Ex Vivo Biomechanical Comparison of Titanium Locking Plate, Stainless Steel Nonlocking Plate, and Tie-in External Fixator Applied by a Dorsal Approach on Ostectomized Humeri of Pigeons (Columba livia).

To compare the bending strength of a locking plate (LP), nonlocking plate (NLP), and an external skeletal fixator intramedullary pin (ESF-IM) tie-in fixation applied by a dorsal approach in an avian humerus fracture model, 5 left humeri obtained from pigeon (Columba livia) cadavers were randomly assigned to each repair technique (n = 15). The ESF-IM group was repaired with a 0.062-inch intramedullary pin tied-in with two 0.035-inch positive profile transfixation pins using acrylic filled plastic tubing. The LP group was repaired with a dorsally applied titanium 1.6-mm screw 7-hole locking plate (1 bicortical and 2 monocortical screws in each segment). The NLP group was repaired with a dorsally applied 6-hole stainless steel 1.5-mm dynamic compression plate (all bicortical screws). All constructs were applied before complete ostectomy to allow perfect reconstruction. Constructs were cyclically tested nondestructively for 1000 cycles in four-point bending before being tested to failure. Outcome measures included stiffness, strength, and strain energy. All specimens cycled without failure. The ESF-IM specimens were significantly stiffer and stronger than the plated repair groups. Plated constructs had significantly higher strain energies than ESF-IM. LP and NLP were of equal stiffness, strength, and strain energies. This study demonstrated that bending biomechanical properties of the ESF-IM configuration were superior to those of the dorsal plate fixation. Exact properties of fixation required to facilitate avian fracture healing are largely unknown. Further study, including assessments of optimal plate position and configuration, and torsional and in vivo studies in avian species are warranted.

Qualitative and quantitative evaluation of avian demineralized bone matrix in heterotopic beds.

OBJECTIVE: To evaluate the osteogenic potential of avian demineralized bone matrix (DBM) in the context of implant geometry. STUDY DESIGN: Experimental. ANIMALS: Rock pigeons (n = 24). METHODS: Tubular and chipped forms of DBM were prepared by acid demineralization of long bones from healthy allogeneic donors and implanted bilaterally into the pectoral region of 24 pigeons. After euthanasia at 1, 4, 6, 8, 10, and 12 weeks, explants were evaluated histologically and compared by means of quantitative (bone area) and semi quantitative measures (scores). RESULTS: All explants had new bone at retrieval with the exception of tubular implants at the end of week 1. The most reactive part in both implants was the interior region between the periosteal and endosteal surfaces followed by the area at the implant-muscle interface. Quantitative measurements demonstrated a significantly (P = .012) greater percentage of new bone formation induced by tubular implants (80.28 ± 8.94) compared with chip implants (57.64 ± 3.12). There was minimal inflammation. CONCLUSIONS: Avian DBM initiates heterotopic bone formation in allogeneic recipients with low grades of immunogenicity. Implant geometry affects this phenomenon as osteoconduction appeared to augment the magnitude of the effects in larger tubular implants.

Radiographic and ultrasonographic characteristics of ventral abdominal hernia in pigeons (Columba livia).

Five female egg-laying pigeons presented with painless, reducible, ventral abdominal swellings located between the keel and the pubis, or close to the cloaca. Based on clinical, radiographic, and ultrasonographic examination, these pigeons were diagnosed with ventral abdominal hernia requiring surgical interference. Reduction was successfully performed under general anesthesia. Radiographic and ultrasonographic examinations were beneficial for confirming the diagnosis and visualizing the hernial content for surgical planning. Lateral radiographs were more helpful than ventrodorsal radiographs for identification of the hernial content and its continuation with the abdominal muscles. Ultrasonographic examination offered a non-invasive diagnostic tool that allowed for the differentiation of hernia from other abdominal swellings. In addition, it played a beneficial role in identification of the hernial content and follow up after surgical interference. In conclusion, radiographic and ultrasonographic examinations were beneficial in the diagnosis, surgical planning, and follow up after surgical interference of ventral abdominal hernia in pigeons.

