Body temperature measurement in anesthetized dogs - comparison of nasal, axillary, rectal and esophageal temperature

OBJECTIVE

To evaluate different methods of monitoring body temperature in anesthetized dogs with comparison to core temperature obtained via esophageal probe.

METHODS

Client-owned dogs undergoing general anesthesia for various procedures were included in this observational study. The temperature was taken sequentially every 10 minutes from the rectum, axilla, and nasal cavity with a digital thermistor thermometer, and compared to esophageal core temperature via paired t-tests. Differences from the gold standard esophageal temperature were assessed via Bland-Altman plots and further evaluated for factors like time under anesthesia and presence of Hypo-/Normo- or Hyperthermia. In addition, it was analyzed whether a correction factor for peripheral measurement sites (nasal cavity and axilla) would be applicable in a reliable representation of the body temperature. The level of significance in all tests was set at p<0.05.

RESULTS

In this study, 95 simultaneous temperature measurements at the 4 different sites were obtained from 30 dogs. Mean difference and limits of agreement from esophageal temperature for the different measurement methods were 0.0±0.72°C for rectal temperature, -1.2±1.42°C for axillary and -1.0±2.02°C for nasal temperature. Axillary and nasal temperatures were not significantly different (p=0.5721 and p=0.9287, respectively) from esophageal temperature with a +1.2°C and +1°C correction factor, respectively.

CONCLUSION AND CLINICAL RELEVANCE

During perioperative temperature measurement in anesthetized patients, rectal and esophageal measurements can be used interchangeable. However, if these are not available, the use of axillary or nasal sites is only reliable after applying a correction factor.

[Venous catheters in horses - early ultrasonographic venous abnormalities and evidence of biofilms]

OBJECTIVE

Complications associated with indwelling intravenous catheters vary from minor to severe. Changes in tissue architecture and vein structure may be detectable prior to clinical alterations. The aim of the study was to characterize and compare changes in a catheterized vein and surrounding tissue by clinical and ultrasonographic examination. Microbiological infestation of catheter specimens was assessed.

MATERIAL AND METHODS

In this prospective, observational, clinical study 55 horses with an indwelling intravenous catheter have been included. Subsequent to catheter placement, vein and surrounding tissue were daily examined clinically and by ultrasonographic examination at predetermined localizations. After sterile removal of the catheters, specimens underwent microbiological testing and scanning electron microscopy. Obtained data were analyzed via descriptive statistics. Thickness of the venous wall was compared at predetermined localizations and time points for several parameters with the help of non-parametric tests (level of significance at p < 0.05, post-hoc Bonferroni correction).

RESULTS

Overall, in 41.8 % of the horses transient alterations (swelling) of the surrounding tissue occurred during catheterization. Median catheterization was 69.5 hours (19 hour-10 days). With ultrasonography, venous valves and collateral vessels could be detected reliably. Significant alterations in wall thickness during catheterization were associated with various factors (location site [p ≤ 0.001], season [p = 0.006], anesthesia [p ≤ 0.001]).Microbiological analysis revealed a positive result in 23.5 %, 12 of the 51 samples; raster electron microscopy showed presence of bacteria in 25.0 %, 4 of the 16 investigated catheter samples.

CONCLUSION AND CLINICAL RELEVANCE

Local tissue changes at the insertion site of the catheter are commonly associated with catheterization, and are easily detectable with ultrasonography. Despite the easy performance in a clinical setting, the benefit of routine ultrasonographic monitoring of catheterized veins might be questionable with regard to early identification and prediction of catheter-associated venous disease. Bacteria might be detectable morphologically on the catheter but frequently lack a positive result from standard bacterial cultivation.

[Evaluation of clinical examination parameters and a scoring system in equine colic as well as the assessment of their prognostic value]

SUBJECT AND AIM

In horses, colic is associated with relatively high mortality rates. Identification of parameters associated with poor outcome may aid in providing a more accurate prognosis. This study aimed to assess the early prognostic value towards survival of the horse based on parameters of the clinical examination.

MATERIAL AND METHODS

In a retrospective study (2013-2017), results of the clinical examination of horses with colic were analyzed. Obtained parameters were categorized from physiologic up to different pathophysiologic manifestations. The risk of death was calculated as odds ratios in comparison to normal values of these parameters. Individual score points were obtained and related to the respective outcome. Cut-off values for prognosis and treatment were calculated to distinguish between outcome and treatment group.

RESULTS

A total of 492 colic horses were analyzed, presenting 433 survivors (88 %). Overall, medical treatment was selected in 346 (70.3 %) horses (with 96 % survivors) and surgical treatment (laparotomy) was performed in 146 (29.7 %) horses (69.2 % survivors). An increased likelihood of the outcome "death" was found in horses aged over 20 years (OR = 5.498, p < 0.0005), with colic signs of > 6 hours duration (OR = 3.590, p = 0.035) and, also, for breeds of draft horses (OR = 8.364, p < 0.0005). Horses with significant increases in heart and respiratory rates (OR = 24.294, p < 0.0005 and OR = 20.375, p < 0.0005, respectively) and increased blood lactate concentrations (> 90 mg/dl: OR = 26.390, p < 0.0005) were more likely to succumb to the disease. However, a scoring system failed to show an association between high score points and poor prognosis.

