Yersiniosis is a zoonosis causing gastroenteritis, diarrhoea, and occasionally reactive arthritis and septicaemia. Cases are often linked to meat consumption and the most common aetiological agent is the Gram-negative bacilliform Yersinia enterocolitica bacterium. The occurrence of Yersinia spp. among wild animals has mostly been studied in wild boar, but it has seldom been in other species. A total of 1,868 faecal samples from animals found dead or hunted were collected between 2015 and 2018 in the Valle d’Aosta region of the northwestern Italian Alps. Alpine ibex faecal samples were collected during a health monitoring program in 2018. Bacteria were isolated via PCR and confirmed as Y. enterocolitica biochemically. Strain antimicrobial susceptibility was tested by Kirby–Bauer disc diffusion, and the presence of virulence factors and antimicrobial resistance genes was investigated using whole-genome sequencing. Yersinia enterocolitica strains of biotype 1A were detected in six faecal samples from red deer (0.93%), roe deer (0.49%) and red foxes (0.7%). Strains found in beech martens (3.57%) and Alpine ibex (2.77%) belonged to biotypes 1B and 5, respectively and harboured the pYPTS01 plasmid that had only been detected in Y. pseudotuberculosis PB1/+. All the isolates were resistant to ampicillin and erythromycin. The biovar 1A strains exhibited different virulence factors and behaved like non-pathogenic commensals. The strain from an Alpine ibex also harboured the self-transmissible pYE854 plasmid that can mobilise itself and the pYPTS01 plasmid to other strains. The beech marten could be considered a sentinel animal for Y. enterocolitica. Phenotypic resistance may account for the ability of all the strains to resist β-lactams.

While serum amyloid A (SAA) has been investigated as a potential marker for septic arthritis in horses, no study has reported on whether SAA can be used to detect eradication of joint infection. Therefore, the objective of this study was to investigate whether the eradication of joint infection in experimentally induced septic arthritis in horses can be detected using serum and synovial fluid SAA. A total of 17 horses were randomly assigned to 3 groups. A middle carpal joint of each horse was injected with saline (control group, n = 3), lipopolysaccharide (LPS) (nonseptic synovitis group, n = 6), or Escherichia coli (septic arthritis group, n = 8) on day 0. Starting on day 1, horses underwent treatment for septic arthritis. Sequential samples of serum and synovial fluid were collected, and quantification of SAA was carried out. Concentrations of serum and synovial fluid SAA were compared among groups and time points. A concurrent study was conducted and determined that infection was eradicated on day 4 in this experimental model of septic arthritis. Concentrations of serum and synovial fluid SAA rapidly increased after inoculation of E. coli and were highest on day 3 and day 4, respectively. Thereafter, both serum and synovial fluid SAA decreased with eradication of joint infection, although they remained significantly increased from baseline until day 9 and day 10, respectively. Serum and synovial fluid SAA did not increase in the control or nonseptic synovitis group. These findings suggest that serial measurements rather than a single measurement of SAA are required to determine eradication of infection from septic arthritis in horses.

Septic arthritis is an important disease in horses, necessitating aggressive and prolonged therapy. In order to guide therapy, reliable methods of detecting the eradication of infection are needed. Therefore, the objective of this study was to investigate detection of eradication of infection in an experimental model of equine septic arthritis using standard diagnostic techniques. For this purpose, 17 adult horses were assigned to 3 experimental groups. The middle carpal joint of each horse was injected with Escherichia coli (Septic group, n = 8), lipopolysaccharide (LPS) (LPS group, n = 6), or sterile saline (Control group, n = 3) at day 0. Contralateral joints were not injected. Standard therapy was applied to all joints except non-injected joints in the Control group at day 1. Sequential samples of synovial fluid (SF) were collected for bacterial culture using 3 culture media [Columbia blood agar (CBA), brain heart infusion broth (BHI), and Signal blood culture medium] and for cytological evaluation [percentage neutrophils (PN), total nucleated cell count (TNCC), and total protein (TP)]. Escherichia coli-specific polymerase chain reaction (PCR) was carried out to detect E. coli DNA in synovial fluid. Culture and PCR were positive for E. coli in all joints injected with E. coli at day 1 and 1 joint was positive on BHI at day 4. Based on the results of bacterial culture, PCR, and TNCC, the elimination of infection in our experimental model occurred by day 4 post-infection in 6 out of 7 cases. Total protein (TP) and PN remained elevated at clinical threshold used for diagnosis of septic arthritis until day 14. In our experimental model of E. coli-induced arthritis, we conclude that TP and PN may not be good indicators for detecting the eradication of bacterial infection caused by E. coli from infected and subsequently treated joints.

