Hyoscine‐N‐butylbromide premedication on cardiovascular variables of horses sedated with medetomidine

ObjectiveTo evaluate the effects of intravenous (IV) or intramuscular (IM) hyoscine premedication on physiologic variables following IV administration of medetomidine in horses.Study designRandomized, crossover experimental study.AnimalsEight healthy crossbred horses weighing 330 ± 39 kg and aged 7 ± 4 years.MethodsBaseline measurements of heart rate (HR), cardiac index (CI), respiratory rate, systemic vascular resistance (SVR), percentage of patients with second degree atrioventricular (2^oAV) block, mean arterial pressure (MAP), pH, and arterial partial pressures of carbon dioxide (PaCO₂) and oxygen (PaO₂) were obtained 5 minutes before administration of IV hyoscine (0.14 mg kg^?1; group HIV), IM hyoscine (0.3 mg kg^?1; group HIM), or an equal volume of physiologic saline IV (group C). Five minutes later, medetomidine (7.5 μg kg^?1) was administered IV and measurements were recorded at various time points for 130 minutes.ResultsMedetomidine induced bradycardia, 2^oAV blocks and increased SVR immediately after administration, without significant changes in CI or MAP in C. Hyoscine administration induced tachycardia and hypertension, and decreased the percentage of 2^oAV blocks induced by medetomidine. Peak HR and MAP were higher in HIV than HIM at 88 ± 18 beats minute^?1 and 241 ± 37 mmHg versus 65 ± 16 beats minute^?1 and 192 ± 38 mmHg, respectively. CI was increased significantly in HIV (p ≤ 0.05). Respiratory rate decreased significantly in all groups during the recording period. pH, PaCO₂ and PaO₂ were not significantly changed by administration of medetomidine with or without hyoscine.Conclusion and clinical relevanceHyoscine administered IV or IM before medetomidine in horses resulted in tachycardia and hypertension under the conditions of this study. The significance of these changes, and responses to other dose rates, requires further investigation.     

Nitrogen Assimilation and Growth of Cotton Seedlings under NaCl Salinity and in Response to Urea Application with NBPT and DCD

Salinity stress and inefficient nitrogen fertilization adversely affect cotton growth and yield. The effect of salinity on the growth and stress response of cotton seedlings and the effect on N‐use efficiency from the use of the inhibitors of urease (NBPT) and nitrification (DCD) under salinity stress were studied in growth chambers. The study consisted of three levels of salinity – low (0.45 dS m^?1), moderate (8 dS m^?1) and high (16 dS m^?1) – and five N treatments – unfertilized control, 100 % N rate with urea, 80 % N rate with urea, 80 % N rate with urea +NBPT and 80 % N rate with urea +NBPT + DCD. The results indicated that salinity stress reduced plant growth (low leaf area and plant dry matter), decreased N assimilation (low NR, GS and protein), increased plant stress response (high GR and SOD), and decreased leaf chlorophyll, stomatal conductance and quantum yield. Addition of NBPT to urea improved N uptake by 22 % under low salinity; however, this effect was not observed with increasing salinity. No benefit of addition of DCD was observed in any of the parameters collected. In conclusion, salinity stress hindered the performance of the additive NBPT and negatively affected the growth and physiology of cotton.     

Comparison of core needle biopsy and fine-needle aspiration of enlarged peripheral lymph nodes for antemortem diagnosis of enzootic bovine lymphosarcoma in cattle

OBJECTIVE: To determine whether antemortem core needle biopsy and fine-needle aspiration of enlarged peripheral lymph nodes could be used to distinguish between inflammation and lymphosarcoma in cattle. DESIGN: Prospective study. ANIMALS: 25 cattle with enlarged peripheral lymph nodes. PROCEDURES: Antemortem biopsies of the selected lymph nodes were performed with an 18-gauge, 12-cm core needle biopsy instrument. Fine-needle aspirates were performed with a 20-gauge, 4-cm needle. Specimens were analyzed by pathologists who were unaware of clinical findings and final necropsy findings, and specimens were categorized as reactive, neoplastic, or nondiagnostic for comparison with necropsy results. RESULTS: Sensitivity and specificity of core needle biopsy ranged from 38% to 67% and from 80% to 25%, respectively. Sensitivity of fine-needle aspiration ranged from 41% to 53%, and specificity was 100%. Predictive values for positive test results ranged from 77% to 89% for core needle biopsy and were 100% for fine-needle aspiration. Predictive values for negative test results were low for both core needle biopsy and fine-needle aspiration. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that core needle biopsy and fine-needle aspiration can aid in the antemortem diagnosis of bovine enzootic lymphosarcoma. Results of fine-needle aspiration of enlarged peripheral lymph nodes were more specific and more predictive for a positive test result than were results of core needle biopsy.     

Lymphoreticular alterations in neonatally thymectomized and antilymphocyte globulin treated Holstein-Friesian calves

Neonatal calves were thymectomized when 4 to 10 days old and treated briefly with antilymphocyte globulin. Non-thymectomized calves were treated with normal horse globulin or not treated with antilymphocyte globulin. The lymph nodes were examined at selected times by light microscopy and immunofluorescence and after necropsy.The prescapular lymph nodes at 5 weeks represented normal, normally reactive and abnormally reactive structure. Peripheral lymph nodes from 5-week-old calves not treated by thymectomy or antilymphocyte globulin had a low level of lymphopoietic activity. The thymus intact calves treated with normal horse globulin had reactive lymphoid hyperplasia primarily of the cortex. The thymectomized, antilymphocyte globulin treated calves at this age had increased primary follicle activity and depletion of paracortical areas in peripheral lymph nodes. The degree of lymphoid hyperplasia corresponded to the relative frequency of cells with surface immunoglobulin at 5 weeks of age.The lymph nodes and spleen collected at necropsy at 16 to 26 weeks did not segregate into three distinct categories, probably a reflection of the additional stimulation on the immune system by experimental and natural antigen exposure. The differences between treatments were not observed at the time of necropsy. These morphological observations strongly support the conclusion that the calves were affected by neonatal thymectomy, but had recovered from the effect of thymectomy by 16 to 26 weeks of age.     

Cardiac arrhythmias associated with multiple trauma in dogs

Premature ventricular contractions and ventricular tachycardia were detected in 10 dogs 1 to 48 hours after trauma. All dogs were treated aggressively if the arrhythmias became severe. One dog died, 8 were discharged with stable cardiac rhythm, and 1 was euthanatized. Necropsy revealed gross and microscopic lesions of acute myocardial necrosis, probably of ischemic origin. Cardiac arrhythmias were associated with thoracic trauma, neurologic injury, severe shock, and/or extensive tissue trauma.     

Multiple organ metastasis of an aortic body tumor in a boxer

A 9-year-old sexually intact male Boxer with a history of multiple episodes of syncope and various cardiac arrhythmias was determined radiographically to have a large mass in the heart-base region and was subsequently euthanatized upon worsening of clinical signs. Histologic and ultrastructural examination of tissue from the heart-base mass indicated that the tumor was most likely a chemodectoma derived from the aortic body (aortic body tumor, extra-adrenal paraganglioma). Macroscopic and/or microscopic evidence of metastasis of the tumor was seen in the lungs, myocardium, spleen, liver, kidneys, and dura mater over the cerebellum.