Arguments as to whether and how animals experience pain have been conducted for more than a century. The consensus of scientific opinion is that animals do feel pain, that it is an aversive sensory and emotional experience (J4.191.w3) and that while discussions on the exact nature of pain in animals may continue, they should be given the benefit of the doubt that they do indeed feel pain. (J284.71.w1)

The next question therefore is: "when is pain severe enough to intervene on behalf of the animal?" (J284.71.w1)

• There is a spectrum of procedures and conditions which, while some may be recognised clearly as being associated with insignificant pain (e.g. subcutaneous vaccination) and others just as clearly recognised as being associated with severe pain requiring pain relief (e.g. Caesarean section), some procedures, such as castration, are in a central area where the degree of pain, and whether and to what extent pain relief is required, are unclear or there is no consensus. (J284.71.w1)

"It should be assumed that if a procedure is likely to cause pain in man, it will produce a similar degree of pain in animals." (J83.18.w1)

In order for pain in animals to be managed, the possibility of pain must be recognised, personnel must recognise pain, and then effective steps must be taken to relieve pain. (J4.221.w4) Failure of any of these points may lead to failure to provide pain relief.

It is important to recognise that failure to provide adequate pain relief may have an adverse effect on wound healing and on production. See: Reasons for Pain Relief - Disadvantages of pain

Note: Many publications, whilst recognising pain as a symptom of a clinical condition in ruminants and using it in diagnosis, do not address pain alleviation in the treatment of the condition. This may partially be due to the fact that pain management is a relatively recent discipline and its importance is only now being recognised. (V.w5, V.w6)

• --

• There has until recently generally been rather less concern for pain in animals than for pain in humans. (J290.21.w1)
• There has been reluctance by many people to accept that pain may be experienced by non-human animals in a similar way to how it is experienced in humans. (N12.34.w1)
  • This has occurred despite the similarity in anatomy, physiology and pathophysiology between certain animals and humans, and the fact that such animals are considered useful for research into pain. (N12.34.w1)
• In a survey of attitudes of veterinary students, house officers, clinical faculty and staff at a veterinary teaching hospital and a veterinary school in the USA, most, but not all respondents agreed that "animals experience pain much in the same way people do." (J4.214.w2)
  • The results of the survey overall were considered to "suggest that severity and clinical importance of postoperative pain in animals is often discounted." (J4.214.w2)
• Some veterinarians believe that farm animals are less sensitive to pain than are small animals. (J35.165.w1)
• "It is a widespread opinion that in neonate and young animals the nociceptive system has not yet developed completely. From a biological point of view, there are no reasons for such a speculation, in particular in precocial animals such as cattle." (J288.62.w1)

• Assessment of Pain in Ruminants
• Neurophysiology of Pain

• Tradition is a very important reason why use of analgesics in farm animals is low. (P61.62.w1) 
• "Failure to adopt new practices and improved ideas is a possible reason for not using analgesics." (P53.24.w1)
• Analgesics may be less likely to be given for surgical procedures which are regarded as "routine" than for broadly similar procedures which are not carried out routinely. (J3.145.w2)

• Animals cannot communicate directly the fact that they are in pain. (J3.145.w2)
• The difference in expression of pain in herd animals such as ruminants, compared to expression of pain in humans, has been taken by many people to suggest that these species feel less pain than do humans. (J290.21.w1)
• Behaviours shown by animals in pain may also occur due to illness and depression, which makes recognition of pain difficult; it may also be difficult to identify the source, location and intensity of pain. (J4.221.w4)
• Many measures used for pain assessment in animals are subjective. (J83.18.w1)
• There are problems with establishing numerical behavioural indices of pain because of the many confounding factors which may influence behaviour. (P61.26.w2). 
• Lack of knowledge about animal behaviours indicative of pain, particularly lack of identification of subtle behaviours indicating pain, may contribute to lack of use of pain relief. (J4.214.w2)
• Pain, and the importance and effects of pain, may be less likely to be recognised in stoical species such as sheep. (P53.24.w1)