Endoscopic orchidectomy and salpingohysterectomy of pigeons (Columba livia): an avian model for minimally invasive endosurgery.

To evaluate a minimally invasive endosurgical system in birds, endoscopic orchidectomy and salpingohysterectomy were evaluated in 11 male and 14 female pigeons (Columba livia). Anesthesia was maintained by using isoflurane delivered by a pressure-cycle ventilator and produced good to excellent anesthesia during 96% of procedures. Endosurgery was performed with a 2.7-mm telescope system, 3-mm human pediatric laparoscopy instruments, and a 4.0-MHz radiofrequency device. Mean +/- SD surgery times for bilateral orchidectomy and salpingohysterectomy procedures were 39 +/- 18 minutes and 34 +/- 15 minutes, respectively. Procedures were generally straightforward, with any minor complications easily overcome. Surgical complications were generally minor, with mild hemorrhage and focal coagulative damage to the kidney being most common. All pigeons recovered quickly (20 +/- 11 minutes), with 95% displaying good to excellent recoveries. No birds exhibited any clinically apparent morbidity or mortality associated with endosurgery. At least 1 male and 1 female bird were subjected to elective euthanasia and necropsy on postoperative days 1, 3, 5, 10, 20, and 90 to determine the success and side effects of surgery. Gross and histologic abnormalities, when observed, were generally mild, with hemorrhage and partial necrosis of the cranial kidney present in 27% of males. Mild damage or hematoma associated with the left kidney was also reported in 28% of females. The surgical objectives were achieved in 23 of 25 pigeons. The 2 surgical failures (regenerated testes in a male and large oviductal remnant in a female) were attributed to endosurgical inexperience and occurred during the first procedures. Salpingohysterectomy does not appear to prevent ovarian development and ovulation in the pigeon, at least not during the first 3 postoperative months. Orchidectomy and salpingohysterectomy appear to be safe procedures when performed using appropriate equipment and techniques. Endosurgery offers a valuable, minimally invasive alternative to the standard coeliotomy techniques commonly used in birds.

Ex vivo biomechanical evaluation of pigeon (Columba livia) cadaver intact humeri and ostectomized humeri stabilized with caudally applied titanium locking plate or stainless steel nonlocking plate constructs.

OBJECTIVE To evaluate mechanical properties of pigeon (Columba livia) cadaver intact humeri versus ostectomized humeri stabilized with a locking or nonlocking plate. SAMPLE 30 humeri from pigeon cadavers. PROCEDURES Specimens were allocated into 3 groups and tested in bending and torsion. Results for intact pigeon humeri were compared with results for ostectomized humeri repaired with a titanium 1.6-mm screw locking plate or a stainless steel 1.5-mm dynamic compression plate; the ostectomized humeri mimicked a fracture in a thin cortical bone. Locking plates were secured with locking screws (2 bicortical and 4 monocortical), and nonlocking plates were secured with bicortical nonlocking screws. Constructs were cyclically tested nondestructively in 4-point bending and then tested to failure in bending. A second set of constructs were cyclically tested non-destructively and then to failure in torsion. Stiffness, strength, and strain energy of each construct were compared. RESULTS Intact specimens were stiffer and stronger than the repair groups for all testing methods, except for nonlocking constructs, which were significantly stiffer than intact specimens under cyclic bending. Intact bones had significantly higher strain energies than locking plates in both bending and torsion. Locking and nonlocking plates were of equal strength and strain energy, but not stiffness, in bending and were of equal strength, stiffness, and strain energy in torsion. CONCLUSIONS AND CLINICAL RELEVANCE Results for this study suggested that increased torsional strength may be needed before bone plate repair can be considered as the sole fixation method for avian species.

The effect of endoscopic sterilization on reproductive behavior and pair bond maintenance of feral pigeons (Columba livia).

