BACKGROUND
published information indicates that degenerative joint disease  is common in domesticated cats  <cit> .
in humans, pain is the major clinical symptom in osteoarthritis  and a key determinant for seeking medical care.
this pain is the leading cause of mobility impairment in aging humans  <cit> .
relatively little is known about the direct relationship between djd, pain and mobility impairment in companion animals.
in a feline cruciate transection model of oa, ground reaction forces and limb kinematics recovered to pre-surgical levels over  <dig> year, despite progression of radiographic oa  <cit> .
in a discussion of this model, it was indicated that after  <dig> years the joints have severe radiographic signs of oa without associated pain  <cit> .
in contrast, several studies have identified cats with radiographic djd and mobility impairment  <cit>  and nsaid administration significantly improved mobility  <cit> .
it appears that in some cats, radiographically apparent djd is associated with pain and results in impaired mobility.
however, available information suggests a mismatch between radiographic and orthopedic examination findings in cats with djd.
in a study by clarke and bennett,  <cit>  34% of joints assumed to be painful on manipulation during a orthopedic examination did not have any radiographic signs of osteoarthritis.
in another recent study that evaluated 'radiographic djd' and 'pain on manipulation',  <cit>   <dig> joints had radiographic signs of osteoarthritis , but only  <dig> of these  were painful on manipulation.
a similar discrepancy between radiographic features of oa and pain exists in humans, being best characterized for the knee  <cit>  but also present in other joints  <cit> .
the extent of the discrepancy between orthopedic examination findings and radiographic signs of oa in companion animals has not been described.
also, while we know how clinical signs predict radiographic signs of oa in humans,  <cit>  this information is not known for companion animals.
the aim of this study was to evaluate the relationship between radiographic signs of djd, orthopedic examination findings, and joint goniometry in cats.
RESULTS
twenty-five cats in each age group were successfully recruited and included in the study.
of the  <dig> cats recruited,  <dig> were purebred, and  <dig> were domestic shorthaired or longhaired.
the mean  age was  <dig>  ±  <dig>  years , and mean bodyweight was  <dig>  ±  <dig>  kg.
.
the median  body condition score  was  <dig>  out of  <dig>  the temperament scores were  <dig> in 40% of the cats,  <dig> ,  <dig> ,  <dig> , or  <dig> .
due to this fact, incomplete pain scores were present in 8-15% of individual joints and spinal segments for a total of  <dig> missing pain scores out of  <dig>  conscious goniometry could not be performed in  <dig> cats due to their temperament, but goniometry was performed in all cats when sedated.
radiographic assessment was complete in every cat.
the prevalence of radiographic djd in this population has been described previously  <cit> .
the number of affected joints, or spinal segments and associated manipulation scores for pain, crepitus, effusion and thickening , as well as the number of joints with no abnormalities apparent on examination, are summarized in table  <dig>  the elbow and hip joints were most frequently found to be painful, followed by the stifle and tarsus.
the lumbar and lumbo-sacral  segments were the most frequently painful segments in the axial skeleton.
the elbow joint most frequently had an elevated sc, se, and st, followed by the stifle and tarsus.
cats with unfriendly temperament  had higher radiographic djd  than cats with friendly temperament .
r, right; l, left.
na = not assessed.
column showing number of joints with no pain, crepitus, effusion or thickening shows numbers out of 100; numbers in this column for axial skeleton are for pain only
there were significant associations between radiographic djd and pain scores, which held true for the right and left elbows  and the lumbar and l-s region  when collapsed djdn/y and painn/y were used in the analyses.
there were significant associations between djdn/y and normal/abnormal sc, se, st, for both elbows  and tarsi  with the exception of the right tarsus sc  and left elbow se .
the sens, spec, ppv, and npv of normal/abnormal sc, se, st, values and painn/y with regards to djdn/y are listed in table  <dig>  sens was low overall, and was highest for painn/y.
ppv was highest for sc and st but was generally low.
spec and npv were higher, suggesting that the absence of orthopedic examination findings of pain, crepitus, effusion and thickening could be used to rule out djd with a high degree of certainty.
