Evaluation of chitosan-GP hydrogel biocompatibility in osteochondral defects: an experimental approach.

BACKGROUND: Articular cartilage, because of its avascular nature, has little capacity for spontaneous healing, and tissue engineering approaches, employing different biomaterials and cells, are under development. Among the investigated biomaterials are the chitosan-based hydrogels. Although thoroughly studied in other mammalian species, studies are scarce in equines. So, the aim of the present study was to investigate the biocompatibility of chitosan-GP in horse joints submitted to high mechanical loads. RESULTS: An osteochondral defect was created by arthroscopy in the medial surface of lateral trochlea of talus of left or right leg, randomly selected, from six healthy geldings. The defect was filled up with chitosan-GP. The contralateral joint received an identical defect with no implant. The chondral fragment removed to produce the defect was collected, processed and used as the "Initial" sample (normal cartilage) for histology, immunohistochemistry, and metabolic labelling of PGs. After 180 days, the repair tissues were collected, and also analyzed. At the end of the experiment (180 days after lesion), the total number of cells per field in repair tissues was equal to control, and macrophages and polymorphonuclear cells were not detected, suggesting that no significant inflammation was present. These cells were able to synthesize type II collagen and proteoglycans (PGs). Nevertheless, the cell population in these tissues, both in presence of chitosan-GP and in untreated controls, were heterogeneous, with a lower proportion of type II collagen-positives cells and some with a fibroblastic aspect. Moreover, the PGs synthesized in repair tissues formed in presence or absence of chitosan-GP were similar to those of normal cartilage. However, the chitosan-GP treated tissue had an disorganized appearance, and blood vessels were present. CONCLUSIONS: Implanted chitosan-GP did not evoke an important inflammatory reaction, and permitted cell growth. These cells were able to synthesize type II collagen and PGs similar to those synthesized in normal cartilage and in healing tissue without implant, indicating its chondrocyte nature.

Ultimobranchial body cyst in an adult horse: clinical, histopathologic, and immunohistochemical features.

A 9-y-old Mangalarga Marchador gelding was referred to a veterinary hospital because of a swelling on the upper right side of the neck. Ultrasound examination revealed a multilocular structure adjacent to the thyroid gland with low echogenic content suggestive of fluid. The mass was removed surgically. Histologically, the cystic cavities in the surgical sample were filled with abundant eosinophilic secreta and lined by cuboidal, segmentally ciliated, columnar epithelium with interspersed goblet cells. Segmental crowding of the multilayered lining of the cyst was noted. Immunohistochemistry suggested the presence of both C cells and follicular cells, given the positivity of the immunomarkers calcitonin and TTF-1, respectively. The histogenesis of ultimobranchial cysts is uncertain. Based on clinical, histopathologic, and immunohistochemical identification, the cystic structure in this case is compatible with an ultimobranchial body cyst.

3-D technology used to accurately understand equine ileocolonic aganglionosis.

Ileocolonic aganglionosis (ICA) is the congenital and hereditary absence of neurons that constitute the enteric nervous system and has been described in various species including humans - Hirschsprung's disease - and horses - overo lethal white syndrome (OLWS). Hirschsprung's disease affects circa 1 in 5,000 live births. At best, this disease means an inability to absorb nutrients from food (humans). At worse, in horses, it always means death. Despite our general understanding of the functional mechanisms underlying ICA, there is a paucity of reliable quantitative information about the structure of myenteric and submucosal neurons in healthy horses and there are no studies on horses with ICA. In light of these uncertainties, we have used design-based stereology to describe the 3-D structure - total number and true size - of myenteric and submucosal neurons in the ileum of ICA horses. Our study has shown that ICA affects all submucosal neurons and 99% of myenteric neurons. The remaining myenteric neurons (0.56%) atrophy immensely, i.e. 63.8%. We believe this study forms the basis for further research, assessing which subpopulation of myenteric neurons are affected by ileocolonic aganglionosis, and we would like to propose a new nomenclature to distinguish between a complete absence of neurons - aganglionosis - and a weaker form of the disease which we suggest naming 'hypoganglionosis'. Our results are a step forward in understanding this disease structurally.

Effect of ephedrine and phenylephrine on cardiopulmonary parameters in horses undergoing elective surgery.

