Christopher B. Riley

Regional differences in wound oxygenation during normal healing in an equine model of cutaneous fibroproliferative disorder

Wound repair in horse limbs is often complicated by the development of exuberant granulation tissue (EGT) and excessive scarring while body wounds tend to repair uneventfully. EGT resembles the human keloid. While the events leading to keloid formation are not fully elucidated, tissue hypoxia has been proposed as a major contributing factor. The objective of this study was to investigate tissue oxygen saturation in healing full‐thickness wounds created on the horse limb and body, using near‐infrared spectroscopy. Spectroscopic reflectance data were collected from both anatomic sites at specific times following wounding. The oxygen saturation values of limb wounds were significantly inferior to those of body wounds during the early period of healing, indicating a temporary, relative state of hypoxia in the former during the inflammatory phase of repair. Horses present a weak, persistent inflammatory response to wounding, especially at the limb level. The relative hypoxia present acutely in limb wounds of horses may promote a feeble yet prolonged inflammatory response, which could interfere with and retard the subsequent phases of healing. Ongoing low‐grade inflammation in horse wounds is accompanied by up‐regulation of various inflammatory and profibrotic mediators, which might ultimately promote the development of fibroproliferative disorders such as EGT.

Skin temperature during cutaneous wound healing in an equine model of cutaneous fibroproliferative disorder: kinetics and anatomic-site differences

OBJECTIVE To map skin temperature kinetics, and by extension skin blood flow throughout normal or abnormal repair of full-thickness cutaneous wounds created on the horse body and limb, using infrared thermography. STUDY DESIGN Experimental. ANIMALS Standardbreds (n = 6), aged 3-4 years. METHODS Three cutaneous wounds were created on the dorsolateral surface of each metacarpus and on the lateral thoracic wall. Thoracic skin wounds and those on 1 randomly chosen forelimb healed by second intention without a bandage, whereas contralateral limb wounds were bandaged to induce formation of exuberant granulation tissue (EGT). Thermal data were collected from all planned wound sites before the surgical procedure (baseline), and at 24, 48, 96 hours, 1, 2, and 4 weeks after wounding. Data were analyzed using repeated measures ANOVA and a priori contrasts submitted to Bonferroni sequential correction. Level of significance was P < .05. RESULTS Cutaneous wound temperature (CWT) increased temporally from preoperative period to week 1 postwounding, independently of anatomic location (P < .0001). CWT of limb wounds was significantly less than that of body wounds throughout healing (P < .01). CWT of limb wounds managed with bandages and developing EGT was significantly less than that of unbandaged limb wounds, which did not develop EGT (P ≤ .01). CONCLUSIONS CWT varied with anatomic location and throughout healing. CWT of wounds developing EGT was significantly less than that of wounds without EGT.

Optoacoustic characterization of prostate cancer in an in vivo transgenic murine model

Abstract. Optoacoustic (OA) imaging was employed to distinguish normal from neoplastic tissues in a transgenic murine model of prostate cancer. OA images of five tumor-bearing mice and five age-matched controls across a 14  mm×14  mm region of interest (ROI) on the lower abdomen were acquired using a reverse-mode OA imaging system (Seno Medical Instruments Inc., San Antonio, Texas). Neoplastic prostate tissue was identified based on the OA signal amplitude in combination with spectral analysis of the OA radio frequency (RF) data. Integration of the signal amplitude images was performed to construct two-dimensional images of the ROI. The prostate tumors generated higher amplitude signals than those of the surrounding tissues, with contrast ratios ranging from 31 to 36 dB. The RF spectrum analysis showed significant differences between the tumor and the control mice. The midband fit was higher by 5 dB (62%), the intercept higher by 4 dB (57%) and the spectral slope higher by 0.4  dB/MHz (50%) for neoplastic prostate tissue compared to normal tissues in the control mice. The results demonstrate that OA offers high contrast imaging of prostate cancer in vivo.

Comparison of the effects of xylazine bolus versus medetomidine constant rate infusion on cardiopulmonary function and depth of anesthesia in horses anesthetized with isoflurane

OBJECTIVE To compare the effects of xylazine bolus versus medetomidine constant rate infusion (MCRI) on cardiopulmonary function and depth of anesthesia in dorsally recumbent, spontaneously breathing, isoflurane-anesthetized horses. DESIGN Prospective, randomized crossover study. ANIMALS 10 healthy adult Standardbreds. PROCEDURES Horses were premedicated with xylazine or medetomidine IV. Anesthesia was induced with diazepam and ketamine and maintained with isoflurane for 150 minutes. For the xylazine treatment, end-tidal isoflurane concentration was maintained at 1.7%, and xylazine (0.2 mg/kg [0.09 mg/lb], IV) was administered as a bolus at the end of anesthesia. For the MCRI treatment, end-tidal isoflurane concentration was maintained at 1.4%, and medetomidine (0.005 mg/kg/h [0.0023 mg/lb/h], IV) was infused throughout anesthesia. Physiologic data (ie, heart rate, respiratory rate, rectal temperature, bispectral index, and electromyographic values) were compared between treatments with xylazine bolus versus MCRI. RESULTS Heart rate was lower, but mean arterial blood pressure was higher from 20 to 40 minutes with MCRI treatment, compared with conventional treatment with xylazine. Respiratory rate and rectal temperature were greater with MCRI treatment. Bispectral index was lower with MCRI treatment from 80 to 150 minutes, and electromyographic values were lower with MCRI treatment from 30 to 150 minutes. CONCLUSIONS AND CLINICAL RELEVANCE In isoflurane-anesthetized horses, premedication with medetomidine followed by administration of medetomidine as a constant rate infusion resulted in decreased heart rate, higher arterial blood pressure from 20 through 40 minutes after induction of anesthesia, and better preserved body temperature, compared with conventional treatment with xylazine. Greater depth of anesthesia and muscle relaxation were seen with MCRI treatment, despite the lower isoflurane concentration.

