Date Published: September 11, 2008
Publisher: BioMed Central
Author(s): Lena Pelander, Ragnvi Hagman, Jens Häggström.
Canine pyometra is a common disease in countries where routine spaying of young dogs is not common practice. This disease is known to lead to systemic inflammation potentially affecting multiple organs in the body, including the heart. Cardiac-specific Troponin I (cTnI) is a sensitive marker of myocardial cell damage, which can result from ischemia, trauma, toxins or inflammation. Dogs with pyometra are also exposed to anaesthesia which can potentially result in myocardial cell damage. The aims of the study were 1) to evaluate the occurrence of myocardial cell damage as indicated by increased serum concentrations of cTnI in dogs with pyometra and relate these to presence of systemic inflammation and 2) to evaluate the change in cTnI-concentrations after anaesthesia and surgery.
Serum cTnI concentration was measured preoperatively and one day after surgery in 46 female dogs with pyometra and 15 female dogs that underwent surgery for other reasons (ovariohysterectomy and mammary tumours).
Forty-six female dogs of different breeds diagnosed with pyometra were included. The dogs had a median age of 8.5 years (IQR 7.5–10) and a median weight of 29 kg (IQR 9–32). Of the 46 dogs, 37 (80%) fulfilled the chosen criteria for systemic inflammatory response syndrome (SIRS) at inclusion. Thirteen (28%) of the dogs had increased cTnI concentrations (> 0.2 μg/l) before surgery and 18 (39%) had increased cTnI-concentrations the day after surgery. The cTnI concentrations in the 13 dogs with increased preoperative cTnI concentrations decreased in 8 dogs, increased in 4 dogs, and was unchanged in one dog. Seven dogs with nondetectable preoperative cTnI concentrations had increased postoperative concentrations. The only significant association between the studied laboratory or clinical variables (including SIRS) and cTnI concentration was preoperative percentage band neutrophils (PBN) and postoperative cTnI concentration (P = 0.016). In total, 20 dogs (43%) had increased pre- or postoperative cTnI concentrations. Seven dogs (15%) had pre-or postoperative concentrations of cTnI of 1.0 μg/l or higher.
Mild to moderate increases in cTnI appears to be common in dogs with pyometra before and after surgery, but the clinical importance of this finding is uncertain. None of the studied clinical variables were found to reliably predict increased preoperative cTnI concentrations. Because of the pre- and postoperative variation in cTnI concentrations, it was not possible to identify a negative effect of anaesthesia and surgery on myocardial cell integrity.
Myocardial damage can be caused by multiple conditions including ischemia, trauma, toxins or inflammation. Cardiac-specific Troponin I (cTnI) is currently the most sensitive and specific marker of myocardial cell damage in the dog [1,2]. Cardiac-specific Troponin I is a protein that is expressed at high concentrations only in the myocardium. When cardiac myocytes are damaged, cTnI leaks into the bloodstream and can be detected in serum [1,3]. In normal dogs serum concentrations of cTnI are low or, most often, undetectable .
This study was approved by the Uppsala County local ethical committee.
In total, 20 out of 46 dogs (43%) with pyometra had increased concentrations of cTnI at some time during the study, which indicates that increased cTnI concentrations are common during the perioperative period in dogs with pyometra. This finding is supported by the results of our previous study in which increased preoperative cTnI concentrations were documented in 12% of 58 dogs with pyometra . The present study is different from our previous one because, to our knowledge, this is the first study that documents both pre-and postoperative measurements of cTnI concentrations in dogs with pyometra. It should be pointed out that only 7 of the 20 dogs with increased concentrations of cTnI (10 out of the total 31 samples with increased concentrations) had values ≥ 1.0 μg/l and none of the dogs measured higher than 13.2 μg/ml, indicating that cTnI concentrations were mildly increased in the majority of cases. The lower limit of detection of cTnI in our assay is 0,2 μg/l. It is possible that the upper reference range for cTnI in dogs is lower than 0,2 μg/l and that a greater number of dogs would have had increased concentrations of cTnI if we had used a more sensitive assay, as recently described .
Mild to moderate increases in cTnI appears to be common in dogs with pyometra before and after surgery, but the clinical importance of this finding is uncertain. None of the studied clinical variables (including SIRS) were found to reliably predict increased preoperative cTnI concentrations. Because of the pre- and postoperative variation in cTnI concentrations it was not possible to identify a negative effect of anaesthesia and surgery on myocardial cell integrity. Consequently, analysing serum cTnI concentrations from dogs with pyometra could possibly help detect subclinical myocardial damage. Further studies are needed to investigate whether increased concentrations of cTnI are associated with a higher risk of perioperative complications.
The authors declare that they have no competing interests.
LP participated in the design of the study and carried out the practical recruitment of cases. She also drafted the manuscript. RH participated in the design of the study and the manuscript writing. JH participated in the design of the study and performed the statistical analysis. He also parcipitated in the writing of the manuscript. All authors read and approved the final manuscript.