Differential cell count as an alternative method to diagnose dairy cow mastitis

Abstract

Changes in relative cell proportions occurring in diseased mammary glands of dairy cows can be determined using differential cell count (DCC). The present study was carried out in 2 consecutive trials, with 2 goals: (a) to test the consistency of DCC results on subsequent days, and (b) to establish an effective cutoff value for the diagnosis of mastitis. In the first trial, quarter milk and blood samples were taken from 8 healthy cows for 5 consecutive days. Milk samples were tested by somatic cell count (SCC) and bacteriological analysis, and DCC was performed on blood and milk samples by flow cytometer. In the second trial, 16 animals were randomly selected from a different herd and quarter milk samples taken on 3 consecutive milkings. All samples were cyto-bacteriologically analyzed and DCC was performed on the second sampling. In the first trial, mean SCC was 77,770 cells/mL and 4 samples were bacteriologically positive. No fixed or random effect had a significant influence on percentages of individual cell populations or ratios in blood or milk. A cutoff value of 0.495 for logarithmic polymorphonuclear neutrophilic leukocyte:lymphocyte ratio was established. Mean SCC of milk samples collected in the second trial was 543,230 cells/mL, and infection was detected in 53.1% of quarters, mostly caused by Staphylococcus aureus. When the cutoff value was applied to the data along with SCC, sensitivity and specificity of the diagnostic method were 97.3 and 92.3%, respectively.

Evaluation of 3 esterase tests for the diagnosis of subclinical mastitis at dry-off and freshening in dairy cattle

“…However, the distribution of leukocytes differs between normal and mastitic milk (Nickerson, 1989); the proportions of neutrophils may reach 95% in mastitic milk (Paape et al, 1979;Kehrli and Shuster, 1994), whereas macrophages and lymphocytes are the predominant cells in uninfected quarters (Schwarz et al, 2011a,b;Pilla et al, 2012). The results of recent studies suggest that milk with SCC <100,000 cells/mL and an elevated proportion of neutrophils indicates a local inflammatory reaction triggered by pathogens (Schwarz et al, 2011a,b;Pilla et al, 2012Pilla et al, , 2013. A stronger correlation may therefore exist between an elevated neutrophil count, a main source of esterase activity in milk, and the presence of IMI, compared with a correlation between SCC and IMI.…”

Estudo comparativo das diferentes técnicas empregadas na contagem diferencial de leucócitos no leite

“…Deve-se salientar que diferentemente dos demais trabalhos (Pillai et al 2001, Rivas et al 2001, Dosogne et al 2003, Koess & Hamann 2008, Pilla et al 2013) que avaliaram as diferentes populações leucocitárias no leite por citometria de fluxo, o presente estudo identificou a população de PMN utilizando anticorpo monoclonal específico (CH138A), não sendo identificado apenas pelas características de tamanho e granulosidade e/ou anticorpos monoclonais não específicos (p. ex. CD11b).…”

“…Trabalhos empregando a citometria de fluxo (Rivas et al 2001, Koess & Hamann 2008, Schwarz et al 2011, Pilla et al 2013, Blagitz et al 2015, citocentrifugação (Dulin et al 1982, Mira et al 2013) e contagem microscópica direta por esfregaços (Dosogne et al 2003, Pilla et al 2013) já foram realizados. Portanto, o trabalho em questão apresenta suma importância para a comunidade científica uma vez que até o momento, até onde se sabe, não há relatos de trabalhos que avaliem as três técnicas de contagem de células somáticas e sua respectiva relação com o diagnóstico microbiológico.…”

Technological advances in bovine mastitis diagnosis

“…63 Recent studies 57 have shown that DCC can reveal inflammatory mastitis processes with a sensitivity and specificity of 97.3% and 92.3%, respectively, even in milk with an SCC of 1,000 cells/mL. 56 The California Mastitis Test (CMT) is a common indirect method for measurement of SCC. The test is performed by adding a detergent to a milk sample with a high cell count, which promotes cell lysis, nucleic acid release, and formation of a "gel-like" matrix.…”

“…DCCs are performed on quarter milk samples by cytometry 56 and have been proposed as a valid tool for the identification of inflammatory processes in cases with low SCC. 63 Recent studies 57 have shown that DCC can reveal inflammatory mastitis processes with a sensitivity and specificity of 97.3% and 92.3%, respectively, even in milk with an SCC of 1,000 cells/mL.…”