Pen-side diagnostic comparisons for nursed-off sows and fallback pigs

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hand of a lab technician or medical doctor holding blood tube test and background a rack of color tubes and microscope with blood samples other patients in laboratory

Source: PigHealthToday.com

For both the sow and piglet, an animal that does not perform to its potential or falls behind its counterparts will negatively impact the sow farm’s productivity and profitability. Nursed-off sows and fallback pigs present particular challenges in high-health herds as traditional antigen and antibody diagnostics have fallen short in determining a direct cause for either development.

Will Miller, a veterinary student at Michigan State University, carried out a study to determine whether such cases had a metabolic or infectious component, for which he used on-site, point-of-care biochemical, blood gas and hematological diagnostic equipment.1

“I also evaluated the practicality and workability of the on-site diagnostic equipment,” Miller told Pig Health Today.

He applied the following case definitions for the study:

  • Nursed-off sows: Sows that were off feed for at least 2 days or those with poor milk production 3 to 15 days after farrowing.
  • Fallback pigs: Piglets that by 3 to 7 days of age had poor body condition compared to littermates.

Setting up the study

Blood samples were collected from a total of 142 sows and 300 piglets at two 5,600-head, breed-to-wean sow farms, involving two genetic lines. “We observed sows and piglets each morning during routine daily observations,” Miller noted. “When we found one that met our criteria, we restrained it, collected blood and found a control to compare blood samples.”

He added that rectal temperatures were collected before restraining the animal to ensure an accurate reading.

To further evaluate the identified 71 nursed-off sows and 100 fallback pigs, blood was collected from the jugular vein and placed into 1.3 mL lithium heparin and EDTA blood tubes which were gently inverted 10 to 15 times. The study ran from the last week of May through August 5.

An equal number of control sows (71) were matched to the nursed-off sows by parities, total born (± three pigs) and farrow dates (± 2 days). To rule out the possibility of gender correlation, once the experimental piglet was identified, Miller selected two control piglets from that same litter. One was the same sex as the experimental pig and the other was the opposite sex.

The VETSCAN® VS2 large-animal profile, i-STAT® Alinity® v CG8+ profile and VETSCAN® HM5 three-part differential were used to measure quantitative biochemical, blood gas, electrolyte and hematological analytes. Sow and piglet data were analyzed, and tests were performed at 5% level of significance.

The findings

Analyte differences and demographic-analyte interactions are reported in the accompanying table. The findings show that nursed-off sows and fallback pigs may be associated with an inflammatory/infectious process, a possible cause for the clinical presentations, Miller noted.

“Interestingly, fevers were not associated with increased white-blood-cell parameters in this study,” he added. “Elevated blood-urea nitrogen and decreased glucose can be associated with metabolic processes and, therefore, could suggest more than one physiological component affecting fallback pigs.”

Identifying an inflammatory/infectious or metabolic cause is important in selecting medications and treatment plans to improve the conditions of nursed-off sows and fallback pigs.

“Some of the findings indicate that the clinical sows and piglets may have been dehydrated compared to their controls,” Miller said. “If that is the case, when farm staff or veterinarians find similar diagnostic results, they can add hydration to the treatment as it could be a factor predisposing the animals to their diseased state.”

In the end, these findings will help swine veterinarians narrow the investigation into causes of such cases and more quickly implement preventative measures, he added. “It shows that on-farm diagnostic equipment can play an integral role in determining individual treatment and prevention plans and should be investigated further for best-use applications in production facilities and swine veterinary clinics.”

Analyte identification of key and significant directional differences between treatment and control groups

Test groups Significance VS2 i-STAT HM5 Blood smear Rectal temp
Nursed-off sows (NOS) vs. control sows (CS) NOS > CS
significant
P ≤ 0.05
GGT, GLOB, TP MON, RBC, WBC BAS, MYELO, Band, WBC
NOS < CS
significant
p ≤ 0.05
ALB, Mg K+ P
Not significant ALP, AST, BUN, Ca, CK, PHOS BE, GLU, HGB, HCO3, HCT, iCa, pCO2*, pH, pO2, sO2, tCO2 HCT, HGB, LYMP, MCH, MCHC, MCV, NEU, PLT EOS, LYMP, META, MON, NEU
Fallback pigs (FBP) vs. control pigs (CP) FBP > CP
significant
p ≤ 0.05
BUN, GGT, GLOB, TP BE, HGB, HCT, Na+, pH, pO2*, sO2*! HCT, HGB, NEU, PLT, RBC, WBC META, NEU, Band, WBC
FBP < CP
significant
p ≤ 0.05
ALB, ALP, Ca, CK, PHOS GLU, iCa, pCO2 MON EOS, LYMP# P
Not significant AST, Mg HCO3*, K+, tCO2* LYMP, MCH, MCHC, MCV BAS, MON, MYELO
Identification key: ALB= Albumin
ALP= Alkaline phosphatase
AST= Aspartate aminotransferase
Band= Band neutrophil
BAS= Basophil
BE= Base excess
BUN= Blood urea nitrogen
Ca= Calcium
CK= Creatine kinase
EOS= Eosinophil
GGT= Gamma-glutamyl transferase
GLOB= Globulin
GLU= Glucose
HCO3= Bicarbonate
HCT= Hematocrit
HGB= Hemoglobin
iCa= Free calcium
K+= Potassium
LYMP= Lymphocyte
MCH= Mean cell hemoglobin
MCHC=Mean cell hemoglobin concentration
MCV= Mean cell volume
META= Metamyelocyte
Mg= Magnesium
MON= Monocyte
MYELO= Myelocyte
Na+= Sodium
NEU= Neutrophil
pCO2= Partial pressure of carbon dioxide
PHOS= Phosphorus
PLT= Platelet
pO2= Partial pressure of oxygen
RBC= Red blood cell
tCO2= Total carbon dioxide
sO2= Oxygen saturation
WBC= White blood cell

* = significant group-parity interaction;
! = significant group-genetic interaction;
# = significant group-gender interaction

  

 

1 Miller W, et al. Pen-side comparison of biochemical, blood gas, and hematological analytes between two common clinical conditions and case-controls: nursed-off sows and individual fallback piglets. Student Research Posters, 51st Am Assoc Swine Vet Annual Meeting. 2020; 242.

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