OBJECTIVE: To assess the cardiopulmonary effects of ephedrine and phenylephrine for management of isoflurane-induced hypotension in horses. STUDY DESIGN: Prospective randomized clinical study. ANIMALS: Fourteen isoflurane-anesthetized horses undergoing digital palmar neurectomy. METHODS: Ephedrine (EPH group; 0.02 mg kg(-1) minute(-1); n = 7) or phenylephrine (PHE group; 0.002 mg kg(-1) minute(-1); n = 7) was administered to all horses when mean arterial pressure (MAP) was <60 mmHg. The infusions were ended when the target MAP was achieved, corresponding to a 50% increase over the pre-infusion MAP (baseline). The horses were instrumented with an arterial catheter to measure blood pressure and allow the collection of blood for pH and blood-gas analysis and a Swan-Ganz catheter for measurement of cardiac output using thermodilution. Cardiopulmonary parameters were recorded at baseline and at 5, 30, 60 and 90 minutes after achieving the target MAP. RESULTS: In both groups, the MAP and systemic vascular resistance (SVR) increased significantly at 5, 30, 60 and 90 minutes post infusion compared to baseline (p < 0.05). The EPH group had a significant increase in cardiac index (CI) and systemic oxygen delivery index at 5, 30, 60 and 90 minutes post infusion compared to baseline (p < 0.05) and compared to the PHE group (p < 0.05). The PHE group had significantly higher SVR and no decrease in oxygen extraction compared with the EPH group at 30, 60 and 90 minutes post infusion (p < 0.05). No significant differences in ventilatory parameters were observed between groups after the infusion. CONCLUSIONS: Ephedrine increased the MAP by increasing CI and SVR. Phenylephrine increased MAP by increasing SVR but cardiac index decreased. Ephedrine resulted in better tissue oxygenation than phenylephrine. CLINICAL RELEVANCE: Ephedrine would be preferable to phenylephrine to treat isoflurane-induced hypotension in horses since it increases blood flow and pressure.

Effect of pressure support ventilation during weaning on ventilation and oxygenation indices in healthy horses recovering from general anesthesia.

OBJECTIVE: To determine if pressure support ventilation (PSV) weaning from general anesthesia affects ventilation or oxygenation in horses. STUDY DESIGN: Prospective randomized clinical study. ANIMALS: Twenty client-owned healthy horses aged 5 ± 2 years, weighing 456 ± 90 kg. METHODS: In the control group (CG; n = 10) weaning was performed by a gradual decrease in respiratory rate (fR ) and in the PSV group (PSVG; n = 10) by a gradual decrease in fR with PSV. The effect of weaning was considered suboptimal if PaCO2 > 50 mmHg, arterial pH < 7.35 plus PaCO2 > 50 mmHg or PaO2 < 60 mmHg were observed at any time after disconnection from the ventilator until 30 minutes after the horse stood. Threshold values for each index were established and the predictive power of these values was tested. RESULTS: Pressure support ventilation group (PSVG) had (mean ± SD) pH 7.36 ± 0.02 and PaCO2 41 ± 3 mmHg at weaning and the average lowest PaO2 69 ± 6 mmHg was observed 15 minutes post weaning. The CG had pH 7.32 ± 0.02 and PaCO2 57 ± 6 mmHg at weaning and the average lowest PaO2 48 ± 5 mmHg at 15 minutes post weaning. No accuracy in predicting weaning effect was observed for fR (p = 0.3474), minute volume (p = 0.1153), SaO2 (p = 0.1737) and PaO2 /PAO2 (p = 0.1529). A high accuracy in predicting an optimal effect of weaning was observed for VT > 10 L (p = 0.0001), fR /VT ratio ≤ 0.60 breaths minute(-1) L(-1) (p = 0.0001), VT /bodyweight > 18.5 mL kg(-1) (p = 0.0001) and PaO2 /FiO2 > 298 (p = 0.0002) at weaning. A high accuracy in predicting a suboptimal effect of weaning was observed for VT < 10 L (p = 0.0001), fR /VT ratio ≥ 0.60 breaths minute(-1) L(-1) (p = 0.0001) and Pe'CO2 ≥ 38 mmHg (p = 0.0001) at weaning. CONCLUSIONS AND CLINICAL RELEVANCE: Pressure support ventilation (PSV) weaning had a better respiratory outcome. A higher VT , VT /body weight, PaO2 /FiO2 ratio and a lower fR /VT ratio and Pe'CO2 were accurate in predicting the effect of weaning in healthy horses recovering from general anesthesia.

