Abstract: Previous work (Marc et al., 2000) suggested that plasma cortisol responses to treadmill exercise or ACTH injection are a reliable marker for performance evaluation in warmblood horses. For practical purposes blood sample collections and treadmill exercise tests are somewhat troublesome and time consuming. The goal of this study was thus to evaluate the use of saliva for cortisol determination (by direct EIA) as a marker for performance and to investigate the reliability and repeatability of plasma cortisol responses to a single i.v. injection of ACTH (50 micrograms or 250 micrograms). Furthermore, the effect of training horses for 8 weeks 3 times per week covering the same distance (increasing from 3.5 km during the first week to 8 km during the last week) either by trotting (approximately 240 m/min) or by cantering (375 m/min) was investigated. For this purpose initially ten four-year-old Hannovarian geldings, all reared in the same State stud, were used. Mean overall correlation between salivary cortisol and plasma cortisol concentrations was 0.64 when samples of various points of time were used. However, in spite of attempts to standardize saliva sample collection, correlation between salivary cortisol levels and plasma cortisol levels at distinct points of time in different tests were low and significant (r = 0.85, p < 0.02) only in one test. Thus, salivary cortisol measurements for diagnostic purposes are not reliable or useful. The repeatability of plasma cortisol responses to ACTH for untrained and trained horses were r = 0.86 and r = 0.8 respectively (p < or = 0.01 and p < or = 0.05 respectively). Training horses either by trotting or cantering did not affect the cortisol response either to treadmill exercise or to stimulation by ACTH. It is concluded that the relationship between salivary cortisol levels and plasma cortisol levels is not close enough to allow the use of salivary cortisol determination as marker of the training status/fitness of horses. The repeatability of the cortisol response to ACTH is similar to the cortisol response to treadmill exercise. Based on plasma cortisol responses to ACTH or treadmill exercise training horses by cantering at low speed is not superior to training by trotting for the fitness of horses.

Abstract: This study aimed to increase the knowledge on salivary antibodies in the horse since these constitute an important part of the immune defence of the oral cavity. For that purpose assays to detect horse immunoglobulin A (IgA) including secretory IgA (SIgA) were set up and the molecular weights of different components of the horse IgA system were estimated. Moreover, samples from 51 clinically healthy horses were tested for total SIgA and IgG amounts in saliva and relative IgG3/5 (IgG(T)) and IgG4/7 (IgGb) content were tested in serum and saliva. Results showed a mean concentration of 74μg SIgA/ml horse saliva and that there was a large inter-individual variation in salivary SIgA concentration. For total IgG the mean concentration was approx. 5 times lower than that of SIgA, i.e. 20μg IgG/ml saliva and the inter-individual variation was lower than that observed for SIgA. The saliva-serum ratio for IgG isotypes IgG3/5 and IgG4/7 was also assessed in the sampled horses and this analysis showed that the saliva-serum ratio of IgG4/7 was in general approximately 4 times higher than that of IgG3/5. The large inter-individual variation in salivary SIgA levels observed for the normal healthy horses in the present study emphasises the need for a large number of observations when studying this parameter especially in a clinical setting. Moreover, our results also indicated that some of the salivary IgG does not originate from serum but may be produced locally. Thus, these results provide novel insight, and a base for further research, into salivary antibody responses of horses.

Abstract: IgA antibodies reflecting airways or intestinal mucosal immune responses can be found in saliva and feces, respectively, and IgG antibodies reflecting serum antibodies can be found in saliva. In this study, antibodies were detected in samples of saliva and feces which had been air-dried at room temperature (+20°C) or +37°C, and stored at these temperatures for up to 6 months. In saliva the antibody levels increased, while the antibodies in feces decreased upon storage. The individual IgA antibody concentrations which were adjusted by using the ratios of specific IgA/total IgA were relatively stable in both saliva and feces, and correlated with corresponding antibody levels in samples which had been stored at -20°C. The results indicate that air-dried saliva and feces can be used for semiquantitative measurements of mucosal antibodies, even after prolonged storage at high temperatures and lack of refrigeration.