Comparison of analgesia provided by lidocaine or morphine delivered epidurally in rabbits undergoing hindlimb orthopedic surgery.

The aim of the study was to compare anaesthesia protocol utilizing combination ketamine/ medetomidine with epidural lidocaine or morphine to orthopaedic surgery in rabbits. All rabbits received intramuscularly medetomidine (0.5 mg/kg) and ketamine (20 mg/kg). In group L (n=13) epidural injection was performed with lidocaine (3 mg/kg) and in group M (n=13) with morphine (0.1 mg/kg) diluted with sterile saline to 0.6 ml. Rabbits underwent bilateral mosaicplasty surgery. Heart rate (HR), systolic (SBP), diastolic (DBP) and mean arterial blood pressure (MAP), arte- rial oxygen saturation (SpO2) and respiratory rate (RR) were measured every 5 minute during surgical procedure. Duration of sensory blockade was measured based on toe pinch reflex and recorded. Hemodynamic parameters were comparable at baseline in both groups. We did not observe significant differences in HR, RR, SBP, DBP, MAP between group L and M. Intragroup statistical analysis revealed differences at different time points in group M in terms of HR, SBP, DBP, MAP. In rabbits in group M blood pressure dropped while HR increased over time. In both groups a decrease in SpO2 was observed. Mean duration of loss of the toe pinch reflex was similar between group L and M, and amounted to 72.79±34.48 and 82.80±17.85 minutes, respectively.

Experimental osteoporosis in sheep--mechanical and histological approach.

The implementation of new methods of osteoporotic therapy requires tests on animal model. The use of sheep as model has numerous advantages over other animals. The aim of this study was to describe the change in parameters in sheep with osteoporosis induced using steroids and ovariorectomy methods as opposed to the parameters in healthy sheep. The study was performed on female "merinos" breed sheep divided into the three groups: negative control (NC)--healthy animals, positive control (PC)--ovariorectomized animals and steroid control group (SC)--in which methylprednisolone was administered. This paper presents histological and ultrastructural examination with mechanical comparative tests for force/strength values as well as indentation tests of joint cartilage. The obtained results confirm the loss of bone mass associated with mineral composition content in bones, which has an influence on bone strength.

Evaluation of serum cytokine levels in recurrent airway obstruction.

Recurrent airway obstruction (RAO) represents a serious health problem and is traditionally classified as an allergic disease, where contact with an antigen can induce clinical airway inflammation, bronchial hyper-responsiveness and reversible airway obstruction. Previous studies have demonstrated the presence of the Th2 response in the lungs of human patients with asthma and horses with heaves. These cells are involved in the production of cytokines which regulate the synthesis of immunoglobulins. 40 horses were evaluated: 30 horses with RAO and 10 healthy animals. The expression levels of interferon-alpha 1 (IFN-α1), interferon-gamma (IFN-γ), interleukin-1ß, (IL-1ß), IL-2, IL-4, IL-13 and tumor necrosis factor alpha (TNF-α) were measured in the serum obtained from control and RAO-susceptible horses during crisis. In all the patients, serum cytokine levels were detected. Serum median IL-13 and IFN-γ levels were significantly higher in RAO-affected horses than in the healthy group (p < 0.001). The serum median IFN-α1, IL-1ß, IL-2, IL-4, and TNF-α levels were similar in both groups. These results indicate a low variability of the levels of cytokines and a high frequency of their detection in serum samples from horses with RAO. Immune mechanisms involved in equine RAO are more complex than those defined by a simple Th1/Th2 dichotomy.

The experimental osteoporosis in sheep--clinical approach.

