Abstract
To date, the only reliable laboratory method for the detection of blood in avian feces has been cytologic examination. This test relies upon the presence of intact red blood cells, which might remain intact during gastrointestinal transit, but are likely to break down when transit time is increased. Although some authors have advocated the use of a variety of laboratory tests for fecal blood detection, no test methods have been validated for birds.5 The purpose of this study was to evaluate fecal cytology, Hematest (Bayer, Philadelphia, PA), Hemoccult and Hemoccult SENSA (Beckman Coulter, Inc., Fullerton, CA) for the detection of blood and/or hemoglobin in cockatiel excrement.
Twenty healthy adult cockatiels (Nymphicus hollandicus) were used in this study. The health status of the birds was evaluated by physical examination, packed cell volume, fecal direct smear, fecal Gram stain, and Wright-Giemsa stained fecal cytology. The study was divided into two phases (in vitro and in vivo evaluation). Both phases involved standardizing cockatiel whole and lysed blood to 150 g/L of hemoglobin (Hb).
The in vitro phase tested excrement mixed with whole blood or lysed blood at 0.75, 1.5, 3, 6, and 12 mg of Hb per g of excrement. These test concentrations were based on a pilot study and reports of assay sensitivities in dogs and humans.1-3 All four test methods (fecal cytology, Hematest, Hemoccult, and Hemoccult SENSA) were performed on excrement samples (n=20) spiked with each concentration of whole, but cytologic examination was not performed on feces spiked with lysed blood. Two different observers read each test for all samples. One gram of feces from each bird was mixed with 0.24 ml of 0.9% saline and tested by all four methods to serve as controls.
The in vivo phase of this study included the same 20 cockatiels as the in vitro phase. For control birds (n=20), 2.5 ml of 0.9% saline was administered via soft rubber 5-French oro-ingluvial (gavage) tube. Pooled excrement from each bird was collected for a 12-hour period prior to saline gavage and 8-hour post gavaging. In addition, excrement passed between 8 and 24 hours post gavage was pooled and collected for testing. All samples were tested with all four methods by the same two observers as the in vitro phase of the study. A small amount of 0.9% saline was added to moisten dry excrement in preparation for testing. One week later, gavage administration of whole blood was begun. Dosages of 5, 10, 20, and 40 mg Hb per kg of body weight were each administered to all 20 birds. These dosages were chosen according to the methods of a similar study with dogs.4 Droppings were collected and tested at the same time intervals as the controls. Each bird was given the lowest dosage first and advanced to the next higher dosage after 2 consecutive days of negative fecal blood tests (via fecal cytology and Hemoccult SENSA). One week after whole blood administration (the last 2 days with negative fecal cytology and Hemoccult SENSA tests), the birds were gavaged with lysed blood and the same collection and analysis of excrement was performed as previously described.
Preliminary results determined that Hemoccult and Hemoccult SENSA were easy to use and read. Bird excrement dries quickly if it is not collected immediately after passage. However, saline can be added to dried excrement to allow it to be used with the test methods in this study. It is important to keep in mind that dietary peroxidases have been shown to cause false positive results with Hematest, Hemoccult, and Hemoccult SENSA. Examples of foods that contain peroxidases include uncooked or undercooked red meats and some raw vegetables including broccoli, cauliflower, radishes, turnips, horseradish, and some melons.6 It is hoped that upon completion of this study the results will determine which diagnostic test is most useful to diagnose occult bleeding and to justify further diagnostic testing. In addition, these tests may also be useful for indicating the need for therapeutic intervention in the treatment of ulcerative gastrointestinal disease.
Acknowledgments
This project was supported by a grant from the Center for Companion Animal Health, School of Veterinary Medicine, University of California, Davis.
Literature Cited
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