CONCLUSION AND CLINICAL RELEVANCE

Parameters of the clinical examination as well as the history of the patient may be indicative for the patient's outcome. However, no clear-cut distinction of the evaluated parameters towards survival and treatment options was obtained. A careful investigation of the patient remains mandatory for selection of treatment and a proper assessment of prognosis.

Biplanar High-Speed Fluoroscopy of Pony Superficial Digital Flexor Tendon (SDFT)-An In Vivo Pilot Study

The superficial digital flexor tendon (SDFT) is the most frequently injured structure of the musculoskeletal system in sport horses and a common cause for early retirement. This project's aim was to visualize and measure the strain of the sound, injured, and healing SDFTs in a pony during walk and trot. For this purpose, biplanar high-speed fluoroscopic kinematography (FluoKin), as a high precision X-ray movement analysis tool, was used for the first time in vivo with equine tendons. The strain in the metacarpal region of the sound SDFT was 2.86% during walk and 6.78% during trot. When injured, the strain increased to 3.38% during walk and decreased to 5.96% during trot. The baseline strain in the mid-metacarpal region was 3.13% during walk and 6.06% during trot and, when injured, decreased to 2.98% and increased to 7.61%, respectively. Following tendon injury, the mid-metacarpal region contributed less to the overall strain during walk but showed increased contribution during trot. Using this marker-based FluoKin technique, direct, high-precision, and long-term strain measurements in the same individual are possible. We conclude that FluoKin is a powerful tool for gaining deeper insight into equine tendon biomechanics.

Stereoselective methadone disposition after administration of racemic methadone to anesthetized Shetland ponies assessed by capillary electrophoresis

The enantioselectivity of the pharmacokinetics of methadone was investigated in anesthetized Shetland ponies after a single intravenous (0.5 mg/kg methadone hydrochloride; n = 6) or constant rate infusion (0.25 mg/kg bolus followed by 0.25 mg/kg/h methadone hydrochloride; n = 3) administration of racemic methadone. Plasma concentrations of l‐methadone and d‐methadone and their major metabolites, l‐ and d‐2‐ethylidene‐1,5‐dimethyl‐3,3‐diphenylpyrrolidine (EDDP), respectively, were analyzed by CE with highly sulfated γ‐cyclodextrin as chiral selector and electrokinetic analyte injection from liquid/liquid extracts prepared at alkaline pH. In both trials, the d‐methadone concentrations were lower than those of l‐methadone and the d‐EDDP levels were lower than those of L‐EDDP. For the case of a single intravenous bolus injection, the plasma concentration versus time profile of methadone enantiomers was analyzed with a two‐compartment pharmacokinetic model. l‐methadone showed a slower elimination rate constant, a lower body clearance, and a smaller steady‐state volume of distribution than d‐methadone. d‐methadone and d‐EDDP were eliminated faster than their respective l‐enantiomers. This is the first study that outlines that the disposition of racemic methadone administered to anesthetized equines is enantioselective.

Xylazine or detomidine in dairy calves: a comparison of clinically relevant pharmacodynamic parameters under sedation

OBJECTIVE

Chemical restraint in dairy calves is necessary to enable diagnostic and surgical procedures. It is unclear whether xylazine or detomidine differ with regard to desirable and unwanted effects.

MATERIAL AND METHODS

In a prospective randomized interventional study, 10 healthy Holstein-Friesian calves (age range 3-6 month) were sedated with either xylazine (0.1 mg/kg, Group X, n = 5) or detomidine (0.03 mg/kg, Group D, n = 5) intravenously, followed by butorphanol (0.1 mg/kg i. v.) in all animals. Characteristics of sedation and selected pharmacodynamic parameters were compared between groups using a non-parametric Mann-Whitney U test.

RESULTS

All calves (5/5) in Group X and (3/5) calves in Group D became laterally recumbent within 5 minutes. Two calves (40 %) in Group D remained standing and could not been positioned in lateral recumbency 15 minutes after initial administration of the sedation agents. Sedation scores, onset and duration of sedation did not differ between groups. Heart and respiratory rate decreased in both groups. Mean arterial pressure was with around 30 mmHg significantly higher in Group D (t₂₅, t₃₀, t₃₅, t₄₀ with p = 0.018, 0.036, 0.029 and 0.016, respectively). In Group X, glucose level (t₆₀) and packed cell volume (t₃₀) were significantly lower (p = 0.032 and 0.048, respectively).

CONCLUSION

and clinical relevance The xylazine-butorphanol combination provided reliable recumbent chemical restraint. With detomidine-butorphanol recumbency failed in some individuals, but a sufficient clinical sedation was achieved. Based on the limited monitoring used in this study, the side effects are of minor clinical relevance in healthy individuals.

