Why different painkillers are only effective for certain types of pain

Maree Smith, The University of Queensland

Whether it’s your head, tooth or back, when you’re in pain, it’s hard to think about anything else. If it’s not too strong, some can ride it out. But in many cases, the pain just gets worse and won’t go away until you take something.

Medicines that kill pain are called analgesics and they vary in how they work. No single painkiller can relieve all types of pain. Those that work for mild pain usually have little effect on severe pain unless combined with a stronger painkiller.

If you want to effectively control your pain, you will need to match your medication to its type and severity.

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Nociceptive pain

Nociceptive pain is caused by damage to body tissue. If the pain is mild, such as a headache or a sprained ankle, commonly used over-the-counter painkillers are effective. These include tablets containing paracetamol (Panadol), aspirin, or non steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen (Nurofen).

Paracetamol helps to dampen pain signals to the brain. NSAIDs inhibit the activity of the enzymes that lead to pain, inflammation and fever being produced in the body.

If you want to control your pain, you will need to match your
medication to its type and severity. Author provided

Combination tablets, which have a small dose of codeine plus paracetamol, aspirin or ibuprofen, can be used to treat moderate pain. In Australia, you can buy these kinds of painkillers only in a pharmacy. Those sold over the counter have brand names such as Panadeine, Aspalgin and Nurofen Plus.

The government recently announced it will make any medication containing codeine available only with a prescription from mid-2016.

It is important to remember the maximum adult dosage for paracetamol is four grams (eight tablets) per day. Taking more than the recommended dose can cause damage to your liver.

Painkillers typically prescribed by a doctor to relieve acute to moderate pain are codeine together with paracetamol tablets (Panadeine Forte) and tramadol tablets, which are opioid pain killers.

The severe pain you experience following a broken bone or an operation usually needs strong painkillers that your doctor would prescribe. This may be morphine given as a tablet or by injection.

Morphine-like medicines relieve pain by interacting with specific proteins called opioid receptors, which are located in the brain, spinal cord and other parts of the body. These opioid receptors are the same ones the body’s own natural pain-killer molecules, called endorphins, use.

Neuropathic pain

Neuropathic pain is pain caused by damage to the nerves. Painkillers such as morphine, NSAIDs and paracetamol that are effective for the relief of nociceptive and inflammatory pain conditions are not effective for the relief of neuropathic pain.

This is because the underlying mechanisms that cause neuropathic pain following nerve injury are different from those that induce nociceptive and acute inflammatory pain.

Medications originally developed to treat depression and epilepsy are recommended as first-line treatments for the relief of neuropathic pain.

Antidepressants alleviate neuropathic pain by boosting the body’s own pain-fighting pathways. This includes boosting signalling in the brain which inhibits pain-signalling at the level of the spinal cord. The detailed mechanisms by which anti-epileptic drugs alleviate neuropathic pain are diverse but the net effect is to dampen pain signals.

Migraine pain

Paracetemol is an effective painkiller for mild pain.
Pete/Flickr, CC BY

Migraine is a particularly debilitating type of pain. It is often accompanied by nausea, vomiting and sensitivity to light and sound. It can last for a few hours or several days.

Migraine affects about 12% of Australians. Some experience auras such as flashing lights or changes in smell perception, which can serve as early warning signs the migraine is coming.

If painkillers such as paracetamol, aspirin, ibuprofen or ergotamine (made specifically to relieve migraine by narrowing blood vessels in the brain) are taken at the onset of the aura, the migraine can often be stopped or its severity reduced. For those suffering a severe migraine attack, prescription medications known as triptans can be effective treatments by reversing the brain blood vessel dilation.

Chronic inflammatory pain

Chronic pain affects up to one in five adults. One of the most common is pain from osteoarthritis, the most common type of arthritis.

Osteoarthritis pain is a chronic inflammatory pain caused by arthritic joint disease, typically in the knee or hip. As the joint cartilage and underlying bone break down, the joint becomes inflamed and this triggers the pain. The first-line painkiller for osteoarthritis pain is paracetamol.

For people with more severe pain, NSAIDs such as naproxen may be more effective. But chronic use of these is associated with an increased risk of side effects, especially bleeding and ulceration of the stomach lining. Less commonly, morphine or strong morphine-like analgesics are prescribed.

