Tracheal Resection in a Secretary Bird (Sagittarius serpentarius) with Granulomatous, Foreign-body Induced Tracheitis.
Key words: trachea, stenosis, inflammation, resection, anastomosis, foreign body, avian, secretary bird, Sagittarius serpentarius
A 24-year-old female secretary bird (Sagittarius serpentarius) was presented with acute open-mouth breathing whenever food items were swallowed. It had been housed with a male conspecific in a large mixed aviary together with 2 vulture species at a zoological facility for several years. Conservative therapy for parasitic, bacterial, and fungal infection was initiated (day 0), consisting of metronidazole (50 mg/kg PO q24h for 3 days), doxycycline (100 mg/kg IM every 7 days), meloxicam (0.5 mg/kg PO q24h for 7 days), and terbinafine (10 mg/kg PO q24h).
Despite treatment, the bird's condition deteriorated. Therefore, on day 9, the bird was anesthetized with isoflurane administered by face mask (initially 5% in 2 L/min, maintained at 3%) for physical examination and diagnostic testing. At physical examination, the bird was in poor body condition (bodyweight, 3.6 kg) and exhibited increased respiratory effort with mild stridor, suggestive of an upper airway obstruction. A blood sample was collected from the brachial vein and submitted for a complete blood cell count (CBC) and serum biochemical profile. Results revealed leukocytosis and increased hepatic enzyme levels (Table 1). On orthogonal radiographs of the cervical region, an intratracheal opacity was seen suggestive of a sharp stricture at the beginning of the caudal third of the trachea (Fig 1). Swab samples for bacterial and fungal cultures were obtained from the trachea, oropharynx, and cloaca. Tracheal and oropharyngeal cultures were negative for growth; cloacal culture demonstrated normal flora.
Because of potential traumatic, neoplastic, or inflammatory reasons for tracheal obstruction in birds, (1-3) a second anesthesia was scheduled on day 12 for further examination and possible surgical intervention. The secretary bird was anesthetized as described previously. An incision was made caudal to the last rib and cranial to the pubic bone in the left lateral flank for endoscopic examination (3 mm rigid endoscope; Olympus Deutschland GmbH, Hamburg, Germany) and placement of an air sac cannula. The cannula was fashioned from a 3.0-mm uncuffed endotracheal tube placed into the left caudal thoracic air sac to allow for oxygenation and to maintain anesthesia. The air sac cannula was sutured in place by Roman sandal technique. During endoscopic evaluation, mild fungal growth (suspected to be Aspergillus species) was observed in the air sacs, and the caudal pole of the left kidney appeared enlarged.
Vital signs were monitored during anesthesia by pulse oximetry with a probe placed on the left foot. Oxygen saturation ranged from 82% to 98% and heart rate ranged from 167 to 220 beats per minute throughout the procedure. Intravenous fluids (approximately 100 mL 0.9% NaCl solution) were administered through an intravenous catheter placed into the metatarsal vein (vena metatarsea plantaris superficialis).
Tracheoscopy was performed with a flexible fiberoptic endoscope (5.2-mm diameter, 85-cm length; Karl Storz GmbH & Co KG, Tuttlingen, Germany. The obstruction was visualized easily, forming a fibrous diaphragm and leaving only a small opening of approximately 10% of the original tracheal lumen (Fig 2). On palpation, an external thickening of the trachea was appreciated. Tracheotomy and resection of the affected tracheal rings were elected.
Feathers were removed from the neck and the area was prepared aseptically for surgery. A 5 cm longitudinal skin incision was made over the palpable abnormal trachea by a left lateral cervical approach. The soft tissues were dissected and the thickened section of the trachea was elevated manually. On examination of the trachea, a brown mass was visible on the exterior tracheal surface (Fig 3a). Approximately 1.5 cm of tracheal rings were removed surgically (Fig 3b). The tracheal ends (approximately 1 cm in diameter) were anastomosed with 3/0 polydioxanone (PDS II; Ethicon, Scottsdale, AZ, USA) by placing 5 evenly-spaced, simple interrupted sutures. After endoscopic reexamination of the trachea and esophagus (to confirm no accidental injury of the latter occurred), the musculature and underlying tissues were closed with a continuous suture pattern with 3/0 polygalactin 910 suture (Vicryl, Ethicon). The skin then was closed with the same suture in a continuous suture pattern.
Postoperatively, normal breathing was confirmed and the air sac cannula was removed. The insertion site was closed using a single cruciate suture with 3/0 polygalactin 910 suture. Recovery from anesthesia was uneventful. Postoperatively, the bird received meloxicam (0.5 mg/kg IM) and antimicrobial, anti-inflammatory, and antifungal treatment was continued as described above for 7 days while the bird was housed indoors. The dosage of terbinafine was increased to 50 mg/kg PO q24h for another 4 weeks then reduced to 25 mg/kg PO q24h for an additional 2 weeks. Repeat CBCs and plasma biochemical analyses were done weekly to monitor leucocyte count and renal and liver values (Table 1).
