogs or cats. Conversely, serum pancreatic lipase immunoreactivity (PLI) concentration is currently considered to be the clinicopathological test of choice for the diagnosis of canine and feline pancreatitis. Abdominal radiography is a useful diagnostic tool for the exclusion of other diseases that may cause similar clinical signs to those of pancreatitis. Abdominal ultrasonography can be very useful for the diagnosis of pancreatitis, but this depends largely on the clinician's experience. Histopathological examination of the pancreas is considered the gold standard for the diagnosis and classification of pancreatitis, but it is not without limitations. In clinical practice, a combination of careful evaluation of the animal's history, serum PLI concentration and abdominal ultrasonography, together with pancreatic cytology or histopathology when indicated or possible, is considered to be the most practical and reliable means for an accurate diagnosis or exclusion of pancreatitis compared with other diagnostic modalities.

Management of acute pancreatitis in dogs: a critical appraisal with focus on feeding and analgesia

Knowledge about acute pancreatitis has increased recently in both the medical and veterinary fields. Despite this expansion of knowledge, there are very few studies on treatment interventions in naturally occurring disease in dogs. As a result, treatment recommendations are largely extrapolated from experimental rodent models or general critical care principles. General treatment principles involve replacing fluid losses, maintaining hydrostatic pressure, controlling nausea and providing pain relief. Specific interventions recently advocated in human medicine include the use of neurokinin-1 antagonists for analgesia and early interventional feeding. The premise for early feeding is to improve the health of the intestinal tract, as unhealthy enterocytes are thought to perpetuate systemic inflammation. The evidence for early interventional feeding is not supported by robust clinical trials to date, but in humans there is evidence that it reduces hospitalisation time and in dogs it is well tolerated. This article summarises the major areas of management of acute pancreatitis in dogs and examines the level of evidence for each recommendation.

Pancreatitis in cats

Pancreatitis was considered a rare disease in the cat until a couple of decades ago when several retrospective studies of severe acute pancreatitis were published. It was apparent that few of the diagnostic tests of value in the dog were helpful in cats. With increasing clinical suspicion, availability of abdominal ultrasonography, and introduction of pancreas-specific blood tests of increasing utility, it is now accepted that acute pancreatitis is probably almost as common in cats as it is in dogs, although the etiology(s) remain more obscure. Pancreatitis in cats often co-exists with inflammatory bowel disease, less commonly with cholangitis, and sometimes with both. Additionally, pancreatitis may trigger hepatic lipidosis, while other diseases, such as diabetes mellitus, may be complicated by pancreatitis. Therapy is similar to that used in dogs, with added emphasis on early nutritional support to prevent hepatic lipidosis. Less is known about chronic pancreatitis than the acute form, but chronic pancreatitis is more common in cats than it is in dogs and may respond positively to treatment with corticosteroids.

The antiinflammatory effect of dopamine in alcoholic hemorrhagic pancreatitis in cats. Studies on the receptors and mechanisms of action

Hemorrhagic pancreatitis was induced in cats by perfusing pancreatic enzymes through a pancreatic duct after the administration of intragastric ethanol. Dimethyl prostaglandin E2 was administered concurrently. In the first study, dopamine's antiinflammatory effect on the pancreas was determined in the presence of haloperidol, propranolol, or both. Next, dopamine's effects on blood flow in the normal and inflamed pancreas were compared using a hydrogen gas-clearance technique. In the final study, the effect of dopamine on fluorescein isothiocyanate-labeled dextran leakage from the pancreatic duct to portal venous blood was investigated. It was found that blockade of either dopamine or beta-adrenergic receptors reduced, and blockade of both receptors completely eliminated, the antiinflammatory effect. Dopamine had no effect on pancreatic blood flow in normal cats. In pancreatitis, although dopamine transiently reduced blood flow, after an hour flow had returned to normal. Dopamine reversed the leakage of fluorescein isothiocyanate-labeled dextran from the pancreatic duct caused by ethanol and by ethanol and prostaglandin E2. It was concluded that dopamine ameliorated pancreatitis by reducing pancreatic ductal and/or microvascular permeability rather than by altering pancreatic blood flow. The antiinflammatory effect was mediated by both dopamine and beta-adrenergic receptors.

A study of the time course of conversion of edematous to hemorrhagic pancreatitis

We studied the conversion of acute edematous pancreatitis (AEP) to acute hemorrhagic pancreatitis (AHP) in an experimental model in cats. In the model, 16,16 dimethyl PgE2 effects this conversion by increasing microvascular permeability. First, we induced AEP in cats and then gave PgE2 at increasing intervals after the induction of AEP to see how long an interval would still allow conversion. In 6 groups of cats, PgE2 was administered for 2 h, starting at 2, 4, 6, 8, 10, or 12 h after the creation of AEP. Twelve h later, the cats were sacrificed and the pancreases were graded for inflammation and hemorrhage. Significant pancreatic hemorrhage did not occur when the PgE2 was administered at 12 h compared to 2 h. Next, we determined that PgE2 still retained its ability to increase pancreatic vascular permeability when administered 12 h after the creation of AEP. This was done by perfusing a marker molecule through the MPD (fluorescein isothiocyanate labeled dextran: FITC-D, mol wt 20,000) and then finding it in portal venous blood (PVB). The presence of FITC-D in PVB signified increased vascular permeability, since normally none was present. We concluded that conversion of AEP to AHP was possible during the first 12 h after induction of AEP. Lack of conversion at 12 h was not caused by a lack of vascular reactivity at that time.