Optoacoustic signal amplitude and frequency spectrum analysis laser heated bovine liver ex vivo

Optoacoustic imaging is being investigated as a potential tool for monitoring the onset and progression of laser thermal therapy. In this study OA images were acquired from ex vivo bovine liver using a reverse-mode OA imaging system consisting of a pulsed laser operating at 775 nm, and an 8 element annular array ultrasound transducer. LTT was performed with an 810 nm laser at 4 W for five minutes. OA signals were acquired for two minutes prior to, five minutes during, and seven minutes post treatment at a rate of 2 Hz. Treatment induced effects were identified based on the OA signal amplitude in combination with spectral analysis of the OA radio frequency (RF) data. The OA signal amplitude was compared with the measured tissue temperatures. Spectrum analysis commonly performed on ultrasound backscatter RF data, which calculate the spectral midband fit, slope, and intercept of the data was used to quantify the changes in the photoacoustic RF signal. The spectral midband fit and intercept increased on average 11 dB and 10 dB respectively. The amplitude of the OA signals increased during treatment on average 350%. However, posttreatment, the response varied. The results of this study support our hypothesis that LTT causes detectable changes in the amplitude and frequency components of OA signals. Both of these parameters may provide independent information about tissue state. These results demonstrate the potential of OA detection for monitoring LTT.

Exploration of attenuated total reflectance mid-infrared spectroscopy and multivariate calibration to measure immunoglobulin G in human sera

Immunoglobulin G (IgG) is crucial for the protection of the host from invasive pathogens. Due to its importance for human health, tools that enable the monitoring of IgG levels are highly desired. Consequently there is a need for methods to determine the IgG concentration that are simple, rapid, and inexpensive. This work explored the potential of attenuated total reflectance (ATR) infrared spectroscopy as a method to determine IgG concentrations in human serum samples. Venous blood samples were collected from adults and children, and from the umbilical cord of newborns. The serum was harvested and tested using ATR infrared spectroscopy. Partial least squares (PLS) regression provided the basis to develop the new analytical methods. Three PLS calibrations were determined: one for the combined set of the venous and umbilical cord serum samples, the second for only the umbilical cord samples, and the third for only the venous samples. The number of PLS factors was chosen by critical evaluation of Monte Carlo-based cross validation results. The predictive performance for each PLS calibration was evaluated using the Pearson correlation coefficient, scatter plot and Bland-Altman plot, and percent deviations for independent prediction sets. The repeatability was evaluated by standard deviation and relative standard deviation. The results showed that ATR infrared spectroscopy is potentially a simple, quick, and inexpensive method to measure IgG concentrations in human serum samples. The results also showed that it is possible to build a united calibration curve for the umbilical cord and the venous samples.

Measurement of serum immunoglobulin G in dairy cattle using Fourier-transform infrared spectroscopy: A reagent free approach

Simple, rapid and cost-effective methods are sought for measuring immunoglobulin G (IgG) concentrations in bovine serum, which can be applied for diagnosis of failure of transfer of passive immunity (FTPI). The aim of the present study was to investigate the potential use of Fourier-transform infrared (FTIR) spectroscopy, with partial least squares (PLS) regression, to measure IgG concentrations in bovine serum. Serum samples collected from calves and adult cows were tested in parallel by radial immunodiffusion (RID) assay and FTIR spectroscopy. The sample IgG concentrations obtained by the RID method were linked to pre-processed spectra and divided into two sets: a combined set and a test set. The combined set was used for building a calibration model, while the test set was used to assess the predictive ability of the calibration model, resulting in a root mean squared error of prediction (RMSEP) of 307.5 mg/dL. The concordance correlations between the IgG measured by RID and predicted by FTIR spectroscopy were 0.96 and 0.93 for the combined and test data sets, respectively. Analysis of the data using the Bland-Altman method did not show any evidence of systematic bias between FTIR spectroscopy and RID methods for measurement of IgG. The clinical applicability of FTIR spectroscopy for diagnosis of FTPI was evaluated using the entire data set and showed a sensitivity of 0.91 and specificity of 0.96, using RID as the reference standard. The FTIR spectroscopy method, described in the present study, demonstrates potential as a rapid and reagent-free tool for quantification of IgG in bovine serum, as an aid to diagnosis of FTPI in calves.