Volumetric measurements of paranasal sinuses and examination of sinonasal communication in healthy Shetland ponies: anatomical and morphometric characteristics using computed tomography

Background

Despite clinical importance and frequent occurrence of sinus disease, little is known about the size of paranasal sinuses and their communication in ponies and small horses. To examine the shape and volume of the paranasal sinuses and evaluate the sinonasal communication, three-dimensional (3D) reconstructions of computed tomography (CT) datasets of 12 healthy adult Shetland ponies were performed and analysed. Linear measurements of head length and width were taken. Using semi-automatic segmentation, 3D-models of all sinus compartments were created. Volumetric measurement of the seven sinus compartments were conducted and statistical analysis was performed. Sinus volumes were compared between the left and right sinuses and the relation to age and head size was evaluated.

Results

Structure and shape of the paranasal sinus system in Shetland ponies was similar to that of large horses. All seven sinus compartments on each side of the head were identified (rostral maxillary sinus, ventral conchal sinus, caudal maxillary sinus, dorsal conchal sinus, middle conchal sinus, frontal sinus, sphenopalatine sinus). The existence of a bilateral cranial and a caudal system formed by a maxillary septum was visible in all 12 individuals. The volumetric sizes of the left and right sinuses did not differ significantly (p > 0.05). A positive correlation between the size of the paranasal sinuses and the head length was shown. A relation between sinus volumes and age could not be proved in adult ponies aged > six years. Communication between single sinus compartments was identified. Furthermore, communication with the nasal cavity over the nasomaxillary aperture (Apertura nasomaxillaris) and a common sinonasal channel (Canalis sinunasalis communis) as well as its splitting up into a rostral and a caudolateral channel could be seen. Examination of the sinonasal communication was challenging and only a descriptive evaluation was possible.

Conclusions

Our findings concerning the size, shape and volumetric dimensions of Shetland pony CT images could help improve CT interpretation of abnormal clinical cases as well as aiding clinicians to develop and select appropriate instruments for medical inspection and treatments.

An anatomical study of the dorsal and ventral nasal conchal bullae and middle nasal conchae in normal Shetland ponies: Computed tomographic anatomical and morphometric findings

Equine paranasal sinuses are susceptible to inflammation. Insufficient drainage through the nasal passages and meatus may lead to the accumulation of inspissated purulent discharge. Particularly in ponies, these anatomical structures are suspected to be relatively small. To date, there are no reports considering the morphology of nasal conchal bullae in small horse breeds such as Shetland ponies. The aim of the present study was to evaluate the size of the conchal bullae and the medial nasal conchae of Shetland ponies and their relation to the skull dimension using computed tomography. Reconstructed images of healthy adult heads of Shetland ponies were used. Linear skull measurements as well as two cranial indices of the head dimensions were taken. Length, width and height of the dorsal and ventral conchal bullae and the medial nasal conchae were measured in relation to the skull and compared with the data of skulls of large breed horses. The anatomical proportions of pony heads were characterized by a smaller cranial index and a greater nasal index than those of large breed horses. Shetland ponies showed a longer cranial length compared with the nasal length. Heads are consistently smaller, and the relationship of the bullae to the head length was also smaller than those measured in large breed horses. A negative correlation between the head and bullae size was found. In conclusion, this study suggests that Shetland ponies have distinguishing proportions of the head. These findings are relevant for clinical examination and surgical treatment of equine sinus disease in those breeds.

Pharmacokinetics and pharmacodynamics of l-methadone in isoflurane-anaesthetized and mechanically ventilated ponies

OBJECTIVE

To evaluate the pharmacokinetics and selected pharmacodynamic effects of a commercially available l-methadone/fenpipramide combination administered to isoflurane anaesthetized ponies.

STUDY DESIGN

Prospective single-group interventional study.

ANIMALS

A group of six healthy adult research ponies (four mares, two geldings).

METHODS

Ponies were sedated with intravenous (IV) detomidine (0.02 mg kg^-1) and butorphanol (0.01 mg kg^-1) for an unrelated study. Additional IV detomidine (0.004 mg kg^-1) was administered 85 minutes later, followed by induction of anaesthesia using IV diazepam (0.05 mg kg^-1) and ketamine (2.2 mg kg^-1). Anaesthesia was maintained with isoflurane in oxygen. Baseline readings were taken after 15 minutes of stable isoflurane anaesthesia. l-Methadone (0.25 mg kg^-1) with fenpipramide (0.0125 mg kg^-1) was then administered IV. Selected cardiorespiratory variables were recorded every 10 minutes and compared to baseline using the Wilcoxon signed-rank test. Adverse events were recorded. Arterial plasma samples for analysis of plasma concentrations and pharmacokinetics of l-methadone were collected throughout anaesthesia at predetermined time points. Data are shown as mean ± standard deviation or median and interquartile range (p < 0.05).

