iseases of the alimentary tract occur fre- quently in birds. Nonspecific clinical signs CHAPTER of gastrointestinal diseases may include D anorexia, dysphagia, regurgitation, vomit- ing, constipation, diarrhea and tenesmus. With polyuria, the feces are normal and are surrounded by a large volume of clear fluid, while with diarrhea the feces are abnormal (see Color 8). The composition and quality of food and ingestion of bedding material, poisonous plants or chemicals may influence gastro- 19 intestinal signs. Weight loss and generalized weak- ness are characteristic of chronic diseases. Fecal evaluation, hematology, blood chemistry, radiol- ogy and esophago-ingluvio-(gastro)scopy or laparo- scopy are considered indispensable diagnostic tools in avian gastroenterology. Diseases that may affect the gastrointestinal system are listed in Table 19.1. GASTRO- Cytologic examination of a fresh ingluvial aspirate is ENTEROLOGY best for detecting flagellates (Trichomonas spp.). Ex- amination of freshly voided feces is essential to de- tect Histomonas meleagridis, Hexamita spp., Giardia intestinalis, Cochlosoma sp. and Chi- lomastix gallinarum. Direct microscopic examina- tion of feces may reveal helminthic ova and protozoal oocysts. Flotation and sedimentation techniques are best for detecting the low number of eggs or oocysts J. T. Lumeij that occur in an early parasitic infection (see Chapter 36). Parasites infecting the liver, kidney, uterus and pancreas can deposit ova or oocysts that can be de- tected in the feces. Parasite ova originating from the respiratory tract may be coughed up, swallowed and found in the excrement.28,78 483 CHAPTER 19 GASTROENTEROLOGY TABLE 19.1 Differential Diagnosis of Clinical Signs Associated with the Gastrointestinal Tract Regurgitation or Vomiting in Adults Diarrhea28,78 Iatrogenic - apomorphine, levamisole, trimethoprim/sulfadiazine Use of antibiotics (macaws), ketoconazole, doxycycline suspension (particularly Dietary changes macaws and Amazons) Bowel obstruction Fear and excitement (vultures, pelicans, penguins) Toxins Courtship behavior (male psittacines) Obstruction Crop milk feeding in pigeons Foreign bodies Physiological cast formation - (raptors) Organopathy - hepatopathy, renal disease, pancreatitis Goiter (particularly budgerigars) Viral diseases - Newcastle disease virus, paramyxovirus type 3, Callus formation after coracoid fracture influenza, adenovirus, astrovirus, calicivirus, coronavirus, en- Neuropathic gastric dilatation (NGD) terovirus, Pacheco’s disease virus, pigeon herpesvirus, duck Food allergies virus enteritis, herpesvirus (Ciconiidae), herpesvirus (gruiformes), Marek’s disease virus, orthoreovirus, parvovirus, reovirus, rota- Motion sickness virus, togavirus-like agent, retrovirus (leukosis/sarcoma group) Viral diseases - looping ill virus, Pacheco’s disease virus, pigeon Bacterial diseases - borreliosis, spirochaetosis, most Enterobac- herpesvirus, avian polyomavirus, avian viral serositis (togavirus), teriaceae, Campylobacter spp., Streptococcus spp., poxvirus (diphtheritic form) Erysipelothrix rhusiopathiae, Listeria monocytogenes, megabac- Bacterial diseases - megabacterial infection, most Enterobacte- teria, Clostridium spp., Mycobacterium avium, Yersinia pseudo- riaceae, Pasteurella, Serratia tuberculosis, Aeromonas hydrophila, Pasteurella multocida, Pas- Mycotic diseases - candidiasis, aspergillosis teurella anatipestifer (new duck disease) Helminths (oropharynx/ingluvies/esophagus) - capillariasis, ser- Chlamydia ratospiciliasis Mycoplasma Protozoal disease - trichomoniasis of upper digestive tract, Plas- Candida albicans modium (penguins, gyrfalcon) Protozoa - Histomonas meleagridis, Hexamita spp., Giardia spp,, Poisoning - alcohol, arsenic, copper, lead, organochlorine (lin- Cochlosoma sp., Chilomastix gallinarum, coccidiosis dane), organophosphate, carbamate, organomercurial, ro- Helminths - nematodes, trematodes, cestodes tenone, phosphorus, polytetrafluoroethylene (Teflon), sodium chloride, thallium, zinc Hematochezia Plants - Yew (Taxus baccata), Philodendron spp., Rhododen- Cloacal papillomas ■ Aflatoxicosis dron spp. (azalea), Solanaceae (green berries and roots) Egg laying ■ Coagulopathies Obstructed alimentary tract - stricture, foreign body, neoplasia, ■ intussusception, volvulus, hernia, stenosis, parasites, impaction, Ulcers Heavy metal intoxication paralytic ileus Hepatitis ■ Foreign bodies Organopathy - renal disease, hepatopathy, pancreatitis, peritoni- Infectious enteritis - bacterial, ■ Cloacal neoplasias tis, egg binding, electrolyte disturbances viral, parasitic Regurgitation in Neonatal Psittacines (Sour Crop) Passing Undigested Food Overgrowth of bacteria or Gastric foreign body ■ Pancreatitis yeast (improper food storage) Gastrointestinal