Systemic,Renal, and Colonic Effects of Intravenous and Enteral Rehydration in Horses

Background

Intravenous (IV) and intragastric (IG) administration of fluid therapy are commonly used in equine practice, but there are limited data on the systemic, renal, and enteric effects.

Hypothesis

IV fluid administration will increase intestinal and fecal hydration in a rate‐dependent manner after hypertonic dehydration, but will be associated with significant urinary water and electrolyte loss. Equivalent volumes of IG plain water will result in comparatively greater intestinal hydration with less renal loss.

Animals

Six Thoroughbred geldings.

Methods

Experimental study. 6 by 6 Latin square design investigating constant rate IV administration at 50, 100, and 150 mL/kg/d over 24 hours in horses dehydrated by water deprivation. Equivalent volumes of IG plain water were administered by 4 bolus doses over 24 hours.

Results

Water deprivation resulted in a significant decrease in the percentage of fecal water, and increases in serum and urine osmolality. IV fluids administered at 100 and 150 mL/kg/d restored fecal hydration, but increasing the rate from 100 to 150 mL/kg/d did not confer any additional intestinal benefit, but did result in significantly greater urine production and sodium loss. Equivalent 24‐hour volumes of plain water resulted in greater intestinal water and less urine output.

Conclusions and Clinical Importance

IV polyionic isotonic fluids can be used to hydrate intestinal contents in situations where enteral fluids are impractical. IV fluids administered at three times maintenance are no more efficacious and might be associated with adverse physiological findings after withdrawal. Bolus dosing of IG water can be used to restore intestinal water with minimal adverse effects.     

Prospective evaluation of the safety of compounded bulk material L‐asparaginase in dogs with lymphoma

Use of compounded L‐asparaginase became routine in veterinary oncology when manufacturing of Elspar^® was discontinued in 2012. The objective of this study was to evaluate the safety of compounded L‐asparaginase (CLASP, KRS Global Biotechnology, Boca Raton, FL, USA) in comparison with Elspar^® (Lundbeck LLC, Deerfield, IL, USA). In addition, we documented the response to CLASP in combination with a corticosteroid in this population of dogs with lymphoma. Dogs were prospectively treated with 10 000 IU/m² CLASP or Elspar^® subcutaneously. Corticosteroids were administered concurrently. Adverse events (AE) were assessed according to the Veterinary Cooperative Oncology Group Common Terminology Criteria for Adverse Events v1.1 (VCOG‐CTCAE). Response was recorded. Seventy‐three dogs received 75 treatments (CLASP, n = 47; Elspar^®, n = 28). No AE were attributed to CLASP. Grade I and II AE probably or possibly related to treatment were observed following two Elspar^® treatments. The overall response rate to the combination of CLASP and a corticosteroid was 80% (24% CR and 56% PR). In combination with a steroid, the compounded L‐asparaginase evaluated in this study is safe and demonstrates activity against canine lymphoma. In the face of the discontinuation of Elspar^®, veterinarians should seek compounded LASP products that have been tested for activity, purity, and sterility.     

Equine chlamydiosis—An emerging infectious disease requiring a one health surveillance approach

Psittacosis is a rare but potentially fatal zoonosis caused by Chlamydia psittaci, an organism that is typically associated with bird contact. However C. psittaci is capable of infecting other non‐avian hosts, such as horses, sheep, cattle and goats. Stud staff and veterinarians have significant exposure to parturient animals and reproductive materials in their routine work. To investigate the zoonotic potential associated with the emergence of C. psittaci as an abortifacient agent in horses, we established a programme of joint human and animal surveillance in a sentinel horse‐breeding region in Australia. This programme comprised cross‐notification of equine cases to public health agencies, and active follow‐up of known human contacts, including stud workers, foaling staff, veterinarians and laboratory staff. We identified no confirmed cases of acute psittacosis despite intensive surveillance and testing of heavily exposed contacts; however, further work in the area is needed.     

Survey of equine castration techniques,preferences and outcomes among Australian veterinarians

Objectives

(1) To collect the perceptions of veterinarians performing equine castrations in Australia on techniques, preferences and outcomes, (2) to investigate veterinarian use and experience with the Henderson castrating instrument and (3) to investigate potential associations between demographics, castration methods and techniques, and complications.