RESULTS

Plasma concentrations of l-methadone showed a rapid initial distribution phase followed by a slower elimination phase which is best described with a two-compartment model. The terminal half-life was 44.3 ± 18.0 minutes, volume of distribution 0.43 ± 0.12 L kg^-1 and plasma clearance 7.77 ± 1.98 mL minute^-1 kg^-1. Mean arterial blood pressure increased from 85 (±16) at baseline to 100 (±26) 10 minutes after l-methadone/fenpipramide administration (p = 0.031). Heart rate remained constant. In two ponies fasciculations occurred at different time points after l-methadone administration.

CONCLUSIONS AND CLINICAL RELEVANCE

Administration of a l-methadone/fenpipramide combination to isoflurane anaesthetized ponies led to a transient increase in blood pressure without concurrent increases in heart rate. Pharmacokinetics of l-methadone were similar to those reported for conscious horses administered racemic methadone.

The influence of equine body weight gain on inflammatory cytokine expressions of adipose tissue in response to endotoxin challenge

Background

Human obesity is linked with systemic inflammation. However, it is still controversial if equines produce more inflammatory cytokines with increasing body weight and if the production of those show breed type specific patterns. The main objective of this study was to determine if diet induced obesity is associated with increased inflammatory signatures in adipose tissue of equines and if a breed predisposition exists between ponies and horses. Additionally, we aimed to identify adipose tissue depot differences in inflammatory cytokine expression. Nineteen healthy, non-overweight and metabolically healthy equines received a hypercaloric diet for 2 years. Body weight, body condition score and cresty neck score were assessed weekly throughout the study. At three time points, insulin sensitivity was determined by a combined glucose-insulin test. Adipose tissue samples were collected from two intra-abdominal and two subcutaneous depots under general anesthesia at each time point after an endotoxin trigger. In the adipose tissue samples levels of CD68 mRNA (a marker of macrophage infiltration) and pro-inflammatory cytokine mRNA (IL-1β, IL-6 and TNFα) were analyzed with RT-qPCR. As markers of lipid metabolism mRNA levels of lipoprotein lipase (LPL) and fatty acid binding protein 4 (FABP4) were determined with RT-qPCR.

Results

CD68 mRNA levels increased with body weight gain in several adipose tissue (AT) depots (Wilcoxon signed rank test with Bonferroni correction; retroperitoneal AT horses: P = 0.023, mesocolonial AT horses: P = 0.023, subcutaneous tail head AT ponies: P = 0.015). In both abdominal depots CD68 mRNA levels were higher than in subcutaneous adipose tissue depots (Kruskal–Wallis-ANOVA with Bonferroni correction: P < 0.05). No breed related differences were found. Pro-inflammatory cytokine mRNA IL-1β, IL-6 and TNFα levels were higher in subcutaneous depots compared to abdominal depots after body weight gain. IL-1β, IL-6 and TNFα mRNA levels of mesocolon adipose tissue were higher in obese horses compared to obese ponies (Mann–Whitney-U test; IL-1β: P = 0.006; IL-6: P = 0.003; TNFα: P = 0.049). In general, horses had higher FABP4 and LPL mRNA levels compared to ponies in neck AT and tail AT at all time points.

Conclusion

Our findings suggest an increased invasion of macrophages in intra-abdominal adipose tissue with increasing body weight gain in equines in combination with a low dose endotoxin stimulus. This might predispose equines to obesity related comorbidities. In obese horses mesocolon adipose tissue showed higher inflammatory cytokine expression compared to obese ponies. Additionally, subcutaneous adipose tissue expressed more pro-inflammatory cytokines compared to intra-abdominal adipose tissue. Horses had higher FABP4 and LPL mRNA levels in selected AT depots which may indicate a higher fat storage capacity than in ponies. The differences in lipid storage might be associated with a higher susceptibility to obesity-related comorbidities in ponies in comparison to horses.

Mechanical Ventilation Strategies Targeting Different Magnitudes of Collapse and Tidal Recruitment in Porcine Acid Aspiration-Induced Lung Injury