OBJECTIVE To determine reference intervals for total nucleated cell count, total protein concentration, pH, RBC count, and percentages of neutrophils, lymphocytes, and large mononuclear cells in synovial fluid samples (SFSs) obtained from the carpal and tarsal joints of healthy swine. ANIMALS 54 healthy commercial finisher pigs that had no evidence of lameness or gross joint swelling. PROCEDURES Each pig was anesthetized, and SFSs were collected from 1 carpal and 1 tarsal joint for fluid analysis, cytologic evaluation, bacterial culture, and PCR analyses for common swine joint pathogens. Each pig was euthanized after SFS collection, and synovial tissue samples were collected for histologic assessment. If necessary, postmortem SFSs were collected. RESULTS Overall, 37 of 50 tarsal and 46 of 53 carpal SFSs met inclusion criteria of sufficient volume, no gross blood contamination, and negative results of bacterial culture and PCR analyses, and were from joints with histologically normal synovial tissues. For the carpal and tarsal joints, upper reference limits were as follows: total nucleated cell count, 3,281 cells/μL and 2,368 cells/μL, respectively; total protein concentration, 3.6 g/dL and 3.6 g/dL, respectively; pH, 7.2 and 7.0, respectively; RBC count, 0.8 × 10(6) cells/μL and 0.1 × 10(6) cells/μL, respectively; and percentage of neutrophils, 46.5% and 33.7%, respectively; percentage of lymphocytes, 40.6% and 56.3%, respectively; and percentage of large mononuclear cells, 92.0% and 95.3%, respectively. CONCLUSIONS AND CLINICAL RELEVANCE Results have provided reference intervals for selected variables in SFSs obtained from the carpal and the tarsal joints of healthy swine, which should be useful in diagnostic investigations of swine lameness and arthritis.

Histophilus somni, a causative agent of the bovine respiratory disease complex, can also cause a variety of systemic disorders, including bronchopneumonia, myocarditis, pericarditis, arthritis, pleuritis, and infectious thrombotic meningoencephalitis. The purpose of this study was to determine if currently circulating strains differ from those of the 1980s by identifying genomic changes. Single nucleotide polymorphisms (SNPs) and insertion and deletion (INDEL) sites were examined by whole-genome sequencing in 12 samples, 6 old and 6 new. The 31 028 SNP/INDELs recorded were compared against the reference genome sequence of the pathogenic H. somni strain 2336. The distribution of about 75% of these SNPs within a specified gene differed between old and new isolates and did not follow any particular pattern. The other 25% clustered into 2 groups containing the same SNPs in various genes: group I included 5 old isolates and 1 new isolate; group II included 5 new isolates and 1 old isolate. For putative virulence genes there were more SNPs in group I compared with strain 2336, itself an older isolate, than in group II. Although only 25% of all the SNPs formed 2 clusters, the results suggest some genetic difference in various genes between old and new strains.

