Levels of a protein in Endurance horses could point to overtraining – study

The measurement of serum amyloid A in the blood of Endurance horses might be a useful indicator of overtraining, the findings of a study suggest.

Serum amyloid A is an acute-phase protein made mostly in the liver. It has several roles, including the recruitment of immune cells to areas of inflammation.

Olga Witkowska-Piłaszewicz and her colleagues, writing in the journal Animals, said sport training in horses led to adaptations linked to physical effort that are reflected by the changes in blood parameters.

Blood testing is accepted as a support tool in the training of endurance horses, the study team from Poland said.

However, only changes in creatine phosphokinase activity and basic blood parameters before and after exercise are usually measured.

The researchers set out to investigate changes in routinely measured blood parameters and, additionally, serum amyloid A, across seven months.

They used eight privately owned untrained Arabian horses, comprising two mares and six geldings, who were starting their endurance training and sport career. The horses were aged 6 to 7 and in good health.

They found that creatine phosphokinase, aspartate aminotransferase, packed cell volume, hemoglobin concentration, red blood cell count and the concentration of total serum protein increased slightly after training sessions and competitions in a similar manner.

The increase in the white blood cell count was higher after competitions and serum amyloid A increased only after competitions.

“Total protein concentration was the only parameter that increased with training during a seven-month program,” they reported.

The increase in serum amyloid A related only to cases of heavy effort, they said.

“It thus may be helpful in the monitoring of training in young horses. In an optimal program, its concentration should not increase after a training session but only after heavy effort, which should not be repeated too often.”

Discussing their findings, the researchers said increased levels of creatine phosphokinase and aspartate aminotransferase are commonly used in horses as indicators of any kind of muscle fatigue or damage.

After strenuous exercise, they increase from four to 35-fold in the case of creatine phosphokinase and from two to six-fold for aspartate aminotransferase.

They are markedly elevated when there is muscle damage, and clinical signs such as lameness occur.

Exercise-induced rises in creatine phosphokinase may be reduced by conditioning but do not provide information on the extent of muscle damage.

In the current study, both were elevated significantly but only slightly less than two-fold, regardless of the type of effort.

In the case of serum amyloid A, training sessions did not trigger increases when the workload was optimal to produce adaptation to exercise and maintain good health.

“Moderate increases of serum amyloid A after competitions indicated a heavier challenge, particularly when the distance covered two training sessions.

“However, the increases were not high enough to indicate pathology but, rather, the physiological response to the relatively high workload, given that the horses were in their first training season.

“In contrast to routine measurements, which rise in a similar manner regardless of the type of the effort, the increase in serum amyloid A concentration only indicated an excessive stress-load after heavy effort, which should not be repeated too often.

“Thus, in inexperienced horses at the beginning of their carrier, the moderate increases in serum amyloid A level indicate heavy effort, while higher increases can alert the veterinarian to the onset of different diseases, even without clear clinical signs.”

The full study team comprised Witkowska-Piłaszewicz, Piotr Bąska, Michał Czopowicz, Magdalena Żmigrodzka, Jarosław Szczepaniak, Ewa Szarska, Anna Winnicka and Anna Cywińska, from a range of Polish institutions.

Changes in Serum Amyloid A (SAA) Concentration in Arabian Endurance Horses During First Training Season
Olga Witkowska-Piłaszewicz, Piotr Bąska, Michał Czopowicz, Magdalena Żmigrodzka, Jarosław Szczepaniak, Ewa Szarska, Anna Winnicka and Anna Cywińska
Animals 2019, 9(6), 330; https://doi.org/10.3390/ani9060330

The study, published under a Creative Commons License, can be read here.