Reducing ventilator-associated lung injury by individualized mechanical ventilation (MV) in patients with Acute Respiratory Distress Syndrome (ARDS) remains a matter of research. We randomly assigned 27 pigs with acid aspiration-induced ARDS to three different MV protocols for 24 h, targeting different magnitudes of collapse and tidal recruitment (collapse&TR): the ARDS-network (ARDSnet) group with low positive end-expiratory pressure (PEEP) protocol (permissive collapse&TR); the Open Lung Concept (OLC) group, PaO₂/FiO₂ >400 mmHg, indicating collapse&TR <10%; and the minimized collapse&TR monitored by Electrical Impedance Tomography (EIT) group, standard deviation of regional ventilation delay, SD_RVD. We analyzed cardiorespiratory parameters, computed tomography (CT), EIT, and post-mortem histology. Mean PEEP over post-randomization measurements was significantly lower in the ARDSnet group at 6.8 ± 1.0 cmH₂O compared to the EIT (21.1 ± 2.6 cmH₂O) and OLC (18.7 ± 3.2 cmH₂O) groups (general linear model (GLM) p < 0.001). Collapse&TR and SD_RVD, averaged over all post-randomization measurements, were significantly lower in the EIT and OLC groups than in the ARDSnet group (collapse p < 0.001, TR p = 0.006, SD_RVDp < 0.004). Global histological diffuse alveolar damage (DAD) scores in the ARDSnet group (10.1 ± 4.3) exceeded those in the EIT (8.4 ± 3.7) and OLC groups (6.3 ± 3.3) (p = 0.16). Sub-scores for edema and inflammation differed significantly (ANOVA p < 0.05). In a clinically realistic model of early ARDS with recruitable and nonrecruitable collapse, mechanical ventilation involving recruitment and high-PEEP reduced collapse&TR and resulted in improved hemodynamic and physiological conditions with a tendency to reduced histologic lung damage.

Effects of body weight gain on insulin and lipid metabolism in equines

The objective of this study was to illuminate the changes in serum NEFA concentrations during a combined glucose-insulin test (CGIT) and basal serum triacylglycerides (TGs) with increasing BW in Shetland ponies and warmblood horses. Therefore, basal blood samples were taken during fasting and a CGIT was performed in 19 healthy equines (10 Shetland ponies, 9 warmblood horses) (t0). After one (t1) and two (t2) year(s) of receiving 200% of their maintenance metabolizable energy requirement, procedures were repeated in the same equines. Sixteen of 19 equines had no signs of insulin dysregulation confirmed by CGIT. Basal plasma glucose concentrations increased in ponies (P = 0.001) when comparing t0 and t2, and basal serum insulin concentrations increased in ponies (P = 0.009) and horses (P = 0.024) from t0 to t2. Basal serum NEFA concentrations increased in ponies comparing t0 and t2 (P = 0.01). During CGIT, NEFA levels dropped until reaching a nadir and subsequently recovered until reaching basal concentrations. The minimum serum NEFA value did not change over time in ponies or horses. However, a strong correlation between basal serum NEFA concentrations and the percentage drop to minimum NEFA levels was found in ponies. Two of three equines (one horse and one pony) graded as insulin-dysregulated suffered from laminitis at t2. The serum NEFA concentrations of these animals had a delay in recovery of the minimum NEFA levels. Basal serum TG levels did not change with BW gain, and no breed differences were observed. In conclusion, serum NEFA concentrations are useful parameters during CGIT to detect insulin dysregulation in equines. Thus, further investigation should be focused on lipid metabolism during insulin dysregulation.

Impact of body weight gain on hepatic metabolism and hepatic inflammatory cytokines in comparison of Shetland pony geldings and Warmblood horse geldings

Background

Non-alcoholic fatty liver disease is known as determining part of human obesity. The impact of body weight (BW) gain on liver metabolism has not been extensively investigated yet.

Objectives

To investigate hepatic alterations caused by increasing BW in ponies and horses.

Animals

A total of 19 non-obese equines (10 Shetland ponies, geldings; nine Warmblood horses, geldings).

Methods

Animals received 200% of their metabolizable maintenance energy requirements for 2 years. Serum alkaline phosphatase, glutamate dehydrogenase (GLDH), aspartate aminotransferase (AST), and gamma-glutamyl transferase activities and bile acids were analyzed several times during 2 years of hypercaloric diet. Hepatic lipid content and hepatic levels of the interleukin (IL)-6, tumor necrosis factor α (TNFα), cluster of differentiation (CD) 68, IL-1β, lipoprotein lipase (LPL), fatty acid-binding protein 1, chemerin and nuclear factor-κB mRNAs were assessed at the start of the study and after 1 and 2 years of excess energy intake.

Results

The mean (±SD) BW gain recorded during 2 years of excess energy intake was 29.9 ± 19.4% for ponies and 17 ± 6.74% for horses. The hepatic lipid content was not profoundly affected by increasing BW. Levels of the IL-6, TNFα, CD68 and IL-1β mRNAs did not change during BW gain. Levels of the chemerin mRNA increased significantly in both breeds (ponies: P = 0.02; horses: P = 0.02) in response to BW gain. Significant differences in serum GLDH and AST activities, serum bile acid concentrations and hepatic levels of the LPL mRNA were observed between ponies and horses at the end of the study.

Conclusions

Chemerin might represent an interesting marker for future equine obesity research. Interestingly, steatosis caused by increasing BW may occur later in the development of obesity in equines than in humans. Additionally, the hepatic metabolism exhibits differences between ponies and horses, which may explain in part the greater susceptibility of ponies to obesity-associated metabolic dysregulations.