Cancer pain

Most cancer pain is caused by the tumour pressing on bones, nerves or other organs in your body. Pain can also be caused by the cancer treatment such as chemotherapy or radiotherapy. Oral morphine-like analgesics taken regularly, often in combination with paracetamol, are prescribed for moderate to severe chronic cancer pain.

Although drowsiness usually occurs at the start of treatment or after a dosage increase, this typically reduces after a couple of weeks. Anti-nausea and laxative agents are given at the beginning of treatment to minimise the side effects of nausea, vomiting and constipation. Nausea usually lasts no more than two to three weeks.

However, as constipation persists, it is very important that laxative use is maintained. For cancer pain involving nerve impingement, your doctor will add a prescription painkiller for neuropathic pain.

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This article is part of a series focusing on Pain. Read other articles in the series here.

Maree Smith, Executive Director, Centre for Integrated Preclinical Drug Development and Professor of Pharmacy, The University of Queensland

This article was originally published on The Conversation. (Reblogged by permission). Read the original article.
 

Health Check: what causes headaches?

Michael Vagg, Barwon Health

We all get headaches from time to time. In fact, nearly every second person in the world had a headache at least once in the past year. But these can feel very different, depending on which of the nearly 200 types of headache you have.

More than half (52%) of people will have a tension-type headache at some point in their life, around 18% will get a migraine, and 4% will suffer from chronic daily headaches. These are the most common headache-related diagnoses. Although there are some variations globally, the figures seem remarkably consistent across populations.

Secondary headaches can be initiated by triggering factors such as medication overuse, medication side effects, neck pain, sinus disease or dental problems. These account for small percentages individually compared to the primary headaches, but may be more treatable if the predisposing problem can be sorted out.

Tension-type headache

Tension-type headaches (TTH) feel like a dull or heavy, non-pulsating band of pain, usually on both sides of the head. The name comes from an erroneous belief that overly tight muscles are the main reason for the headache.

TTH usually occurs in episodes, with each lasting from several hours up to a few days at a time. There is not usually much associated nausea, light sensitivity or sound sensitivity.

Chronic TTH is a less common form and is diagnosed when you have experienced at least 180 days with a headache per year. It is generally not aggravated by routine physical activity; it’s just there all the time.

Genetic tendencies explain some of the risk for developing TTH, with your own risk increased threefold if you have an immediate family member with the condition.

Infrequent episodic TTH does not appear to be strongly associated with psychological stress, despite this common belief. Chronic TTH has a stronger association with higher psychological distress, but it is unclear whether this is a cause or effect of having long-term disabling headaches.

Strangely for such a common and problematic condition, there is still little agreement about exactly how the pain is produced in TTH.

The most attractive hypothesis to me is that it represents a “virtual” pain whereby multiple low-grade inputs (likely including inputs that are “almost-painful”, or below the threshold for conscious pain) add up to produce sensitisation of the trigeminal nerve nuclei (the nerve shown in orange below).

stihii/Shutterstock

This turmoil registers as pain referred to the distribution of the head, usually the forehead, temple and back of the head locations. Examination of these areas doesn’t show any abnormalities because in TTH, there is no one driving mechanism of the headache.

Treatment remains almost trivially simple, despite years of research. It’s almost true to say that the proverbial “cup of tea, a Bex and a good lie down” sums it up. Aspirin, paracetamol or ibuprofen plus rest and possibly some cold packs seem to be the most reliable treatment. There is conflicting or negative evidence for almost every other, fancier therapy.

Migraine

Migraine alone is the sixth most disabling condition globally.

Migraines are usually one-sided, associated with nausea and light sensitivity (photophobia) and may also be preceded by idiosyncratic sensory experiences called an “aura”. Aura phenomena can include moods or emotions, such as deja vu, visual symptoms (flashing lights or jagged lines are common) or problems with speech.

Migraine is a clinical diagnosis; there is no objective test that can verify it with our current technology. But compared to the frustration of researching and treating tension-type headaches, migraine has been steadily giving up its secrets over the past decade.

Migraine physiology is extremely complex. The headaches seem to arise because of dysfunctional regulation of the tone of some of the blood vessels inside the skull.

Migraine sufferers – Migraineurs – may have genetic vulnerability to migraines because of overly responsive calcium channels in their nerve membranes or other mutations which result in them having overactive signalling pathways in the brain.

Environmental or internal triggers can provoke these nerves to over-react, resulting in the activation of a reflex pathway. This dysregulation of normal structures causes the headache, nausea, photophobia and phonophobia (sound sensitivity) typical of an attack.

