By Jessie Collins
What is pain? – Pain is defined by the International Association for the Study of Pain (IASP) as “an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in term of such damage.” The IASP adds, “The inability to communicate verbally does not negate the possibility that an individual is experiencing pain and is in need of appropriate pain-relieving treatment.”
Types of Pain
- Acute Pain – caused by an injury to the body. It warns of potential damage that requires action by the brain, and it can develop slowly or quickly. It can last for a few minutes or six months and goes away when the injury heals properly. It is usually associated with quantifiable changes to processes providing the body with protection from damage (defensive body processes).
- Chronic Pain – pain that persists long after the trauma has healed, and in some cases it occurs in the absence of any trauma or tissue damage. Chronic pain does not warn the body to respond, and it usually lasts longer than 6 months. Quantifiable changes to the functioning of defensive body processes may NOT be seen.
- Chronic Inflammatory Pain – occurs when healing persists beyond the expected time, due to infection or other inflammatory processors.
- Chronic Neuropathic Pain – may not have a well defined onset and may not respond to treatments that are effective against acute or chronic inflammatory pain. It is sometimes described as “intractable” (hard to control or deal with) pain.
- Cancer (malignant) Pain – pain associates with malignant (very virulent or infectious) tumors. Tumors invade healthy tissues and exert pressure on nerves or blood vessels, producing pain. Cancer pain can also be associates with invasive procedures or treatments.
The taxonomy (classification) of pain is also categorized based on the source. The purpose of each category is to suggest possible causes for pain, its severity and most appropriate therapy.
Sites of Origin Pain
- Somatic (relating to the body) Pain – originates from the body including skin, bone, muscles, tendons and other tissues.
- Visceral (internal) Pain – originates from the internal organs – heart, lungs, alimentary canal and reproductive organs. The pain from internal organs can be localized to superficial sites.
- Neuropathic (nerves) Pain – originates from the nerves, the spinal cord and brain because of abnormal processing of nervous activity.
The longer the pain persists, the more intense it becomes. There are actual changes in sensory processing in the spinal cord. Central sensitization refers to activity in the entire central nervous system (CNS). When pain lasts a very long time, either from injury or chronic disease, it creates “windup” or constant neuroexcitability, which means that the noxious (harmful or unpleasant) stimuli produce prolonged, long term sensitivity in the dorsal horn of the spinal cord. This sensitization of the dorsal horn (when pain signals are modulates and then sent on to the brain), is thought to be responsible for increases in the hyperalgesia (over-sensitivity to pain), and allodynia (pain resulting from activity that doesn’t usually cause pain, usually touch). This lowers the threshold of pain on a permanent basis. Continuous noxious stimuli lasting longer than several hours actually change the genetic code and are responsible for long term structural changes (neuroplasticity) to the CNS.
Visceral pain is not easily or quickly identified due to the lower number of nociceptors (a sensory receptor of painful stimuli) in the viscera compared to the peripheral nociceptors. This means that it is difficult to pinpoint the exact location of pain since each nociceptor covers a large area. Also, pain may not even be perceived in the beginning of an assult by noxious stimulus; however, generalized inflammation and tissue damage activate “silent” nociceptors in the intestines and bladder and increase sensitivity to otherwise innocuous (harmless/safe) mechanical stimuli. In other words, constant pain will cause the individual to feel pain from stimuli which ordinarily are not painful. They lower the threshold of pain to the point that ordinary touch is painful.
Referred Pain – pain that is felt in uninjured tissue a distance away from the causative injury or lesion. The “dermatome” is the area innervated by a nerve ganglion. Everything in this dermatome (muscles, bones, joints, and tendons) will feel pain from the injury. It develops slowly, usually triggered by a deep somatic and visceral, rather than a superficial injury and it referred to regions derived from the same dermatome.
Pain Memory – pain perception and memory correlate strongly with the peak intensity of pain, but interestingly, not with its duration. The more the site is traumatized, the more severe the pain, This suggests that injury produces neurochemical changes in the CNS that affect the nociceptive behavior. This is true for humans and animals.
If painful stimuli establish a memory of pain, then therapies that prevent central sensitization and neuroplastic changes should be beneficial in restoring normal pain sensitivity. This is the reason medical doctors and veterinarians are providing preemptive analgesia – pain medication given before the traumatic event occurs (such as surgery). Doctors and veterinarians reason that preventing the pain from occurring will prevent or reduce the subsequent pain, and the need for medication for additional pain will lessen. Once the intensity of the pain is raised to a high level (hyperexcitability), larger doses of analgesia are required, and often the treatment is ineffective. Therefore, all pain should be treated as early as possible and preemptively when possible.
Assessing Pain – chickens are very stoic and do not cry out in pain despite the fact that they can be very loud when they want to be. Chickens have a flock mentality; meaning they are a prey species and if they make their illness conspicuous to the rest of the flock they risk being ostracized by the rest of the flock (so as not to attract the attentions of a predator). Chickens know there is no survival advantage to displaying their pain outwardly; however, they do perceive and respond to noxious stimuli in the same way other animals and mammals do.
Try to observe your chicken before they are aware of you observing them. When they realize you are there, you will probably observe them straightening up, opening their eyelids more ans they may even turn partially to face you in and attempt to look alert. Because of their reluctance to demonstrate pain, chickens are often under treated for it.
