Gastroenterology for practitioners: part 1 (Proceedings)

Case 1: 12 week old puppy just adopted from shelter. Now vomiting/diarrhea/ listless and dehydrated.

Parvovirus with diagnosed with appropriate clinical signs, SNAP ELISA, and the presence of neutropenia. Sepsis is especially likely when the neutrophil count is less than 1,000/microliter. False positive SNAP results may result from recent vaccination (to the patient or through contact with a recently vaccinated pet). Treatment for parvovirus is supportive: fluids, antibiotics (ampicillin or amoxicillin, metronidazole, and enrofloxacin or an aminoglycoside), antiemetics (metoclopramide, ondansetron, maropitant*, chlorpromazine), and pain control (buprenorphine). There has been research into nutritional support, hematopoietic growth factors, and immune serum; however none of these therapies have become widely adopted.

Case 2: 12 month old german shephard has diarrhea for 3 months.

Exocrine pancreatic insufficiency (EPI) is diagnosed most frequently in young, large breed dogs. The classic signs are weight loss, diarrhea, and excessive appetite. In the early stages signs may be intermittent. The test of choice is the trypsin-like immunoreactivity (TLI) assay.

Case 3: 6 year old dog has chronic diarrhea. Total protein is 3.0 (ALB 1.5, GLOB 1.5).

Differential diagnoses for panhypoproteinemia include protein and/or blood loss. A normal hematocrit excludes blood loss. Low albumin with normal globulin level is consistent with renal loss or decreased hepatic production. Decrease of both albumin and globulin is consistent with protein loss from the intestine. The 3 main differential diagnoses for protein-losing enteropathy are lymphoma, inflammatory bowel disease, and lymphangiectasia. Appropriate diagnostics include complete blood count (CBC), biochemical profile, urinalysis (protein/creatinine ratio if appropriate), possibly bile acids (pre- and post prandial), fecal flotation, chest radiographs, abdominal ultrasound, and gastrointestinal biopsies. In rare cases alpha-1-antiprotease is used. Careful consideration should be given whether to obtain surgical or endoscopic gastrointestinal biopsies. Treatment for IBD/lymphangiectasia involves low fat and/or hypoallergenic diet, metronidazole, and glucocorticoids. Additional immunosuppressants (azathioprine, cyclosporine) are frequently added. Antithrombotics (clopidogrel) are recommended while the albumin is low. The prognosis is guarded to fair.

Case 4: 3 year old dog with intermittent vomiting/diarrhea and weight loss. CBC revealed eosinophilia.

Eosinophilia is often associated with parasitism and a fecal flotation is suggested. The lack of a stress leukogram may also suggest hypoadrenocorticism. An ACTH stimulation test (or screening with a resting serum cortisol) is recommended.

Case 5: 10 year old dog with poor appetite/weight loss. Profile shows tp 4.5 (ALB 1.0, GLOB 3.5).

It may be difficult to distinguish hypoalbuminemia from panhypoproteinemia because the normal range for globulin is broad. Look for a split between the albumin and globulin concentrations; even if globulins are within the normal range, a lack of difference between albumin and globulin concentration suggests panhypoproteinemia (compare this example with case #3, above). Hypoalbuminemia (with normal or elevated globulin concentration) is most commonly secondary to renal loss (protein-losing nephropathy) or decreased hepatic production. Urine protein/creatinine ratio and bile acids (pre- and post-prandial) are suggested.

Case 6: 3 year old dog: acute vomiting/bloody diarrhea. PCV 65%/TS 6.5 G/DL.

Hemorrhagic gastroenteritis (HGE) is diagnosed when the packed cell volume is > 60% and total solids are normal to low. These PCV/TS results are consistently present. Despite obvious hemorrhage into the gastrointestinal tract the packed cell volume is elevated, suggesting severe volume depletion. The total protein value is normal to low, suggesting a massive protein loss in excess of red cell loss. The syndrome rapidly responds to aggressive IV fluid administration and the prognosis is good.

Case 7: 12 year old dog that drinks a lot of water. ALK PHOS 1200, ALT 120, BILI 0.3.

I diagnose hyperadrenocorticism with a low-dose dexamethasone suppression test. This test is more sensitive than the ACTH stimulation test and also offers (in some cases) the ability to differentiate pituitary vs. adrenal origin of the disease. Urinary tract infection (often without pyuria) and systemic hypertension are often present in dogs with hyperadrenocorticism; urine culture and measurement of systemic blood pressure are routinely recommended. Treatment is with Lysodren or trilostane.