Design

Online survey of members of the Australian Veterinary Association’s Special Interest Group, Equine Veterinarians Australia (EVA).

Methods

A link to the survey was included in the EVA e‐newsletter and practices on the EVA website were contacted by telephone and follow‐up email. Fisher’s exact test was used to determine associations between ligation and complications. A generalised linear model with a negative binomial family was used to determine associations between count response variables and categorical independent variables.

Results

Responses were obtained from 138 veterinarians (response rate, 13.1%) who performed 5330 castrations over 12 months. Castrations were most commonly performed in the field, on anaesthetised horses, using emasculators, via an open approach and without ligation of the spermatic cord. Estimated complications after use of emasculators were swelling (25%), haemorrhage (5%) and infection (5%). The Henderson instrument was used by approximately 10% of respondents and its use for castration was associated with fewer reports of postoperative swelling compared with emasculators (P = 0.002). Rates of evisceration with the Henderson and emasculator methods were comparable (0.43% and 0.9%, respectively).

Conclusion

Castration preferences varied widely among survey participants. Reported complication types and rates were comparable to those reported previously in other countries. Perceptions that the Henderson instrument was associated with less swelling should be investigated further via a prospective controlled investigation.     

Occupational swine exposure and Hepatitis E virus,Leptospira, Ascaris suum seropositivity and MRSA colonization in Austrian veterinarians, 2017–2018—A cross‐sectional study

We investigated the prevalence of Hepatitis E Virus (HEV), Leptospira and Ascaris suum (A. suum) seropositivity, and of nasal methicillin‐resistant Staphylococcus aureus (MRSA) colonization among Austrian practising veterinarians, and assessed the association with occupational swine livestock exposure. The 261 participants completed a questionnaire on demographics, intensity of occupational swine livestock contact and glove use during handling animals and their secretions. Participants' blood samples were tested for HEV, Leptospira and A. suum seropositivity and nasal swabs cultured for MRSA. We compared swine veterinarians (defined as >3 swine livestock visits/week) to non‐swine veterinarians (≤3 swine livestock visits/week) with regard to the outcomes through calculating prevalence ratio (PR) and 95% confidence interval (CI). Furthermore, the relationship between occupational swine livestock contact and the study outcomes was examined by age (</≥55 years) and glove usage. The prevalence of nasal MRSA colonization was 13.4% (95% CI: 9.3–17.6), of HEV seropositivity 20.8% (95% CI: 15.8–25.7) and A. suum seropositivity 44% (95% CI: 37.7–50.2). The highest anti‐leptospiral antibodies titres were 1:200 (L. hebdomadis) and 1:100 (L. autumnalis, L. caicola) found in three non‐swine veterinarians. Compared to non‐swine veterinarians, swine veterinarians were 1.9 (95% CI: 1.0–3.4) and 1.5 (95%CI: 1.0–2.3) times more likely HEV seropositive and A. suum seropositive, respectively, and 4.8 (95%CI: 2.5; 9.3) times more likely nasally colonized with MRSA. Among glove‐using veterinarians, occupational swine contact was no longer a determinant for HEV seropositivity (PR 1.6; 95% CI: 0.8–2.9). Similar was found for A. suum seropositivity, which was no longer associated with occupational swine livestock contact in the subgroup of glove using, ≥55‐year‐old veterinarians (PR: 1.07; 95% CI: 0.4–3.3). Our findings indicate that >3 occupational swine livestock visits per week is associated with HEV and A. suum seropositivity and nasal MRSA colonization and that glove use may play a putative preventive role in acquiring HEV and A. suum. Further analytical epidemiological studies have to prove the causality of these associations.     

Bartonella Seroepidemiology in Dogs from North America, 2008–2014

Background

Improved understanding of Bartonella species seroepidemiology in dogs may aid clinical decision making and enhance current understanding of naturally occurring arthropod vector transmission of this pathogen.