Objective-To determine the effects of recombinant equine interleukin -1beta (reIL-1beta) and 4 anti-inflammatory compounds on the expression and activity of cyclooxygenase (COX)-2 in cultured equine chondrocytes. Sample Population-Articular cartilage from 9 young adult horses. Procedure-Reverse transcriptase-polymerase chain reaction methods were used to amplify a portion of equine COX-2 to prepare a cDNA probe. Northern blot analysis was used to quantify the expression of COX-2 in first-passage cultures of equine articular chondrocytes propagated in media containing dexamethasone (DEX), phenylbutazone (PBZ), polysulfated glycosaminoglycan, and hyaluronan, each at concentrations of 10 and 100 micrograms/ml and each with or without reIL-1beta. A commercial immunoassay was used to determine prostaglandin E2 (PGE2) concentrations in conditioned medium of similarly treated cells to quantify COX-2 activity. Results-Addition of reIL-1beta increased the expression of COX-2 in a dose-dependent manner, which was paralleled by an increased concentration of PGE2 in culture medium. Concentration of PGE2 in spent medium from reIL-1beta-treated chondrocytes was significantly reduced by DEX and PBZ; however, only DEX significantly reduced gene expression of COX-2. Conclusions and Clinical Relevance-Prostaglandin E2 is considered to be an important mediator in the pathophysiologic processes of arthritis, and cultured chondrocytes respond to interleukin-1 with enhanced expression and activity of COX-2. Palliative relief in affected horses is probably attributable, in part, to inhibition of PGE2 synthesis; however, analysis of these data suggests that of the 4 compounds tested, only DEX affects pretranslational regulation of the COX-2 gene in cultured equine chondrocytes.

Canine granulocytic ehrlichiosis was diagnosed in 37 dogs by finding ehrlichial morulae in 0.1 to 26.2% of their blood neutrophils and eosinophils. All 37 dogs had clinical signs of arthritis or muscular stiffness. Titer to Ehrlichia canis was determined in sera from 31 of the 37 dogs; 25 dogs had titer ranging from 1:20 to 1:5,120. In the other 6 dogs, titer to E canis was < 1:10. The most common hematologic abnormality in these dogs, other than rickettsiemia, was thrombocytopenia. Granulocytes infected with ehrlichial organisms were not found in another 10 dogs that had clinical signs of arthritis or muscular stiffness. Of these 10 dogs, 3 had titer to E canis ranging from 1:40 to 1:320. Titer in the other 7 dogs was < 1:10. Ehrlichial morulae were not found in the granulocytes of 18 healthy dogs. Of these 18 dogs, 9 had titer to E canis ranging from 1:20 to 1:5,120. Titer in the other 9 dogs was < 1:10. Titer to Borrelia burgdorferi was determined in dogs with granulocytic ehrlichiosis, arthritic dogs without detected rickettsiemia, and in healthy dogs. Low titer determined by 2 laboratories was considered to be nonspecific reaction in all 3 groups of dogs and, thus, did not indicate that the arthritic disorders were attributable to canine borreliosis.

Six calves with suppurative arthritis were given a single IM injection of sodium cephapirin at a dosage of 10 mg/kg of body weight. Cephapirin concentrations were serially measured in serum and in normal and suppurative synovial fluid over a 24-hour period. Mean peak serum concentration was 6.33 microliter/ml at 20 minutes after injection. The highest cephapirin concentrations in normal and suppurative synovial fluid were 1.68 and 1.96 microgram/ml, respectively, 30 minutes after injection. Overall mean cephapirin concentration in normal synovial fluid for the first 4 hours (1.04 +/- 0.612 microgram/ml) was not significantly different from that in suppurative synovial fluid (0.88 +/- 0.495 microgram/ml; P > 0.05). Elimination half-life was 0.60 hours and clearance was 1,593 ml/h/kg.

