A long-acting pain killer that can be offered to pet owners to safely and effectively treat their animals at home would be the next great step forward in veterinary analgesia, BSAVA members heard at the congress last month.
Ian Self from the University of Nottingham told colleagues at the association’s conference in Birmingham on 7th April that better products for controlling chronic pain would tackle one of the major unmet needs in small animal veterinary practice. Prof. Self, a European diplomate in veterinary anaesthesia and analgesia, gave a presentation on the history of his clinical specialism in one of a series of lectures marking the 60th anniversary of the BSAVA.
He pointed out that a look at developments in the discipline will demonstrate that “progress in science is neither linear nor inevitable” and the medical professions cannot always reflect back with pride on all the practices and attitudes adopted by previous generations of anaesthetists in human and veterinary medicine.
While it was known in ancient times that herbal-based drugs such as morphine, aspirin and cannabis are useful in controlling pain from disease, and both during and after surgery, there was a curious reluctance to use them in both people and animals. Indeed, there was a widely-held belief before the first modern anaesthetics became available during the Victorian era that pain was a positive thing. It was beneficial in speeding up recovery and reducing the risk of further injury by restricting the patient’s ability to move around, he said.
Even after anaesthetics became routine in human surgery, leading veterinarians spoke about the need for drugs to control patients in order to facilitate their work, rather than concerns about the interests of the animal. In case anyone believed that vets are now solely focused on patient welfare, Prof. Self noted comments published as recently as 2011 which argued that the main purpose of anaesthesia in farm animal patients was to eliminate the risk of injury to the surgeon. However, there have been remarkable advances in anaesthesia and in controlling acute pain, starting around the time that the BSAVA was established.
Halothane, the first modern inhaled anaesthetic, was introduced in 1956, allowing theatre staff to work without fear of the explosions that would sometimes occur when using ether. There was a rapid succession of other new and increasingly safe anaesthetic agents in the years following, along with the development of reliable pre-medication agents, intravenous anaesthetics and both local and systemic analgesics, he said.
Looking forward, Prof. Self believed that some of the most important future developments will occur as a result of better delivery systems for existing products rather than innovations in the agents available. There is also a need for better methods for assessing the efficacy of the treatments being given to veterinary patients. “We need more developments of pain scales which have revolutionised what we do in our treatment of pain and in the welfare assessments used in animals,” he said. “Now we need more validated scales that can be used in assessing chronic pain – I run a lot of clinics for patients with chronic disease conditions and I have real problems in defining how well I am doing.”
There is also an urgent need for better methods to identify and assess pain in other species seen in veterinary practice – horses, ruminants and in exotic pets such as birds and reptiles, he said. Veterinary anaesthesiologists should also be concentrating on developing methods to allow safer general anaesthesia. The mortality rate in canine procedures is very much lower than it was for earlier generations, he said. But the current death rate of around one in 800 cases is still much higher than in human anaesthesia, where there is a risk of fatal complications in around one in 100,000 to 200,000 cases. Meanwhile, in horses the death rate can be as high as one case in 100. “That is certainly something that we need to improve over the next 10 to 20 years,” he said.
