This study directly demonstrates that cardiac troponin I (cTnI) is a sensitive, specific, and persistent biomarker in laboratory animals. Histopathological and pathophysiological cardiac changes in dogs, rats and mice correlated with increased serum cTnI with various cardiac inotropic agents, and cardiotoxic drugs and with cardiac arrhythmias, tachycardia, cardiac effusion with dyspnoea, and ageing. A comparison of six immunoassays for cTnI and cardiac troponin T (cTnT) to detect and monitor cardiac injury in a rodent model indicated that enzyme-linked immunosorbent (Life Diagnostics Inc and TriChem Resources Inc, West Chester, Philadelphia, USA) and Immulite (Diagnostic Products Corporation, Llanberis, UK) assays had low sensitivity and less than 1% of the dynamic range of Centaur (Bayer Healthcare Diagnostics, Newbury, UK) cTnI and Elecsys (Roche Diagnostics, Basel, Switzerland) and M8 (Bioveris Europe, Whitney, UK) cTnT assays. In dogs, however, the Immulite assay was effective and correlated with the Centaur. Serum concentrations were highly correlated but 10-fold lower for cTnT compared with cTnI with cardiac injury. Centaur assay also detected cTnI in myocardium from marmosets, swine, cattle, and guinea pigs, indicating it to be candidate cardiac biomarker for these species as well. Purified rat cTnI was 50% more reactive than purified human cTnI in the Centaur assay. In the rat, an age- and gender-dependent variation in serum cTnI was found. Male rats aged six and eight months had a 10-fold greater serum cTnI than age-matched females and three-month-old rats. These increases correlated with minimal histopathological change. Isoproterenol-induced serum cTnI increased up to 760-fold the minimal detectable concentration of 0.07 microg/L, within 4-6 h and decreased with a half-life of 6 h, with an expected return to baseline of 60 h. Severity of histopathological change correlated with serum cTnI during the ongoing injury.

Summary Three radioimmunoassays (RIA) for the pancreas specific proteins TLI, PASP and CA 19–9 were evaluated in serum from normal control dogs (n = 40) and dogs with pancreatitis (n = 20). Statistically significant differences (P < 0.05) were found for serum TLI and PASP levels between the control and pancreatitis groups. However, only 3/20 dogs with pancreatitis had serum TLI concentrations greater than the highest concentration in control dogs. Concentrations of PASP in serum were higher in 15/20 dogs with pancreatitis than in the control dogs. The magnitude of the increase in concentrations of PASP in pancreatitis was small in the majority of cases. Thus these assays are of limited clinical value in the diagnosis of pancreatitis. There was no cross‐reactivity with dog serum in the CA 19–9 assay.

No abstract

Summary Serum ionized calcium and total calcium concentrations were measured in 16 dogs with lymphoma and 49 healthy control dogs. Blood samples for all determinations of ionized calcium were collected into tubes containing silicone separator gel and processed under a closed anaerobic system. An ionized calcium analyser with ion selective electrodes was used to determine pH, ionized calcium and ionized calcium adjusted to pH 7.4. Reference ranges for ionized calcium (iCa pH 7.4) of 1.30–1.46 mmol/l, and for total calcium of 2.37–2.82 mmol/l were established. A stronger correlation (r = 0.85) was found between measured ionized calcium and total calcium levels in dogs with lymphoma and hypercalcaemia than in those with lymphoma and normocakaemia (r = 0.64). Measurement of serum ionized calcium was diagnostically concordant with the measurement of serum total calcium in the determination of calcium status in all dogs with lymphoma. Serum ionized calcium did not provide a diagnostic advantage over total calcium in the detection of hypercalcaemia of malignancy in these dogs.

A reference interval for plasma glutamate dehydrogenase (GD) (E.C. 1.4.1.3) activity, of 0-8 IU/L, was established for the cockatiel (Nymphicus hollandicus). An automated modification of a commercial manual assay was used. This enzyme is considered liver specific in humans and numerous domestic animals, due to its organ distribution. A similar distribution was found in cockatiels in this study. Maximal enzyme activity was recovered from liver and kidney homogenate supernatants. Minimal activity was detected in skeletal muscle preparations. These results suggest a potential use for plasma GD activity in the evaluation of hepatocelluar injury/necrosis in cockatiels.