The resected tracheal tissue was fixed in 10% neutral buffered formalin solution and submitted for histopathologic examination (Fig 3b). Results showed severe inflammatory reaction of the excised tracheal rings, with heterophils, lymphocytes, histiocytes, multinucleated giant cells, and fibrin, chronic active fibroplasia, complete loss of the respiratory epithelium, and necrosis of the tracheal cartilage. Coccoid bacteria and multifocal, black-brown foreign body particles were observed. Results of PAS reaction as well as acid-fast stain were negative, leading to the diagnosis of granulomatous-bacterial foreign body tracheitis (Fig 4).
The CBC and serum biochemical values were reevaluated on days 9, 20, 27, 32, and 41 after first occurrence of symptoms (Table 1). When examined initially, hepatic enzyme activities were elevated up to 10-fold above references values for this species, (4) and the white blood cell count (WBC) and total protein concentrations were increased. At the end of a 2-week course of doxycycline after surgery, leukocytosis was again identified, and a second course of antibiotics (marbofloxacin, 15 mg/kg q24h for 6 days; Marbocyl, Vetoquinol GmbH, Ravensburg, Germany) was initiated. The WBC reduced markedly from 32 300 cells/[micro]L to 19 800 cells/[micro]L thereafter. However, the serum uric acid values increased considerably from 10.7 mg/ dL (636 [micro]mol/L) to 15.5 (922 [micro]mol/L). By 20 days postoperatively, a weight gain was assumed because of improved palpable body condition. The bird recovered uneventfully and was released back into the aviary 45 days after initial symptoms were seen and about 4 weeks postoperatively. Terbinafine treatment was discontinued on day 56 postoperatively.
We describe the diagnosis and successful treatment of a foreign body-induced inflammatory obstruction of the trachea in a secretary bird. Tracheal strictures, compression, or obstruction resolved by resection have been described in a variety of birds, including a pied imperial pigeon (Ducula bicolor), (3) ducks, (3,5) a goose (Anser species), (6) a crane (Grus species), (7) a stork (Ardeola ibis), (3) a curassow (Crux globulosa), (3) blue and gold macaws, (8,9) a barn owl (Tyto alba), (10) a red-tailed hawk (Buteo jaimaicensis), (11) and an eagle (Halieaeetus leucocephalus). (12) To our knowledge, this case in a secretary bird is the first report of tracheal resection in such a large bird of prey.
Common reasons for obstruction and subsequent respiratory distress in birds are inflammatory processes caused by internal trauma after intubation, (3) inhaled foreign bodies, (7) external trauma with tracheal cartilage fracture, (5,6,13) or neoplasia. (1)
Causes of tracheal stenosis related to infectious disease include parasitologic, fungal, viral, or bacterial infection. Bacterial tracheitis may result from lower airway disease. (14) Tracheal infections with Aspergillus species are described commonly (2,14) and may cumulate in an obstructing fungal granuloma. (12) Pox and herpes viruses have been identified to cause pseudomembranous tracheitis. (14,15)
What kind of foreign body caused the inflammation and obstruction in this secretary bird remains elusive. The bird may have aspirated a piece of a food item or, alternatively, an induced foreign-body reaction caused by external trauma appears conceivable. The secretary bird was observed as being attacked by one of the cohoused cinereous vultures (Aegypius monachus) 2 months before the initial symptoms were apparent. The vultures were nesting above the night rooms of the secretary birds and may have been disturbed by them. One could speculate that a vulture talon penetrated the skin of the neck, through the tracheal cartilage, introducing foreign material and causing an inflammatory reaction. This could explain the external appearance of the trachea (Fig 3). Although white plaques were observed within the air sacs, typical for Aspergillus species infection, histopathologic examination revealed no fungal involvement with the tracheal lesion.