Migraines are often associated with light sensitivity. Rishi Bandopadhay/Flickr, CC BY-NC

The period of headache in a migraine attack corresponds with a rise in the blood levels in the head of a peptide called calcitonin gene-related peptide (CGRP). CGRP is one of the most common pain-inducing signal molecules in the body. When the CGRP falls, the headache goes away. Where the extra CGRP comes from is not clear but it probably is released from the overactive networks of cells in the brainstem.

The most effective group of drugs for migraine are the triptans. So effective and specific are these drugs that the diagnosis of migraine needs to be reconsidered if they don’t abort the headache attacks most of the time.

Triptans work by activating certain subtypes of serotonin receptors in the brain. Taking a triptan early in a migraine attack seems to directly lower the CGRP release and oppose its effects on blood vessels thereby stopping the attack. Triptans are not however useful to prevent frequent attacks of migraine.

Migraine prophylaxis is achieved by several drugs of different classes, with radically differing mechanisms of action. Some are anticonvulsants, which clearly work by suppressing the nerve overactivity typical of migraineurs. Others, such as the beta-blockers (propranolol) and calcium-channel blockers (verapamil) target the nerve endings on the blood vessels. Others which are known to be effective, such as botulinum toxin (Botox) and amitriptyline (Endep) work by means which are yet to be fully understood.

Severe migraineurs suffer years of disability and as a public service I would like to suggest that if you know someone who has severe migraines (you almost certainly do) please read this excellent list of what not to say to them when trying to be sympathetic or helpful.

Chronic daily headache

Imagine that you never had a day without headache. You can remember vaguely the time when you didn’t feel that pounding in the temples, squeezing in the back of the head or piercing pain above the eyes but it seems like another life. Such is the lot of sufferers of chronic daily headache (CDH).

Some headaches begin as as frequent but clearly episodic tension-type headache, or migraine, but then “transform” into what seems to be basically a continuous headache for at least some part of every day.

There are a number of rare headache types which may cause chronic daily headache and diagnosis of the these can lead to specific treatments which work well. This is the role of a neurologist or pain specialist with a special interest in headache.

If you have more than just the occasional headache, it pays to get a proper diagnosis. Jared Earle/Flickr, CC BY-NC-ND

Possibly the most common reason why tension-type headache or migraine can transform is medication overuse, especially short-acting opioids such as codeine. The best solution to this problem is to avoid long-term regular use of codeine for headaches, though the evidence would suggest we may never achieve this goal except by making codeine prescription-only.

Frequent use of triptans is also believed to sensitise the trigeminovascular networks in the brainstem, thereby lowering the bar for triggering of migraine attacks. If the threshold for an attack becomes too low, they may never quite switch off, and one attack will run into the next one.

If you have more than just the occasional headache, it pays to get a proper diagnosis, as the reasons for your headache can be many and varied. Some have specific treatments for them, and others such as TTH seem quite difficult to find a specific treatment for. There are new classes of drug treatment under development, for migraine in particular, so it looks hopeful that future generations may not have to labour under the burden of poorly treated headaches.

Michael Vagg, Clinical Senior Lecturer at Deakin University School of Medicine & Pain Specialist, Barwon Health

This article was originally published on The Conversation. (Reblogged by permission). Read the original article.

Do animals feel pain like we do?

Andrea Nolan, Edinburgh Napier University

Pain is a complex experience involving sensory and emotional components: it is not just about how it feels, but also how it makes you feel. And it is these unpleasant feelings that cause the suffering we humans associate with pain.

The science of suffering is well documented in the book of the same name by Patrick Wall. We know that animals certainly feel physical pain, but what is less clear is whether this emotional suffering that we feel can be said to be true of animals. And if it is, how we go about measuring it.

As a subjective emotion, pain can be experienced even in the absence of physical tissue damage, and the level of feeling can be modified by other emotions including fear, memory and stress. Pain also has different dimensions – it is often described in terms of intensity but it also has “character”, for example the pain of a pin-prick is very different from that of a toothache, a slipped disc or labour pain. Nearly all of us have experienced pain in our lives, but for each person, the experience is uniquely individual.

To understand or appreciate others’ pain we mostly rely on what they report. But there are many who either cannot communicate their pain verbally, babies for example, or effectively, like those with dementia or learning disabilities. In these situations, others must use a range of factors to judge the presence of pain and its impact on the individual.

