The anatomy, physiology, and diseases of the avian proventriculus and ventriculus

Adenocarcinoma of the distal esophagus and esophageal-proventricular junction in a yellow-naped parrot

A 57-y-old male yellow-naped parrot (Amazona auropalliata) was presented because of lethargy, inappetence, and weight loss. Hematology and serum biochemistry were unremarkable, and imaging revealed a mass in the distal esophagus at the coelomic inlet. The luminal diameter of the esophagus was reduced in this area, and passage of ingesta was limited. Following gavage feeding, the patient died and was submitted for autopsy. At postmortem examination, the noted mass effect was a thickening of the distal esophagus with adherent, coalescing, soft, pale-tan plaques on the mucosal surface. Additional gross findings included pale-tan, opaque feed material oozing from the dorsum of the lungs and covering the cranial air sacs. Histology of the esophagus, esophageal-proventricular junction, and proximal proventriculus revealed an unencapsulated, infiltrative, transmural neoplasm that extended from the mucosal surface deep into the muscularis, almost to the adventitia. The neoplasm was composed of cuboidal cells arranged in islands and tubules, consistent with an adenocarcinoma, a rarely reported entity in the esophagus of psittacine birds and to our knowledge not reported previously at the esophageal-proventricular junction.

Morphological studies on the prehatching development of the glandular stomach of Japanese quails using light, electron, and fluorescent microscopy

The development of the glandular stomach was studied using light, electron, and fluorescent microscopy. The research used 130 Japanese quail eggs from the second to the seventeenth days of incubation.The proventriculus could be distinguished on the3rd day. Its wall consisted of four tunics: tunica mucosa, very thin tunica submucosa, tunica muscularis, and outermost tunica serosa. Mucosal folds appeared on the 8th day. The luminal epithelium was pseudostratified columnar in type and transformed into simple columnar by the 10th day. The mucosal papillae emerged on the 11th day, spiraled on the 15th day, and had a distinct whorled look by the 17th day. Two types of proventricular glands were recognized: compound tubuloalveolar and simple tubular glands. Both types were situated within the tunica mucosa. On the 4th day, the compound glands emerged as evaginations of the lining epithelium. It began to branch on the 8th day and became well established by the 11th day. The simple glands appeared on the 11th day as localized down-growths of the luminal epithelium forming solid cords. On the 15th day, many of them showed complete canalization. On the 8th day, the muscular coat was differentiated into the lamina muscularis mucosae and tunica muscularis.

Long-Term Prognosis and Treatment of Crop Impaction in Chickens via Ingluviotomy with Local Infiltration Anesthetic: Case Report

Two hens from two backyard chicken flocks were presented to a private veterinary practice specializing in poultry, both with a chief complaint of crop distention. Crop impaction was diagnosed based on physical examinations and radiographic findings. The hens were admitted for ingluviotomy surgery to remove the impacted fibrous material under local anesthesia. Even though one of the hens was diagnosed with pendulous crop, both hens recovered uneventfully after ingluviotomy and postoperative care. Follow-up examinations and interviews with the owners confirmed excellent long-term recovery.

Histomorphological, histochemical and scanning electron microscopic investigation of the proventriculus (Ventriculus glandularis) of the hooded crow (Corvus cornix)

The current investigation aimed to clarify the histomorphological features, scanning electron microscopy (SEM) and histochemistry of the proventriculus in the adult hooded crow (Corvus cornix). Twenty-two adult birds of both sexes were collected from El-Fayoum and Beni-Suef governorates, Egypt; ten were used for anatomical investigation, two were scanned using SEM, and ten were subjected to routine histological technique. The obtained anatomical results revealed a small-sized spindle-shaped proventriculus obliquely located in the left ventral part of the body cavity with an average body weight, length and diameter of 1.689 ± 0.231 gm, 1.54 ± 0.383cm and 3.51 ± 0.416cm, respectively. The histological examination revealed a typical tubular organ. The mucosa exhibited several plicae and sulci that were lined with simple columnar cells. The lamina propria was composed of collagenous connective tissue infiltrated by lymphocytes, lymphatic aggregations and tubular glands. The submucosa consisted of collagenic fibres and compound tubuloalveolar glandular lobules lined with oxynticopeptic cells and enteroendocrine cells. The oxynticopeptic cells reacted negatively with PAS and Alcian Blue stains, whereas the ductal cells reacted positively with PAS only. Enteroendocrine cells were seen singly in the lamina epithelialis mucosae and were abundant in submucosal glands. The tunica musclaris was arranged in two layers covered by serosa. The proventricular glands' openings were noticed by SEM as raised tubes with regular circular outlines surrounded by anastomosed microscopic folds. The obtained histomorphological structure of the hooded crow's proventriculus revealed some shared morphological features with most species of birds and some variations that might be attributed to their diet and feeding behaviour.

