Abstract
Impaction of the anterior alimentary tract has been reported in various avian species, most notably ratites, although impaction with bedding or other enclosure materials has also been reported in juvenile psittacines and turkeys.1,4-7 Impaction due to phytobezoars have seldom been described in avian species, with only a few reports in ratites and domestic poultry.2,4,8 This report describes three cases of ventricular impaction with plant material in Micronesian kingfishers (Halcyon cinnamomina cinnamomina).
Three juvenile male Micronesian kingfishers (Halcyon cinnamomina cinnamomina) housed in the same enclosure were presented for evaluation of coelomic distention and sudden weight gain. Attitude, feed consumption, and defecation were normal. Maintenance ration consisted of neonatal mice, crickets, and occasional mealworms. The kingfishers had been observed stripping the leaves from two of several species of plants in the enclosure, the corn plants Dracaena fragrans massangeana and D. f. sanderiana. The birds were immobilized with isoflurane (Isoflurane, Phoenix Pharmaceutical, St. Joseph, MO) via a facemask for induction and endotracheal tube for maintenance. Physical examination and coelomic palpation revealed a large, single, firm coelomic mass in each bird, which was confirmed radiographically. A heparinized blood sample was obtained from each bird; CBC and chemistries were evaluated (System 9010+ CP, Serona Baker, and Kodak Ektachem 250 Analyzer, Johnson and Johnson/Orthoclinical Diagnostic), and results were within normal limits. Two individuals were recovered from anesthesia uneventfully, and exploratory laparotomy was performed on the third.
Case 1: Exploratory laparotomy and ventriculotomy revealed a ventricular foreign body. The bird died during the procedure and was submitted for necropsy. The foreign body was also submitted, in 10% neutral buffered formalin, and weighed 5.8 g (wet weight), was 2.5 cm in diameter with a 3.5×0.3 cm tubular projection that had extended into the proventriculus. On examination with a dissecting microscope, the foreign body was composed of long, fine, frequently split plant fibers admixed with moderate amounts of less fibrous plant material and other debris. The phytobezoar was examined by a plant anatomist; the fibers from the phytobezoar were deemed compatible with the leaves of a corn plant. On necropsy, the only noted abnormalities were a markedly dilated ventriculus and surgical wounds. Histologic abnormalities were restricted to moderate thinning and fragmentation of the ventricular koilin. The diagnosis was ventricular phytobezoar impaction with mild koilin degradation. The remaining two kingfishers had a clinical diagnosis of ventricular impaction, presumably phytobezoar.
Case 2: Medical treatment was chosen for one of the remaining birds, and following consultation (pers. com., L. Phillips, University of California, Davis), 0.5 ml natural peanut butter was tube fed BID in addition to continuation of the maintenance ration. Live plants were removed from the enclosure. The bird cast a mass 14 days following initiation of treatment; this mass was 2.0 cm in diameter, and examination with a dissecting microscope revealed the same plant fibers as in case 1. Histologically the mass was composed of numerous plant fibers, with admixed nonfibrous plant material, insect exoskeleton remnants, and rare feather remnants. This individual remained clinically normal following expulsion of the phytobezoar.
Case 3: Following the successful medical treatment of case 2, the same treatment was initiated for the remaining bird. Throughout treatment the bird remained clinically normal, with normal feed consumption and defecation. Physical examinations under manual restraint were performed at regular intervals during the treatment period. Radiography under anesthesia was also performed at regular intervals. During treatment the mass enlarged but became softer, and appeared to be breaking up on day 49. However, on day 64 the mass again appeared discrete. Since medical treatment did not seem to be resolving the impaction, endoscopic evaluation and phytobezoar retrieval was attempted on day 64, using a 2.3-mm rigid endoscope (R. WOLF GmbH, Knittlingen, Germany); the bird died during the procedure.