• Assessment of Pain in Ruminants

• There is a spectrum of procedures and conditions which, while some may be recognised clearly as being associated with insignificant pain (e.g. subcutaneous vaccination), and others just as clearly recognised as being associated with severe pain requiring pain relief (e.g. Caesarean section), some procedures, such as castration, are in a central area where the degree of pain, and whether and to what extent pain relief is required, are unclear or there is no consensus. (J284.71.w1).
• There are some circumstances where the amount of pain is so minor and short lived that procedures to relieve pain are not warranted, for example giving a vaccination injection. (J284.71.w1)

In general, "It should be assumed that if a procedure is likely to cause pain in man, it will produce a similar degree of pain in animals." (J83.18.w1).

• Assessment of Pain in Ruminants

It is not appropriate to provide pain relief if the negative effects of stress from pain relief, or the risks to the animal associated with providing pain relief, would outweigh benefits of the analgesia. (V.w5, V.w6)

• Administration of local anaesthetic may itself cause distress to the animal, therefore such administration may not be appropriate when the procedure which is to be carried out causes only minor, low-grade  pain. (P61.53.w1)
• Negative effects of stress from administering pain relief, or risks associated with provision of pain relief, are of particular concern when dealing with non-domestic animals. (V.w5, V.w6)
  • For non-domestic animals there may be stress associated with separation from the herd (B322.4.w4), enclosure in a small space (box rest for restriction of movement), and parenteral administration of analgesic drugs either by hand injection (requiring restraint, which may be stressful) or by remote injection (darting) which carries a risk of injury and may itself induce a flight response. (V.w5)
• The development of analgesics which are longer lasting and thus require less frequent dosing have the potential to partially overcome this limitation. (P56.1.w25)

• Groups of Analgesic Drugs
• Routes of Drug Administration in Ruminants
• Understanding Pharmacokinetics for Pain Management in Ruminants

• Many large animal practitioners avoid using analgesics because of concern that they mask symptoms and impair diagnosis. (B351.3.w3)
• However, once diagnosis has been achieved there is no useful purpose of continuing pain and it should then be immediately alleviated. (J16.28.w1)
  • In some cases, severe pain may hamper clinical examination and provision of analgesia may be required in order to allow examination and diagnosis. (J16.28.w1)

• Assessment of Pain in Ruminants

There is sometimes concern that providing analgesia will remove the protective effect of pain, leading to excessive use of damaged tissues. This concern is excessive in animals receiving veterinary care.  (B207.2.w2, B322.1.w1, J3.145.w2  J15.24.w1, J16.28.w1, J35.165.w1, P54.2.w4, Th8.2.w2)

• Surveys have shown that approximately one third of British and a similar proportion of Finnish veterinarians believe that a certain level of postoperative pain is useful to prevent excessive movement in the postoperative period. (J3.145.w2, J35.165.w1) 
  • In a survey of attitudes of veterinary students, house officers, clinical faculty and staff at a veterinary teaching hospital and a veterinary school in the USA only 55% of staff, 68% of clinical faculty and 72% of house officers totally disagreed with the statement that "I believe that experiencing pain during the postoperative period is beneficial for recovery in animals." (J4.214.w2)

HOWEVER:

• This concern for removal of the protective effect of pain presumes that analgesics are sufficiently effective to remove all pain sensation: this is rarely the case. (B322.1.w1)
  • Normal doses of analgesic drugs are unlikely to block pain so completely that the animal will behave in a way likely to cause further injury to the affected area. (J15.24.w1)
• Abolishing the detrimental effects of pain almost always outweighs any possible disadvantage from removing the protective effect of pain. (B322.1.w1, B322.4.w4)
  • "Once a diagnosis has been established, pain is serving no useful purpose and it should be alleviated immediately." (J16.28.w1)
• If protection is required, this can be met by e.g. bandaging and splinting to protect a limb, or confinement in a small area to promote inactivity. (B322.1.w1, J16.28.w1)
• Use of an analgesic to reduce pain, and a sedative or tranquillising drug to reduce activity, is preferable to leaving pain untreated in order to prevent activity. (J16.28.w1, P54.2.w4)
• Administration of analgesics is more likely to reduce tissue damage from self-trauma than to increase tissue damage due to excessive activity. (P54.2.w4)
  • Prevention of disruption of sutures in the post-surgical period is preferably by good wound closure, rather than relying on pain to produce immobility. (J16.28.w1, P54.2.w4)
• Concern has also been expressed regarding relief of pain possibly masking signs of complications, such as infection in the post-operative period; complications should be detectable even when pain relief is provided. (Th8.2.w2)