Acute oral toxicity and tissue residues of saxitoxin in the mallard (Anas platyrhynchos)

Since 2014, widespread, annual mortality events involving multiple species of seabirds have occurred in the Gulf of Alaska, Bering Sea, and Chukchi Sea. Among these die-offs, emaciation was a common finding with starvation often identified as the cause of death. However, saxitoxin (STX) was detected in many carcasses, indicating exposure of these seabirds to STX in the marine environment. Few data are available that describe the effects of STX in birds, thus presenting challenges for determining its contributions to specific mortality events. To address these knowledge gaps, we conducted an acute oral toxicity trial in mallards (Anas platyrhynchos), a common laboratory avian model, using an up-and-down method to estimate the median lethal dose (LD₅₀) for STX. Using an enzyme-linked immunosorbent assay (ELISA), we tested select tissues from all birds and feces from those individuals that survived initial dosing. Samples with an ELISA result that exceeded approximately 10 µg 100 g^-1 STX and randomly selected ELISA negative samples were further tested by high-performance liquid chromatography (HPLC). Tissues collected from mallards were also examined grossly at necropsy and then later by microscopy to identify lesions attributable to STX. The estimated LD₅₀ was 167 µg kg^-1 (95% CI = 69-275 µg kg^-1). Saxitoxin was detected in fecal samples of all mallards tested for up to 48 h after dosing and at the end of the sampling period (7 d) in three birds. In those individuals that died or were euthanized <2 h after dosing, STX was readily detected throughout the gastrointestinal tract but only infrequently in heart, kidney, liver, lung, and breast muscle. No gross or microscopic lesions were observed that could be attributable to STX exposure. Given its acute toxicity, limited detectability, and frequent occurrence in the Alaska marine environment, additional research on STX in seabirds is warranted.

Ultrasonography of the gastrointestinal tract of toco toucans (Ramphastos toco)

Baseline data for wall thickness in healthy toucans can be used to diagnose disease in sick individuals. This study aimed to evaluate the use of ultrasonography for the examination of the gastrointestinal tract of healthy toco toucans (Ramphastos toco). Ten non-anaesthetized healthy adult toco toucans were evaluated. Food was withheld for 3 h prior to the ultrasound examination. Longitudinal and transverse images of the gastrointestinal tract were obtained using ventromedian cranial and ventromedian caudal approaches to evaluate the morphology and stratification. The wall thickness of the sections was measured: proventriculus and ventriculus, duodenum, jejunum/ileum, and cloaca. Additionally, the thickness of the mucosal layer of the duodenum and jejunum/ileum was also measured. Subsequently, the ratios of the duodenal wall thickness to the duodenal mucosa layer and the total wall thickness of the jejunum/ileum to the jejunum/ileum layer mucosa were stablished. The wall thickness of the proventriculus was significantly higher than the wall thickness of ventriculus. The wall thickness of the duodenum was significantly higher than the wall thickness of jejunum/ileum. The mean ratios of the duodenal wall thickness to the duodenal mucosa layer and the wall thickness of the jejunum/ileum to the jejunum/ileum layer were 83.15% and 80.07%, respectively. In conclusion, it was possible to assess the stomach and intestines using ultrasound examination in healthy toco toucans, due to their medium body size and no interference by surrounding air sacs.

Avian stomach anatomy – a mini review

The stomach of birds comprises three parts – glandular (proventriculus gastris), muscular (ventriculus gastris) and pyloric (pars pylorica gastris). Depending on the diet, these three parts are well differentiated in omnivorous, herbivorous, insectivorous and granivorous birds and slightly differentiated in fish- and meateaters. In fruit-eating, nectar-eating and testacivorous birds, the stomach has an intermediate structure between the two types. In some birds from the genus Tangara, the stomach is reduced to a diverticulum.

THE RADIOGRAPHIC AND ENDOSCOPIC ANATOMY AND DIGESTIVE MECHANISMS OF CAPTIVE AFRICAN PENGUINS (SPHENISCUS DEMERSUS)

