Publications by authors named "Gregg M Griffenhagen"

7 Publications

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Comparison of equine synovial sepsis rate following intrasynovial injection in ambulatory versus hospital settings.

Equine Vet J 2021 Jun 11. Epub 2021 Jun 11.

Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO, USA.

Background: Frequency of synovial sepsis in horses following intrasynovial injection has been reported, but not compared with respect to the environment in which the injection was performed.

Objectives: To describe occurrence of synovial sepsis following intrasynovial injections performed in ambulatory vs hospital settings.

Study Design: Retrospective cohort study.

Methods: Records from the Colorado State University were evaluated (2014-2018) and horses receiving intrasynovial injections were identified. Patients presenting for septic synovial structures were excluded. Patient signalment, primary supervising service, medications injected, location (field/hospital), whether synovial sepsis resulted, and at what time sepsis was recognised were recorded. Logistic regression was used to estimate the contributions of covariates to the occurrence of synovial sepsis following injection.

Results: During the study period, 3866 intrasynovial injections were performed in 1112 horses during 1623 sessions, with 643/1623 sessions performed in the field. The most frequently used medications were hyaluronate (846/1623, 52.1%), triamcinolone acetonide (780 /1623, 48.1%) and amikacin sulfate (684/1623, 42.1%). Four horses developed synovial sepsis (0.2% sessions, 0.1% synovial structures); 3/4 were injected in the field, 2/4 received antibiotics with the injection. The frequency of septic synovitis was 10.4 cases per 10 000 injections, or 1 in 967 injections. All horses recovered following synovial lavage and antibiotic therapy. Performing injections in the field (P = .2) or without antibiotics (P = .7) did not alter the risk of synovial sepsis.

Main Limitations: Limitations include the retrospective nature of data collection and low rate of infection overall, which prohibited evaluation of individual medication regimes as factors associated with resultant infection.

Conclusions: The frequency of synovial sepsis in this population of horses was not higher when injections were performed in the field or without concurrent antibiotic administration. These data may help to inform practitioners and clients regarding the relative potential risk of complications following intrasynovial medication in different environmental settings.
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http://dx.doi.org/10.1111/evj.13485DOI Listing
June 2021

Evaluation of Intra-Articular Amikacin Administration in an Equine Non-inflammatory Joint Model to Identify Effective Bactericidal Concentrations While Minimizing Cytotoxicity.

Front Vet Sci 2021 21;8:676774. Epub 2021 May 21.

Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO, United States.

Septic arthritis causes significant morbidity and mortality in veterinary and human clinical practice and is increasingly complicated by multidrug-resistant infections. Intra-articular (IA) antibiotic administration achieves high local drug concentrations but is considered off-label usage, and appropriate doses have not been defined. Using an equine joint model, we investigated the effects of amikacin injected at three different doses (500, 125, and 31.25 mg) on the immune and cartilage responses in tibiotarsal joints. Synovial fluid (SF) was sampled at multiple time points over 24 h, the cell counts determined, and amikacin concentrations measured by liquid chromatography-mass spectrometry. Cytokine concentrations and collagen degradation products in SF were measured by ELISA and multiplex immunoassays. The mean amikacin concentrations in SF were greater than or equal to the minimum inhibitory concentration (MIC) (0.004 mg/ml) for most common equine joint pathogens at all time points tested to 24 h for all three amikacin doses evaluated. The inflammatory cytokines tumor necrosis factor-alpha (TNF-α) and interleukin-1 beta (IL-1β) increased significantly in SF in the highest amikacin dose group, despite the fact that increases in SF cell counts were not observed. Similarly, the biomarkers of cartilage type II collagen cleavage (C2C and C12C) were increased in SF following amikacin injection. Mechanistically, we further demonstrated using studies that chondrocytes and synoviocytes killed by exposure to amikacin underwent apoptotic cell death and were phagocytosed by macrophages in a non-inflammatory process resembling efferocytosis. Neutrophils and T cells were susceptible to amikacin cytotoxicity at clinically relevant doses, which may result in blunting of cellular inflammatory responses in SF and account for the lack of increase in total nucleated cell counts following amikacin injection. In summary, decisions on whether to inject cytotoxic antibiotics such as aminoglycosides intra-articularly and what doses to use should take into account the potential harm that antibiotics may cause and consider lower doses than those previously reported in equine practice.
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http://dx.doi.org/10.3389/fvets.2021.676774DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8175670PMC
May 2021

Toll-like receptor activation of equine mesenchymal stromal cells to enhance antibacterial activity and immunomodulatory cytokine secretion.

Vet Surg 2021 May 2;50(4):858-871. Epub 2021 Apr 2.

