Pain management in pigs: practical approaches

Over the last twenty years, there has been an ever-increasing focus on welfare in all sectors of animal agriculture.

(Iakov Filimonov | Dreamstime)
(Iakov Filimonov | Dreamstime)

Over the last twenty years, there has been an ever-increasing focus on welfare in all sectors of animal agriculture. Each sector has its own challenges, and in swine these include, but are not limited to, pain control, housing expectations, transport and enrichment. Currently in Canada these topics are becoming increasingly important to both consumers and producers because of both awareness and global expectations. This article will focus specifically on ways pig pain can be controlled in a practical manner.

There are three general types of medication used to control the sensation of pain in humans and animals. The first, analgesics, the most commonly used analgesics in swine in North America, are non-steroidal anti-inflammatory drugs (NSAIDs) such as meloxicam or ketoprofen. These commonly used medications can be used for anything from farrowing pain, mastitis, lameness, and pain due to castration or tail docking. The second medication is an anesthetic, which causes a loss of sensation. An anesthetic can be administered by injection or inhalation and can be local or general. Isoflurane is an example of an inhalation, general anesthetic, and lidocaine is an example of an injectable, local anesthetic. Opioids are the third method of pain control. Opioids are more commonly used in small animal practice and can only be administered by a veterinarian or prescribed in small courses of medication due to being a controlled substance. These are an effective method of pain control but have many barriers to their use including side effects and controlled substance labeling.

An anesthetic can be administered by injection or inhalation and can be local or general.

At our practice in Canada, we primarily use NSAIDs. NSAIDs are a good solution to numerous issues. The primary use of meloxicam in our practice is for lameness in sows; meloxicam is a good first choice when treating sows for locomotive pain as it has minimal adverse effects on the sow, such as ulcers. When feasible, we recommend the use of an NSAID for therapy secondary to an antibiotic in pigs from the nursery to finishing stages as well. It has also been shown that the use of meloxicam post-farrowing can decrease the time between farrowing and when the sow returns to eating, thus, likely improving lactation and piglet growth and well-being. Post-farrowing, NSAIDs can serve as adequate treatments for post-farrowing pain as well as secondary treatments to antibiotics for mastitis and metritis. Our practice highly recommends the use of NSAIDs in the treatment protocol for these diseases as well.

Pain control requirements

Recently, in Canada, the pain control requirements of the 2014 Code of Practice For the Care and Handling of Pigs came into effect. As of July 1, 2016, it is required that all piglets under 10 days of age are to be given analgesia at tail docking and castration. These expectations for pain control vary throughout the world. Every country also has varying regulations, and often these regulations are restricted to the drug handling regulations and availability of licensed products. For example, in some countries, it is permitted for producers and staff to use isoflurane (an inhalation anesthetic) on farm after receiving training; however, in Canada, isoflurane can only be used in licensed veterinary practices by animal health technicians or veterinarians. Regulations and cost can greatly limit the ability of producers within certain countries to achieve the gold standard for pain control. In response, our practice has recommended one of two treatment protocols: injection of meloxicam (Metacam for swine) at castration or oral administration of meloxicam to mitigate the post-castration pain.

Considering the barriers to use of a gold standard pain control protocol, in Canada the expectation now is that analgesics alone are used at castration and tail docking. A recent study in Canada using a novel behavioral analysis tool, shown in the photos, has shown promising results using injectable analgesics for pain control post-castration. The piglets are timed running through the chute and over two hurdles to analyze pain. The study has shown that piglets given injectable meloxicam (0.4 mg/kg IM, Metacam for swine, Boehringer Ingelheim Canada) are significantly faster after castration compared to piglets given no pain control. The study specifically looked at whether there was a difference in post-procedural pain control when the meloxicam was given 30 minutes prior to castration versus immediately before castration.

The study showed that there were no significant differences in the speed post-castration at any time point between the two treatment groups. This study is one of many worldwide that analyzes pain after castration using one of the few tools we have available to measure pain. However, it is the first of it’s kind using this novel behavioral analysis. There are more studies to be published using this tool that show the promising effects of using NSAIDs at castration.

Continuing to improve

Despite the positive results of studies comparing piglets treated with an NSAID at or before castration, the pain at the time of castration is not controlled, just the post-castration inflammation and pain. This speaks to the need for anesthetics, local or general. At this point in time there are ongoing debates as to the feasibility of anesthetics in regards to cost and time. In regards to local anesthetics, it has been determined they can be painful to inject and the appropriate injection technique (intratesticular or subcutaneous) continues to be disputed. Local anesthetics such as lidocaine have been shown to take up to 2 minutes to take effect as well. As for general anesthetics and opioids, the main push-backs to their use are the cost and the drug handling regulations, which vary from country to country.

As we move forward, regulations will change and new techniques will be developed. As for now, we can continue to analyze the effects of the protocols we are using in each country and continue to improve based on research and availability of the products required. Above all, it is essential to continue to be cognizant and ensure that the protocols that are put into place are effective.

Piglet pain medicine can be delivered through sow milk: www.WATTAgNet.com/articles/20570

 

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