Tracheal stenosis is diagnosed by radiographic imaging of the trachea and intratracheal endoscopy. (1,3) For successful treatment, conservative, endoscopic, and surgical approaches have been reported. However, in a large study on postintubation tracheal obstruction, the surgical approach with tracheal resection has been found to be the most effective therapy. (3) Recurrence rates appear high with conservative and endoscopic approaches, which consist of endotracheal, parenteral, and/or oral application of anti-inflammatory and antimicrobial drugs, drug nebulization, tracheoscopic and manual removal of excessive tissues, balloon catheter dilation, or a combination of several nonoperative measures. (3,9) Only mild cases seem to respond to these conservative therapeutic approaches. In most cases where conservative approaches were used, the birds usually either died (only 33% survival rate) (3) or recovered only after surgery subsequently was performed. (9)
In our case, tracheal resection and anastomosis was elected because neoplasia was considered as a differential diagnosis, attributed to the intra- and extraluminal extension of the mass. The surgical procedure was very similar to that of previous reports in other bird species. (3,9) Postoperative complications of tracheal resection and anastomosis relevant to birds may include dehiscence secondary to tension, mucosal edema, and tracheal stenosis secondary to the inflammation and stricture or bacterial infection. (3,9) Tension is considered to be the limiting factor for long tracheal resection, especially in birds with long and flexible necks as in this secretary bird. However, Jankowski et al (9) reported successful removal of 15 tracheal rings in two sessions with subsequent survival for at least 2 years in a blue and gold macaw. In another report, 12 tracheal rings were resected from a mallard duck. (5) In the report of Sykes et al, (3) between 0.1 and 6.0 cm of trachea were removed in different bird species. Considering the relatively high recurrence rates reported, generous excision of the affected area appears important. Any remaining fibrotic or inflamed tracheal tissue may result in recurrent tracheal stenosis. '
This 24-year-old secretary bird underwent several blood collections to screen organ health and inflammatory reaction. Liver enzyme levels remained increased during the course of treatment of this bird. This was likely attributed to the medication, especially high doses of terbinafine, but also may be associated with the age of the bird. More recent studies indicated that a higher dose of terbinafine must be administered to be therapeutic. (16,17) Postprandial or catabolic changes are likely the reason for the increase in uric acid values. Increased uric acid values also could be associated with the higher burden on kidneys due to the antibiotic and anti-inflammatory treatment and the constantly elevated serum total protein concentrations.
We described a successful tracheal resection in a secretary bird. Resolution of clinical respiratory signs, improvement of body condition, and return of the WBC count and hepatic enzyme levels to reference values indicated successful therapy. Although this particular female was older than 20 years and appeared to have additional health problems, the bird tolerated the surgery and postoperative care very well.
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Carsten Ludwig, DVM, Imke Lueders, DVM, PhD, Volker Schmidt, Dr med vet, Dipl ECZM (Avian, Herpetology), and Hermann Kempf, DVM
From the Westfalischer Zoologischer Garten Munster, Sentruper Strasse 315, 48161 Munster. Germany (Ludwig, Lueders); the Clinic for Birds and Reptiles. University of Leipzig, An den Tierkliniken 17, 04103 Leipzig. Germany (Schmidt); and Tierarztliche Praxis fur Exoten. Neuburger Strae e 30, 86167 Augsburg, Germany (Kempf).
Caption: Figure 1. Dorsoventral radiograph of the cervical region of a 24-year-old secretary bird shows a clearly visible stricture (arrow) in the trachea.
Caption: Figure 2. Tracheoscopic image of the tracheal stricture of the secretary bird described in Figure 1 on day 12 after symptoms began.
Caption: Figure 3. (a) Intraoperative photograph of the affected portion of the trachea before removal in the bird described in Figure 1. Note the brownish mass on the exterior surface of the trachea (arrow), (b) Cross-sectional view of the affected tracheal rings, showing the extent of the inflammatory reaction with destruction of the tracheal cartilage.
Caption: Figure 4. Photomicrograph of the affected portion of the trachea of the secretary bird described in Figure 1. Severe inflammatory reaction consisting of heterophils, lymphocytes, histiocytes, multinucleated giant cells (<), fibrin, complete loss of the respiratory epithelium and necrosis of the tracheal cartilage (*) are shown. Hematoxylin and eosin stain, X100 magnification. Inlay demonstrates 2 black-brown foreign bodies (+) embedded in fibrin and heterophils. Hemotoxylin and eosin stain, X400 magnification.
Table 1. Selected hematologic and serum biochemical values over the course of treatment in a female secretary bird with tracheal stenosis. White blood cells, AST, GLDH, Day of treatment (a) /[micro]L U/L U/L 9 29 600 4144 1015 20 25 100 759 66 27 -- 692 71 32 31 300 596 <2 41 19 800 699 <2 Mean (reference 16 400 336 -- range) (4) (5100-41 600) (138-627) LDH, Total protein, Uric acid, Day of treatment (a) U/L g/dL mg/dL [[micro]mol/L] 9 11 238 6.4 10.7  20 3383 6.2 9.6  27 -- 6.8 -- 32 2837 -- -- 41 3262 6.4 15.5  Mean (reference 859 3.7 (2.6-4.8) 11.7 (0.6-21.3) range) (4)  ([37-1269]) (a) Days from first clinical signs. Abbrev: AST, aspartate dehydrogenase; LDH, lactate dehydrogenase; GLDH, glutamate dehydrogenase.
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|Title Annotation:||Original Study|
|Author:||Ludwig, Carsten; Lueders, Imke; Schmidt, Volker; Kempf, Hermann|
|Publication:||Journal of Avian Medicine and Surgery|
|Date:||Dec 1, 2017|
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