the overlap of radiographic and orthopedic findings is listed in table  <dig>
na = not assessed
romc and roms differed significantly for the stifle joints, right shoulder and right carpus, although the differences were small, ranging from 1° to 5° .
roms data were collected more rapidly than romc data .
the odds ratios indicated that higher sc, se, st, and spain increased the likelihood of a joint having djd present .
for example, cats with positive spain in the right elbow were  <dig>  times more likely to have djd compared to cats with negative spain.
similar increases were present for the left elbow, the lumbar, and lumbo-sacral areas.
the likelihood of a joint having djd was also increased for joints with positive sc, se, and st, particularly for the elbows and tarsi.
larger romc in shoulders, elbows and tarsi were associated with a lower likelihood of there being djd present  larger roms in elbows, shoulders, carpi, and tarsi was associated with a lower likelihood of there being djd present .
only statistically significant odds ratios are included
*pain, effusion, crepitus and thickening scores were classified as present or absent
§ the significance of these odds ratios was lost due to 'age,' acting as a confounding variable
age had a large effect  on the relationship of spain, sc, se, and st, and djdn/y.
weight, sex, temperament, and time point during the study had a minor effect .
bcs had a variable effect, but on average it was < 10% for all parameters, and it did not change the significance of the relationship between the parameter and djd.
for the appendicular skeleton, controlling for age decreased the likelihood that a joint with a positive orthopedic parameter  had radiographic djd by between  <dig> and 37% .
this effect resulted in a change in significance .
study time point  had the next largest effect on ors for se  but not on other or; however significance was not altered.
for the axial skeleton, controlling for age decreased the likelihood that a positive pain response would be associated with radiographic djd by between  <dig> and 76% , and this resulted in a loss of significance for the lumbar and lumbo-sacral segments.
when an interaction term was included in the model to evaluate or, age was not shown to be an effect modifier, and stratification analysis supported this conclusion.
age had no confounding effect on the association between an abnormal romc or roms and the likelihood of a joint having djd.
discussion
there is no validated assessment system to measure joint pain in cats although recently some progress has been reported in this  <cit> .
in the present study, the level of aversive response interpreted as indicative of pain was evaluated subjectively during joint manipulation by a single investigator.
the scores were recorded without consideration to viewing of the radiographs.
this does not make it valid as an absolute measure, but the authors believe it is a valid comparison between different cats and different joints.
there was no effect of time point of the study on the or for the relationships between orthopedic findings and radiographic djd, suggesting that the examining investigator did not change interpretation of parameters during the course of the study.
additionally, there did not appear to be any learned effect within each cat, and no biasing effect of sedation.
using this approach, it was found that the most frequently painful joints were the elbows and hips, and the most frequently painful spinal areas were the lumbar and lumbo-sacral segments.
these data suggest that these would be the most impactful areas to target for further investigation as to the potential cause of pain.
cats with higher sdjd and spain were less friendly than cats with lower sdjd and spain.
little work has been performed on determining how best to evaluate temperament in domesticated cats  <cit>  and none on the association between temperament and disease.
several studies have evaluated aspects of behavior in relation to the presence of djd  <cit>  but none have evaluated temperament thus far.
from the present study, one can speculate that higher pain scores are logically associated with a worse temperament, but the finding of a strong association between temperament and djdy/djdn suggests that radiographic djd is associated with pain, and thus unfriendly temperament.
having a valid measure of temperament, or change in temperament may be a useful surrogate measure of pain.
future work could evaluate this relationship further by looking at the effect of an analgesic on temperament in cats with djd.
some work in humans has suggested increased aggression in association with oa  <cit>  and treatment of oa with joint replacement has been shown to improve mood and well-being in human patients  <cit> .
in the human field, there has been a recent interest in understanding the psychological effects of joint pain  <cit> .
our study is unique in its evaluation of veterinarian-assessed temperament, but limited and answers to the effect of chronic oa associated pain on temperament, mood, and aggression in companion animals deserve further exploration.
significant relationships were found between pain on examination and radiographic djd for the elbows, and the lumbar and lumbo-sacral areas.
