Antimicrobial delivery by intrasynovial catheterisation with systemic administration for equine synovial trauma and sepsis

Objective To present the technique for intra-articular catheter placement and report the clinical outcomes of 38 cases of equine synovial trauma and/or infection treated with broad-spectrum antimicrobials administered via an intrasynovial catheter (ISC). Design Retrospective study. Procedure Medical records of 38 horses treated for synovial trauma and sepsis with frequent antimicrobial administration through an ISC from 1995 to 2008 were reviewed. Follow-up information was obtained via clinical re-evaluation or telephone contact with the owners. Results The majority of horses (84%) received amikacin and Timentin® four times daily. In addition, synovial lavage through the ISC was carried out in 27 horses (71%). Only radiological evidence of osteolysis had a significant negative impact on both lameness at the time of hospital discharge and the long-term outcome. In total, 92% of horses treated with frequent antimicrobial administration through an ISC had clinical resolution of infection. Catheter obstruction occurred in three cases, necessitating replacement or removal, and two synovial fistulae developed at sites of open drainage. The majority of horses treated had a favourable outcome, with 86% being at least pasture sound and 43% returned to riding. Conclusion Septic synovial structures treated with frequent antimicrobial administration through an ISC had a good prognosis for survival and 43% returned to riding, which is consistent with the results of other studies. The use of a simple ISC should be considered when broad-spectrum intrasynovial antimicrobial administration and lavage of a septic synovial structure are indicated.     

Blood culture status in mature horses with diarrhoea: A possible association with survival

Reasons for performing study: The incidence and implications of positive blood cultures in mature horses with diarrhoea is unknown. The diagnosis of bacteraemia may alter treatment and prognosis. Hypothesis: The proportion of horses with diarrhoea that are blood culture positive is higher than previously assumed and a positive blood culture has a negative impact on survival. Methods: Blood cultures were taken at admission and 24 h after admission from 31 mature horses with diarrhoea. Results: Nine (29%) horses were blood culture positive within 24 h of admission. Organisms isolated included Corynebacterium spp. (n = 6), Streptococcus spp. (n = 2), Pantoea agglomerans (n = 1), Gram‐negative rod (n = 1), Bacillus spp. (n = 1) and yeast (n = 1). Horses with positive blood cultures were significantly less likely to survive. Prior treatment with antimicrobial drugs had no significant effect on blood culture status. Horses with positive blood cultures had a significantly higher heart rate, packed cell volume (PCV) and plasma potassium concentration at admission, and a higher PCV and lower total plasma protein concentration 24 h after admission. Conclusions: Positive blood cultures occur more frequently than previously reported, and may have a negative impact on survival in horses with diarrhoea. Potential relevance: Results of blood cultures may be useful in formulating a prognosis for horses with diarrhoea. Further research is required to determine the effect of antimicrobial treatment on outcome.     

Alternative surgical treatment for synovial ganglion cyst of the digital tendon sheath in one horse

A 6-year-old Highland pony gelding was presented with severe left fore (LF) limb lameness of acute onset. The lameness occurred concomitantly with mild digital flexor tendon sheath (DFTS) effusion and focal painful swelling on the lateral aspect of the LF fetlock region. Clinical examination and diagnostic analgesia localised the lameness to the fetlock region and on ultrasound, a cyst-like structure filled with anaechoic fluid was detected just proximal to the lateral sesamoid bone, at the proximo-lateral aspect of the DFTS and adjacent to the lateral neurovascular bundle. Communication between the cyst-like structure and the DFTS was suspected ultrasonographically and then confirmed with contrast tenography. Tenoscopic examination of the LF DFTS was performed and the communication between the fluid-filled structure and the synovial cavity was detected. The defect in the DFTS wall was enlarged tenoscopically and the lining of the cyst-like structure was debrided. The horse recovered well post-operatively and was back in work with no evident lameness 8 months after surgery. This alternative minimally invasive surgical treatment had an excellent outcome and has the advantage of reducing the risk associated with en bloc resection.     

Use of blood culture medium enrichment for synovial fluid culture in horses: A comparison of different culture methods

Reasons for performing study: Standard methods for culturing equine synovial fluid (SF) are often unrewarding. Evidence‐based information on the relative efficiency of different systems used for optimisation of isolation of microorganisms from equine SF is lacking. Objectives: To compare the results of different culture systems performed in parallel on SF samples from horses clinically diagnosed with synovial sepsis. Methods: Synovial fluid specimens were collected between February 2007 and October 2008 from all horses admitted to a referral hospital that were clinically diagnosed with synovial sepsis and from control horses. Synovial fluid samples were cultured in parallel by: 1) direct agar culture (DA); agar culture after: 2) lysis‐centrifugation pretreatment (LC); 3) conventional enrichment (CE); 4) combined LC/CE; or 5) blood culture medium enrichment using an automated system (BACTEC 9050). Results: Ninety SF samples from 82 horses were included, together with 40 control samples. Seventy‐one of 90 samples (79%) were culture‐positive by using blood culture medium enrichment (BACTEC), which was significantly higher compared to all other methods. BACTEC enrichment was never negative while any of the other methods was positive. Although agar culture following LC and/or CE resulted in a slightly higher number of positive samples compared to DA, this difference was not significant. All control samples were culture negative by the 5 different techniques. Although the majority of samples containing isolates recovered without enrichment, culture results after BACTEC enrichment were available on the same day as for agar culture with or without LC (19/23 samples), while CE postponed recovery by at least one day in 20/23 samples. Conclusion: Blood culture medium enrichment is superior to other techniques for isolation of bacteria from SF of horses. The use of an automated system allows enrichment without substantially postponing recovery of microorganisms. Potential relevance: The efficient and fast isolation of microorganisms from infected SF by the BACTEC system allows for rapid susceptibility testing and a more appropriate antibiotic treatment.     

Intravenous formalin for treatment of haemorrhage in horses

There is limited information in the literature regarding the clinical use of formalin for the treatment of haemorrhage in horses. This uncontrolled retrospective study summarises 11 cases that were treated with intravenous formalin at the Veterinary Health Center at Kansas State University from 2009 to 2019. The objective of this study was to describe signalment, clinical and laboratory findings, treatment and outcome of horses treated with intravenous formalin for potentially life-threatening haemorrhagic conditions. This study does not attempt to prove efficacy of intravenous formalin, but rather to report its clinical use and the associated details of those cases. Horses ranged in age from 2 to 23 years old. There were nine Quarter Horses, one Thoroughbred and one Appaloosa. Treated conditions included haemoabdomen (4/11), uterine haemorrhage (1/11), epistaxis (3/11), haemorrhage secondary to a mandibular laceration (2/11) and haemothorax (1/11). The most utilised dose was 0.476% formalin (50 mL 10% neutral buffered formalin diluted in 1 L of isotonic fluid). Some horses were also treated with aminocaproic acid, Yunnan Baiyao, whole blood transfusions and surgery. Ten out of the 11 horses survived to discharge with one horse reported by the owner to have died 2 weeks later of an unknown cause.