The anatomy of the avian gastrointestinal (GI) tract is uniquely suited to each species' dietary requirements. African penguins (Spheniscus demersus) are charismatic and popular exhibit animals. As their prevalence grows, there is a need to understand their unique digestive tract to diagnose abnormalities. Reference material specific to the digestive tract of piscivores is scant, and knowledge of the GI tract of a healthy penguin is based on information from other birds. The purpose of this study is to determine the normal gross anatomy, transit time, and histopathologic structures of the penguin GI tract. Twelve clinically healthy penguins were selected for this study from the colony at the Maryland Zoo in Baltimore, which, at the time of this study, consisted of 55 birds. All penguins underwent a barium contrast study, and radiographic images were obtained until the entire GI tract was empty. Approximately 2 wk later, each penguin was anesthetized, and an endoscopic evaluation of the anterior GI tract was performed. Time from barium administration to defecation ranged from 17 to 70 min, and on average, barium clearance was 17.6 hr (range, 5-36 hr). Fluid from the ventriculus had an average pH of 2.75 and contained a mixed bacterial population. Koilin presence and thickness appreciated on endoscopy did not correspond with the thickness determined on histopathology. The results of this study provide a comparative baseline to use during diagnostic workups and help guide treatment decisions.

Effect of dietary coarse corn inclusion on broiler live performance, litter characteristics, and ammonia emission

Ammonia (NH3) emission from nondigested nutrients in poultry creates additional adverse environmental impacts on soil, water, air, and health. Mitigating NH3 emission has become vital for the poultry industry to remain sustainable. As the presence of large particles in the feed stimulates the broiler gizzard to retain ingesta in the gastrointestinal tract longer and improve digestive efficiency, the inclusion of large particles in feed may lead to less nitrogen (N) and moisture content (MC) in feces such that lower NH3 production would be expected. This chamber study investigated the effects of dietary coarse corn (CC) inclusion on broiler live performance, litter characteristics, and NH3 emission. One hundred eighty female broilers (Ross 344 × 708 strains) at day 21 were randomly placed in 6 chambers with 2 dietary treatments (0% CC and 50% CC), with 3 chambers per treatment and 30 birds per chamber for 3 wks. The results showed that the 50% CC inclusion (1) decreased broiler feed intake and BW without affecting mortality-adjusted feed conversion ratio from day 21 to 42; (2) increased gizzard weight and decreased proventriculus weight; (3) decreased N content and MC in litter; and (4) decreased NH3 concentrations in the chambers, as well as NH3 emission from the chambers. Dietary CC inclusion could be an effective way to mitigate broiler litter N content and MC as well as NH3 emission.

Perforating foreign body in the ventriculus of a pet pigeon (Columba livia domestica)

CASE DESCRIPTION A 2-year-old female pigeon was evaluated because of a 5-day history of lower than typical activity level, weight loss, and polyuria. CLINICAL FINDINGS Whole-body radiography revealed a linear metallic foreign body in the area of the ventriculus. Fluoroscopy followed by contrast-enhanced CT was performed to further characterize the lesion location, revealing that the foreign body had perforated the ventral aspect of the ventriculus wall and that the ventral extremity of the foreign body was surrounded by a mass, consistent with a granuloma. TREATMENT AND OUTCOME A midline celiotomy was performed, and a large granuloma was identified ventral to the ventriculus, adherent to the dorsal aspect of the keel bone. The metallic foreign body (a nail) was removed, and the content of the granuloma was debrided. Amoxicillin-clavulanic acid (150 mg/kg [68.2 mg/lb], PO, q 12 h for 10 days), meloxicam (1 mg/kg [0.45 mg/lb], PO, q 12 h for 5 days), and sucralfate (100 mg/kg [45 mg/lb], PO, q 8 h for 10 days) were prescribed. The pigeon made a successful recovery and was still doing well at a 1-year recheck evaluation. CLINICAL RELEVANCE Although traumatic gastritis in pigeons has been reported, use of advanced diagnostic imaging for the pigeon of this report facilitated identification of the precise nature of the lesion and, therefore, surgical planning. The outcome for this pigeon suggested that successful resolution of traumatic gastritis may be possible in other affected birds with surgery.

Evaluation of gastroscopy and biopsy of the proventriculus and ventriculus in pigeons (Columba livia)

OBJECTIVE To evaluate the efficacy and safety of gastroscopy and biopsy of the proventriculus and ventriculus in pigeons (Columba livia). ANIMALS 15 adult pigeons. PROCEDURES Each pigeon was anesthetized, and the upper gastrointestinal tract (from the cervical portion of the esophagus to the ventriculus) was endoscopically evaluated by use of a rigid endoscope inserted orally. Saline (0.9% NaCl) solution was orally infused to achieve lumen dilation and visibility. Two mucosal biopsy specimens were collected from each of the proventriculus and ventriculus, histologically evaluated, and graded for crush artifacts and depth. Pigeons were monitored for adverse effects for 3 to 6 days after the procedure, after which they were euthanized for necropsy. RESULTS Gastroscopy via the oral approach provided excellent visibility of the lumen and mucosal surfaces of the proventriculus and cranial portion of the ventriculus and was safe provided that appropriate precautions were taken. Two intraoperative deaths occurred at the beginning of the study; following procedure refinement, no additional deaths occurred. No major adverse effects of the procedure were detected in the remaining 13 pigeons during the postoperative monitoring period or at necropsy. Diagnostic quality of proventriculus specimens was adequate for 10 of 13 pigeons. Eight of 13 ventriculus specimens were of inadequate quality, and only 3 were of adequate quality. CONCLUSIONS AND CLINICAL RELEVANCE Gastroscopy was useful for evaluating the lumen and mucosal surface of the proventriculus and ventriculus in pigeons, and biopsy of those organs was safely performed with the appropriate technique. Further evaluation of these techniques is needed in birds with clinical disease and birds of other species.

