Sunday, July 24, 2011
Notes from July 2011 St. Louis AVMA Conference-Pain and Behavior
These are papers from the July 2011 St. Louis AVMA conference. I’ve edited them to delete some of the vet only jargon and for space considerations. If you see (…) that means that information has been deleted due to these considerations. The ones listed here include HCM, and other heart related papers, treatments, papers on x-rays and echos, thrombosis, kidney disease, idiopathic cystitis, pain management, anesthesia and cardiac disease, supplements and other hazards for pets, and some other basic information I hope is helpful.
EFFECT OF PAIN ON THE BEHAVIOR OF CATS
Mary P. Klinck, DVM, BSc, DACVB
Faculty of Veterinary Medicine, University of Montreal
Feline pain can be particularly difficult for both cat owners and veterinarians to assess, and
has historically been under-recognized and under-treated in veterinary medicine. Clearly,
untreated pain is a direct welfare concern, but it can also have an indirect effect through
alterations in behavior, which have the potential to affect the human-animal bond and to
increase the risk of pet relinquishment. Along with increased awareness of pain
management in the profession as a whole has come a growing interest in the problem of
feline pain in particular, resulting in a small but rapidly growing body of research on this
Pain assessment is challenging across species…In nonverbal subjects, a variety of approaches to pain
measurement have been used, including: a) physiological measures, either absolute or
compared to base line values, such as heart or respiratory rate, blood pressure,
temperature, pupil dilation, skin electrical conductivity, and hormone levels (e.g., cortisol);
b) behavioral measures such as facial expression, body tension and posture, and
responsiveness to the environment, interactions, or to palpation of the painful area.
Physiological measures often require procedures that are somewhat invasive or disturbing
to the patient, in and of themselves. Wide “normal” ranges for physiologic values and
variation simply due to the act of measurement itself may also limit the sensitivity and
specificity of these measures. Behavioral measures can be assessed via observation
combined with limited manipulations, and can be used in contexts where physiological
measures are impractical or costly (e.g., in the pet’s home). Both physiological and
behavioral criteria for assessment of pain may be affected by other factors, for instance,
stress in the clinic or in the home, or other illnesses. Individual differences can also make
comparison between patients difficult…
Pain can be divided into different categories on the basis of its cause or physiology. The
context of assessment tends to differ in acute vs. chronic pain in cats; veterinarians and
veterinary staff may have more opportunities for direct monitoring of acute pain in
hospitalized patients (e.g., surgery, trauma, or infection), while cats with chronic causes of
pain may need to be evaluated less directly, by questioning the owner in order to 1) detect
the presence of pain, and 2) to monitor it over time. In a clinical setting, pain can often be
anticipated on the basis of the disease or procedures…observable symptoms of pain include: 1)
altered demeanor (lack of interest in surroundings, increases or decreases in general
aggression or avoidance behaviors), 2) altered responses to handling (tension, flinching,
withdrawal, growling, hissing, scratching, biting in response to palpation or manipulation);
3) altered or tense body posture (a hunched or rounded back, reluctance to adopt usual
resting postures), 4) changes in weight bearing or lameness, 5) changes in facial
expression (such as squinted eyes), 6) abnormal vocalization, 7) alterations in normal self maintenance
behaviors such as a) grooming… b) toileting (not using the litter box for urine and/or feces or having
“accidents” over the sides, not scratching in the litter), c) eating (decreased appetite or
reluctance to eat certain foods). As there are individual differences in these behaviors, it
is ideal to assess them at baseline and make comparisons over time, if this is possible.
If there is uncertainty regarding the presence of pain, reassessment after a trial dose of an analgesic may help to clarify whether the apparent abnormality was due to pain.