this may reflect a stronger association between disease and pain for these joints over others, or may reflect the fact that these joints may be easier to examine and manipulate appropriately.
however, overall, the data indicated that the presence of signs of pain did not result in a high degree of certainty that radiographically evident djd was present.
this discordance has been suggested in other studies of cats with djd, although the relationships were not described in detail  <cit> .
this discordance between pain and radiographic signs is in line with studies in humans, although in human studies the pain is generally self-reported  <cit> .
the discordance between pain and radiographic signs may be partly explained by the discordance between radiographic signs and grossly assessed signs of joint degeneration, as highlighted recently in cats  <cit> .
the higher values for spec and npv than sens and ppv suggest the absence of pain  can be used clinically to help rule out djd with a high degree of certainty.
the presence of pain, crepitus, effusion or thickening was found to be associated with an increased the chance  of there being djd present for certain joints.
age was found to be a confounding variable in the calculation of these ors.
as age is strongly associated with the presence of radiographic djd,  <cit>  it could be argued that controlling for age gives a more realistic overall view of the association between an orthopedic examination finding and the presence of radiographic djd, avoiding the overestimation of the association between djd and pain.
it is clear from the human literature that as radiographic oa becomes more severe, there is a closer association between joint pain and radiographic oa,  <cit>  and radiographic severity becomes greater with age.
in a recent review of the association between knee pain and radiographic oa,  <cit>  decreasing discordance with increasing age was seen in all the reviewed studies except one  <cit> .
given that we found no evidence of an effect modifier for age, the clinical interpretation should be that increasing age is associated with less discordance between radiographic and orthopedic examination findings.
overall, the present study found that radiographic djd is associated with decreased rom in the shoulder, elbow, carpus and tarsus, and that there was no effect of age on these relationships.
this suggests that this parameter holds true regardless of age.
although a previous study in clinically normal cats found no significant difference between conscious and sedated goniometric measurements in cats,  <cit>  the present study found small differences.
the magnitude of the differences between rom measured in conscious and sedated cats would, from the results of this study, appear to be minimal, and likely have no clinical significance.
however, further research would be needed to substantiate or refute this.
the difference between the studies may be partly explained by the use of individual angles of flexion and extension for comparison in the former study,  <cit>  and the use of rom and the inclusion of joints with djd in the present study.
increased rom measurements were associated with decreased odds of there being radiographic djd present, and therefore rom may be of value in helping to rule out djd.
CONCLUSIONS
overall, this study suggests that radiographic djd cannot be diagnosed with certainty using palpation or goniometry.
however, negative findings with respect to pain, crepitus, effusion and thickening, tend to predict radiographically normal joints.
increased rom measurements were associated with decreased odds of there being radiographic djd present, and therefore rom may be of value in helping to rule out djd.

 published information indicates that degenerative joint disease is common in domesticated cats. in humans, pain is the major clinical symptom in osteoarthritis and a key determinant for seeking medical care. this pain is the leading cause of mobility impairment in aging humans. relatively little is known about the direct relationship between djd, pain and mobility impairment in companion animals. in a feline cruciate transection model of oa, ground reaction forces and limb kinematics recovered to pre-surgical levels over year, despite progression of radiographic oa. in a discussion of this model, it was indicated that after years the joints have severe radiographic signs of oa without associated pain. in contrast, several studies have identified cats with radiographic djd and mobility impairment and nsaid administration significantly improved mobility. it appears that in some cats, radiographically apparent djd is associated with pain and results in impaired mobility. however, available information suggests a mismatch between radiographic and orthopedic examination findings in cats with djd. in a study by clarke and bennett, 34% of joints assumed to be painful on manipulation during a orthopedic examination did not have any radiographic signs of osteoarthritis. in another recent study that evaluated'radiographic djd' and'pain on manipulation', joints had radiographic signs of osteoarthritis, but only of these were painful on manipulation. a similar discrepancy between radiographic features of oa and pain exists in humans, being best characterized for the knee but also present in other joints. the extent of the discrepancy between orthopedic examination findings and radiographic signs of oa in companion animals has not been described. also, while we know how clinical signs