There is no ‘one size fits all’ regarding resistance development. Its very much 'bug/drug' related, and even more so on the mechanism of resistance i.e. chromosomal vs acquired resistance being a key factor.
On the human side, resistance is definitely a more pressing problem than in animals. This means animal antibiotics currently remain, on balance, more effective at treating animal bacterial disease.
However, if antibiotics are not used responsibly in the veterinary sector, it is estimated that resistance will increase. Numerous publications (e.g. CEESA VetPath publications) are showing increasing upward trends of resistance in disease-causing bacteria in animals, such as the Staphylococcus aureus bacteria which cause mastitis in cows, which is why it is important to use all antibiotics responsibly.
Statistics on the issue of antibiotic resistance in human health can be found from ESPAUR and other publications collated by the devolved governments. Internationally, WHO carried out surveillance. In animal health, the VARSS reports from the Veterinary Medicines Directorate publish annual surveillance. A range of reports from the UK and EU can be found on this website at www.farmantibiotics.org/media-news-updates/useful-documents-links/.