NOTE: The American College of Veterinary Anaesthesiologists has emphasised the fact that there are no beneficial effects of unrelieved pain for animals under veterinary care. (J4.213.w2)

The use of analgesics in ruminants may be poor due to lack of familiarity with current therapeutic strategies for use of analgesics in these species (J4.219.w4, P61.62.w1) including lack of information on:

• Available drugs and strategies for pain control. (J3.145.w2)
• The pharmacological properties of analgesic drugs. (J4.214.w2)
• Appropriate analgesics for use in a particular species. (B322.1.w1, J83.18.w1, J3.145.w3)
• Appropriate doses and dose rates of analgesics for a particular species. (B322.1.w1, J83.18.w1)
• Variations between species in pharmacokinetics and pharmacodynamics of systemic, local and regional analgesics. (B323.1.w1)

Note: Many publications, whilst recognising pain as a symptom of a clinical condition in ruminants and using it in diagnosis, do not provide information on pain alleviation in the treatment of the condition. This may partially be due to the fact that pain management is a relatively recent discipline and its importance is only now being recognised. (V.w5, V.w6)

• Understanding Pharmacokinetics for Pain Management in Ruminants

Use of any drugs, including analgesics, can result in unwanted side effects and toxicity. Use of analgesics may be limited due to concern regarding undesirable side-effects or toxicity, (J35.165.w1, J4.219.w4) and lack of information regarding ways to avoid or manage such problems. (B322.1.w1)

Opiates:

• Concern regarding respiratory depression if opiates are used for pain relief. (J16.28.w1)
  • Respiratory depression is not likely to occur following use of opiates for analgesia at normal dose rates; (J16.28.w1) if it does occur it may be reversed either with an opiate antagonist (which will also reverse the analgesia) or with a specific respiratory stimulant such as doxapram, repeated as required. (J16.28.w1)
• Concern regarding hypotension is cited as a contraindication for use of opiates following surgery or trauma. (J16.28.w1)
  • Intramuscular or subcutaneous administration of opiates does not usually cause hypotension, although this may occur if these drugs are given intravenously. (J16.28.w1)
• Concern regarding difficulty in monitoring the clinical state of the patient following cranial injury, leading to a delay in diagnosis and essential treatment of complications. (J16.28.w1)
  • Unless craniotomy in response to problems such as subdural haemorrhage is a realistic proposition, then this is not an appropriate reason to withhold analgesia. (J16.28.w1)

NSAIDs:

• Concern regarding side effects of NSAIDs such as abomasal ulceration. (B351.3.w3, P53.24.w1)
• One practitioner noted that in "several years" of using NSAIDs in sheep they had not noticed any side-effects. (P53.24.w1)

Analgesics may be specifically withheld if their provision might interfere with other required treatment such as anaesthesia required for correction of the condition causing pain (e.g. with acute abdominal conditions). (P54.2.w15)

Where there is severe continuous pain which may last for several weeks during slow healing, for example associated with infected traumatic injuries in cattle, there are problems due to lack of effective, easily administered analgesics which may be used for prolonged periods without undesirable side effects. (B207.2.w2)

• Groups of Analgesic Drugs

There may be a shortage of products which have been licensed for use in food-producing animals (P61.62.w1, J15.24.w1, P53.24.w1) and there may be concerns about withdrawal times and avoiding residues in meat or milk. (P61.62.w1)

• It should be remembered that in some cases physical methods of pain relief can be used (such as placement of a block or shoe to remove pressure on a painful claw) and that there are no drug residue concerns with such methods. (P61.62.w1)
  • See: Block or Shoe Placement in Cattle

The choice of analgesics, including local anaesthetics, sedatives with analgesic effects, and NSAIDs, for use in ruminants intended for human consumption, is limited. Regulations vary between countries.