On necropsy the bird had a 1.5×1.8×2.0 cm ventricular mass, which was similar to those found in the other birds, although more friable. Examination with a dissecting microscope revealed plant fibers as per case 1. Histologically the mass was similar to those previously examined, with small amounts of admixed koilin and other debris. Other lesions included mild, diffuse, adrenal cortical hyperplasia, and random hepatocellular lipid vacuolation. The primary diagnosis was ventricular phytobezoar impaction. Adrenal cortical hyperplasia was attributed to stress, likely secondary to chronic impaction and repeated immobilizations.
Discussion
Live plants are often used in exhibits to improve the appearance of the enclosure and to provide a more natural habitat for the inhabitants. These cases illustrate how this may lead to unintended morbidity and mortality, and that selection of safe materials are vital for the health of the animals. In these cases, several live plants were utilized, and the birds ingested material from two subspecies of Dracaena fragrans, resulting in phytobezoar formation and ventricular impaction. The impactions were not complete, as feed consumption and defecation remained normal. In poultry, pica and crop impaction have been associated with environmental stress3,5; however, no such stressors were identified in these cases. In free-range chickens, ingestion of increased amounts of indigestible material leads to the formation of phytobezoars and subsequent impaction.2 In these cases, the kingfishers ingested fibrous plant material, which presumably was highly indigestible, as plants are not normally a part of their diet.
Medical treatment with natural peanut butter was successful in one case and proved to be a reasonable alternative to surgical extraction. Similar treatment, including other vegetable oils, may be of use in other avian species, and may soften and help break up the phytobezoar, enabling easier expulsion. Surgical or endoscopic extraction may be possible; however, death occurred during these procedures in cases 1 and 3. The cause of death in these cases may have been due to respiratory and cardiovascular compromise following compression of air sacs, the heart, and major vessels, which was exacerbated during surgical manipulation. In endangered species, surgical or endoscopic treatment may be prudent only following ineffectual conservative medical treatment.
Acknowledgments
We thank Dr. Richard Crang for his assistance in identifying the plant fibers, Jane Chladny and the University of Illinois College of Veterinary Medicine Histopathology Laboratory, and the keepers and technicians of Brookfield Zoo.
Literature Cited
1. Bruning, D. F. and Dolensek, E. P. 1978. Ratites. In: Zoo and Wild Animal Medicine. 2nd ed., Fowler, M. E., ed. W.B. Saunders Company, Philadelphia, Pennsylvania, USA, pp. 277–291.
2. Christensen, N. H. 1998. Alleviation of grass impaction in a flock of free-range hens. Vet Rec. 143: 397.
3. Cooper, J. E., and Harrison, G. J. 1994. Dermatology. In: Avian Medicine: Principles and Application. Ritchie, B. W., Harrison, G. J., and Harrison, L. R., eds. Wingers Publishing, Inc. Lake Worth, Florida, USA, pp. 607–639.
4. Lumeij, J. T. 1994. Gastroenterology. In: Avian Medicine: Principles and Application. Ritchie, B. W., Harrison, G. J., and Harrison, L. R., eds. Wingers Publishing, Inc. Lake Worth, Florida, USA, pp. 482–521.
5. Morishita, T. Y., Aye, P. P., and Harr, B. S. 1999. Crop impaction resulting from feather ball formation in caged layers. Avian Dis. 43: 160–163.
6. Reissig E. C. and Robles C. A. 2001. Gizzard impaction in lesser rhea chicks (Pterocnemia pennata) raised on farms in Patagonia, Argentina. Avian Dis. Jan–Mar;45(1):240–244.
7. Riddell, C. 1997 Developmental, metabolic, and other noninfectious disorders. In: Diseases of Poultry. 10th ed. Calnek, B. W., ed. Iowa State University Press, Ames, Iowa, USA, pp. 913–950.
8. Sato Y, Yasuda J, Sinsungwe H, Chimana H, and Sato G. 1994. An occurrence of stomach impaction in ostriches (Struthio camelus) on a farm in Zambia associated with high mortality. J Vet Med Sci. 56(4):783–784.