OBJECTIVE: Problems related to feral pigeons (Columba livia) in cities mainly result from their large numbers due to uncontrolled population growth. The aim of this study was to evaluate whether endoscopic guided sterilization affects the reproductive behavior of feral pigeons under experimental conditions, with the intention of assessing this technique as a potential method for feral pigeon population control. MATERIALS AND METHODS: Five groups of four pairs of feral pigeons each were studied from 8 weeks before, to 7 weeks after sterilization. Both the male and female of the first pair of each group were sterilized, in the second pair only the female and in the third pair only the male was sterilized. The fourth pair acted as a control. All eggs laid were candled to assess fertility. RESULTS: Surgical sterilization had minimal effects on behavior and therefore seems not to have impact on possible field application for population control. All pairs maintained their pair bonds and continued to defend their nesting sites against other pigeons. Only one female copulated with a foreign fertile male while her primary partner was debilitated due to surgery, but returned to him as soon as he recovered. All eggs laid more than 5 days after male sterilization were infertile, whereas all control pairs had fertile eggs. Only one fertile clutch was produced, 5 days after the male's sterilization. Therefore it is assumed that males remain fertile for a limited period of time. CONCLUSION: Endoscopic sterilization seems to be a promising method for field control of feral pigeon populations and sterilization of the male only seems sufficient.

Cardiopulmonary effects of controlled versus spontaneous ventilation in pigeons anesthetized for coelioscopy.

OBJECTIVE: To evaluate the cardiorespiratory effects of controlled versus spontaneous ventilation in pigeons anesthetized for coelioscopy. DESIGN: Prospective study. ANIMALS: 30 healthy adult pigeons (Columbia livia). PROCEDURE: During isoflurane anesthesia, 15 pigeons were allowed to breathe spontaneously (SP group) and 15 were mechanically ventilated (MV group) by use of a pressure-limited ventilator. In each group, cardiopulmonary variables (including end-tidal CO2 concentration [ETCO2]) were measured before (baseline), during, and after coelioscopy. An arterial blood sample was collected for blood gas analyses from each pigeon before coelioscopy and after the procedure, when the caudal thoracic air sac was still open. RESULTS: At baseline, hypoventilation was greater in the SP group than the MV group. Compared with the SP group values, ETCO2 overestimated PaCO2 to a greater degree in the MV group. Cardiovascular variables were not different between groups. After coelioscopy (when the air sac was open), PaCO2 had decreased significantly from baseline in the MV group. In the SP group, hypoventilation worsened despite an increase in respiratory rate. After coelioscopy, PaO2 in the SP group had decreased from baseline and was lower than PaO2 in the MV group; arterial blood pressure and heart rate in the MV group had decreased from baseline and were lower than values in the SP group. CONCLUSIONS AND CLINICAL RELEVANCE: In adult pigeons, controlled ventilation delivered by a pressure-limited device was not associated with clinically important adverse cardiopulmonary changes but may be associated with respiratory alkalosis and cardiovascular depression when air sac integrity has been disrupted.

The reduction of humeral fracture in pigeons with intramedullary poly (methyl methacrylate) and neutralization plate fixation.

The reduction of experimental humeral fracture in pigeons was performed with intramedullary bone cement (poly (methyl methacrylate): PMMA) and neutralization plate fixation to investigate the effect on bone fracture healing and the recovery of flying ability. As a result, neither plate nor bone cement fixation held for more than 2 weeks, but not refracture was observed in any cases with both plate and bone cement. In the latter group, it was confirmed by flight tests that almost normal flying ability was recovered in 6 weeks. In pathological findings, blood supply to the fractured ends recovered within 2 weeks and no cortical bone necrosis was observed at the time except for a disturbance of endosteal callus formation. The process of fracture healing on the plate side took place slightly later than that on the non-plate side, and when much PMMA remained between the fractured ends of the cortical bone the bone formation became spongioid. In view of the quick recovery of flying ability, however, plate and bone cement fixation is considered appropriate to prevent the displacement of a humeral fracture in the pigeon.

Chronic oesophageal fistulation for studying oropharyngeal and gastric influences on ingestive behaviour in the pigeon.

