Castration of piglets with the use of isoflurane-anaesthesia in combination with an analgesic has been proven to be a welfare-friendly approach. However, castration is performed with an equipped anaesthetic device which is not profitable for small farms. Thus, this study aimed at investigating whether sharing the anaesthetic device among farms results in an elevated risk of bacteriological contamination and further spreading in spite of a thorough disinfection. The study included two groups of organic farms. Piglets (n = 1579) were anaesthetised with isoflurane supplied from an equipped device and castrated. Stationary anaesthetic devices were used in the first group of farms, whereas farms in the second group shared one device. Each farm was visited four times and the colony forming units (CFU) of total mesophilic bacteria, Staphylococcus spp., Methicillin-resistant Staphylococcus aureus (MRSA) and Escherichia coli were determined. Sampling took place before castration and after disinfection, and included snout masks, retaining fixtures, pedals and wheels of the device (n = 376). The results indicated presence of Staphylococcus species in 56.5% and 40.3% of samples obtained from farms using stationary and shared devices, respectively. MRSA was detected in 2.4% of the samples and only one pathogenic Shiga toxin-producing E. coli (Stx2e, F18) could be detected. Bacterial counts were lower on the shared device than on the stationary devices (p = 0.038), particularly on restraining fixtures (p < 0.05). In both groups wheels were the most and pedals the least contaminated materials (p < 0.05). It is concluded that sharing an anaesthetic device on several farms does not increase bacteriological contamination after a thorough disinfection and thus imposing no additional hygiene risk to farms with similar hygienic conditions.