Risks, Realities and Responsibilities Associated with Mastitis Treatments
Mastitis remains the most common disease of dairy cows and treatment or prevention of this disease is the most common reason that antibiotics are administered to cows (Pol and Ruegg, 2007, Saini et al., 2012). Mastitis is detected by inflammation that is caused by infection by microorganisms and occurs in both clinical and subclinical forms. Milk obtained from quarters of cows with subclinical mastitis looks normal (even when millions of somatic cells are present) but the milk contains an excessive number of somatic cells, (with or without the detectable presence of pathogenic organisms) (Dohoo and Leslie, 1991). Unless the herd prevalence of subclinical mastitis is high, subclinical infections are usually managed by antimicrobial treatments administered at the end of the lactating period. Inflammation that results in visible abnormalities of milk or the gland is defined as clinical mastitis. Most symptoms of clinical mastitis are quite mild and cannot be detected unless foremilk is observed, thus the perceived incidence of clinical mastitis on individual dairy farms is dependent on the intensity of detection. In a study that enrolled almost 800 cases of clinical mastitis occurring on 50 Wisconsin dairy farms, 50% of clinical cases presented with only abnormal milk, 35% of cases had abnormal milk accompanied by swelling of the affected quarter and only 15% of clinical cases presented with systemic symptoms (Oliveira et al. 2013). In most countries, milk from cows affected with clinical mastitis cannot be sold for human consumption and most farmers administer antimicrobials to affected cows. The use of antimicrobials to treat food animals is under increased scrutiny by consumers, governmental officials and regulatory agencies and must be well justified. The purpose of this paper is to review the risks, realities and responsibilities associated with treatment of clinical mastitis.