In 2017, the charity received 925 separate complaints about horse welfare, the highest number in England, and seized 40 horses.
Chief Inspector Heidi Jenner, who oversees its team in Leeds, Wakefield, Bradford and Harrogate, said it was unclear why West Yorkshire was proving a particular hotspot for horse welfare issues, but factors could include a high number of working horses found in urban areas like Bradford.
She said: “We probably get more calls now because the value of horses is getting less and less but the cost of looking after them isn’t.
“When something goes wrong with horses, because they are not worth much, instead of getting them treated people will just dump them at the side of a road.”
The RSPCA’s national equine co-ordinator, Christine McNeil, said it had seized 980 horses across England last year.
She said: “Last year we took in more horses than we have in any of the past four years, and with our inspectors being called to rescue more and more every week, we are stretched to the limits.
“Up and down the country, horses are being found sick, or dumped liked rubbish, dying or dead.”
West Yorkshire also had the country’s third-highest number of overall calls to RSPCA inspectors in 2017, with most relating to the care of dogs, cats or horses.
A total of 54 people were convicted of 110 animal welfare offences. Chief Inspector Jenner said these were often the saddest cases, as it meant they “haven’t managed to help the animal” from suffering serious harm.