Objectives

To identify demographic groups in which Bartonella exposure may be more likely, describe spatiotemporal variations in Bartonella seroreactivity, and examine co‐exposures to other canine vector‐borne diseases (CVBD).

Animals

A total of 15,451 serology specimens from dogs in North America were submitted to the North Carolina State University, College of Veterinary Medicine Vector Borne Disease Diagnostic Laboratory between January 1, 2008, and December 31, 2014.

Methods

Bartonella henselae, Bartonella koehlerae, and Bartonella vinsonii subspecies berkhoffii indirect fluorescent antibody (IFA) serology results, as well as results from a commercial assay kit screening for Dirofilaria immitis antigen and Ehrlichia species, Anaplasma phagocytophilum, and Borrelia burgdorferi antibodies, and Ehrlichia canis, Babesia canis, Babesia gibsoni, and Rickettsia species IFA results were reviewed retrospectively.

Results

Overall, 3.26% of dogs were Bartonella spp. seroreactive; B. henselae (2.13%) and B. koehlerae (2.39%) were detected more frequently than B. vinsonii subsp. berkhoffii (1.42%, P < 0.0001). Intact males had higher seroreactivity (5.04%) than neutered males (2.87%, P < 0.0001) or intact or spayed females (3.22%, P = 0.0003). Mixed breed dogs had higher seroreactivity (4.45%) than purebred dogs (3.02%, P = 0.0002). There was no trend in seasonal seroreactivity; geographic patterns supported broad distribution of exposure, and co‐exposure with other CVBD was common.

Conclusions and Clinical Importance

Bartonella spp. exposure was documented throughout North America and at any time of year. Male intact dogs, mixed breed dogs, and dogs exposed to other CVBD have higher seroreactivity to multiple Bartonella species.     

Cartilage-derived retinoic acid-sensitive protein in equine synovial fluid from healthy and diseased joints

Reasons for performing study: More sensitive and specific diagnostic methods for early detection of changes in the joint cartilage are needed. Cartilage‐derived retinoic acid‐sensitive protein (CD‐RAP) is a potential marker of cartilage synthesis and regeneration. This is the first study on equine CD‐RAP. Objectives: To evaluate the ability of a commercially available human sandwich ELISA assay to detect equine CD‐RAP in synovial fluid from healthy and diseased joints. Methods: Synovial fluid was collected from 28 horses with no signs of joint disease and from 5 with induced inflammatory arthritis. CD‐RAP concentrations were measured using a human CD‐RAP ELISA. Intra‐ and interassay imprecision of the assay were evaluated by multiple measurements on pools of equine synovial fluid. Assay inaccuracy was determined by linearity under dilution. Results: The assay showed moderate to large intra‐ and interassay variation when applied to equine synovial fluid. Equine CD‐RAP was detected in synovial fluid from healthy horses ranged at 8.2–52 ng/ml. Repeated arthrocentesis (after injection of isotonic saline), age, joint or gender did not significantly affect CD‐RAP concentrations. Twelve hours after intra‐articular injection of lipopolysaccharide, concentrations of CD‐RAP were significantly lower than after injection of isotonic saline and remained significantly lower until the end of the study at 144 h. Conclusion and potential relevance: The assay is suitable for longitudinal monitoring of CD‐RAP concentration in individual horses. Disease significantly influenced CD‐RAP levels. Similar to previous results obtained in man, CD‐RAP seems to be a marker of cartilage synthesis and/or regeneration in horses.     

Effect of Heat‐treatment on Accuracy of Infrared Spectroscopy and Digital and Optical Brix Refractometers for Measuring Immunoglobulin G Concentration in Bovine Colostrum

Background

Heat‐treatment of colostrum is a method developed to reduce calf exposure to pathogens. Infrared (IR) spectroscopy and Brix refractometers can be used for measuring colostral IgG concentration and assessing colostrum quality.

Objectives

To determine the impact of heat‐treatment on accuracy of IR spectroscopy and Brix refractometers for measuring colostral IgG concentration and assessing colostrum quality before and after heat‐treatment.

Animals

A total of 60 Holstein dairy cows on 8 commercial dairy farms.