Nephrosplenic Space Ablation in Horses After Homologous Pericardium Implant Using a Laparoscopic Stapler.

This study aimed to describe and evaluate a laparoscopic technique to promote nephrosplenic space ablation in horses using a homologous pericardium implant, preserved in 98% glycerin and fixed using laparoscopic polydioxanone staples. In this experimental study, six Arabian horses without previous related abdominal diseases were used. The surgical procedures were performed in the standing position under sedation with alpha-2 agonists and opioids, associated with local infiltration of the local anesthetic in the portal sites. The horses were restrained in a stock, and the left flanks were clipped and aseptically prepared. Three portals were created on the left flank, and the homologous pericardium implant, measuring 10 × 5 cm, was introduced into the abdominal cavity covering the nephrosplenic space, positioned between the dorsal border of the spleen and perirenal fascia, fixed with polydioxanone staples using a laparoscopic stapler. Physical examination and blood and peritoneal fluid sample collection were performed on days 0, 1, 3, 7, 14, 30, and 60 of the postoperative period, and an exploratory laparoscopy was performed on day 60 to assess the effectiveness of the technique and eventual complications. There were no difficulties or significant complications during the surgical procedure, and the total average time to perform was 49.83 minutes (±10.19). In the postoperative period, there was a significant increase (P < .05) in the plasma fibrinogen concentration on days 7 and 14 compared with the preoperative moment. The total nucleated cell count in the peritoneal fluid increased (P < .05) on days 1, 3, 7, 14, and 30. After 60 days of the surgical procedure, the physical examination and laboratory data were within the normal range. Exploratory laparoscopy performed on day 60 revealed complete occlusion of the nephrosplenic space, and it was not possible to differentiate the pericardium implant from the scar tissue, not even in the histological evaluation performed on the collected samples. In two horses, omentum adhesion was observed in the region where the implant was fixed, and in two others, a synechia was observed between the implant area and mesocolon without association with clinical complications. The animals were followed up for 36 months at surgery, and no colic signs were observed along this period. It was concluded that the technique of ablation of the nephrosplenic space, using homologous pericardium preserved in 98% glycerin, fixed by polydioxanone staples by laparoscopy, was simple to perform, effective, and free of clinical complications during the period of evaluation, and its use may be indicated as a surgical option in clinical cases of horses with recurrent nephrosplenic entrapment.

Bilateral sinus cysts in a filly treated by endoscopic sinus surgery.

Bilateral cysts in the frontal and caudal maxillary sinuses in a filly treated by endoscopic sinus surgery (sinoscopy) and triangulation technique are described. Sinoscopy has the advantage of being a minimally invasive technique and permits a complete inspection of the frontal and maxillary sinuses, which is not possible through flap sinusotomy.

Ultrasonographic changes of the equine stifle following experimental medial patellar desmotomy.

The objective of this study was to evaluate, through ultrasonography, the effect of medial patellar desmotomy. Middle patellar desmitis, enthesophytes in the patella, and irregularities in the cartilage of the femoral trochlear groove were observed. Medial patellar desmotomy leads to lesions in the stifle, and restriction of movement does not prevent these lesions from occurring.

Physiotherapy protocol during initial postoperative period of arthroscopy in horses / Protocolo fisioterápico durante o período pós-operatório inicial de cirurgia artroscópica em equinos

