Caracterização patológica e microbiológica de lesões na glândula mamária de vacas leiteiras no sul do Brasil

Abstract

Lesões na glândula mamária de bovinos leiteiros são de grande importância, pois geram grande impacto à cadeia produtiva leiteira. Devido a isso, nessa tese estão incluídos dois artigos científicos acerca do tema, com destaque para as mastites e a papilomatose de tetos. O primeiro trabalho objetivou caracterizar os achados macroscópicos e histológicos de mastites em vacas leiteiras e correlacioná-las com os patógenos envolvidos. Para isso, amostras de leite e fragmentos de tecido de cada quarto mamário de vacas leiteiras abatidas foram encaminhados para análise microbiológica e histopatológica, respectivamente. No total, 148 vacas e 592 quartos mamários foram coletados. Desses, 432 (73%) apresentaram lesões inflamatórias (mastite), classificadas em sete padrões de acordo com a análise histopatológica. Os padrões misto, linfoplasmocítico e supurativo foram os mais prevalentes com 35,9% (155/432), 27,1% (117/432) e 14,3% (62/432) dos casos, respectivamente, e associaram-se aos mesmos patógenos: Streptococcus spp., Staphylococcus coagulase negativa (SCN), Staphylococcus aureus, Streptococcus agalactiae, Streptococcus uberis e Corynebacterium bovis. Lesões piogranulomatosas foram observadas em 7,2% (31/432) dos casos, com diferentes padrões de acordo com o agente envolvido, principalmente ocasionadas por S. aureus e Nocardia sp. Mastite abscedativa representou 6,0% (26/432) dos casos, predominantemente associada a Trueperella pyogenes. O padrão necrossupurativo foi observado em 5,8% (25/432) dos casos, associado a bactérias como SCN e Escherichia coli. Mastite granulomatosa representou apenas 3,7% (16/432) dos casos e foi ocasionalmente associada ao Mycobacterium sp. O segundo estudo teve por objetivo descrever os aspectos moleculares e patológicos de papilomas em tetos de 73 vacas leiteiras encaminhadas ao abate. Fragmentos das lesões foram coletados em pools individuais por animal e submetidas à análise molecular. Os tetos com as lesões remanescentes processados e submetidos à análise histopatológica. Os papilomas apresentaram três padrões macroscópicos: exofítico (5 [6,9%]), plano (29 [39,7%]) e misto (39 [53,4%]). Histologicamente, todas as amostras foram identificadas como papilomas escamosos. Na análise molecular, em 27 amostras foram identificados oito tipos clássicos de papilomavírus bovino (BPVs 4, 6, 7, 8, 9, 10, 11 e 12); em 17 amostras, seis prováveis tipos de BPV previamente descritos; e em 15 amostras, 10 prováveis novos tipos de BPV.

Lesions in the mammary gland of dairy cattle are very important once they have a big impact on dairy industry. Thus, two scientific articles on this subject, especially mastitis and teat papillomatosis, are included in this thesis. The first research aimed to characterize the gross and microscopic features of mastitis in dairy cows, and to correlate them with the pathogens involved. For this, milk samples and tissue fragments from each mammary quarter of slaughtered dairy cows were sent for microbiological and histopathological analysis, respectively. A total of 148 cows and 592 mammary quarters were collected. From these, 432 quarters (73%) had inflammatory lesions (mastitis) that were classified into seven patterns based on the histopathological findings. Mixed, lymphoplasmacytic and suppurative patterns were the most prevalent with 35.9% (155/432), 27.1% (117/432) and 14.3% (62/432) of the cases, respectively, and they were associated with the same set of pathogens: Streptococcus spp., coagulase-negative Staphylococcus (CNS), Staphylococcus aureus, Streptococcus agalactiae, Streptococcus uberis and Corynebacterium bovis. Pyogranulomatous lesions were observed in 7.2% (31/432) of the cases with distinct patterns based on the agent involved, mostly S. aureus and Nocardia sp. Abscedative mastitis accounted for 6.0% (26/432) of the cases, predominantly associated with Trueperella pyogenes. The necrosuppurative pattern was observed in 5.8% (25/432) of the cases, and it was associated with bacteria such as CNS and Escherichia coli. Granulomatous mastitis represented only 3.7% (16/432) of the cases, and it was occasionally associated with Mycobacterium sp. The second research aimed to describe the molecular and pathological aspects of teat papillomas in 73 slaughtered dairy cows. Fragments of the lesions were collected in individual pools per animal and were subjected to molecular analysis. The teats with the remaining lesions were processed and subjected to histopathological analysis. Papillomas presented three macroscopic patterns: exophytic (5 [6.9%]), flat (29 [39.7%]) and mixed (39 [53.4%]). Histologically, all samples were identified as squamous papillomas. Based on the molecular analysis, eight classical types of bovine papillomavirus (BPVs 4, 6, 7, 8, 9, 10, 11 and 12) were identified in 27 samples; six previously reported putative BPV types in 17 samples; and 10 putative new BPV types in 15 samples.