Methods

A cross‐sectional study was designed to determine the effect of heat‐treatment at 60°C and 63°C each for 30 and 60 minutes duration on colostral IgG concentration measured by the reference radial immunodiffusion (RID) assay, IR spectroscopy, and digital and optical refractometers.

Results

Colostrum IgG concentration significantly decreased after heat‐treatment at 63°C for 30 or 60 minutes as measured by RID, but the IgG values remained unchanged when measured by IR spectroscopy and refractometers. The lowest correlation coefficient found between IR spectroscopy (r = 0.70) and RID results was in colostrum heat‐treated at 63°C for 60 minutes. For digital (r = 0.48) and optical (r = 0.50) refractometers, the lowest correlation coefficient was at 63°C for 30 minutes when compared to RID. The accuracy of the IR spectroscopy, digital and optical Brix refractometers was decreased from 91.7 to 80%, 81.7 to 45%, and 80 to 45%, respectively, when colostrum heat‐treated at 63°C for 60 minutes.

Conclusions and Clinical Importance

Radial immunodiffusion, IR spectroscopy, and Brix refractometers exhibit utility for measuring IgG concentration when colostrum heat‐treated at 60°C but does not detect decrease IgG concentrations when heat‐treated at 63°C.     

Case series: Persistent dorsal displacement of the soft palate in eight horses

Persistent dorsal displacement of the soft palate (pDDSP) is a relatively rare equine disorder. This case series reports histories and clinical findings in 8 cases of pDDSP, and outcome after treatment of concurrent epiglottic entrapment (n = 3), laryngeal tie‐forward (n = 6) ± laser staphylectomy (n = 2), and/or sectioning of mucosa ventral to the epiglottis and the hyoepiglotticus muscles (n = 2). Four of 6 horses that underwent tie‐forward ± laser staphylectomy had complete resolution of pDDSP and returned to their previous level of work, as did one horse that had a subepiglottic releasing incision. Correction of concurrent epiglottic entrapment in 3 horses with pDDSP did not result in resolution of pDDSP in any case. Previous laryngeal surgery including laryngoplasty and ventriculocordectomy appear to be risk factors for the development of pDDSP.     

Cardiovascular and pulmonary effects of hetastarch plus hypertonic saline solutions during experimental endotoxemia in anesthetized horses

BACKGROUND: Small volume resuscitation has been advocated as a beneficial therapy for endotoxemia in horses but this therapy has not been investigated in a prospective manner. The objective of this study was to determine the cardiopulmonary effects of small-volume resuscitation using hypertonic saline solution (HSS) plus Hetastarch (HES) during experimental endotoxemia in anesthetized horses. HYPOTHESIS: Treatment of horses with induced endotoxemia using HES-HSS does not alter the response of various cardiopulmonary indices when compared to treatment with either small- or large-volume isotonic crystalloid solutions. ANIMALS: Eighteen healthy horses were randomly assigned to 1 of 3 groups. Anesthesia was maintained with halothane. Endotoxemia was induced by administering 50 microg/kg of Escherichia coli endotoxin IV. The horses were treated over 30 minutes with 15 mL/kg of balanced polyionic crystalloid solution (control), 60 mL/kg of balanced polyionic crystalloid solution (ISO), or 5 mL/kg of HSS followed by 10 mL/kg of HES (HSS-HES). METHODS: Prospective randomized trial. RESULTS: Cardiac output (CO) after endotoxin infusion increased significantly (P < .05) from baseline in all groups, whereas mean central venous pressure increased significantly (P < .05) in the ISO group only. Mean pulmonary artery pressure increased from baseline (P < .05) in horses treated with isotonic fluids and HSS-HES. There was no effect of treatment with HSS-HES on CO, systemic vascular resistance (SVR), mean arterial pressure, blood lactate concentrations, or arterial oxygenation. CONCLUSIONS AND CLINICAL IMPORTANCE: The use of HSS-HES failed to ameliorate the deleterious hemodynamic responses associated with endotoxemia in horses. The clinical value of this treatment in horses with endotoxemia remains unconfirmed.     