Pain is not all bad – it serves a protective function, to keep us away from further danger, to help us heal, for example by stopping us from putting weight on a sprained ankle. But if it isn’t managed effectively it can have a major negative impact on our lives inducing fear, anger, anxiety or depression – all emotions which may in turn exacerbate it. And chronic pain is a major concern to millions of individuals and to our societies around the world.

Pain in animals

The nature of pain is perhaps even more complex in animals. How pain is sensed and the physical processes behind this are remarkably similar and well conserved across mammals and humans. There are also many similarities in pain behaviours across the species, for example they may stop socialising with people and/or other animals, they may eat less, they may vocalise more and their heart rate may rise. The capacity of animals to suffer as sentient creatures is well established and enshrined in law in many countries, however we don’t understand well how they actually experience pain.

Some aspects of the experience and expression of pain are not likely to be the same as in humans. First, animals cannot verbally communicate their pain. Dogs may yelp and you may notice behaviour change but what about your pet rabbit, cat, tortoise or horse? Animals rely on human observers to recognise pain and to evaluate its severity and impact. Without the ability to understand soothing words that explain that following surgery to repair a bone fracture, their pain will be managed (hopefully) and will subside, animals may also suffer more when in pain than we do.

Loud and clear. William Heron, CC BY-SA

The debate around animals’ capacity to experience pain and suffer raged in the 20th century, but as we developed a greater understanding of pain, and studied its impact on the aspects of animal life that we could measure, we veterinary surgeons, along with many behavioural and animal scientists, recognised the significant impact of untreated pain, and we now believe this experience causes them to suffer.

For example, we know that animals and indeed birds with clinical signs of pain (limping) will choose to eat food containing pain-killing drugs (analgesics) over untreated food, and by measures of behaviour, they will improve.

Similarly many studies in a range of domestic animals have indicated that animals who have had surgery but not had adequate pain relief demonstrate behaviours reflective of pain which are alleviated when they are treated with analgesics such as morphine.

We also know that it is not just our dogs and cats that can suffer pain – there is an equally strong evidence base for the presence and negative impact of pain in sheep, cattle, pigs and horses among other species. But recognising pain in these different species is part of the complexity associated with animal pain. Managing it in animals that we rear for food and those that we keep as companions is equally challenging.

Behavioural disturbances have long been recognised as potential indicators of the presence of pain in animals. However it is important to recognise that each species manifests its own sometimes unique pain-related behaviours or behavioural disturbances in different ways, often rooted in the evolutionary process, so prey species, for example, are less likely to “advertise” an increased vulnerability to predators. Dogs may become aggressive, or quiet, or may stop socialising with “their” humans and other dogs. Sheep, on the other hand, may appear largely the same when casually observed.

Some expressions of pain however may be conserved. A recent paper suggested commonality in some features of facial expression during acute pain experiences in several animal species and humans.

These findings and much other work are being incorporated into tools to evaluate animal pain, because in the words of Lord Kelvin, the great Glaswegian scientist behind the Kelvin temperature scale, said: “When you cannot measure it, when you cannot express it in number … you have scarcely, in your thoughts, advanced to the stage of science, whatever the matter may be”.

So in order to treat and manage pain effectively we must measure it.

And there is a huge demand for these tools. The Glasgow Composite Pain Scale, a simple tool to measure acute pain in dogs and
first published in 2007, has been translated into six languages. It is used in veterinary practices to measure pain to treat it effectively. It has also been used to evaluate the effectiveness of new analgesic drugs that are being developed by animal health companies. Tools to measure the impact of chronic pain, such as osteoarthritis, on the quality of life of dogs are now available and are a significant advance in managing chronic conditions.

There is now a global effort to raise awareness of pain in animals. Recently the World Small Animal Veterinary Association launched the Global Pain Council and published a treatise for vets and animal keepers worldwide to promote pain recognition, measurement and treatment. Dogs may be man’s best friend, but for all those who work with, care for and enjoy the company of animals, understanding how their pain feels is essential to improving the quality of their lives.

Andrea Nolan is Principal and Vice-Chancellor at Edinburgh Napier University .

This article was originally published on The Conversation. (Reblogged by permission). Read the original article.

Why fish (likely) don’t feel pain

Scientia Salon

by Brian Key

What’s it feel like to be a fish? I contend that it doesn’t feel like anything to be a fish.  Interestingly, much of our own lives are led without attending to how we feel. We just get on with it and do things. Most of the time we act like automatons. We manage to get dressed in the morning, or walk to the bus station, or get in the car and drive to the shops without thinking about what it feels like. Consequently, much of what we do is accomplished non-consciously.