Surgical and postoperative procedures were developed in the pigeon to study the influence of oropharyngeal and postingestional factors in the control of food and water intake. Pigeons were prepared with an oesophageal fistula so that material swallowed emerged from a tube exteriorized at the neck. Nutrient solutions were injected into the lower portion of the oesophagus through a feeding tube inserted in the fistula. A postoperative tube-feeding regimen, using commercially available laboratory chow, was established to maintain the pigeon at its preoperative weight.

Needle catheter duodenostomy: a technique for duodenal alimentation of birds.

A technique for duodenal alimentation (needle catheter duodenostomy) of birds was developed, using the domestic pigeon (Columba livia) as the experimental model. A needle catheter was inserted into the descending duodenum of 5 pigeons and was secured to the body wall and dorsum of each bird. A liquid diet was administered daily (in equal amounts of 0, 4, 8, 12, and 16 hours) for 14 days without adverse effects. On day 15, the catheters were removed, and the birds immediately resumed normal consumption of a pigeon ration and water diet. Although 4 of the 5 birds had minor weight loss, dietary alterations probably could be used on an individual basis to alleviate this problem. After oral alimentation was resumed, the 5 birds exceeded their initial body weight within 7 days. Four weeks after catheter removal, positive-contrast radiographic evaluations indicated that the duodenum of each pigeon appeared normal. Needle catheter duodenostomy was a viable method of alimentation in the domestic pigeon. This technique should be applicable for other avian species requiring bypass of the upper gastrointestinal tract proximal to the region of catheter insertion in the duodenum.

Lactated Ringer's solution or 0.9 por cento sodium chloride as fluid therapy in pigeons (Columba livia) submitted to humerus osteosynthesis / Fluidoterapia com Ringer lactato ou cloreto de sódio 0.9 percent em pombos (Columbia livia) submetidos à osteossíntese de úmero

The study aimed to compare the effects of intraosseous infusion of lactated Ringer's and 0.9% sodium chloride solutions on the electrolytes and acid-base balance in pigeons submitted to humerus osteosynthesis. Eighteen pigeons were undergoing to isoflurane anesthesia by an avalvular circuit system. They were randomly assigned into two groups (n=9) receiving lactated Ringer's solution (LR) or 0.9% sodium chloride (SC), in a continuous infusion rate of 20mL/kg/h, by using an intraosseous catheter into the tibiotarsus during 60-minute anesthetic procedure. Heart rate (HR), and respiratory rate (RR) were measured every 10 min. Venous blood samples were collected at 0, 30 and 60 minutes to analyze blood pH, PvCO2, HCO3 -, Na+ and K+. Blood gases and electrolytes showed respiratory acidosis in both groups during induction, under physical restraint. This acidosis was evidenced by a decrease of pH since 0 min, associated with a compensatory response, observed by increasing of HCO3 - concentration, at 30 and 60 min. It was not observed any changes on Na+ and K+ serum concentrations. According to the results, there is no reason for choosing one of the two solutions, and it could be concluded that both fluid therapy solutions do not promote any impact on acid-base balance and electrolyte concentrations in pigeons submitted to humerus osteosynthesis...

O presente estudo avaliou os efeitos da infusão das soluções de Ringer lactato ou cloreto de sódio 0,9%, no equilíbrio ácido-base e hidroeletrolítico de pombos submetidos à osteossíntese de úmero. Foram utilizados 18 animais, os quais foram submetidos à anestesia por isofluorano, e mantidos em circuito avalvular durante o período anestésico (60 min). Os animais foram distribuídos aleatoriamente em dois grupos (n=9) recebendo Ringer lactato (LR) ou cloreto de sódio 0,9% (SC), administradas na taxa de 20mL/kg/h pela via intraóssea (tibiotarso). Foram monitoradas as frequências cardíaca e respiratória a cada 10 minutos e colhidas amostras sanguíneas venosas aos 0, 30 e 60 min de anestesia, obtendo-se a partir destas, valores de pH sanguíneo, bicarbonato (HCO3), pressão venosa de CO2 (PvCO2), sódio (Na+) e potássio (K+). Os valores referentes ao equilíbrio ácido-base indicam que houve acidose respiratória em ambos os grupos, a qual foi decorrente do processo de indução sob contenção física, caracterizada por diminuição no pH desde o 0 min, associado ao aumento compensatório nos valores de HCO3 -, nos momentos 30 e 60 min. No entanto, no que se refere aos valores obtidos de Na+ e K+ séricos, durante a infusão de ambos os fluidos, não foram observadas alterações que justifiquem a predileção por alguma destas soluções. Diante destes resultados conclui-se que a escolha entre uma das soluções avaliadas não promoveu impacto sob o equilíbrio ácido-base e hidroeletrolítico de pombos submetidos a osteossíntese de úmero...