Enantioselective capillary electrophoresis for pharmacokinetic analysis of methadone and 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine in equines anesthetized with ketamine and isoflurane

An enantioselective assay for the determination of methadone and its main metabolite 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine in equine plasma based on capillary electrophoresis with highly sulfated γ-cyclodextrin as chiral selector and electrokinetic analyte injection is described. The assay is based on liquid/liquid extraction of the analytes at alkaline pH from 0.1 mL plasma followed by electrokinetic sample injection of the analytes from the extract across a buffer plug without chiral selector. Separation occurs cationically at normal polarity in a pH 3 phosphate buffer containing 0.16% (w/v) of highly sulfated γ-cyclodextrin. The developed assay is precise (intra- and interday RSD < 4% and < 7%, respectively), is capable to determine enantiomer levels of methadone and 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine in plasma down to 2.5 ng/mL, and was successfully applied to monitor enantiomer drug and metabolite levels in plasma of a pony that was anesthetized with racemic ketamine and isoflurane and received a bolus of racemic methadone and a bolus followed by constant rate infusion of racemic methadone. The data suggest that the assay is well suited for pharmacokinetic purposes.

The use of a combined sliding skin graft and a free labial mucocutaneous graft for reconstruction of the equine upper eyelid after full-thickness excision of a melanoma

A melanoma of the upper eyelid was resected in a gray warmblood gelding. A full functional eyelid could be obtained by completion a sliding skin graft with a free labial mucocutaneous graft transplantation to restore the mucocutaneous junction and to decrease the risk of postoperative trichiasis.

Comparison of incisional complications between skin closures using a simple continuous or intradermal pattern: a pilot study in horses undergoing ventral median celiotomy

Background

Development of incisional complications following ventral median celiotomy might depend on suture pattern for skin closure.

Methods

In this prospective study, 21 healthy male horses underwent celiotomy. Skin closure was either performed via a continuous percutaneous pattern (CO group; 5 warmbloods/5 ponies) or an intradermal pattern (ID group; 5 warmbloods/6 ponies). Follow-up examination of the incisional site included daily monitoring for edema, dehiscence, and drainage. Transcutaneous ultrasound was performed at Days 3, 6, and 10 as well as on Week 8 and 12 to evaluate size of edema and presence or absence of sinus formation, and hernia formation. Prevalence of incisional infection on base of positive microbiological analysis at any time up to Day 10 was evaluated and compared between ID and CO group. Furthermore, edema size was analysed by a linear mixed-effect model for group and time dependency.

Results

Observed incisional complications included edema (9/10 in CO, 10/11 in ID), suture sinus formation (2/10 in CO, 1/11 in ID), surgical site infection (2/10 in CO, 0/11 in ID), and incisional hernia (1/10 in CO, 0/11 in ID). The overall prevalence of incisional infection was 9.5% without significant differences between both groups (20% in CO, 0% in ID; p = 0.214). Edema size was not dependent on time or group (p = 0.545 and p = 0.627, respectively).

Discussion

CO and ID suture pattern are appropriate for skin closure following ventral median celiotomy in horses. None of the animals in the continuous ID group developed surgical site infections, even without the use of antibiotics.

Effects of mesenchymal stromal cells versus serum on tendon healing in a controlled experimental trial in an equine model

BACKGROUND

Mesenchymal stromal cells (MSC) have shown promising results in the treatment of tendinopathy in equine medicine, making this therapeutic approach seem favorable for translation to human medicine. Having demonstrated that MSC engraft within the tendon lesions after local injection in an equine model, we hypothesized that they would improve tendon healing superior to serum injection alone.

METHODS

Quadrilateral tendon lesions were induced in six horses by mechanical tissue disruption combined with collagenase application 3 weeks before treatment. Adipose-derived MSC suspended in serum or serum alone were then injected intralesionally. Clinical examinations, ultrasound and magnetic resonance imaging were performed over 24 weeks. Tendon biopsies for histological assessment were taken from the hindlimbs 3 weeks after treatment. Horses were sacrificed after 24 weeks and forelimb tendons were subjected to macroscopic and histological examination as well as analysis of musculoskeletal marker expression.

RESULTS

Tendons injected with MSC showed a transient increase in inflammation and lesion size, as indicated by clinical and imaging parameters between week 3 and 6 (p < 0.05). Thereafter, symptoms decreased in both groups and, except that in MSC-treated tendons, mean lesion signal intensity as seen in T2w magnetic resonance imaging and cellularity as seen in the histology (p < 0.05) were lower, no major differences could be found at week 24.

CONCLUSIONS

These data suggest that MSC have influenced the inflammatory reaction in a way not described in tendinopathy studies before. However, at the endpoint of the current study, 24 weeks after treatment, no distinct improvement was observed in MSC-treated tendons compared to the serum-injected controls. Future studies are necessary to elucidate whether and under which conditions MSC are beneficial for tendon healing before translation into human medicine.

Incisional complications following ventral median coeliotomy in horses. Does suturing of the peritoneum reduce the risk?