There is an enormous amount of neural processing of information in the brain that never reaches our consciousness (that is, we never become aware of it and hence are unable to report it). I propose that fish spend all of their lives without ever feeling anything. In a recent paper in the academic journal Biology &…

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Ten Animal Welfare Myths

by Tim Harding, B.Sc.

(An edited version of this essay was published in The Skeptic magazine, June 2014, Vol 34 No 2, under the title ‘Creature Features’. The essay is based on a talk presented to the Mordi Skeptics in February 2012).

The term ‘animal welfare’ is not easy to define, but it usually includes the mental and physical aspects of an animal’s well-being, as well as people’s subjective ethical preferences as to how animals should be treated.  These preferences can give rise to a range of opinions about animal welfare; but as we skeptics are fond of saying: ‘people are entitled to their own opinions but not their own facts’.

I realise that this article may be controversial, even amongst my fellow skeptics.  Nevertheless, I would like to focus on some common factual misunderstandings about animal welfare; and try to dispel a few myths.

There appear to be two extreme polarised positions in the community regarding animal welfare.  An outdated view, often attributed to Rene Descartes (1596 –1650 CE), is that animals are not consciously aware, and are therefore unable to experience pain and suffering.  At the opposite pole are those who believe that animals have rights like humans do; and that hunting, farming and other uses of animals for human purposes are morally unacceptable.  Between these two extremes are various other views, including evidence-based or scientific approaches versus the so-called ‘organic’ or free-range farming industries.

Animal welfare science is a relatively new field of study; but some good research is now being done – including in Australia.  The two main experimental approaches are firstly, animal physiological and biochemical testing (e.g. blood tests) to objectively measure stress in animals under different conditions; and secondly, animal behavioural and preference studies (such as testing whether animals prefer more food or better surroundings).

Myth #1: Animals are best treated like humans

The attribution of human characteristics to non-human animals is known as anthropomorphism.  It is sometimes used to appeal to human emotions in campaign slogans about animal welfare (e.g. ‘Meat is murder!’ and ‘How would YOU like to be kept in a cage?’).

There are two main problems with an anthropomorphic approach to animal welfare. Firstly, it is emotional rather than evidence-based – and is therefore unscientific or lacking in objectivity.  Secondly, treating animals like humans is often a projection of human preferences rather than a consideration of the real needs of the animal.  Apart from the obvious differences in intelligence, anatomy and physiology, animals have different instincts to humans and they express a much more limited range of emotions than humans do.

Most of us love our pets and regard them as members of the family.  But treating them like little humans may not actually be in their best interests.  For instance, most of us are aware that chocolate is poisonous to dogs, but we may not be as aware that onions, garlic, grapes, avocados and macadamia nuts are also toxic to canine animals.[1]  Many dogs are also lactose intolerant, so dairy products are not a good idea for them either.[2]  So we should be careful about feeding human leftovers to dogs.

Myth #2: Dogs are tame wolves

Our treatment of dogs has been shaped by a historical view that they are basically wolves with nicer table manners. This is the concept behind much of traditional dog training – that dogs are pack animals competing with humans for dominance over the family.  This outdated view is now being challenged by modern canine science.[3]

All dogs are different varieties of one species descended from wolves.  Archaeological evidence now shows that dogs were first domesticated over 20,000 years ago – long before the first human settlements (around 9000BCE) and while we were still hunter-gatherers.  Dogs used to follow human hunters and scavenge from our leftovers.  We may have even used dogs to assist in our hunting.

Over this quite long period, dogs have been selected by humans for their mental temperaments as much as their physical characteristics.  As a result, modern pet dog breeds often bond more closely with humans than with other dogs.  It can therefore be bad welfare to deprive pet dogs (not farm dogs) of human contact for extended periods.

