Ectonucleotidase and adenosine deaminase as inflammatory marker in dairy cows naturally infected by Dictyocaulus viviparus.

The aim of this study was to evaluate the influence of dictyocaulosis (mild or severe) on enzymes of NTPDase, 5'-nucleotidase, and adenosine deaminase (ADA) of dairy cows naturally infected by Dictyocaulus viviparus. Blood and faeces were collected from 22 dairy cows of the same farm to evaluate NTPDase (ATP and ADP substrate), 5'-nucleotidase, and ADA activities on days 0 (pre-treatment) and 10 (post-treatment). Seric activities of NTPDase (ATP substrate), 5'-nucleotidase, and ADA were lower (P<0.05) in D. viviparus infected animals compared to uninfected cows. The number of D. viviparus larvae per gram of faeces varied among the animals, and they showed different degrees of severity according to respiratory clinical signs of the disease (cough and nasal discharge). Later, these cows were divided into two groups: those with mild (n=10) and severe (n=12) disease. Cows with severe disease showed higher NTPDase activity (ATP substrate) than those with mild disease (P≤0.05). The opposite occurred with NTPDase (ADP substrate), 5'-nucleotidase, and ADA in cows with severe disease, that is, the enzymatic activity of these seric enzymes significantly decreased (P≤0.05) compared to animals with mild disease. Infected animals showed reduced NTPDase activity (ATP and ADP substrate) after treatment. No enzymatic changes were observed for 5'-nucleotidase, and ADA pre- and post-treatment (P>0.05). Based on these results, we conclude that dictyocaulosis alters NTPDase, 5'-nucleotidase, and ADA activities of cow naturally infected by the parasite, in consequence the enzymes act as inflammatory markers.

Dictyocaulosis in dairy cows in Brazil: an epidemiological, clinical-pathological and therapeutic approach.

An outbreak of severe parasitic pneumonia caused by Dictyocaulus viviparus was diagnosed in adult dairy cows in the municipality of Arabutã, Southern Brazil. The total morbidity in the herd was 71.9%, and the morbidity amongst adult lactating cattle was 100%. The main clinical signs observed were dyspnea, tachypnea, nasal discharge, decreased milk production, and cough. A necropsy was conducted on one animal in order to establish the diagnosis. The herd had been treated previously with levamisole; however, clinical signs persisted and became worse. After treatment with eprinomectin the severity of clinical signs decreased, and the respiratory condition subsequently disappeared. It is believed that the high morbidity presented in this outbreak is related to epidemiological factors, such as increased rainfall in 2014 and 2015, associated with low immunity of the herd. This is the first report of dictyocaulosis in adult dairy cattle in Brazil. Furthermore, it describes an outbreak presenting very high morbidity.