Rate of transmission: A major determinant of the cost of clinical mastitis

Abstract

The aim of this research was to use probabilistic sensitivity analysis to evaluate the relative importance of different components of a model designed to estimate the cost of clinical mastitis (CM). A particular focus was placed on the importance of pathogen transmission relative to other factors, such as milk price or treatment costs. A stochastic Monte Carlo model was developed to simulate a case of CM at the cow level and to calculate the associated costs for 5 defined treatment protocols. The 5 treatment protocols modeled were 3 d of antibiotic intramammary treatment, 5 d of antibiotic intramammary treatment, 3 d of intramammary and systemic antibiotic treatment, 3d of intramammary and systemic antibiotic treatment plus 1 d of nonsteroidal antiinflammatory drug treatment, and 5 d of intramammary and systemic antibiotic treatment. Uniform distributions were used throughout the model to enable investigation of the cost of CM over a spectrum of clinically realistic scenarios without specifying which scenario was more or less likely. A risk of transmission parameter distribution, based on literature values, was included to model the effect of pathogen transmission to uninfected cows, from cows that remained subclinically infected after treatment for CM. Spearman rank correlation coefficients were used to evaluate the relationships between model input values and the estimated cost of CM. Linear regression models were used to explore the effect that changes to specific independent variables had on the cost of CM. Risk of transmission was found to have the strongest association with the cost of CM, followed by bacteriological cure rate, cost of culling, and yield loss. Other factors such as milk price, cost of labor, and cost of medicines were of minimal influence in comparison. The cost of CM was similar for all 5 treatment protocols. The results from this study suggest that, when seeking to minimize the economic impact of CM in dairy herds, great emphasis should be placed on the reduction of pathogen transmission from cows with CM to uninfected cows.

Control of infectious diseases in dairy cattle

“…Mastitis during early lactation is associated with higher losses (450-550 kg) than cases seen later in lactation. Probabilistic sensitivity analysis carried out by Down et al (2013) suggests that, when seeking to minimize the economic impact of clinical mastitis in dairy herds, great emphasis should be placed on the reduction of pathogen transmission from cows with clinical mastitis to uninfected cows.…”

Prediction of Streptococcus uberis clinical mastitis risk using Matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS) in dairy herds

“…If routinely applied, information on the presence of potentially contagious S. uberis strains would be available 2 weeks before high risk periods occurred, prioritising immediate and timely enhancement of appropriate preventive measures (Barkema et al, 2009). Transmission to other cows is a critical component of udder health costs (Down et al, 2013), meaning these warnings could be particularly valuable in the control of contagious disease. For instance, prediction of increased risk could be used to increase compliance with unpopular, labour intensive interventions (Huijps et al, 2009) such as post milking teat disinfection (Galton, 2004), or segregation of cows.…”

Severe Mycoplasma bovis outbreak in an Austrian dairy herd

“…30 In the longer term, however, the risk of transmission was demonstrated to be a major determinant of the cost of clinical mastitis. 7 In the present outbreak, culling of all cattle, in particular before they achieved the best body condition for slaughtering, and costs for purchasing new animals increased the total costs. Furthermore, current costs for the farm (e.g., costs for feeding animals, electricity, bank loans, and several other cost factors) must be included in a full financial calculation.…”