Surgical Removal of a Ventricular Foreign Body in a Captive African Black-footed Penguin ( Spheniscus demersus )

Anterior gastrointestinal tract obstruction by a foreign body has been reported in several avian species, most commonly in captive birds. It is often associated with behavioral issues that lead to compulsive consumption of bedding materials or bright moving objects. In penguins, foreign bodies are most commonly identified at necropsy and often are found in the ventriculus because of anatomic characteristics of the species. A captive African black-footed penguin ( Spheniscus demersus ) was diagnosed with a ventricular foreign body. The anatomic and physiologic differences that should be taken into account when surgically removing a ventricular foreign body in a penguin are described. These differences include the caudal location in the coelom and the large size of the ventriculus in proportion to the penguin's body size; the presence of a simple stomach, uniform in thickness and lacking muscular development; a simple gastrointestinal cycle (gastric contraction); and variability in pH of stomach contents. No complications were observed after surgery, and the bird recovered completely. Management of foreign bodies in birds should be based on the clinical signs of the individual bird, the species affected and its anatomic characteristics, the nature and location of the foreign body, available tools, and the preference and experience of the surgeon. This particular case demonstrates that the most indicated and preferred method is not always possible and that knowledge of biologic, anatomic, and physiologic differences of the species may allow the use of an alternative and more invasive approach with favorable outcomes.

Ventricular Habronemiasis in Aviary Passerines

A variety of Habronematidae parasites (order Spirurida) have been described as occasional parasites of avian species; however, reports on passerines are relatively uncommon. From 2007 to 2008, 11 passerine deaths at The North Carolina Zoological Park in Asheboro, NC, USA, were associated with ventricular habronemiasis, which was determined to be the cause of death or a major contributing factor in 10 of the 11 individuals. The number and species affected were 5 Red-billed Leiothrix (Leiothrix lutea), 2 Japanese White-eye (Zosterops japonicus), 2 Golden-headed Manakin (Pipra erythrocephala), 1 Blue-grey Tanager (Thraupis episcopus), and 1 Emerald Starling (Coccycolius iris). Affected animals displayed nonspecific clinical signs or were found dead. The ventricular nematodes were consistent in morphology withProcyrneasp. Koilin fragmentation with secondary bacterial and fungal infections was the most frequently observed pathologic lesion. Secondary visceral amyloidosis, attributed to chronic inflammation associated with nematodiasis, was present in 4 individuals. An insect intermediate host is suspected but was not identified. Native passerine species within or around the aviary may be serving as sylvatic hosts.

Use of a duodenal serosal patch in the repair of a colon rupture in a female Solomon Island eclectus parrot

Case Description-A 444-g (0.98-lb) 4-year-old sexually intact female Solomon Island eclectus parrot (Eclectus roratus solomonensis) was referred and evaluated for a suspected colonic obstruction. Clinical Findings-The parrot had a 3-day history of not passing feces and lack of appetite following treatment of dystocia that included percutaneous collapse of the egg and manual removal of egg fragments via the cloaca. During this procedure, a tear in the cloacal mucosa developed. The tear was repaired via a midline cloacotomy. Although clinically stable at the time of referral, the parrot became lethargic and bradycardic and had delayed crop emptying. Treatment and Outcome-A midline celiotomy and cloacotomy were performed to relieve the colonic obstruction, during which the severely distended colon ruptured. The colonic defects were closed in a simple interrupted pattern, and a serosal patch was applied by use of the adjacent duodenum. The bird recovered uneventfully from anesthesia and was passing voluminous feces with mildly increased effort within 1 hour after surgery. At 3 weeks after surgery, the parrot was passing feces with no increase in effort and had a normal appetite. Clinical Relevance-Application of a duodenal serosal patch for repair of a colon rupture was successful in this parrot. Gastrointestinal obstruction is rare in birds, but should be considered in birds that have regurgitation, decreased fecal production, and gastrointestinal dilation. Because birds lack an omentum, serosal patching with adjacent duodenum should be considered as a viable option in avian surgery.