Myth #3: Some dog breeds bite humans more than others

Statistical research by the Victorian Bureau of Animal Welfare (BAW) has shown that the major contributing factor to dog attacks in urban public places is the inadequate confinement of dogs to their property, rather than the breed of dog.  Most incidents occur on the footpath or road bordering the dog owner’s property, as a result of dogs displaying territorial aggression toward people passing by or attempting to access the front door.  If owners ensured their dogs were adequately confined to the house or back yard, over 80% of dog attack incidents in public places could be prevented.[4]

The BAW studies have not shown that ‘restricted breed dogs’ (i.e. dogs bred for fighting) are excessively represented in the incidence of dog attacks on humans.  Any dog can bite if sufficiently provoked.  However, because of the relative strength of fighting dogs and their habit of tenaciously gripping their victims with their teeth and shaking them, anecdotal evidence suggests that the risks of injury and death may be greater from these types of dogs if and when they do attack humans.

Myth #4: Feeding stray cats is being kind

A survey by Monash University in 2005 found that 22 per cent of people said they sometimes fed a cat that did not belong to them.[5]  People may feel they are being kind because they know that stray cats suffer from starvation, disease and injuries from fights with other cats. But because they are ‘unowned’, stray cats are deprived of the regular meals, shelter, grooming and veterinary care that owned cats receive.  Feeding stray cats provides people with a short-term ‘feel good factor’ that acts against the long-term welfare of the cats.  It is a form of preference failure. Being a stray cat is not a sustainable lifestyle, with an average life-expectancy of only 3 years.  So feeding them actually perpetuates the misery of these poor animals (and their kittens), which on a rational basis should either be adopted as pets or euthanased.

An adverse side-effect is that stray cats are also more likely to kill birds, possums and other native animals than owned cats, at least some of which are kept indoors overnight.  The kindest thing to do for a stray cat would be to ‘adopt’ it (but have it checked for a microchip by a vet first).  If this is not possible, contact an animal welfare organisation such as the RSPCA or the Cat Protection Society.

Myth #5: Livestock are slaughtered inhumanely in Australia

Slaughter standards in Australian abattoirs are dictated by the Australian Standard for the Hygienic Production of Meat and Meat Products for Human Consumption (AS 4696 — 2007), which requires that:

1. Animals are slaughtered in a way that prevents unnecessary injury, pain and suffering to them and causes them the least practicable disturbance; and.

2. Before killing commences, animals are stunned in a way that ensures that the animals are unconscious and insensible to pain beforehand, and do not regain consciousness or sensibility before dying.[6]

There is provision for a religious exemption under an approved arrangement that allows ritual slaughter involving the commencement of killing without prior stunning.  However, such animals must then be stunned without delay to ensure that they are rendered unconscious whilst dying.  Personally, I am opposed to such religious exemptions, on the grounds of cruelty.

Myth #6: Meat chickens are kept in cages

Many people are surprised to learn that no meat chickens (also known as broilers) are kept in cages, at least in Australia.  They are farmed in large ventilated barns or sheds where they are free to roam large distances, albeit under crowded conditions, as shown in the photograph below.  Traditionally, this has not been done for welfare reasons but to allow faster and easier collection for processing, which is usually done at night.

An RSPCA approved Australian meat chicken shed

In Australia, feed lines and pans run the length of the shed and are supplied automatically by silos from outside. Water lines run the length of the shed, with drinkers at regular intervals. Water and feed are placed so that chickens are never more than about 2 metres from food and water.

Myth #7: Free range chooks live mainly outdoors

Chickens naturally prefer to live under cover from predators and bad weather. In the wild, they forage for insects and other food beneath shrubs and undergrowth, only venturing out into the open for short periods of time.

Free range chickens preferring shade (source: Wikimedia Commons)

There are no government regulations about free-range farming practices – this is left to industry self-regulation.  Australian industry standards specify that free-range chickens only need free access to the outdoors – they don’t actually need to spend any time outside a shed to qualify as free-range.  As a result, free-range chickens don’t usually spend the bulk of their time in the open, as illustrated by the photograph above. Some free-range farms have sheds on wheels or other movable housing structures.

Myth #8: Pigs are permanently kept in sow stalls

This claim is often made by animal rights activists but is untrue.  The reason for confinement in sow stalls (gestation stalls) is to minimise early abortions as a result of stress from aggressive behaviour between adult female pigs (sows).[7]

The endorsed Australian national standards for pig farming specify a maximum confinement period of 6 weeks during the initial stages of pregnancy.  Parts of the pork industry are voluntarily introducing shorter periods, but these will require more supervision (and thus higher labour costs) to separate sows that fight.

There is also some public confusion between gestation stalls and farrowing crates, especially when photographs of the latter (see below) are described as the former.