OBJECTIVE

Despite advances in surgical technique in abdominal surgery, incisional complications are frequently reported following ventral midline laparotomy in horses. The aim of this study was to determine the incidence of incisional complications at our clinic and to identify possible risk factors. Furthermore, we investigated whether suturing the peritoneum leads to a reduction of incisional complications.

MATERIAL AND METHODS

In this retrospective study, records of patients of the Large Animal Clinic for Surgery of the University of Leipzig from January 2010 to December 2015 were analysed. Horses with ventral midline laparotomy following colic were included in the study. Evaluated parameters comprised breed, sex, age of the horse, localisation of the colic disease, invasiveness of the surgical intervention, duration of general anaesthesia, suture pattern of the laparotomy wound and postoperative fever or leukopenia. Incisional complications included suture dehiscence, exudation from the wound and incisional hernia formation. Wound oedema formation was evaluated separately.

RESULTS

Incisional complications in the form of exudation and suture dehiscence occurred in 8.9% (18/202) of the horses. Postoperative hernia formation was observed in 5.2% (9/173) of patients. Breed, sex, localisation of the colic disease, invasiveness of the surgical intervention, duration of general anaesthesia and postoperative leukopenia did not influence the frequency of incisional complications. An increased risk of incisional complications was found in horses aged 20 years and older (odds ratio [OR] 17.90), in animals with postoperative fever (OR 7.48) and in horses with unsutured peritoneum (OR 7.68). Furthermore, patients with moderate and severe wound oedema displayed a significantly increased risk for the development of incisional complications.

CONCLUSION AND CLINICAL RELEVANCE

Suture pattern is the only risk factor that can be directly influenced by the surgeon. Because a peritoneal suture is associated with a decreased risk of incisional complications, it should be standard practice when closing a laparotomy wound in the horse.

Gene expression of tendon markers in mesenchymal stromal cells derived from different sources

Background

Multipotent mesenchymal stromal cells (MSC) can be recovered from a variety of tissues in the body. Yet, their functional properties were shown to vary depending on tissue origin. While MSC have emerged as a favoured cell type for tendon regenerative therapies, very little is known about the influence of the MSC source on their properties relevant to tendon regeneration.

The aim of this study was to assess and compare the expression of tendon extracellular matrix proteins and tendon differentiation markers in MSC derived from different sources as well as in native tendon tissue. MSC isolated from equine bone marrow, adipose tissue, umbilical cord tissue, umbilical cord blood and tendon tissue were characterized and then subjected to mRNA analysis by real-time polymerase chain reaction.

Results

MSC derived from adipose tissue displayed the highest expression of collagen 1A2, collagen 3A1 and decorin compared to MSC from all other sources and native tendon tissue (p < 0.01). Tenascin-C and scleraxis expressions were highest in MSC derived from cord blood compared to MSC derived from other sources, though both tenascin-C and scleraxis were expressed at significantly lower levels in all MSC compared to native tendon tissue (p < 0.01).

Conclusions

These findings demonstrate that the MSC source impacts the cell properties relevant to tendon regeneration. Adipose derived MSC might be superior regarding their potential to positively influence tendon matrix reorganization.

Electronic supplementary material

The online version of this article (doi:10.1186/1756-0500-7-826) contains supplementary material, which is available to authorized users.

Basic science and clinical application of stem cells in veterinary medicine

Stem cells play an important role in veterinary medicine in different ways. Currently several stem cell therapies for animal patients are being developed and some, like the treatment of equine tendinopathies with mesenchymal stem cells (MSCs), have already successfully entered the market. Moreover, animal models are widely used to study the properties and potential of stem cells for possible future applications in human medicine. Therefore, in the young and emerging field of stem cell research, human and veterinary medicine are intrinsically tied to one another. Many of the pioneering innovations in the field of stem cell research are achieved by cooperating teams of human and veterinary medical scientists.Embryonic stem (ES) cell research, for instance, is mainly performed in animals. Key feature of ES cells is their potential to contribute to any tissue type of the body (Reed and Johnson, J Cell Physiol 215:329-336, 2008). ES cells are capable of self-renewal and thus have the inherent potential for exceptionally prolonged culture (up to 1-2 years). So far, ES cells have been recovered and maintained from non-human primate, mouse (Fortier, Vet Surg 34:415-423, 2005) and horse blastocysts (Guest and Allen, Stem Cells Dev 16:789-796, 2007). In addition, bovine ES cells have been grown in primary culture and there are several reports of ES cells derived from mink, rat, rabbit, chicken and pigs (Fortier, Vet Surg 34:415-423, 2005). However, clinical applications of ES cells are not possible yet, due to their in vivo teratogenic degeneration. The potential to form a teratoma consisting of tissues from all three germ lines even serves as a definitive in vivo test for ES cells.Stem cells obtained from any postnatal organism are defined as adult stem cells. Adult haematopoietic and MSCs, which can easily be recovered from extra embryonic or adult tissues, possess a more limited plasticity than their embryonic counterparts (Reed and Johnson, J Cell Physiol 215:329-336, 2008). It is believed that these stem cells serve as cell source to maintain tissue and organ mass during normal cell turnover in adult individuals. Therefore, the focus of attention in veterinary science is currently drawn to adult stem cells and their potential in regenerative medicine. Also experience gained from the treatment of animal patients provides valuable information for human medicine and serves as precursor to future stem cell use in human medicine.Compared to human medicine, haematopoietic stem cells only play a minor role in veterinary medicine because medical conditions requiring myeloablative chemotherapy followed by haematopoietic stem cell induced recovery of the immune system are relatively rare and usually not being treated for monetary as well as animal welfare reasons.In contrast, regenerative medicine utilising MSCs for the treatment of acute injuries as well as chronic disorders is gradually turning into clinical routine. Therefore, MSCs from either extra embryonic or adult tissues are in the focus of attention in veterinary medicine and research. Hence the purpose of this chapter is to offer an overview on basic science and clinical application of MSCs in veterinary medicine.

