A group of vets has said they are concerned by European Commission proposals to legitimise the use of homeopathic remedies for animals.
There are concerns over using homeopathy on animals
In an open letter to the Royal College of Veterinary Surgeons, the group says there is no clinical evidence that homeopathy works.
The vets have signed the letter to the RCVS, calling for it to increase support for conventional medicine.
The RCVS has said it does not take a stance either way on homeopathy.
Professor Derek Knottenbelt, from the University of Liverpool, is spokesman for the group of forty concerned vets, professors and veterinary nurses.
He told BBC Radio Four's Farming Today programme that homeopathic treatments had not gone through the rigorous clinical trials of conventional medicines.
"Homeopathic medicine, in the broadest sense of the word, is unproven, unscientific, and unvalidated," he said.
"In any sense of the word it is an unjustified approach to an ill animal."
The RCVS says it only registers qualified vets and it is up to them whether or not they practise homeopathic medicine alongside their conventional treatments.
Its president, Lynn Hill said: "At the present time the Royal College does believe very strongly in clinical choice both for the veterinary surgeon and also the client."
Homeopathy is the treatment of 'like with like', its supporters say. Minute doses of substances that can cause signs of illness in a healthy person are used to treat the same symptoms in a sick patient.
Some homeopathic practitioners dilute the dose so much that no molecules remain of the substance being diluted - believing that the solution retains a "memory" or imprint" of the substance.
The vets who are objecting to homeopathic treatment say none of the remedies have gone through the rigorous clinical trials that usual medicines have to.
Animal welfare risk
Dr Simon Baker, a vet from Essex who signed the letter told the BBC: "Our main concern is that homeopathy is unlikely to benefit animals.
"Very little work has been done with homeopathy and animals at all. The main risk is that if anything does not go well their welfare has suffered.
"There is the potential for things to get worse and worse and homeopathy has the potential to provide explanations for all outcomes, whether things get better or worse.
"If an animal does get worse then it's not had the opportunity to have treatment that might have made them better.
"As vets, it's not our obligation to take regard of the owner's choice if that choice is not for the benefit of the animal's welfare."
But vet John Saxton, president of the faculty of homeopathy at the Royal London Homeopathic Hospital, told BBC News homeopathy was only used, where appropriate, as an "additional tool" in conjunction with conventional medicine.
It was backed up by "basic research, evidence and scientific theories," he added.
But its "great strength" was the ability to approach medical problems from "an entirely different point of view".
Carl Barton, farm manager for the Goodwood Estate in West Sussex, told Farming Today that homeopathy works.
"What one's got to remember is that these beasts we rely on for our livelihood," he said.
"So we're not going to do anything lightly. So we treat them with homeopathy, and it works very well. My herd is case proven."