Sow farrowing crate (source: Wikimedia Commons)

Sows are moved in groups to farrowing sheds approximately one week prior to giving birth.  In Australia, a farrowing crate is only used for piglet feeding purposes.  It allows the sow less movement than a gestation stall, but provides creep areas along either side for the piglets. Adjustable rails alongside the sow slow her movement when she is lying down, thus protecting piglets from being crushed.  As soon as the piglets are weaned, the sow is moved to either a much larger pen or outdoors.

Myth #9: Sheep mulesing is cruel and unnecessary

Mulesing is the removal of wrinkled skin from the breech or breech and tail of a sheep using mulesing shears.  Until accepted alternatives are developed and the current practice can be phased out, mulesing of lambs remains an important husbandry practice in Australia for animal health, welfare and management reasons.  The principal reason is to reduce urine and faecal soiling or dag formation in the breech and tail wool; and thus minimise susceptibility to even more painful breech and tail flystrike.

Currently, cost effective chemical, management and breeding solutions are not available for all types of production systems in Australia and mulesing is a valuable tool for the prevention of breech flystrike for certain production environments and sheep types.  Although potentially painful, mulesing can be a net welfare benefit.

Available scientific research suggests that it is possible to achieve pain relief in conjunction with mulesing. Pain relief is most effectively achieved through a combination of approaches such as the pre-mulesing administration of a systemic pain relief drug, followed by a post-mulesing application of topical anaesthetic to deal with the ensuing period of pain associated with the inflammatory phase.  That is to say, a combination of short and long-acting pain relief drugs may be needed to provide more complete pain relief.[8]

Myth #10: Fish can’t feel pain

The International Association for the Study of Pain’s widely used definition states: ‘Pain is an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage’.[9]  Unlike in humans, pain is difficult to observe and measure in fish, especially in the absence of tissue damage.

Even when pain avoidance is observed experimentally in fish, a possible explanation is that it is a conditioned response to stimuli without the adverse emotional experience necessary for suffering.  Because of these observational difficulties, the conclusion that fish experience pain is often inferred on the basis of comparative neural anatomy and physiology. Some scientists are currently of the view that all higher vertebrates feel pain; and that certain invertebrates, like the lobster and octopus, might too.

The current approach in Australian animal welfare regulation is to give the fish the benefit of the doubt, and to presume until further research that fish can feel pain.  Whilst painless fishing may be almost impossible to achieve, banning fishing would also be politically impossible in a democracy.  The current regulatory approach is to minimise pain by requiring fish to be either killed or released as soon as possible after capture.

Conclusion

It may come as no surprise that I support the current scientific approach to animal welfare rather than an anthropomorphic or animal rights approach.  My main reasons for this view are:

• Evidence-based animal welfare standards are being progressively adopted by Australian governments.
• Such standards are more likely to be enforced and complied with than other approaches.
• As a result, animal welfare is steadily improving in Australia.
• This approach maintains the competitiveness of Australian agriculture.

Tim Harding B.Sc. has worked for the last 13 years as a regulatory consultant, amongst other things evaluating state and national animal welfare regulations for both domestic animals and livestock.  

References: 

[1] Warren, Katrina.  DrKatrina.com web site.

[2] Pet MD web site. Dietary Reactions in Dogs.

[3] Bradshaw, John (2011) In Defence of Dogs. Penguin Books, London.

[4] Harding, Tim (2005)  Proposed Domestic (Feral And Nuisance) Animals Regulations 2005 – Regulatory Impact Statement. Department of Primary Industries, Attwood.

[5]  http://www.theage.com.au/environment/animals/citys-stray-cat-problem-has-melbourne-throwing-a-hissy-fit-20130610-2o07j.html

[6] Browne, Gavin  (2007)  Australian Standard for the Hygienic Production of Meat and Meat Products for Human Consumption (AS 4696 — 2007). Food Regulation Standing Committee Technical Report Series 3.  CSIRO PUBLISHING / Food Regulation Standing Committee, Collingwood.

[7] Harding, Tim and Rivers, George (2006) Proposed Model Code Of Practice For The Welfare Of Animals – Pigs: Regulatory Impact Statement. CSIRO PUBLISHING, Collingwood.

[8] Harding, Tim and Rivers, George (2013) Proposed Australian Animal Welfare Standards And Guidelines – Sheep: Consultation Regulation Impact Statement. Animal Health Australia, Canberra.

[9] Bonica, John (1979) The need of a taxonomy. Pain. 1979; 6(3): 247–8.

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