The ISPCA is on course to receive twice as many calls about cruelty to horses this year as it did last year, reflecting an alarming increase in the number of recession-hit owners abandoning their animals.

In the first five months of this year alone, the animal welfare organisation received almost 1,000 calls to its helpline from members of the public concerned about sick or malnourished horses.

Most had been ill-treated by their owners or had been dumped and left to fend for themselves.

This compares to 1,141 such calls in the whole of 2009.

Worryingly, the 2009 figure was itself more than double the number of calls which it received in 2008, when it received 453 horse-related calls to its national animal cruelty helpline.

The ISPCA is aware of cases where horses have been dumped in fields or forests late at night, and frequently comes across animals tied up on the side of the road. It says that around one in three of the horses it deals with are thoroughbreds whose owners can no longer afford to pay for their upkeep.

The organisation has now warned that it is struggling to cope with demand for its services, meaning it may no longer be able to rescue horses from their owners.

"This year is continuing to throw up hungry, emaciated horses even in the month of June, which previously would have been most unusual due to improved weather and growth of grass," the ISPCA chairwoman Barbara Bent told the Sunday Tribune.

"This is a very worrying trend and highlights to our organisation that if this is to continue we must prepare now for what is likely to happen over the coming winter.

"The lack of capacity and finance to manage the numbers that need rescuing leaves ISPCA with the difficulty that in future once our centres are full we will have to leave the horses with their owners and supervise their care and welfare by many return visits.

"This frequently fails to achieve the necessary outcome as on many occasions all that happens is the owner moves the horses to a different location and just says they have been sold on."

Bent said the impact of the recession has meant less worming or lice treatment, less castration or veterinary care and less fodder or winter feedstuffs.

"The overproduction of low-grade, low-value horses is really coming to the fore and once a horse has little or no value it just descends to the bottom and gets abandoned," she said. "Another concern is the numbers of horses not being registered, not being castrated and left running with related mares and fillies. Such a case was found by one of our affiliated SPCAs recently where mares had foals at foot who were half blind and two produced blind strange foals since coming into our care.

"If this continues it will throw up more difficulties with the potential of inbred foals and very young fillies in foal which will add to the problem of poor quality foals."

The organisation has called on the various horse industries to adopt a more proactive approach to equine welfare problems, and increased funding to horse welfare organisations to deal with the current crisis.

"Extending the age of registering foals to one year rather than six months would also help," Bent said. "Having higher standards for breeding and a code of practice for sales and fairs would make a difference."