Pharmacokinetics of chloramphenicol base in horses and comparison to compounded formulations

Chloramphenicol is commonly used in horses; however, there are no studies evaluating the pharmacokinetics of veterinary canine‐approved tablets. Studies using different formulations and earlier analytical techniques led to concerns over low bioavailability in horses. Safety concerns about human health have led many veterinarians to prescribe compounded formulations that are already in suspension or paste form. The objective of this study was to evaluate the pharmacokinetics of approved chloramphenicol tablets in horses, along with compounded preparations. The hypothesis was that chloramphenicol has low absorption and a short half‐life in horses leading to low serum concentrations and that compounded preparations have lower relative bioavailability. Seven horses were administered chloramphenicol tablets (50 mg/kg orally). In a crossover design, they were administered two compounded preparations to compare all three formulations at the same dose (50 mg/kg). C_max was 5.25 ± 4.07 μg/ml at 4.89 hr, 4.96 ± 3.31 μg/ml at 4.14 hr, and 3.84 ± 2.96 μg/ml at 4.39 hr for the tablets, paste, and suspension, respectively. Elimination half‐life was 2.65 ± 0.75, 3.47 ± 1.47, and 4.36 ± 4.54 hr for tablets, paste, and suspension, respectively. The AUC_0→∞ was 17.93 ± 7.69, 16.25 ± 1.85, and 14.00 ± 5.47 hr*μg/ml for the tablets, compounded paste, and compounded suspension, respectively. Relative bioavailability of compounded suspension and paste was 78.1% and 90.6%. C_max after administration of all formulations did not reach the recommended MIC target of 8 μg/ml set by the Clinical Laboratory Standards Institute (CLSI) for most bacteria. Multidose studies are warranted, but the low serum concentrations suggest that bacteria with MIC values lower than CLSI recommendations should be targeted in adult horses.     

Ruminal phytate degradation of maize grain and rapeseed meal in vitro and as affected by phytate content in donor animal diets and inorganic phosphorus in the buffer

The ruminal disappearance of phytate phosphorus (InsP₆‐P) from maize grain and rapeseed meal (RSM) was determined in two in vitro studies. In experiment 1, two diets differing in phosphorus (P) and InsP₆‐P concentration were fed to the donor animals of rumen fluid (diet HP: 0.49% P in dry matter, diet LP: 0.29% P). Maize grain and RSM were incubated in a rumen fluid/saliva mixture for 3, 6, 12 and 24 h. In experiment 2, a diet similar to diet HP was fed, and the rumen fluid was mixed with artificial saliva containing 120 mg inorganic P/l (Pi) or no inorganic P (P0). Maize grain and RSM were incubated with either buffer for 3, 6, 12 and 24 h. Total P (tP) and InsP₆ concentration were analysed in the fermenter fluids and feed residues. The disappearance of InsP₆‐P from maize was completed after 12 h of incubation in both experiments. From RSM, 93% (diet LP) and 99% (diet HP) of the InsP₆‐P in experiment 1 and 80% (Pi) and 89% (P0) in experiment 2 had disappeared after 24 h of incubation. InsP₆‐P disappearance was higher when diet HP was fed (maize: 3 and 6 h; RSM: 6 and 24 h of incubation) and when rumen fluid was mixed with buffer P0 (maize: 6 h; RSM: 12 and 24 h of incubation). InsP₆‐P concentration in the fermenter fluids was higher for maize, but no accumulation of InsP₆‐P occurred, indicating a prompt degradation of soluble InsP₆. These results confirmed the capability of rumen micro‐organisms to efficiently degrade InsP₆. However, differences between the feedstuffs and diet composition as well as the presence of inorganic P in the in vitro system influenced the degradation process. Further studies are required to understand how these factors affect InsP₆ degradation and their respective relevance in vivo.     

Feline Musculoskeletal Pain Index: Responsiveness and Testing of Criterion Validity

Background

Progress in establishing if therapies provide relief to cats with degenerative joint disease (DJD)‐associated pain is hampered by a lack of validated owner‐administered assessment methods.

Hypothesis

That an appropriately developed subjective owner‐completed instrument (Feline Musculoskeletal Pain Index‐FMPI) to assess DJD‐associated impairment would have responsiveness and criterion validity.