Properties of standard avian slow muscle grafts following long-term regeneration.

The tonic anterior latissimus dorsi (ALD) of adult pigeons was orthotopically homografted and evaluated after 11 months of regeneration for histological, histochemical, electromyographic (EMG), and mechanical properties. The resting EMG activity of the grafts was lower in amplitude than that of the controls, but showed the tonic pattern typical for these tonic muscles. The control and grafted muscles had a histochemically homogeneous population of fibers with moderate myofibrillar adenosine triphosphatase activity. Succinic dehydrogenase activity was moderate for the control muscles, but low for the grafts. The regenerated muscles had fewer and smaller fibers and had much larger intersynaptic distances. Both the regenerated and the contralateral control muscles were slow contracting and maintained tetanic tension for prolonged periods with direct electrical stimulation. The relaxation was slower in the grafted muscle than in the control. The grafts produced 40% of the maximum tension of the control muscles, but the rate of tension development was similar between the two groups. The results indicate that the tonic properties were regenerated, but the innervation pattern was altered and the grafted muscles did not have normal mature fibers even after long-term regeneration.

Fracture healing after stabilization with intramedullary xenograft cortical bone pins: a study in pigeons.

OBJECTIVE: To investigate the effectiveness of intramedullary xenograft cortical bone pins compared with stainless steel Kirschner wire for the repair of a standardized avian humeral fracture. STUDY DESIGN: Prospective randomized study. SAMPLE POPULATION: Thirty mature pigeons (Columba livia). METHODS: Birds were randomly assigned to 3 groups. Transverse mid-diaphyseal humeral fractures were created in 1 humerus in each bird. Fractures were stabilized with intramedullary ostrich or canine xenograft cortical bone pins or Kirschner wire. Radiographic, histological, and biomechanical assessments were used to compare fracture healing 6 weeks after fracture stabilization. The contralateral humerus of each bird was used as a control. RESULTS: All fractures healed regardless of intramedullary pin type. There were no statistically significant biomechanical differences among groups or within groups. Xenograft cortical bone pins induced a mononuclear inflammatory reaction that did not impair bone healing. Bones stabilized with intramedullary cortical bone pins had more periosteal callus and inflammation at the fracture site than bones stabilized with stainless steel Kirschner wires. CONCLUSIONS: Intramedullary xenograft cortical bone pins, derived from mammalian or avian sources, appear to represent an alternative for the repair of avian humeral fractures. CLINICAL RELEVANCE: Intramedullary xenograft cortical bone pins are biodegradable and may reduce the need for additional surgery to remove implants after fracture healing.

Pino ósseo homólogo conservado em glicerina a 98 por cento e hemicerclagem com fio poliglactina 910 na osteossíntese umeral de pombos domésticos / Homologous bone pin conserved in glycerin at 98 percent and hemicerclagem with a thread of poliglactina 910 in humerus osteosyntesis of domestic pigeons