The implementation of new methods of oseoporotic therapy requires tests on an animal model. One of the best is the sheep, whose numerous advantages over other models are described in the literature. The aim of this study was induction of osteoporosis using steroids and ovariorectomy methods in sheep and description of the change in parameters with regard to healthy sheep. The study was performed on female "merino" breed sheep divided into three groups: Negative control (NC) healthy animals, positive control (PC) ovariorectomised animals and steroid group (SC) where methylprednisolone was implemented. Blood tests, diagnostic arthroscopy, quantitative computed tomography and X-Ray micro-tomography of bone were carried out. Blood tests revealed a decreased level of estrogens, progesterone and increased parathormone and cortisol levels in the SC group. A decrease in bone turnover markers and an increase in bone resorption markers in all groups were also noted. Diagnostic arthroscopy revealed osteoarthrosis in PC and SC groups. Radiological density tests showed a slight decrease in PC and NC groups whereas there was more than a triple decrease in SC. Results obtained from microCT showed quickly developing osteoporosis in the SC group, which is reflected in numerous parameters analysed in this study. The best effects for osteoporosis induction were obtained using ovariorectomised sheep with methylprednisolone injections.

Effect of short-term rapid ventricular pacing followed by pacing interruption on arterial blood pressure in healthy pigs and pigs with tachycardiomyopathy.

Ventricular tachycardia may lead to haemodynamic deterioration and, in the case of long term persistence, is associated with the development of tachycardiomyopathy. The effect of ventricular tachycardia on haemodynamics in individuals with tachycardiomyopathy, but being in sinus rhythm has not been studied. Rapid ventricular pacing is a model of ventricular tachycardia. The aim of this study was to determine the effect of rapid ventricular pacing on blood pressure in healthy animals and those with tachycardiomyopathy. A total of 66 animals were studied: 32 in the control group and 34 in the study group. The results of two groups of examinations were compared: the first performed in healthy animals (133 examinations) and the second performed in animals paced for at least one month (77 examinations). Blood pressure measurements were taken during chronic pacing--20 min after onset of general anaesthesia, in baseline conditions (20 min after pacing cessation or 20 min after onset of general anaesthesia in healthy animals) and immediately after short-term rapid pacing. In baseline conditions significantly higher systolic and diastolic blood pressure was found in healthy animals than in those with tachycardiomyopathy. During an event of rapid ventricular pacing, a significant decrease in systolic and diastolic blood pressure was found in both groups of animals. In the group of chronically paced animals the blood pressure was lower just after restarting ventricular pacing than during chronic pacing. Cardiovascular adaptation to ventricular tachycardia develops with the length of its duration. Relapse of ventricular tachycardia leads to a blood pressure decrease more pronounced than during chronic ventricular pacing.

Assessment of treatment of Osteochondrosis dissecans (OCD) of shoulder joint in dogs--the results of two years of experience.

Osteochondrosis is a common and clinically important joint disorder that occurs in human and many species of animals such as pigs, horses and dogs. The aim of this article is to present the results of conservative and surgical treatment of Osteochondrosis dissecans (OCD) and to compare the recovery time in relation to race, age and extent of cartilage damage. The study was performed on 36 dogs of both sexes, aged from 4 to 24 months, weighing 12-70 kg, of different breeds (predisposed and non-specific for this disease). All patients underwent clinical, orthopedic and radiological examination through which the location of OCD changes in the shoulder joint and the degree of this problem were established. Based on the examinations the patients were qualified for particular treatment procedures. Control tests were performed after 14, 30 and 60 days, which allowed for a precise evaluation of the progress of therapy. Achieved results indicate that dogs age and the lesions extent in the shoulder joint have an impact on the outcome of treatment. Studies showed that the best therapeutic effects were obtained in dogs aged 6-10 months, which underwent surgery. The study proved that the early diagnosis of OCD strongly influence the recovery rate and may inhibit the development of degenerative changes in the joint (DJD).

Contemporary approach to acid-base balance and its disorders in dogs and cats.