In the home, owners will usually recognize signs of acute onset or severe pain; however,
chronic or insidious onset pain can produce subtle or gradual changes that may go
unnoticed or wrongly be attributed to “getting old”, or to environmental or other factors (e.g.,
a response to the addition or removal of an animal or family member). Almost any change
in behavior could be caused by pain or disease. Specifically, if there is an unexpected or
unexplained development of a new or abnormal behavior, or loss of a previous behavior…pain
should be considered as a cause. Not only undesirable (“problem”) changes indicate pain;
owners may interpret a change as desirable, undesirable or neutral (e.g., a cat that stops
clawing the furniture, vs. a cat that becomes more affectionate, vs. a cat that chooses a
new location for resting), but they may be less likely to report desirable changes to the
veterinarian, unless asked. Clinicians should be alert to the possibility of pain as a cause of
apparent behavior problems, and should also be prepared to ask about subtle changes in
behavior as a part of the screening process for cats at risk of chronic pain (e.g., animals
with confirmed disease such as neoplasia or inflammatory bowel disease, or animals at risk
for diseases such as osteoarthritis).
Complaints that may be caused by pain but incorrectly attributed to a primary behavior
Problem include: over-grooming with hair removal or self-inflicted wounds, hyperesthesia
(manifested by skin twitching and running from or attacking the tail or dorsum), aggression
(in response to petting or handling, or in other contexts), or inappropriate elimination. It is
important to remember that pain may be the primary cause, but even in cases where it was
not the original cause, it can contribute to maintenance or to progression of the problem,
and therefore require treatment. Other specific behavior changes due to pain include:
altered activity and sleep/rest habits, changes in appetite, changes in social interactions
with human and animal family members, changes in play or hunting behavior, and changes
in litter box use…
Pain scales using behavioral observation and responses to direct interactions are gaining in
popularity in feline medicine. Their use may be based on observation alone, or based on
observation and interaction (including palpation of the painful site). There exist several
general types of pain scales, listed below roughly from simplest to most complex:
1) Numerical Rating Scale (NRS)
This consists of a range of numbers (e.g., 0-10, where 0 represents no pain, and 10
represents the worst possible pain); a number within the range is selected based on the
level of pain observed.
2) Visual Analog Scale (VAS)
This consists of a 100 mm vertical or horizontal line, where one end (0) represents no pain,
and the other end (100) represents the worst possible pain; it is used by placing a mark
along the line to indicate the level of pain observed. The distance from 0 is then measured
with a ruler to obtain the score.
3) Simple Descriptive Scale (SDS)
For this scale, numbers along a range are assigned to verbal descriptions of the level of
pain (e.g., 1 = no pain, 2 = mild pain, 3 = moderate pain, 4 = severe pain), and the observer
determines which description fits best, then assigns the corresponding score.
4) Composite Pain Scale (CPS)
In this type of scale, several criteria are assessed individually (often based using SDS
format) and the scores for all the criteria added together to determine the total pain score.
Prior to clinical use, a pain scale should be demonstrated to be capable of distinguishing
between different levels of pain (= scale responsiveness, or predictive value) in the
intended context, and to yield consistent results between observers and within observers
over time (= scale reliability). This involves use of the scale to compare subjects with known
differences in intensity of a particular type of pain, to determine if the scale is capable of
distinguishing between levels of pain, or to detect a response to analgesics…It is also important
to consider that a scale that seems to be effective or that has been used for monitoring cat pain after OVH
will not necessarily be as effective for monitoring pain after declaw or tooth extraction, or in painful
medical conditions such as feline lower urinary tract disease. ..
For chronic feline pain, there has been some preliminary work on the validation of specific
pain scales for use in degenerative joint disease. One such scale is the Client Specific
Outcome Measures scale, which was found to be capable of identifying changes in pain in
response to treatment with meloxicam. This type of scale uses criteria selected by the cat
owner with the help of the veterinarian/technician, and is therefore specific to the particular
cat. For instance, criteria might include ability or willingness to jump, use of the litter box,
etc., but will be activities that the owner feels are affected by the cat’s pain.
a. CSU Acute Pain Scale: vapm.evetsites.net/refId,20467/refDownload.pml
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