Low molecular weight polysulfated glycosaminoglycan (PSGAG) stimulated net collagen and glycosaminoglycan synthesis by normal and arthritic equine fetlock cartilage tissues in organ culture. Arthritic tissues were more sensitive to PSGAG stimulation. The rates of cartilage-specific type-II collagen and chondroitin sulfate-rich glycosaminoglycan synthesis by confluent chondrocyte cell cultures obtained from normal and arthritic equine cartilage tissues were increased by 25 and 50 mg of PSGAG/ml. Cells from arthritic cartilage were also more sensitive to the presence of PSGAG. In addition, concentrations of PSGAG (25 and 50 mg/ml) approximate to those in synovial fluid after intra-articular injection of 250 mg of PSGAG inhibited the rate of collagen and glycosaminoglycan degradation in cell culture. These findings suggest that PSGAG may have a role in the healing of mild cartilage degeneration by encouraging the production of replacement hyaline matrix materials, while delaying their subsequent degradation. In contrast, growth of cell cultures was inhibited by PSGAG, suggesting that these compounds may fail to stimulate chondrocyte replication, a prerequisite for tissue regeneration. Nonetheless, these observations provide direct evidence of a truly chondroprotective role for low molecular weight PSGAG in the treatment of equine degenerative joint disease.

Chemical and cytologic effects and bactericidal activity of gentamicin in septic synovial fluid were evaluated in an experimental model of infectious arthritis in horses. Septic arthritis was induced by inoculation of approximately 7.5 x 10(6) colony-forming units of Escherichia coli into 1 antebrachiocarpal joint in each of 16 clinically normal adult horses. Clinical signs of septic arthritis were evident 24 hours after inoculation. Horses were allotted to 3 groups: group-1 horses (n = 5) each were given 150 mg of gentamicin (50 mg/ml; 3 ml) intra-articularly (IA); group-2 horses (n = 5) each were given 2.2 mg of gentamicin/kg of body weight, IV, every 6 hours; and group-3 horses (n = 6) each were given buffered gentamicin, consisting of 3 mEq of sodium bicarbonate (1 mEq/ml; 3 ml) and 150 mg of gentamicin (50 mg/ml; 3 ml), IA. Synovial fluid specimens were obtained at posttreatment hour (PTH) 0, 0.25, 1, 4, 8, 12, and 24 via an indwelling intra-articular catheter. Synovial fluid pH was evaluated at PTH 0, 0.25, and 24. Microbiologic culture and cytologic examination were performed on synovial fluid specimens obtained at PTH 0 and 24, and gentamicin concentration was measured in all synovial fluid specimens. At PTH 0, E coli was isolated from synovial fluid specimens obtained from all horses. Synovial fluid pH was lower (range, 7.08 to 7.16) and WBC count was higher (range, 88,000 to 227,200 cells/microliter) and predominantly neutrophilic (95 to 99%) at PTH 0 than before inoculation. Synovial fluid pH was lowered further (mean, pH 6.63) after IA administration of gentamicin in group-1 horses; mean pH remained unchanged (7.07) after buffered-gentamicin administration in group-3 horses. At PTH 0.25, mean peak synovial fluid gentamicin concentration in horses of groups 1 and 3 (4,745 and 6,190 microgram/ml, respectively) was 1,000 times greater than that in group-2 horses (5.1 microgram/ml) at the same time. Synovial fluid gentamicin concentration in group-1 and group-3 horses was always greater than that in group-2 horses and remained greater than a minimal inhibitory concentration of gentamicin (2 microgram/ml) against many common equine bacterial pathogens for at least 24 hours after injection. Further, the calculated apparent half-life and clearance of gentamicin in synovial fluid calculated after IA administration were similar in horses of groups 1 and 3. By PTH 24, E coli could not be isolated from synovial fluid specimens obtained from group-1 horses. However, moderate to heavy growth of E coli was isolated from synovial fluid specimens obtained at PTH 24 from horses in groups 2 and 3 (80 and 66%, respectively). In selected cases, IA administration of unbuffered gentamicin may be a useful supplement to drainage, lavage, and systemic antibacterial and anti-inflammatory treatment in horses with naturally acquired infectious arthritis.