Animals

Twenty‐five client‐owned cats with DJD‐associated pain.

Methods

FMPI responsiveness (ability to detect the effect of an analgesic treatment) and validity (correlation with an objective measure) were explored through a stratified, randomized, double blinded, placebo‐controlled, crossover 10‐week clinical study. Meloxicam was administered to effect pain relief. A linear mixed model, backward stepwise regression, and Pearson correlations were used to assess responsiveness and criterion validity with the assumption that the NSAID would increase activity.

Results

Positive responses of cats to placebo (P = .0001) and meloxicam treatment (P = .0004) were detected; however, the instrument did not detect any difference between placebo and meloxicam (linear mixed model), even for the high impairment cases. Percent meloxicam target dose administered, temperament, and total baseline FMPI score were covariates that most affected FMPI scores. Controlling for significant covariates, most positive effects were seen for placebo treatment. Positive treatment effects on activity were detected, but only for the cases designated as most highly impaired.

Conclusions and Clinical Importance

Neither responsiveness nor criterion validity were detected by the inclusion criteria for cases in this study. The data suggest that further work is indicated to understand factors affecting activity in cats to optimize inclusion criteria.     

Bacterial Contamination of Stethoscope Chest Pieces and the Effect of Daily Cleaning

Background

Stethoscopes are a potential source of nosocomial infection for hospitalized humans, a phenomenon not previously studied in companion animals.

Objectives

To determine if daily cleaning of stethoscope chest pieces reduces bacterial contamination between cleanings.

Animals

Client‐owned dogs and cats.

Methods

Prospective observational study. In phase 1, bacterial cultures were obtained from the chest pieces of 10 participant stethoscopes once weekly for 3 weeks. In phase 2, stethoscopes were cleaned daily and 2 culture samples were obtained once weekly, immediately before and after cleaning with 70% isopropyl alcohol, for 3 weeks.

Results

Daily cleaning eliminated bacteria immediately after each cleaning (P = .004), but did not reduce the rate of positive cultures obtained before cleaning in phase 2. Cultures were positive for 20/30 (67%) samples during phase 1 and 18/30 (60%) obtained before daily cleaning during phase 2. Recovered organisms included normal skin flora, agents of opportunistic infections, and potential pathogens. The only genus that was repeatedly recovered from the same stethoscope for 2 or more consecutive weeks was Bacillus sp.

Conclusions and Clinical Importance

Daily cleaning was highly effective at removing bacteria, but provided no reduction in precleaning contamination. Cleaning stethoscopes after use on dogs or cats infected with pathogenic bacteria and before use on immunocompromised animals should be considered.     

Usefulness of an auditory aid to improve chest compression rate accuracy during cardiopulmonary resuscitation

Objective

To assess compression rate accuracy among veterinarians and registered veterinary nurses (RVNs) without and with an audible aid.

Design

Prospective study with use of a canine CPR manikin.

Setting

Small animal teaching hospital.

Subjects

Thirty-six participants (20 veterinarians and 16 RVNs).

Interventions

Each participant completed the first 2-minute cycle of chest compressions without an auditory aid on a canine CPR manikin. Each participant was then randomized to 1 of 3 auditory aid groups (Group B: Bee Gees “Stayin’ Alive”; Group Q: Queen “Another One Bites the Dust”; or Group M: traditional metronome) and then completed a second 2-minute cycle of chest compressions with the instruction to synchronize their compression rate with the beat of the auditory aid. An accurate chest compression rate was defined as obtaining a rate between 100 and 120 compressions per minute (cpm).

Measurements and Main Results

Median number of compressions administered by participants during Cycle 1 for the first minute was 111 (range 88–140) and for the second minute was 107 (range 80–151), with 25 of 36 (69%) participants obtaining an accurate chest compression rate. Median number of compressions administered during Cycle 2 for the first minute was 110 (range 76–125) and for the second minute was 110 (range 72–125), with 34 of 36 participants (94%) obtaining an accurate chest compression rate. Participants were more likely to obtain an accurate chest compression rate when an auditory aid was present compared to without (McNemar's test; P = 0.013). Subgroup analysis suggested the auditory aid was beneficial in Groups Q and M but not Group B (Kruskal–Wallis with Dunn's post hoc testing; P = 0.014, P = 0.0455, and P = 0.5637, respectively).