• Lack of analgesic drugs specifically licensed for use may discourage their use. (J15.24.w1)
• Fear of residues is a factor in the low use of analgesic agents in food-producing animals. (P61.62.w1)

NSAIDs

• In the UK, no NSAID is presently [2004] licensed for use in sheep. (P53.24.w1)
  • These drugs may be used under the prescription "cascade"; standard withdrawal periods must then be observed. (P53.24.w1)
• In the UK, flunixin meglumine, ketoprofen and tolfenamic acid are presently licensed for use in lactating cattle. Milk and meat withdrawal times vary between these NSAIDs, and between formulations of flunixin. (B233, J303.12.w1)
• In the UK, carprofen, flunixin meglumine, ketoprofen, tolfenamic acid and meloxicam are presently licensed for use in calves for use in the treatment of pneumonia, although not necessarily for use in other conditions. (J303.12.w1)
• In the USA, phenylbutazone, commonly used in cattle, has recently been added to the list of drugs specifically prohibited for use in female dairy cattle aged 20 months or older in the USA. (W509.June04.w1)

Opiates

Legislative control of drugs which have the potential for human abuse (e.g. opiates) may limit their use. (B207.2.w2, B322.1.w1, J4.219.w4, P61.62.w1)

• In the UK use of most opioids is controlled under the Misuse of Drugs Act 1971. (B322.1.w1)
  • This requires careful record keeping regarding drug purchase, storage and dispensing, may limit the persons able to dispense and administer opioids covered by the legislation and limit dispensing for administration by the owner. (B322.1.w1)

There are additional concerns regarding opiates:

• Safety concerns may limit dispensing of opioid analgesics for outpatient use. (B322.1.w1)
• Concern that the presence of opioid analgesics on the premises will increase the risk of break-in and theft. (B322.1.w1)
  • It should be noted that these are not the only drugs which are kept on veterinary premises and may attract thieves. (B322.1.w1)

• Groups of Analgesic Drugs
• Block or Shoe Placement in Cattle

• There are often concerns regarding the cost of analgesics in agricultural animals; this is recognised as a reason why analgesic use in farm animals is low. (J4.219.w4, P61.62.w1, B207.2.w2, B323.1.w1, P53.24.w1)
• In a survey of the attitudes of cattle practitioners in Britain, the cost of analgesic drugs was often noted as the factor limiting their use. (J303.8.w1, Th8.2.w2)
• Economically, it is often considered that the use of analgesics in food-producing animals, including most domestic ruminants, is not viable (P61.62.w1, J4.219.w4), particularly when carrying out routine husbandry practices such as castration of calves and lambs and tail docking of lambs.
• Cost is an important reason why analgesics are not used in sheep. (P53.24.w1)
  • The low value of individual sheep means that analgesics are even less likely to be used in sheep than in cattle. (P61.62.w1)
  • HOWEVER, the costs should be considered in comparison to the economic losses which are seen associated with untreated pain. (P53.24.w1)
• Options for analgesia are unlikely to be used in routine management procedures if their use is too time-consuming, too costly and generally impractical for the farmer. (P61.53.w1)
• In routine surgical procedures such as castration and tail docking, practical  and logistical issues are of concern. (P61.53.w1, B323.1.w1)
• Livestock undergoing routine management procedures - elective surgical procedures - often are not given analgesics because of logistical and economic constraints. (B323.1.w1)

• Pain Prevention for Calf Castration
• Pain Prevention for Lamb Castration and Tail Docking