O objetivo do presente estudo foi avaliar a utilização de um pino intramedular ósseo homólogo, conservado em glicerina a 98 por cento, associado à hemicerclagem com fio poliglactina 910 na osteossíntese umeral transversa de pombos domésticos (Columba livia). Utilizou-se como pino ósseo a parte distal do tibiotarso, conservado com medula óssea. Foram operados 20 pombos domésticos, adultos, não-sexados e clinicamente sadios. Esses animais foram separados ao acaso em cinco grupos, com quatro indivíduos. O úmero foi seccionado cirurgicamente na sua diáfise, de forma transversa, e o pino ósseo foi devidamente implantado no seio do osso. Orifícios foram realizados e por eles procedeu-se hemicerclagem do tipo pontos de Wolff com poliglactina 910. Os animais foram avaliados clinicamente, por meio de radiografias semanais, e histologicamente após os períodos de 15, 30, 60, 90 e 120 dias. A conservação do pino ósseo em glicerina a 98 por cento foi avaliada por meio de exames microbiológicos. Em todos os animais, pode-se notar, clinicamente, excelente adaptação à cirurgia e normalidade do uso do membro já radiologicamente pode-se observar formação de calo ósseo e cicatrização da fratura. Histologicamente pode-se observar que ocorreu formação de calo ósseo 15 dias após a cirurgia e cicatrização com remodelação completa a partir dos 90 dias. Nesse exame, além de leve a moderada reação inflamatória no período inicial de avaliação, nenhum outro evento foi notado nos períodos subseqüentes. Concluiu-se que a técnica e os materiais utilizados se tornam uma opção altamente viável na osteossíntese umeral transversa de pombos domésticos.

The objective of the present study was to evaluate the use of a homologous bone intramedullary pin, conserved in glycerin at 98 percent associated to hemicerclage with a thread of polyglactina 910 in the transverse humerus osteosynthesis of domestic pigeon (Columba livia). The distal part of the tibialtarsus, conserved with bone marrow, was used as a bone pin. Twenty domestic pigeons were operated, adults, no sex distinction, clinically healthy. Those animals were separated randomly in five groups, with four individuals. The humerus was transversely split up surgically in its diaphysis and the bone pin, properly implanted in the sinus of the bone. Holes were accomplished and through them it was possible to proceed the hemicerclage in Wolff suture form with polyglactina 910. The animals were evaluated clinically through weekly x-rays and histologically after periods of 15, 30, 60, 90 and 120 days. The conservation of the bone pin in glycerin at 98 percent was evaluated through microbiological exams. In all the animals, clinically can be noticed excellent adaptation concerning the surgery and normality of the use of the member, and radiologically, bone callus formation and cicatrization of the fracture can be observed. Histologically, it is observed bone callus formation 15 days after the surgery and cicatrization with complete remodeling from 90 days. In that exam, besides light to moderate inflammatory reaction in the initial period of evaluation, no other event was diagnosed in the subsequent periods. It was concluded that the technique and used materials become a highly viable option in the humerus transverse osteosynthesis of domestic pigeons.

Fixação esquelética externa tipo Ia (unilateral-uniplanar) para osteossíntese diafisária de úmero em pombos domésticos (Columba livia) / Type Ia (unilateral-uniplanar) external Skeletal fixation for treatment of humeral diaphysis fracture in domestic pigeons (Columba livia)

Das várias patologias que podem acometer as aves, são mais freqüentes as fraturas de ossos longos das asas e dos membros pélvicos. Este experimento teve como objetivo observar, por meio de exames clínicos, histológicos e radiográficos, a resposta cicatricial óssea ao uso do fixador externo tipo Ia (unilateral-uniplanar) na redução aberta de fratura diafisária, de úmero em pombos domésticos (Columba livia). Foram estudados 14 pombos com peso variando entre 290 e 420 gramas. A fratura foi realizada na diáfise do úmero direito e, logo após, estabilizada com aparelho de fixação externa tipo Ia, utilizando-se, como barra de fixação, o acrílico autopolimerizável. O tempo médio para o completo desaparecimento da linha de fratura foi de 28±6,44 dias e para formação de calo ósseo, 17±3,26 dias. As aves, mesmo com o aparelho de fixação, retornaram ao vôo aos 28±1,2 dias, exceto uma que não recuperou a capacidade de vôo. A técnica de fixação externa demonstrou ser eficaz para o tratamento de fraturas diafisárias de úmero em pombos domésticos.