predict radiographic signs of oa in humans, this information is not known for companion animals. the aim of this study was to evaluate the relationship between radiographic signs of djd, orthopedic examination findings, and joint goniometry in cats.  twenty-five cats in each age group were successfully recruited and included in the study. of the cats recruited, were purebred, and were domestic shorthaired or longhaired. the mean age was ± years, and mean bodyweight was ± kg.. the median body condition score was out of the temperament scores were in 40% of the cats,,,, or. due to this fact, incomplete pain scores were present in 8-15% of individual joints and spinal segments for a total of missing pain scores out of conscious goniometry could not be performed in cats due to their temperament, but goniometry was performed in all cats when sedated. radiographic assessment was complete in every cat. the prevalence of radiographic djd in this population has been described previously. the number of affected joints, or spinal segments and associated manipulation scores for pain, crepitus, effusion and thickening, as well as the number of joints with no abnormalities apparent on examination, are summarized in table the elbow and hip joints were most frequently found to be painful, followed by the stifle and tarsus. the lumbar and lumbo-sacral segments were the most frequently painful segments in the axial skeleton. the elbow joint most frequently had an elevated sc, se, and st, followed by the stifle and tarsus. cats with unfriendly temperament had higher radiographic djd than cats with friendly temperament. r, right; l, left. na = not assessed. column showing number of joints with no pain, crepitus, effusion or thickening shows numbers out of 100; numbers in this column for axial skeleton are for pain only there were significant associations between radiographic djd and pain scores, which held true for the right and left elbows and the lumbar and l-s region when collapsed djdn/y and painn/y were used in the analyses. there were significant associations between djdn/y and normal/abnormal sc, se, st, for both elbows and tarsi with the exception of the right tarsus sc and left elbow se. the sens, spec, ppv, and npv of normal/abnormal sc, se, st, values and painn/y with regards to djdn/y are listed in table sens was low overall, and was highest for painn/y. ppv was highest for sc and st but was generally low. spec and npv were higher, suggesting that the absence of orthopedic examination findings of pain, crepitus, effusion and thickening could be used to rule out djd with a high degree of certainty. the overlap of radiographic and orthopedic findings is listed in table na = not assessed romc and roms differed significantly for the stifle joints, right shoulder and right carpus, although the differences were small, ranging from 1° to 5°. roms data were collected more rapidly than romc data. the odds ratios indicated that higher sc, se, st, and spain increased the likelihood of a joint having djd present. for example, cats with positive spain in the right elbow were times more likely to have djd compared to cats with negative spain. similar increases were present for the left elbow, the lumbar, and lumbo-sacral areas. the likelihood of a joint having djd was also increased for joints with positive sc, se, and st, particularly for the elbows and tarsi. larger romc in shoulders, elbows and tarsi were associated with a lower likelihood of there being djd present larger roms in elbows, shoulders, carpi, and tarsi was associated with a lower likelihood of there being djd present. only statistically significant odds ratios are included *pain, effusion, crepitus and thickening scores were classified as present or absent § the significance of these odds ratios was lost due to'age,' acting as a confounding variable age had a large effect on the relationship of spain, sc, se, and st, and djdn/y. weight, sex, temperament, and time point during the study had a minor effect. bcs had a variable effect, but on average it was < 10% for all parameters, and it did not change the significance of the relationship between the parameter and djd. for the appendicular skeleton, controlling for age decreased the likelihood that a joint with a positive orthopedic parameter had radiographic djd by between and 37%. this effect resulted in a change in significance. study time point had the next largest effect on ors for se but not on other or; however significance was not altered. for the axial skeleton, controlling for age decreased the likelihood that a positive pain response would be associated with radiographic djd by between and 76%, and this resulted in a loss of significance for the lumbar and lumbo-sacral segments. when an interaction term was included in the model to evaluate or, age was not shown to be an effect modifier, and stratification analysis supported this conclusion. age had no confounding effect on the association between an abnormal romc or roms and the likelihood of a joint having djd. discussion there is no validated assessment system to measure joint pain in cats although recently some progress has been reported in this. in the present study, the level of aversive response interpreted as indicative of pain was evaluated subjectively during joint manipulation by a single investigator. the scores were recorded without consideration to viewing of the radiographs. this does not make it valid as an absolute measure, but the authors believe it is a valid comparison