ijvp

Indian Journal of Veterinary Pathology

0250-47580973-970X

Indian Association of Veterinary Pathologists

ijvp-30-2-thesis002

RESEARCH NOTE

Studies on exfolative cytology in bovine mastitit

Ranjan

Rajeev

¹Gupta

M. K.

Dr.¹

¹Degree/Year: MVSc/2005 University: Birsa Agricultural University, Kanke Ranchi, Jharkhand-834 006

1122006

30211

2006

IndianJournals.com

The study was carried out on 190 milk samples from suspected cases of bovine mastitis over a period of one calendar year. The milk samples were collected from dairy farms of Ranchi and surrounding areas. These samples were critically examined for the presence of causative agents, effect of climate on the prevalence of causative agents, variation in the consistency, somatic cell count, and pH of the milk samples. Exfoliative cytology with Papanicolaou and Leishman stains was carried out to study the morphology of exfoliated cells in the milk sediment and other parameters such as clumping of somatic cells, lipid vacuolation and the presence of reticulin in the sediment using silver impregnation technique. Comparative efficacy of Papanicolaou and Leishman stains in exfoliative cytology was also assessed.

Bacteriological study revealed that the incidence of bovine mastitis due to gram-positive organisms was 46.31%, of which Staphylococcus aureus mastitis was most prevalent (27.37%). The incidence of mastitis due to gramnegative organisms was much lower (18.42%), in which Escherichia coli (08.95%) and Pseudomonas spp. (07.89%) were more prevalent. The incidence of bovine mastitis was found to be higher in summer and winter seasons as compared with rainy season. It was also observed that gram-positive organisms were more prevalent in winter, whereas gram-negative organisms were more prevalent in summer seasons.

In majority of cases, milk samples from mastitic udder had normal consistency without flakes. Considerable number of samples had serous (n=19) or thin (n=15) consistency. Thick or purulent consistency of milk was more commonly observed in Pseudomonas (n=4) and staphylococcal (n=2) mastitis. pH of milk samples in majority of cases (n=134; 70.53%) ranged between 6.5 and 7.0. Development of significant alkalinity in milk was more prominent in S. aureus and other staphylococcal mastitis. High somatic cell counts (SCC) were consistently found in milk samples from cases of mastitis, suggesting its diagnostic potential. This finding was further substantiated by the fact that SCC was found to be within normal range in majority of milk samples (n=39), which showed no bacterial growths. The rise in SCC was most significant in streptococcal mastitis.

Exfoliative cytology study showed higher neutrophilic counts in cases of mastitis caused by gram-positive organisms, whereas lymphocytic counts were more in the mastitis caused by gram-negative organisms. Clumping of somatic cells was most common in E. coil mastitis followed by non-coagulase positive Staphylococcus aureus. Clumping was found to be either due to trapping of cells in fibrin or due to simple fusion of live or degenerated leucocytes forming a nidus around which there was deposition of more leucocytes. Positive reaction of reticulin in mastitis affected milk was suggestive of progression of mastitis toward chronicity. Highest incidence of reticulin positive sample was recorded in yeast mastitis followed by streptococcal mastitis. Lipid vacuolations on the other hand were most prominent in staphylococcus mastitis followed by streptococcus, yeast, E. coli and pseudomonas mastitis. This finding would be helpful in selection of preferably lipophilic drug for treatment of mastitis caused by these isolates.

The most effective antimicrobial agents for both grampositive and gram-negative microorganisms was found to be enrofloxacin, followed by ciprofloxacin, amikacin, ceftriaxone, chioramphenicol, cefotaxime and gentamycin in decreasing order of efficacy. Microorganisms were mostly resistant to drugs like penicillin G, streptomycin, ampicillin, cloxacillin, amoxicillin and neomycin. The selection of drugs after culture and sensitivity test should be based on their ability to cross blood tissue barrier for mammary parenchyma, lipophilicity and ability to work in alkaline pH.

It was concluded from the present study that inclusion of these parameters in the routine reporting of the milk sample of bovine mastitis will be of definite help in assessing the severity of infection, the nature of body response to infection, presence of causative agents in the milk sample and selection of therapeutic drug as well as assessment of the duration of treatment. Papanicolaou stain was stain of choice while demonstration of microorganism was better in Leishman stain.