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The objective of this study was to determine if hematological indicators may be used to identify disease-susceptible (ie, unthrifty) nursery pigs.
Fifty-eight nursery pigs (22 barrows and 36 gilts) with an average weight of 5.6 ± 1.3 kg were utilized in this experiment. Pigs were weaned and were approximately 21 to 28 days old during the study period. Pigs were selected arbitrarily from three nursery rooms and 14 pens. On the first day that blood samples were collected (Day 1), a veterinarian assigned the pigs to two health categories: healthy or unthrifty. Unthrifty pigs were free from abscesses or injury and were characterized via visible indicators of sickness, including, but not limited to, coughing, apparent weakness, distended abdomen, apparent dehydration or malnourishment, lethargy, and emaciation. Healthy pigs did not exhibit any of these signs. Blood samples were collected from arbitrarily selected pigs on 3 consecutive days (Day 1, n = 20; Day 2, n = 22; day 3, n = 16). Pigs ranged in age from 21 to 28 days of age on each sample day; precise ages were not recorded as date of birth for some pigs was unknown. Pigs were euthanized approximately 24 to 32 hours after samples were collected. Blood collected was used for analysis of stress hormones, gases and ion concentrations. After blood sampling, pigs were weighed, ear tagged, and marked with a livestock grease marker. After necropsy, pigs were classified into three categories: pigs with pre-existing lesions (gross evidence of disease not related to euthanasia method), pigs with significant pulmonary lesions (related to the euthanasia process, localized in the lungs, excluding cyanosis), and pigs with no significant lesions.
Healthy nursery pigs had higher concentrations of glucose and sodium than unthrifty pigs. Hemoglobin concentrations and hematocrits were higher in unthrifty pigs than in healthy pigs. No significant differences between healthy and unthrifty nursery pigs were detected in epinephrine, norepinephrine, cortisol, potassium, lactate, pH, or PO2. There was a trend for healthy pigs to have higher concentrations of ionized calcium and greater PCO2 than unthrifty pigs.
The blood parameters measured in the present experiment included markers for stress, energy or nutritional status, and blood composition. Alterations in these parameters may indicate a disruption in homeostasis, and therefore closely monitoring their levels may aid in early detection of diseases or conditions that may be subclinical or simply lead to unthriftiness.
On the basis of the results of this study, it is possible that unthrifty nursery pigs may be identified by blood chemistry analysis at a time when they are showing no outward signs of disease. Early detection of unthriftiness may therefore allow for intervention strategies or early culling by producers. In addition, by assessing blood parameters such as blood glucose, serum sodium, hemoglobin, and hematocrit, it may be possible for researchers to identify and therefore study nursery pigs before they would normally be diagnosed with signs of PFTS (or other wasting diseases), providing the opportunity to assess early causative factors in this economically important but poorly understood syndrome.
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Buzzard BL, Edwards-Callaway LN, Engle TE, et al. Evaluation of blood parameters as an early assessment of health status in nursery pigs. J Swine Health Prod. 2013;21(3):148–151.