Use of Fourier-Transform Infrared Spectroscopy to Quantify Immunoglobulin G Concentrations in Alpaca Serum

Background Rapid, economical, and quantitative assays for measurement of camelid serum immunoglobulin G (IgG) are limited. In camelids, failure of transfer of maternal immunoglobulins has a reported prevalence of up to 20.5%. An accurate method for quantifying serum IgG concentrations is required. Objective To develop an infrared spectroscopy‐based assay for measurement of alpaca serum IgG and compare its performance to the reference standard radial immunodiffusion (RID) assay. Animals One hundred and seventy‐five privately owned, healthy alpacas. Methods Eighty‐two serum samples were collected as convenience samples during routine herd visits whereas 93 samples were recruited from a separate study. Serum IgG concentrations were determined by RID assays and midinfrared spectra were collected for each sample. Fifty samples were set aside as the test set and the remaining 125 training samples were employed to build a calibration model using partial least squares (PLS) regression with Monte Carlo cross validation to determine the optimum number of PLS factors. The predictive performance of the calibration model was evaluated by the test set. Results Correlation coefficients for the IR‐based assay were 0.93 and 0.87, respectively, for the entire data set and test set. Sensitivity in the diagnosis of failure of transfer of passive immunity (FTPI) ([IgG] <1,000 mg/dL) was 71.4% and specificity was 100% for the IR‐based method (test set) as gauged relative to the RID reference method assay. Conclusions and Clinical Importance This study indicated that infrared spectroscopy, in combination with chemometrics, is an effective method for measurement of IgG in alpaca serum.

A cross-sectional survey on wounds in horses in New Zealand.

Abstract AIM: To determine the frequency and type of skin wounds encountered by New Zealand veterinarians in their equine patients, the duration and estimated costs of treatment as well as the expected outcomes for these wounds. METHODS: An online survey was sent to all veterinarians registered with the New Zealand Equine Veterinary Association. The survey comprised questions on the location and experience of respondents, the number of wound-related cases in relation to the total equine caseload, the type and anatomical location of wounds treated, the frequency, duration and costs of treatments, the outcome of wound treatment and an estimate of the most common causes of death or euthanasia in their equine patients. RESULTS: The survey response rate was 110/262 (41.9%). The median number of equine cases seen by respondents was 20 (interquartile range (IQR) 6–60) per month; of these, five (IQR 2–10) were wound related. Wounds ranked third after lameness and respiratory disease for the relative frequency with which respondents encountered them. Of 102 respondents 59 (58%) reported that their clients frequently treated wounds incurred by their horse without consulting a veterinarian. Wounds on the distal limb, whether involving only the skin or also deeper structures, were reported by 86/101 (85%) respondents as the most frequently encountered. Wounds in this location also incurred the longest treatment period and were the most prone to develop complications. Finally, wounds ranked second, after colic, as the most common cause of death/euthanasia in the veterinary respondents’ equine patients. CONCLUSIONS: The data obtained via the survey indicate that skin wounds, particularly on the distal limb, are a common occurrence in horses in New Zealand and, when they involve structures underlying the skin, are costly and time-consuming to manage and may lead to decreased performance, retirement or euthanasia. Consequently, we recommend that more effort be devoted to the education of equine veterinarians and owners, and that appropriate research funds be allocated to help improve patient outcomes.

A cross-sectional study of horse-related injuries in veterinary and animal science students at an Australian university

Specific estimates of the risk of horse-related injury (HRI) to university students enrolled in veterinary and animal sciences have not been reported. This study aimed to determine the risk of student HRI during their university education, the nature and management of such injuries. A retrospective questionnaire solicited demographic information, data on students’ equine experience prior to and during their educational programs, and on HRI during their program of study. Of 260 respondents, 22 (8.5%) reported HRI (27 incidents). Including concurrent injuries the most commonly injured body parts were the foot or ankle (nine of 32 injures), the upper leg or knee (eight of 32), and hands (three of 32). Trampling and being kicked by a hind limb were each associated with 30.4% of HRI, and 13% with being bitten. Bruising (91.3% of respondents) and an open wound (17.4%) were most commonly described. No treatment occurred for 60.9% of incidents; professional medical treatment was not sought for the remainder. Most incidents (56.5%) occurred during program-related work experience placements. Although injury rates and severity were modest, a proactive approach to injury prevention and reporting is recommended for students required to handle horses as part of their education. Student accident and injury data should be monitored to ensure effective evaluation of risk-reduction initiatives. The risk and nature of university student horse-related injury (HRI) was studied. Of 260 students, 22 (8.5%) reported HRI (27 incidents). Including multiple injuries, reports described involvement of the foot or ankle (nine of 32 injures), upper leg or knee (eight of 32), and hands (three of 32). Trampling (30.4%) and being kicked (30.4%) accounted for most HRI. The injuries were usually bruising (91.3%) or an open wound (17.4%). Most (60.9%) injuries were untreated; professional medical treatment was not sought for the rest. Most incidents (56.5%) occurred during program-related off-campus work experiences. A proactive approach to injury prevention is recommended for students handling horses.