dysfunction ■ Use of antibiotics Overheated formula Neuropathic gastric dilatation ■ Food allergies Underheated formula Enteritis - bacterial, viral, ■ Hepatitis Crop burns parasitic Foreign body ingestion (eg, substrates) Tenesmus ■ Improper formula consistency Egg-laying problems (binding) Uterine prolapse ■ Over-stretching the crop Abdominal mass Rectal prolapse ■ Aerophagia Goose venereal disease Enteritis - diarrhea ■ Fear and excitement Cloacal pathology Bacteria ■ Infectious agents Prolapse Parasites Avian polyomavirus Papilloma ■ Fungi Avian viral serositis Stricture ■ Viruses Candida spp. ■ Gas-producing bacteria Cloacolith Toxins Cloacitis ■ Decreased bacteria (eg, in- Intestinal obstruction discriminate antibiotic use) (eg, constipation) 484 SECTION FOUR INTERNAL MEDICINE Bacteriologic cultures of the gastrointestinal tract The median dorsal border of the rhinotheca is called must be interpreted with respect to the normal the culmen, and the median ventral border of the flora.78 Gram-positive microorganisms including lac- gnatotheca is called the gonys. The cutting edges of tobacilli, staphylococci, streptococci and Bacillus the rhamphotheca are called the tomia. The rhino- spp. are common in the oropharynx of healthy psit- theca is perforated by the paired nostrils. Avicultur- tacine birds. Mycoplasma spp. and Aspergillus spp. ists classify caged birds into hardbills (eg, most psit- are sometimes encountered.168,176 Enterobacteriaceae tacine birds) and softbills (eg, mynahs, starlings). are normally not found in the feces of Psittaciformes and Passeriformes, where gram-positive organisms, In ducks and parrots, the tip of the bill contains well especially Corynebacterium sp. and Bacillus sp., pre- developed mechanoreceptor nerve endings. The beak dominate.17 The isolation of a large number of En- is used for prehension, for the physical preparation terobacteriaceae in pure culture from Psittaciformes of food, and in some species such as parrots, for or Passeriformes is suggestive of a primary or secon- locomotion.130 dary infection. E. coli and other Enterobacteriaceae The rate of keratin replacement is strongly depend- are normal inhabitants of the gastrointestinal tract ent on the use of the beak. In large parrots, the in Galliformes, Columbiformes, Falconiformes, complete rhinotheca is replaced in about six months, Strigiformes and Corvidae.140 while in toucans the rhinotheca grows approximately Routine bacteriologic examination of the feces may 0.5 cm over a two-year period. The rate of growth of fail to reveal some important microbes that can cause the gnatotheca is about two to three times faster diarrhea, including mycobacteria, campylobacter than that of the rhinotheca.38 Shedding and replace- and chlamydia. A technique for identifying mycobac- ment of the rhinotheca has been described in caper- teria is described in Table 19.2. Detection of campy- caillie (annually)4 and Suriname finches. lobacter can be augmented by the use of Hemacolor; the bacteria appear S-shaped or in gull-wing form. Beak Diseases Chlamydia is best detected using an antigen capture system.21,102 A variety of congenital and acquired defects, includ- ing scissor beak and mandibular prognathism, can TABLE 19.2 Detection of Acid-fast Bacteria in Feces78 interfere with normal beak function. In gallinaceous birds, a deformed upper mandible has been associ- Combine 4 grams of feces and 12 ml of 15% sputofluol (Merck) ated with embryonic deficiencies of folic acid, biotin Gently mix for 30 minutes or pantothenic acid. Crusty, scab-like lesions in the Centrifuge for 5 minutes 10,000 rpm corners of the mouth are considered a definite sign of Make smear of sediment biotin or pantothenic acid deficiency in these birds.5 Stain with Ziehl-Neelsen Examples of acquired lesions that can lead to malfor- mations or necrosis of the beak include punctures, lacerations, splits and avulsions. Traumatic frac- tures, especially of the mandible, occur frequently in psittacine birds that get caught in hooks suspended from the ceiling of their enclosures or as a result of The Beak fighting. Any bacterial, mycotic, viral or parasitic pathogen that damages the germinative layers of the beak can 108 Anatomy and Physiology cause developmental abnormalities. Examples in- clude Candida albicans, psittacine beak and feather The avian beak is a continuously growing, dynamic disease virus, Knemidokoptes spp. in Psittaciformes structure composed of bone, vascular layers, keratin, or Oxyspirura spp. in cranes. Rhinothecal over- dermis, joints and a germinative layer. In psittacine growth in psittacines, especially budgerigars, has birds, the upper and lower jaws are connected to the been associated with liver disease (Figure 19.1).133 skull via a kinetic