Pain mitigation difficult without drugs

No approved products | Although analgesics have proven beneficial, the USDA still questions their safety

OMAHA, Neb. — New livestock codes of practice recommend pain relief for castration and tail docking, but few approved products are available.

More pain relief medications are likely to be approved in the future, but in the meantime veterinarians may have to rely on non steroidal anti inflammatories (NSAIDS) or extra label use.

“If you keep the inflammation down, the pain isn’t going to be there,” said Dr. Roy Lewis, an Alberta veterinarian and part-time technical services vet for Merck Animal Health.

“As a vet I am all for it, but there is also a limit,” he said.

Products such as Metacam and Banamine are available, but in some cases products may have to be ad-ministered differently than what the label prescribes and different withdrawal periods observed. More research is coming, but the science of pain management is a new field.

“The pharmaceutical companies could come up with these things, but who is going to pay for them?” he said.

New voluntary codes of practice recommend pain relief for various procedures. For example, the hog code of practice recommends that castration performed after 10 days of age be done with anesthetic and analgesic to help control pain. By 2016, all castration will have to be done with analgesics.

Scientists know animals feel pain and that analgesics provide relief, said Donald Lay of the U.S. department of Agriculture. Neurology, etiology, immunology, epidemiology and stress physiology specialists from the department’s livestock behaviour unit are looking at im-proved animal welfare and current practices.

“We know giving analgesics is beneficial and the public says, ‘why don’t you just do it,’ ” he told a pain management session held during the National Institute of Animal Agriculture held in Omaha April 1-4.

“That really puts the producer in the middle because they don’t have options for pain mitigation because there are no analgesics approved,” Lay said.

Dr. Frank Lewis, a veterinarian with the U.S. Food and Drug Administration, said regulators question the safety and effectiveness of these drugs.

They are unsure of withdrawal periods or if there are unsafe residue levels.

“If there is an unknown safety concern, we can’t vouch for it,” he said.

Lewis agreed that products are needed to alleviate suffering. Some extra label use of analgesics and anesthetics is permitted under U.S. rules.

He said producers need a strong relationship with their veterinarians, who must oversee the use of the product and withdrawal times and minimize risk of unsafe residues.

“Technically, it is a vet-client relationship. As far as the legal authority, it gets a little bit tricky,” Lewis said.

“Any food that contains residue or any animal that was treated in an illegal way is considered adulterated under our law.”

Pain is a complex reflex because individuals feel things differently. It is hard to understand how an animal feels pain, so researchers have to depend on other external factors such as behaviour.

Lay said certain procedures leave lingering effects that could be compared to phantom pain experienced by human amputees. A neuroma, which is a collection or swelling of nerves, can form at the end of the in-jury and be painful even after healing takes places.

Neuromas are sensitive to heat and cold, and Lay said chickens with trimmed beaks or pigs and dairy cattle with docked tails may have chronic pain.

It is a balance. Cannibalism among chickens is common so beak trimming is done to keep them from pecking one another to death.

“This is especially a concern in an open housing situation where they are altogether,” he said.

Beak trimming is painful no matter how it is done. United Egg Producers adopted infrared laser beak trimming in 2010 because it was deemed the best of a painful list of options.

Performance of laying hens is the same whether beaks were trimmed or not. People say birds are all right if they are laying eggs, but it has been documented that hens with broken keel bones still lay eggs.

Birds may fracture their keel bones when they jump down from perches after moving into aviaries.

Newborn piglets undergo routine but stressful procedures such as castration, teeth clipping, tail docking, ear notching or ear tagging.

Research shows that these procedures are less stressful if they are done quickly and accurately.

Researchers are also studying humane euthanization.

Tyson Foods banned killing young pigs with blunt force trauma in January.

An alternative is carbon dioxide in a chamber, but it appears to be painful. A two stage system that sedates the piglets first and then exposes them to the toxic gas is better.

Lameness is another common problem among dairy cows and sows, which are often culled when they struggle to walk.

Lay said loose sow housing will likely exacerbate the lameness problem. A USDA project theorized that exercised sows would have fewer incidences of lameness because their bone density and muscular weight would increase compared to control sows.

This was not the case because many sows have premature osteo-arthritis. Researchers e speculate they are growing so fast they are not remodelling bone and cartilage correctly.