Why testing lactate in large animals?

The measurement of lactate in large animals has a number of valuable applications. Particularly with new near patient/subject methods now available to veterinarians and farmers which provide quick and reliable results without leaving the animal’s side, whatever its location.
 
For example, measuring the concentrations of lactate in cattle provides a simple assessment of the severity of a number of conditions, including neonatal diarrhoea, respiratory disease, and displacement of the fourth stomach (abomasum)¹. The ability to also accurately measure lactate in a near subject setting in other ruminants such as sheep has also been demonstrated.²
 
Another application in cattle has been noted for the assessment of the health of new-born calves. Studies have shown that new-born calves requiring assisted delivery due to abnormal labour (dystocia) have higher lactate levels compared with calves not requiring such assistance. The APGAR scoring system, designed to assess the health of new-born calves, has been shown to be negatively correlated with blood lactate levels³. 
 
Lactate has also been utilised to assess the fitness of pregnant cows compared to non-pregnant cows, helping farmers to judge whether or not a cow is fit enough to calf again⁴. Furthermore, measuring lactate can enable animal welfare and agricultural inspectors to analyse how much exercise a cow has had recently.
 
Away from its clinical application within veterinary medicine, lactate has also been demonstrated to have value in agricultural production and the assessment of meat quality. For example, lactate can also be measured in pigs, and studies have shown that blood lactate levels can reliably reflect their physiological response to stress before slaughter and may help to explain variation in pork quality⁵.

References

1.  Burfeind and Heuwieser (2012). Validation of handheld meters to measure blood L-lactate concentration in dairy cows and calves. Journal of Dairy Science. 95: 6449–6456 https://www.journalofdairyscience.org/article/S0022-0302(12)00648-0/fulltext
2.  Kaynar et al (2015). Reliability of the Lactate Scout point-of-care instrument for the determination of blood L-lactate concentration in sheep. Veterinary Clinical Pathology.; 44: 559–563 https://onlinelibrary.wiley.com/doi/abs/10.1111/vcp.12288
3.  Burfeind and Heuwieser (2012). Validation of handheld meters to measure blood L-lactate concentration in dairy cows and calves. Journal of Dairy Science. 95: 6449–6456 https://www.journalofdairyscience.org/article/S0022-0302(12)00648-0/fulltext
4.  https://www.ncbi.nlm.nih.gov/pubmed/19164665
5.  Rocha, Dione et al (2015). Hand-held lactate analyser as a tool for the real-time measurement of physical fatigue before slaughter and porlk quality prediction. Animal (2015)  9:, pp 707-714