The Use of Recombinant Tissue Plasminogen Activator (rTPA) in The Treatment of Fibrinous Pleuropneumonia in Horses: 25 Cases (2007-2012)

Intrathecal enalapril reduces adhesion formation in experimentally induced digital flexor tendon sheath injuries in horses

OBJECTIVE

The objectives of the study were to describe a standing percutaneous adhesion induction model in the digital flexor tendon sheath (DFTS) of horses and to evaluate the effect of intrathecal administration of the angiotensin-converting enzyme (ACE) inhibitor enalapril on tendon healing and adhesion formation.

STUDY DESIGN

Randomized, blinded, controlled experimental study.

ANIMALS

Eight healthy horses.

METHODS

A collagenase-induced adhesion model was implemented in the deep digital flexor tendon (DDFT) of both forelimbs under standing ultrasonographic guidance. Daily intrathecal injections of 5 mg enalapril (the treatment condition) were administered to a randomly assigned forelimb for 5 days, with the contralateral limb receiving an equivalent volume of 0.9% NaCl (the control). Lameness and limb circumference were recorded weekly. Horses were euthanized after 8 weeks and evaluated for gross digital flexor tendon sheath (DFTS) adhesions. Tendons were collected for histopathologic scoring of DDFT healing. Paired data were analyzed using a one-sided alternative sign test and longitudinal regression.

RESULTS

Multiple DFTS adhesions were formed in control limbs of all horses. The median number of gross DFTS adhesions in treated limbs was less than in control limbs (p = .0039). The average reduction in limb circumference and lameness scores over time occurred faster in treated versus control limbs (p < .025). There were no differences in DDFT histopathologic scores between groups.

CONCLUSION

The standing percutaneous DFTS adhesion induction model demonstrated that intrathecal enalapril reduced DFTS adhesion formation, lameness scores, and limb circumference over time.

CLINICAL SIGNIFICANCE

Intrathecal enalapril administration may reduce morbidity in horses with naturally occurring tendon injuries.

An updated description of bacterial pneumonia in adult horses and factors associated with death

BACKGROUND

Available descriptive studies on equine pneumonia are outdated or focus on specific horse or bacterial populations.

OBJECTIVES

To describe the clinical presentation and bacterial isolates of adult horses with bacterial pneumonia and identify factors associated with death.

ANIMALS

One hundred sixteen horses >2 years old with bacterial pneumonia.

METHODS

Retrospective case series. Data regarding history, physical examination, clinicopathologic features, treatment, bacterial culture and sensitivity, and outcome were collected and analyzed retrospectively.

RESULTS

Historical risk factors were present for 60% of cases, whereas abnormal vital signs on intake were present for <50%. Most horses (58%) underwent at least 1 change of antimicrobial treatment, and 67% received the highest-priority critically important antimicrobials. Streptococcus zooepidemicus was the most isolated bacteria (44%), followed by Escherichia coli (19%), Klebsiella spp. (18%), other Streptococcus species (17%), and Bacillus spp. (13%). Fusobacterium spp. were the most common anaerobic isolates (11%). Antimicrobial susceptibility varied widely. Survival to discharge was 73%. Heart rate at presentation (odds ratio [OR] 1.08, 95% confidence interval [CI] 1.008-1.17, P = .03) and higher creatinine (OR 14.1, 95% CI 1.56-127.6, P = .02) increased the risk of death. Higher lymphocyte count (OR 0.27, 95% CI 0.08-0.94, P = .04) reduced risk.

CONCLUSIONS AND CLINICAL IMPORTANCE

Contrasting older literature, Fusobacterium spp. were the most common anaerobes. Streptococcus zooepidemicus remained the most common isolate and was predictably susceptible to penicillin. Antimicrobial susceptibility was otherwise variable and broad applicability is limited as this was a single-center study. Increased risk of death associated with tachycardia and abnormally high serum creatinine concentration is consistent with previous studies.

Alteplase Dose Assessment for Pleural infection Therapy (ADAPT) Study-2: Use of 2.5 mg alteplase as a starting intrapleural dose

BACKGROUND AND OBJECTIVE

Intrapleural tissue plasminogen activator/deoxyribonuclease (tPA/DNase) therapy is increasingly used in pleural infection. Bleeding risks and costs associated with tPA remain the clinical concerns. Our dose de-escalation series aims to establish the lowest effective dosing regimen for tPA/DNase. This study assesses the intrapleural use of 2.5 mg tPA/5 mg DNase for pleural infection.

METHODS

Consecutive patients with pleural infection treated with a starting regime of 2.5 mg tPA/5 mg DNase were included from two centres in Australia and UK. Escalation of tPA dose was permitted if clinical response was inadequate.

RESULTS

Sixty-nine patients (mean age 61.0 years) received intrapleural 2.5 mg tPA/5 mg DNase. Most (88.4%) were treated successfully and discharged from hospital without surgery by 90 days. Patients received a median of 5 [interquartile range [IQR] = 3-6] doses of tPA/DNase. Total amount of tPA used per patient was 12.5 mg [median, IQR = 7.5-15.0]. Seventeen patients required dose escalation of tPA; most (n = 12) for attempted drainage of distant non-communicating locule(s). Treatment success was corroborated by clearance of pleural opacities on radiographs (from median 27.0% [IQR = 17.1-44.5] to 11.0% [IQR = 6.4-23.3] of hemithorax, p < 0.0001), increased pleural fluid drainage (1.98 L [median, IQR = 1.38-2.68] over 72 h following commencement of tPA/DNase) and reduction of serum C-reactive protein level (by 45.0% [IQR = 39.3-77.0] from baseline at day 5, p < 0.0001). Two patients required surgery. Six patients with significant comorbidities (e.g., advanced cancer) had ongoing infection when palliated and died. Two patients experienced self-limiting pleural bleeding and received blood transfusion.

CONCLUSION

A starting intrapleural regime of 2.5 mg tPA/5 mg DNase, with up-titration if needed, can be effective and deserves further exploration.

Emerging concepts in pleural infection

PURPOSE OF REVIEW

Pleural infection remains an important pulmonary disease, causing significant morbidity and mortality. There is a resurgence of disease burden despite introduction of antibiotics and pneumococcal vaccines. A revisit of the pathogenesis and update on intervention may improve the care of pleural infection.

RECENT FINDINGS

Recent studies have uncovered the prognostic implication of the presence of a pleural effusion in patients with pneumonia. Identifying where the bacteria lives may have diagnostic and therapeutic implications. Over-exaggerated pleural inflammation may underlie development of parapneumonic effusion as indirect evidence and a randomized study in children raised a role of corticosteroids in parapneumonic pleural effusions, but data are lacking for adults. Optimization of the delivery regimen of intrapleural fibrinolytic and deoxyribonuclease therapy is ongoing.

SUMMARY

The review aims to review the current practice and explore new directions of treatment on pleural infection.

Successful management of pleural infection with very low dose intrapleural tissue plasminogen activator/deoxyribonuclease regime

Pleural infection managed with intrapleural therapy using a combination of 10 mg of tissue plasminogen activator (tPA) and 5 mg of deoxyribonuclease (DNase) has been shown in randomized and open-label studies to successfully treat >90% of patients without resorting to surgery. Potential bleeding risks, although low, and costs associated with tPA remain important concerns. No phase I studies exist for intrapleural tPA therapy and the lowest effective dose has not been established. In patients with high bleeding risks, lower doses may present a safer alternative. We report a case of a complex parapneumonic effusion in a patient with coagulopathy that was successfully treated with a very low dose tPA (1 mg) and DNase (5 mg) regime.