The issue of the acid-base balance (ABB) parameters and their disorders in pets is rarely raised and analysed, though it affects almost 30% of veterinary clinics patients. Traditionally, ABB is described by the Henderson-Hasselbach equation, where blood pH is the resultant of HCO3- and pCO2 concentrations. Changes in blood pH caused by an original increase or decrease in pCO2 are called respiratory acidosis or alkalosis, respectively. Metabolic acidosis or alkalosis are characterized by an original increase or decrease in HCO3- concentration in the blood. When comparing concentration of main cations with this of main anions in the blood serum, the apparent absence of anions, i.e., anion gap (AG), is observed. The AG value is used in the diagnostics of metabolic acidosis. In 1980s Stewart noted, that the analysis of: pCO2, difference between concentrations of strong cations and anions in serum (SID) and total concentration of nonvolatile weak acids (Atot), provides a reliable insight into the body ABB. The Stewart model analyses relationships between pH change and movement of ions across membranes. Six basic types of ABB disorders are distinguished. Respiratory acidosis and alkalosis, strong ion acidosis, strong ion alkalosis, nonvolatile buffer ion acidosis and nonvolatile buffer ion alkalosis. The Stewart model provides the concept of strong ions gap (SIG), which is an apparent difference between concentrations of all strong cations and all strong anions. Its diagnostic value is greater than AG, because it includes concentration of albumin and phosphate. The therapy of ABB disorders consists, first of all, of diagnosis and treatment of the main disease. However, it is sometimes necessary to administer sodium bicarbonate (NaHCO3) or tromethamine (THAM).

Regulation of cerebral glucose metabolism in normal and polycythemic newborn lambs.

In contrast to previous investigations, a recent study of polycythemic lambs suggested that cerebral glucose delivery (concentration x blood flow), not arterial glucose concentration, determined cerebral glucose uptake. In the present study, the independent effects of arterial glucose concentration and delivery on cerebral glucose uptake were examined in two groups of chronically catheterized newborn lambs (control and polycythemic). Arterial glucose concentration was varied by an infusion of insulin. CBF was reduced in one group of lambs (polycythemic) by increasing the hematocrit. At all arterial glucose concentrations, the cerebral glucose delivery of the polycythemic group was 59.6% of the control group. At arterial glucose concentrations of greater than 1.6 mmol/L, cerebral glucose uptake was constant and similar in both groups. At arterial glucose concentrations of less than or equal to 1.6 mmol/L, cerebral glucose uptake was unchanged in the control group, but was significantly decreased in the polycythemic group. In contrast, the cerebral glucose uptake was similar in both groups over a broad range of cerebral glucose delivery values. At cerebral glucose delivery values less than or equal to 83 mumols/min/100 g, there was a significant decrease in cerebral glucose uptake in both groups. During periods of low cerebral glucose delivery and uptake, cerebral oxygen uptake fell in the control group but remained unchanged in the polycythemic group. Maintenance of cerebral oxygen uptake in the polycythemic group was associated with an increased extraction and uptake of lactate and beta-hydroxybutyrate. We conclude that cerebral glucose delivery, not arterial glucose concentration alone, determines cerebral glucose uptake.

Cerebral metabolism in the newborn lamb with polycythemia.

Infants with polycythemia and hyperviscosity are known to have a reduced cerebral blood flow. Eight newborn lambs were studied to determine what effect the reduction in cerebral blood flow might have on the cerebral delivery and uptake of oxygen, glucose, lactate, pyruvate, beta-hydroxybutyrate, and acetoacetate. Measurements of cerebral blood flow, hematocrit, blood viscosity as well as delivery and uptake of the forementioned substrates were made during a control period and at 60, 180, and 300 min after an exchange transfusion with packed newborn red blood cells was performed to increase the hematocrit. Sixty min after the exchange transfusion, cerebral blood flow fell while cerebral oxygen delivery and uptake were stable. Although arterial glucose concentration remained unchanged, there was a significant fall in cerebral glucose delivery. At 180 min after the exchange transfusion, the arterial glucose concentration fell from 90 to 70 mg/100 ml causing the cerebral glucose delivery to further decrease. This resulted in a significant fall in the cerebral glucose uptake and glucose:oxygen quotient. At 300 min arterial glucose concentration remained low but a rise in cerebral blood flow resulted in a small increase in the cerebral glucose delivery and consequently the cerebral glucose uptake and glucose:oxygen quotient returned to normal. We conclude that polycythemia results in a decrease in cerebral glucose delivery and uptake during normoglycemia.