Prophylaxis is the set of measures necessary to prevent the appearance, limit the spread or reduce the importance of transmissible diseases in animals. These include 'environmental' measures (disinfection, quarantine, restriction of contact between animals, manure management) and measures aimed at the individual animal (i.e. vaccines or drugs).

To prevent new infections it is recommended to avoid the introduction of animals from other farms or, if necessary, to verify the health status of the farm of origin and to buy animals from herds subject to effective vaccination programmes.

Attention should be paid to transport vehicles (preferably one’s own...) and the animals should be placed in quarantine and tested - with the blood tests available - for the presence of any infection (e.g. Infectious Bovine Rhinotracheitis-IBR, Bovine Viral Diarrhoea-BVD).

To increase herd resistance against pathogens it is necessary - together with the farm Veterinarian - to develop an appropriate vaccination programme, reduce environmental stress (heat, cold, overpopulation, bedding hygiene, etc.), nutritional stress (especially during the dry and transition period) and provide adequate colostrum levels to calves.

As for herd management, animals with unusual clinical signs must be isolated, necropsy should be considered when the causes of death are unknown, clean and disinfected individual cages for calves should be used, the contamination of buckets, of feeding equipment and of drinking troughs should be contained and it is necessary to properly disinfect the equipment used for health treatments or to use disposable material (for AI, foot care, injections, etc.).

All the necessary measures for the control of unwanted animals (rats, mice, birds) are also necessary.
In dairy farms the control of mammary infections (infectious mastitis), lameness of bacterial origin and of metritis is of particular importance. The use of vaccines may improve herd resistance against major pathogens and limit their circulation (Clostridia, IBR, BVD, parainfluenza, syncytial virus), while the recent availability of marker vaccines now allows the recognition of infected versus vaccinated animals, increasing the efficacy of control strategies against certain diseases.