This study evaluated the effects of a physiotherapy protocol applied in joints with osteochondritis dissecans submitted to arthroscopy. Twelve horses totaling twenty joints were used and divided into two uniform groups, according to articular lesion grade. Treated Group (TG) received the physiotherapy protocol (cryotherapy, passive rage motion and controlled exercise) that initiate just after anesthetic recovery and extended for five days. Control Group (CG) remained resting in stall during the same period. Physical examination and synovial fluid analysis were used to evaluate the treatment. The synovial fluid examination consisted of physical analysis (color, aspect, and viscosity), mucin clot evaluation, Serum Amyloid A, Prostaglandin E2 and urea concentration. Synovial samples were collected by arthrocentesis at the beginning of the surgical procedure (D1), 48 hours (D3) and 96 hours (D5) after surgery. Before arthroscopy and daily during the postoperative period joints were evaluated by physical exam: superficial temperature (°C), range of motion (degrees) and circumference (centimeters). The joint physical examination showed no significant difference between groups and neither along the days for the same group. The parameters of synovial fluid showed difference over the moments in each group but didn't have difference between groups. Color and aspect had the same patterns across moments, in CG fluid had significant change when compared D1 with D3 (color and aspect: p<0.001) and D5 (color: p<0.001; aspect: p<0.05) becoming mostly bloody and cloudy in D3 and D5. However in TG the difference was significant just between D1 and D3 (color and aspect: p<0.05), showing an improvement of synovial fluid in D5 (color and aspect: p<0.05). Viscosity and mucin clot evaluation showed significant change in CG between D1 and D3 (viscosity: p<0.01; mucin clot: p<0.05) and between D1 and D5 (viscosity: p<0.01;mucin clot: p<0.01). In TG no significant difference of viscosity and mucin clot was observed over the moments, showing an early improvement of synovial fluid quality. The Serum Amyloid A concentration showed an extremely significant increase in CG (p<0.001) when compared D1 (1217.13±664.47µg/mL) and D3 (42423.80±52309.31µg/mL). The comparison between D1 and D5 in CG, and across moments in TG, had no statistical difference. The PGE2 eicosanoid remained statistically unchanged all over the time. Urea showed significant increase in D3 when compared to D1 (p<0.001) in CG, and had no variation in TG. The physiotherapy protocol minimized the inflammatory mediators and provided minor alterations in synovial fluid after arthroscopy.(AU)

Este estudo avaliou os efeitos de um protocolo fisioterápico, aplicado em articulações com osteocondrite dissecante, submetidas à artroscopia. Foram utilizados 12 cavalos, totalizando 20 articulações, divididas em dois grupos homogêneos de acordo com a graduação da lesão articular. O grupo tratado (GT) recebeu o protocolo fisioterápico (crioterapia, movimentação passiva e exercício controlado) que se iniciou imediatamente após a recuperação anestésica e se estendeu por cinco dias. O grupo controle (GC) permaneceu em repouso na baia, pelo mesmo período. Exame físico da articulação e análise do líquido sinovial foram utilizados para avaliar o tratamento. O exame do líquido sinovial consistiu em análise física (cor, aspecto e viscosidade), avaliação do coágulo de mucina e concentrações de amiloide sérica A, prostaglandina E2 e ureia. Amostras de líquido sinovial foram colhidas por artrocentese no início do procedimento cirúrgico (D1) e após 48 (D3) e 96 horas (D5) do procedimento cirúrgico. Antes da artroscopia e diariamente no período pós-operatório, as articulações foram avaliadas por exame físico: temperatura superficial (°C), ângulo de flexão (graus), circunferência (centímetros). A avaliação física das articulações não apresentou diferença significativa entre os grupos nem ao longo dos dias em cada grupo. Nas análises do líquido sinovial, observou-se uma variação diferente entre os momentos em cada grupo porém sem diferença significativa entre os grupos. A cor e o aspecto tiveram resultados semelhantes ao longo do tempo, no GC houve uma alteração significativa quando comparados D1 e D3 (cor e aspecto: p<0,001) e D1 e D5 (cor: p<0,001; aspecto: p<0,05) tornando-se sanguinolento e turvo na maioria das amostras em D3 e D5. Já no GT, houve diferença significativa apenas entre D1 e D3 (cor e aspecto: p<0,05), demonstrando melhora no líquido sinovial em D5 (cor e aspecto: p<0,05). A viscosidade e o coágulo de mucina apresentou alteração significativa no GC entre D1 e D3 (viscosidade: p<0,01; coágulo de mucina: p<0,05) e entre D1 e D5 (viscosidade e coágulo de mucina: P<0,01). No grupo tratado não foram observadas alterações significativas em viscosidade e coágulo de mucina, ao longo dos momentos, demonstrando uma melhora precoce na qualidade do líquido sinovial. A amiloide sérica A apresentou um aumento extremamente significante no GC (p<0,001) quando comparados D1 (1217,13±664,47µg/dL) e D3 (42423,80±52309,31µg/dL). Quando comparados D1 e D5 no GC e ao longo do tempo no GT não foram observadas diferenças significativas. A concentração de PGE2 permaneceu sem alterações. As mensurações de ureia apresentaram aumento significativo em D3 quando comparado a D1 (p<0,001) no GC e não apresentou variação no GT. O protocolo fisioterápico minimizou os mediadores inflamatórios e proporcionou menor alteração do líquido sinovial após artroscopia.(AU)