Conclusions

An auditory aid was associated with improved chest compression rate accuracy. However, as the auditory aid was not beneficial for Group B participants, our findings suggest that some auditory aids are more helpful than others.     

Effect of Continuous Digital Hypothermia on Lamellar Inflammatory Signaling When Applied at a Clinically‐Relevant Timepoint in the Oligofructose Laminitis Model

Background

Although continuous digital hypothermia (CDH) protects lamellae from injury in the oligofructose (OF) model of sepsis‐related laminitis (SRL), conflicting results exist from these studies regarding effects of CDH on lamellar inflammatory events.

Hypothesis/Objectives

To determine the effect of CDH on lamellar inflammatory events in normal and OF‐treated horses when instituted at a clinically relevant time point (onset of clinical signs of sepsis in this model).

Animals

Standardbred geldings (n = 15) aged 3–11 years were used.

Methods

In a randomized, controlled discovery study, animals were administered either OF (OF group, n = 8) or water (CON group, n = 8) by nasogastric tube and CDH was initiated in one forelimb (ICE) 12 hours later. Lamellar tissue samples were collected 24 hours after initiation of CDH (ICE and ambient [AMB] forelimbs). Lamellar mRNA concentrations of inflammatory mediators and lamellar leukocyte numbers were assessed using qPCR and immunohistochemistry, respectively; values from four sample groups (CON AMB, OF AMB, CON ICE, and OF ICE) were analyzed using mixed model linear regression.

Results

Although lamellar mRNA concentrations of multiple inflammatory mediators (IL‐1β, IL‐6, CXCL1, MCP2, COX‐2) were increased after OF administration (OF AMB group versus CON AMB; P < 0.05), only 2 inflammatory mediators (IL‐6 and COX‐2) and lamellar leukocyte numbers were decreased with CDH (OF ICE versus OF AMB; P < 0.05).

Conclusions and Clinical Importance

Continuous digital hypothermia initiated at a time point similar to that commonly used clinically (clinical onset of sepsis) resulted in a more focused inhibition of inflammatory signaling.     

Australian veterinarians who work with horses: attitudes to work and career

OBJECTIVE: To describe the attitudes to their work and career of those Australian veterinarians who work with horses. METHOD: Questionnaires were mailed to 866 veterinarians who had been identified as working with horses, and 87% were completed and returned. Data were entered onto Excel spreadsheets, and analysed using the SAS System for Windows. RESULTS: The main attractions of veterinary work with horses were the horses themselves and the equine industries, but working outdoors and with rewarding clients, and the satisfaction of successful outcomes were attractions for many. The list of disadvantages was longer, and included unreasonable and disagreeable clients as well as those who provided inadequate facilities, could not control their horses or did not care for them. The physical demands and risks of injury, the amount of time required, low rates of return and difficulties in collecting payment, were other major disadvantages. Some mentioned concerns about litigation, unethical behaviour, and recruiting and retaining veterinarians competent with horses. For many in mixed practice, the difficulties in affording modern equipment, and of developing and maintaining their own competence with horses, was a real concern. More than three-quarters of the respondents reported that their careers had lived up to expectations and that they would become veterinarians again; 70% of equine veterinarians would become an equine veterinarian again. Almost all (93%) of the respondents were either very glad, or 'generally glad though with some misgivings' that they had done the veterinary course. Older veterinarians reported suffering less stress, and being more content with their career, than younger colleagues. CONCLUSIONS: The advantages of doing veterinary work with horses outweigh the disadvantages for most veterinarians, especially those well advanced in their careers.     