Isolation of equine multipotent mesenchymal stromal cells by enzymatic tissue digestion or explant technique: comparison of cellular properties

BACKGROUND

The treatment of tendon lesions with multipotent mesenchymal stromal cells (MSCs) is widely used in equine medicine. Cell sources of MSCs include bone marrow, as well as solid tissues such as adipose tissue. MSCs can be isolated from these solid tissues either by enzymatic digestion or by explant technique. However, the different preparation techniques may potentially influence the properties of the isolated MSCs. Therefore, the aim of this study was to investigate and compare the effects of these two different methods used to isolate MSCs from solid tissues.Equine adipose tissue, tendon and umbilical cord matrix served as solid tissue sources of MSCs with different stiffness and density. Subsequent to tissue harvest, MSCs were isolated either by enzymatic digestion with collagenase or by explant technique. Cell yield, growth, differentiation potential and tendon marker expression were analysed.

RESULTS

At first passage, the MSC yield was significantly higher in enzymatically digested tissue samples than in explanted tissue samples, despite a shorter period of time in primary culture. Further analysis of cell proliferation, migration and differentiation revealed no significant differences between MSCs isolated by enzymatic digestion and MSCs isolated by explant technique. Interestingly, analysis of gene expression of tendon markers revealed a significantly higher expression level of scleraxis in MSCs isolated by enzymatic digestion.

CONCLUSIONS

Both isolation techniques are feasible methods for successful isolation of MSCs from solid tissues, with no major effects on cellular proliferation, migration or differentiation characteristics. However, higher MSC yields were achieved in a shorter period of time by collagenase digestion, which is advantageous for the therapeutic use of MSCs. Moreover, based on the higher level of expression of scleraxis in MSCs isolated by enzymatic digestion, these cells might be a better choice when attempting tendon regeneration.

Growth and differentiation characteristics of equine mesenchymal stromal cells derived from different sources

Multipotent mesenchymal stromal cells (MSCs) are a promising therapeutic tool for the treatment of equine tendon and other musculoskeletal injuries. While bone marrow is considered the 'gold standard' source of these cells, various other tissues contain MSCs with potentially useful features. The aim of this study was to compare clinically relevant characteristics of MSCs derived from bone marrow, umbilical cord blood and tissue and from adipose tissue and tendon. Cell yield, proliferation, migration, tendon marker expression and differentiation into adipocytes, chondrocytes and osteoblasts was assessed, quantified and compared. MSC numbers obtained from adipose, tendon or umbilical cord tissues were 222-fold higher than those obtained from bone marrow or cord blood. Cells derived from tendon and adipose tissues exhibited most rapid proliferation. Osteogenic differentiation was most prominent in MSCs derived from bone marrow, and was weak in MSCs derived from umbilical cord blood and tissue. In contrast, the highest levels of chondrogenic differentiation were observed in MSCs derived from these sources. Collagen 1A2 expression was highest in adipose- and tendon-derived MSCs, while scleraxis expression was highest in cord blood- and in tendon-derived MSCs. The findings indicate that MSCs from different sources display significantly diverse properties that may impact on their therapeutic application.

Directed N-terminal elongation of unprotected peptides catalyzed by cathepsin C in water

N-terminal chain extension of unprotected amino acid amides and peptides with dipeptide amides using Cathepsin C (dipeptidyl aminopeptidase I, EC 3.4.14.1)-mediated reverse proteolysis in water was studied. Taking Pro-X-NH2 as the acyl donor, the sensitivity of the kinetically controlled peptide, coupling to pH value, temperature, acetonitrile addition, and nucleophile type were investigated. Basic or hydrophobic amino acids as the alpha-amino-N-nucleophile proved to be much more prone to catalyzed bond formation than their neutral, hydrophilic, or negatively charged analogues. In a preparative run a pentapeptide was obtained with 83% yield by directed and regioselective coupling of ProTrpNH2 with LysLeuPheNH2 catalyzed by Cathepsin C in aqueous buffer.