Department of Clinical Sciences, College of Veterinary Medicine, Colorado State University, Colorado, USA.

Objective: To evaluate effects of Toll-like and nucleotide-binding oligomerization domain (NOD)-like receptor (TLR, NLR) ligand stimulation of equine mesenchymal stromal cells (MSCs) on antibacterial and immunomodulatory properties in vitro.

Study Design: Controlled laboratory study.

Sample Population: Equine bone-marrow-derived MSCs (three horses).

Methods: MSCs were stimulated with TLR (polyinosinic:polycytidylic acid [pIC] and lipopolysaccharide [LPS]) and NLR agonists (γ-d-Glu-mDAP [IE-DAP]) for 2 h, and plated at 1 × 10 cells/well 24 h. MSC-conditioned media (MSC-CM) were collected and assessed for antimicrobial peptide cathelicidin/LL-37 production, bactericidal action against multidrug-resistant planktonic and biofilm Staphylococcus aureus and neutrophil phagocytosis. Bacterial growth was measured by plating bacteria and counting viable colonies, reading culture absorbance, and live-dead staining with confocal microscopy imaging. Following initial comparison of activating stimuli, TLR3-agonist pIC protocols (cell density during activation and plating, culture time, %serum) were further optimized for bactericidal activity and secretion of interleukin-8 (IL-8), monocyte-chemoattractant-protein (MCP-1), and cathelicidin/LL37.

Results: MSCs stimulation with pIC (p = .004) and IE-DAP (p = .03) promoted increased bactericidal activity, evidenced by reduced viable planktonic colony counts. PIC stimulation (2 × 10 cells/ml, 2 h, 10 μg/ml) further suppressed biofilm formation (p = .001), enhanced neutrophil bacterial phagocytosis (p = .009), increased MCP-1 secretion (p < .0001), and enhanced cathelicidin/LL-37 production, which was apparent when serum concentration in media was reduced to 1% (p = .01) and 2.5% (p = .05).

Conclusion: TLR-3 pIC MSCs activation was most effective to enhance antibacterial and cytokine responses, which were affected by serum reduction.

Clinical Significance: In vitro TLR-3 activation of equine MSCs tested here may be a strategy to improve antibacterial properties of MSCs to treat antibiotic-resistant infections.
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http://dx.doi.org/10.1111/vsu.13628DOI Listing
May 2021

Retrospective evaluation of association between perioperative antimicrobial protocol and complications following elective equine synovial endoscopy.

Vet Med Sci 2021 May 17;7(3):609-620. Epub 2021 Feb 17.

Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, CO, USA.

Background: Prophylactic perioperative antimicrobial protocols in equine synovial endoscopy have been described but not compared with respect to post-operative outcomes and complications. Increasing antimicrobial resistance in equine practice and interest in promoting judicious use of antimicrobials has prompted reevaluation of drug selection and dosing strategies.

Objectives: To determine the frequency of and compare post-operative complications following elective synovial endoscopy between horses receiving different perioperative antimicrobial protocols.

Methods: Records from the Colorado State University Veterinary Teaching Hospital were evaluated (2014-2018) and equine patients undergoing elective synovial endoscopy were identified. Patients undergoing endoscopy for sepsis or internal fixation were excluded. Patient signalment, clinician, joint and limb involved, perioperative antimicrobial regimen, number endoscopic portals and closure technique, and post-operative complications including incidence of joint infection were recorded. Generalized linear models were used to estimate the odds of post-operative complications.

Results: Elective synovial endoscopies of 516 horses in 537 procedures evaluating 761 synovial structures were performed. No horses developed post-operative septic synovitis. Administration of post-operative antimicrobials, type used and patient sex were all significantly associated with increased risk of complications, which were predominantly gastrointestinal-related. Complication rates in horses receiving a single preoperative dose of cefazolin were lower than in horses receiving potassium penicillin, gentamicin or multiple doses. Complication rates were lower in females compared to castrated or intact males. Other factors evaluated (breed, age, surgeon, anaesthesia duration or hospitalization, joint/limb operated, number endoscopic portals) were not associated with increased risk of complications post-operatively in this case population.

Conclusions: Prophylactic perioperative antimicrobial protocols in equine practice deserve periodic reconsideration due to increased antimicrobial resistance. Prolonged antimicrobial usage beyond the time of surgery was unnecessary to prevent septic synovitis following synovial endoscopy in this case population and was furthermore associated with an increased risk of gastrointestinal complications.
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http://dx.doi.org/10.1002/vms3.447DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8136966PMC
May 2021

Laparoscopic ovariohysterectomy in goats.