Using the indicator amino acid oxidation technique to study threonine requirements in horses receiving a predominantly forage diet

Threonine has been reported to be the second limiting amino acid in typical equine diets, but its actual requirement has not been determined in horses. To evaluate amino acid metabolism and requirements, the indicator amino acid oxidation (IAAO) method has been successfully used in other species. The objective of this research was to estimate threonine requirements in mature horses fed timothy hay and concentrate in 4:1 ratio using the IAAO method. Six Thoroughbred mares (579.9 ± 46.7 kg) received each of 6 levels of threonine intake, 41, 51, 61, 70, 80 and 89 mg/kg BW/day, in a randomly determined order. Each study period was 7‐day long, and on day 6, blood samples were collected before and 90 min after feeding to measure amino acid concentrations using HPLC. On day 7, horses underwent IAAO procedures, which included a 2‐hr primed, constant intravenous infusion of [¹³C]sodium bicarbonate to measure total CO₂ production and a 4‐hr primed, constant oral administration of [1‐¹³C]phenylalanine to estimate phenylalanine oxidation to CO₂. Blood and breath samples were collected to measure blood [¹³C]phenylalanine, using GC‐MS analysis and breath ¹³CO₂ enrichment, using an infrared isotope analyser. Increasing threonine intake levels did not affect plasma phenylalanine oxidation by the ANOVA test (p > 0.05) but resulted in a linear decrease in phenylalanine oxidation (p = 0.04) without a breakpoint by the orthogonal linear contrast. This study is the first attempt to evaluate threonine requirements in horses by the IAAO method; however, threonine requirements are still unknown in mature horses at this time.     

Comparison of continuous infusion with intermittent bolus administration of cefotaxime on blood and cavity fluid drug concentrations in neonatal foals

Hewson, J., Johnson, R., Arroyo, L. G., Diaz‐Mendez, A., Ruiz‐López, J. A., Gu, Y., del Castillo, J. R. E. Comparison of continuous infusion with intermittent bolus administration of cefotaxime on blood and cavity fluid drug concentrations in neonatal foals. J. vet. Pharmacol. Therap.  36 , 68–77. Healthy neonatal foals were treated with cefotaxime by bolus (40 mg/kg IV q6h for 12 doses; n = 10) or by infusion (loading dose of 40 mg/kg IV followed by continuous infusion of a total daily dose of 160 mg/kg per 24 h for 3 days; n = 5). Population pharmacokinetics was determined, and concentrations in cavity fluids were measured at steady state (72 h). Highest measured serum drug concentration in the bolus group was 88.09 μg/mL and minimum drug concentration (C_min) was 0.78 μg/mL at 6‐h postadministration (immediately before each next dose), whereas infusion resulted in a steady‐state concentration of 16.10 μg/mL in the infusion group. Mean cefotaxime concentration in joint fluid at 72 h was higher (P = 0.051) in the infusion group (5.02 μg/mL) compared to the bolus group (0.78 μg/mL). Drug concentration in CSF at 72 h was not different between groups (P = 0.243) and was substantially lower than serum concentrations in either group. Insufficient data on pulmonary epithelial lining fluid were available to compare the methods of administration for cefotaxime in this cavity fluid. Results support continuous drug infusion over bolus dosing in the treatment for neonatal foal septicemia to optimize time that cefotaxime concentration exceeds the minimum inhibitory concentration of common equine pathogens.     

Di-tri-octahedral smectite for the prevention of post-operative diarrhea in equids with surgical disease of the large intestine: Results of a randomized clinical trial

The aim of this study was to evaluate the effects of a commercially available di-tri-octahedral (DTO) smectite product on clinical signs and prevalence of post-operative diarrhea in horses with colic associated with disease of the large intestine. Sixty-seven horses with surgical disease of the large intestine were randomly assigned to be treated with DTO smectite (n = 37; 0.5 kg via nasogastric intubation every 24 h for 3 days post-operatively) or a placebo (n = 30). The effect of treatment on fecal scores and clinical and hematological parameters, including heart rate, mucous membrane color, temperature, total white blood cell count, total neutrophil count and total plasma protein values, were determined.Horses treated with DTO smectite had a significant reduction in the prevalence of post-operative diarrhea (10.8%), compared with controls (41.4%). A significant improvement in mucous membrane color was observed 72 h post-operatively in horses receiving treatment, compared with placebo. Administration of DTO smectite to colic patients with disease of the large intestine reduced the occurrence of diarrhea in the early post-operative period.