The following guidelines will assist you in better understanding your chicken’s level of comfort and/or pain and help you determine if your bird is indeed suffering and should see a veterinarian.
Physical – Always, Sometimes, or Rarely
- Is their energy level normal
- Are they capable of completing normal, everyday tasks (eating/drinking, preening, foraging, etc.)
- Are they eating normal amounts of food (approximately 1/2 cup)
- Are they eating their normal variety of foods (feed, any scratch, meal worms, forage)
- Do they greet you with alertness and vocalization
- Can they walk easily
- Can they fly/lift of the ground easily
- Do they stumble due to poor vision
- Do they walk/fly into objects/other birds
- Do they hear normally
- Are they breathing normally, without tail-bobbing
- Do they become out of breath after light exertion
- Do they let you touch the painful area
- Do they sleep on a roost
- Do they sleep on the ground
- Do they alternate sleeping positions
- Do they sit for long periods of time with their feathers ruffled and/or head tucked
- Have they reacted adversely to any medications
- Are they currently on any medications
Behavioral – Always, Sometimes, or Rarely
- Is your bird behaving normally
- Does your bird enjoy foraging opportunities
- Do they engage in normal self-grooming/preening behavior
- Do they engage in social grooming of others
- Do they normally preen after a bath
- Do they appear chilled and remain still after a bath instead of preening normally
- Are they easy to awaken
- Are they unusually anxious or nervous
- Do they cry out unexpectedly
- Do they exhibit guarding behavior by changing body positions in order to protect a painful area
- Do they withdraw to a corner or other solitary plpace and sit still
- Do they engage in feather-destructive behavior
- Do they engage in painful grooming behavior or self-mutilation at a specif site
- Do they generally/normally engage in painful grooming behavior or self-mutilation
- Do they experience long periods of decreased activity
- Are they increasingly aggressive toward other birds
- Are they increasingly aggressive toward you
- Is their plumage in good condition
- Are there any unusual lumps or growths on them
- Are their eyes clear and bright
- is there any discharge from the eyes
- When you lift the eyelid, is it red
- Are the nares (nostrils) clear and free of debris
- Is there any discharge from the nares
- Is their vent red, inflamed or swollen
- Is there any tissue coming out the vent
- Does their preening gland appear normal
Social – Always, Sometimes, or Rarely
- Are they interacting normally with you
- Are they interacting normally with the rest of the flock
- Do you think they are happy
Quality of Life – acute pain causes tissue damage and alters behavior in order to avoid further damage. Healing takes place and and the pain ceases when proper healing is complete. Chronic pain on the other hand, continues long after the acute disease process ends and has a significant impact on the psychology of the sufferer. Human chronic pain causes fear, anger, anxiety, depression and fatigue; these in turn exacerbate the pain. Because of this, chronic pain impacts the bird’s social, psychological and physical well being, thereby affecting their quality of life.
Treating Pain – there are no safe and effective pain medications that are available over the counter (OTC). Aspirin has been recommended in the past but now has been linked with kidney and liver damage once an effective dose is reached, it is also not water soluble and when given in water the risk for overdose increases. This is why it is extremely important to establish a relationship with a hands on veterinarian. We understand that not everyone has access to a veterinarian who is experienced with poultry/waterfowl, but in most cases of emergencies, if you have a well established Vet-Client- Patient-Relationship (VCPR) with a vet for your other animals, many vets will see your birds in a true emergency. There is enough well documented veterinary literature on various pain process. xmedications that they would be able to prescribe something after doing a brief exam.
Meloxicam/Metacam is usually the first choice in controlling pain in birds.
When to Treat versus when to Euthanize – while it would be ideal to have pain medical available for all wounds and injuries, we know this is not always possible for more minor wounds.
When a chicken is attacked by any animal and there is exposed muscle tissue and bones, a veterinarian should be sought immediately. Chickens will go into shock and oral pain medications may not always be effective during shock. They may need pain medications given intramuscular (IM).
Broken legs and wings require pain management to aid in the healing process. X-rays also need to be taken to assess the break – setting broken bones t home without knowing the extent of the damage can do more harm than good.
These are two examples that allow pain memory to develop when appropriate pain medications are not given as soon as possible. Pain memory alters their behavioral, emotional, physical and social state in a negative way. If proper vet care cannot be obtained, humane euthanasia is the most compassionate thing to do.
Raising any animal needs to be about quality of life, not quantity. Chickens (animals in general) do not see past today…all they know is they are in pain today and will desperately hide it….they do not realize that tomorrow they may in more or less pain. Raising animals is not about being the hero, it is about being humane.
Pain perception in chickens is likely analogous (comparable) to that in mammals and they need to be treated the same for their injuries.
The Five Freedoms
Freedom from thirst, hunger and malnutrition
- Access to fresh water and a healthful diet
Freedom from discomfort
- Suitable environment, shelter and a resting place
Freedom from pain, injury and diseas
- Prevention of cruelty and illness by care and rapid treatment
Freedom to express normal behavior
- Provision of space, facilities and company of the animal’s own kind
Freedom from fear and distress
- Assurance of conditions that avoid stress and mental suffering
Handbook for Veterinary Pain Management, Second Edition, Mosby Inc., 2009
Pain Management Techniques for Food Producing Animals Could Lead to Pain Control Drugs, 2017
Guidelines for the Recognition and Assessment of Animal Pain, 2008
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