J Am Vet Med Assoc 2019 Jan;254(2):275-281

OBJECTIVE To describe a minimally invasive 3-portal laparoscopic approach for elective ovariohysterectomy and the outcome of that procedure in a population of goats. DESIGN Descriptive clinical study. ANIMALS 16 healthy client-owned goats. PROCEDURES Food but not water was withheld from all goats for 24 hours before the procedure. Goats were anesthetized and positioned in dorsal recumbency. Three laparoscopic portals were created in the caudoventral portion of the abdomen, and the abdomen was insufflated to a maximum pressure of 10 mm Hg. A blunt-tip vessel sealer and divider device was used to transect the left and right mesovarium and mesometrium and uterus, and the resected tissue was removed from the abdomen. After hemostasis was verified, the portals were closed in a routine manner and anesthesia was discontinued. Goats were discharged from the hospital 24 hours after the procedure, and owners were contacted by telephone or email to obtain short- and long-term follow-up information by use of standardized questions. RESULTS All procedures were performed by a surgeon and assistant surgeon. The procedure was not complex and was easily learned. No intraoperative complications were reported, and only 1 goat required rescue analgesia post-operatively. No other postoperative complications were recorded. Median surgery time was 43 minutes (range, 20 to 65 minutes). All owners were satisfied with the outcome of the procedure, and several perceived that the procedure improved goat behavior. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that laparoscopic ovariohysterectomy was a viable alternative for elective sterilization of female goats.
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http://dx.doi.org/10.2460/javma.254.2.275DOI Listing
January 2019

AAFP Feline Anesthesia Guidelines.

J Feline Med Surg 2018 07;20(7):602-634

Colorado State University Veterinary Teaching Hospital, 300 W Drake Rd, Fort Collins, CO 80523, USA.

Aim: The overarching purpose of the AAFP Anesthesia Guidelines (hereafter referred to as the 'Guidelines') is to make anesthesia and sedation safer for the feline patient. Scope and accessibility: It is noteworthy that these are the first exclusively feline anesthesia guidelines authored by an expert panel, making them particularly useful as an extensively referenced, practical resource for veterinary practice teams. Because much of the key content is presented in tabular or visual format, the Guidelines have a high level of accessibility and convenience that invites regular usage. While the recommendations in the Guidelines focus primarily on client-owned cats, the content is also applicable to community-sourced animals with an unknown medical history.
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http://dx.doi.org/10.1177/1098612X18781391DOI Listing
July 2018

Pharmacokinetics and pharmacodynamics of propofol with or without 2% benzyl alcohol following a single induction dose administered intravenously in cats.

Vet Anaesth Analg 2015 Sep 20;42(5):472-83. Epub 2014 Oct 20.

Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO, USA.

Objective: To compare the pharmacokinetics and pharmacodynamics of propofol with or without 2% benzyl alcohol administered intravenously (IV) as a single induction dose in cats.

Study Design: Prospective experimental study.

Animals: Six healthy adult cats, three female intact, three male castrated, weighing 4.8 ± 1.8 kg.

Methods: Cats received 8 mg kg(-1) IV of propofol (P) or propofol with 2% benzyl alcohol (P28) using a randomized crossover design. Venous blood samples were collected at predetermined time points to 24 hours after drug administration to determine drug plasma concentrations. Physiologic and behavioral variables were also recorded. Propofol and benzyl alcohol concentrations were determined using high pressure liquid chromatography with fluorescence detection. Pharmacokinetic parameters were described using a 2-compartment model. Pharmacokinetic and pharmacodynamic parameters were analyzed using repeated measures anova (p < 0.05).

Results: Plasma concentrations of benzyl alcohol were below the lower limits of quantification (LLOQ) at all time points for two of the six cats (33%), and by 30 minutes for the remaining four cats. Propofol pharmacokinetics, with or without 2% benzyl alcohol, were characterized by rapid distribution, a long elimination phase, and a large volume of distribution. No differences were noted between treatments with the exception of clearance from the second compartment (CLD2), which was 23.6 and 38.8 mL kg(-1)  minute(-1) in the P and P28 treatments, respectively. Physiologic and behavioral variables were not different between treatments with the exception of heart rate at 4 hours post administration.

Conclusions And Clinical Relevance: The addition of 2% benzyl alcohol as a preservative minimally altered the pharmacokinetics and pharmacodynamics of propofol 1% emulsion when administered as a single IV bolus in this group of cats. These data support the cautious use of propofol with 2% benzyl alcohol for induction of anesthesia in healthy cats.
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http://dx.doi.org/10.1111/vaa.12233DOI Listing
September 2015