between different cats and different joints. there was no effect of time point of the study on the or for the relationships between orthopedic findings and radiographic djd, suggesting that the examining investigator did not change interpretation of parameters during the course of the study. additionally, there did not appear to be any learned effect within each cat, and no biasing effect of sedation. using this approach, it was found that the most frequently painful joints were the elbows and hips, and the most frequently painful spinal areas were the lumbar and lumbo-sacral segments. these data suggest that these would be the most impactful areas to target for further investigation as to the potential cause of pain. cats with higher sdjd and spain were less friendly than cats with lower sdjd and spain. little work has been performed on determining how best to evaluate temperament in domesticated cats and none on the association between temperament and disease. several studies have evaluated aspects of behavior in relation to the presence of djd but none have evaluated temperament thus far. from the present study, one can speculate that higher pain scores are logically associated with a worse temperament, but the finding of a strong association between temperament and djdy/djdn suggests that radiographic djd is associated with pain, and thus unfriendly temperament. having a valid measure of temperament, or change in temperament may be a useful surrogate measure of pain. future work could evaluate this relationship further by looking at the effect of an analgesic on temperament in cats with djd. some work in humans has suggested increased aggression in association with oa and treatment of oa with joint replacement has been shown to improve mood and well-being in human patients. in the human field, there has been a recent interest in understanding the psychological effects of joint pain. our study is unique in its evaluation of veterinarian-assessed temperament, but limited and answers to the effect of chronic oa associated pain on temperament, mood, and aggression in companion animals deserve further exploration. significant relationships were found between pain on examination and radiographic djd for the elbows, and the lumbar and lumbo-sacral areas. this may reflect a stronger association between disease and pain for these joints over others, or may reflect the fact that these joints may be easier to examine and manipulate appropriately. however, overall, the data indicated that the presence of signs of pain did not result in a high degree of certainty that radiographically evident djd was present. this discordance has been suggested in other studies of cats with djd, although the relationships were not described in detail. this discordance between pain and radiographic signs is in line with studies in humans, although in human studies the pain is generally self-reported. the discordance between pain and radiographic signs may be partly explained by the discordance between radiographic signs and grossly assessed signs of joint degeneration, as highlighted recently in cats. the higher values for spec and npv than sens and ppv suggest the absence of pain can be used clinically to help rule out djd with a high degree of certainty. the presence of pain, crepitus, effusion or thickening was found to be associated with an increased the chance of there being djd present for certain joints. age was found to be a confounding variable in the calculation of these ors. as age is strongly associated with the presence of radiographic djd, it could be argued that controlling for age gives a more realistic overall view of the association between an orthopedic examination finding and the presence of radiographic djd, avoiding the overestimation of the association between djd and pain. it is clear from the human literature that as radiographic oa becomes more severe, there is a closer association between joint pain and radiographic oa, and radiographic severity becomes greater with age. in a recent review of the association between knee pain and radiographic oa, decreasing discordance with increasing age was seen in all the reviewed studies except one. given that we found no evidence of an effect modifier for age, the clinical interpretation should be that increasing age is associated with less discordance between radiographic and orthopedic examination findings. overall, the present study found that radiographic djd is associated with decreased rom in the shoulder, elbow, carpus and tarsus, and that there was no effect of age on these relationships. this suggests that this parameter holds true regardless of age. although a previous study in clinically normal cats found no significant difference between conscious and sedated goniometric measurements in cats, the present study found small differences. the magnitude of the differences between rom measured in conscious and sedated cats would, from the results of this study, appear to be minimal, and likely have no clinical significance. however, further research would be needed to substantiate or refute this. the difference between the studies may be partly explained by the use of individual angles of flexion and extension for comparison in the former study, and the use of rom and the inclusion of joints with djd in the present study. increased rom measurements were associated with decreased odds of there being radiographic djd present, and therefore rom may be of value in helping to rule out djd.  overall, this study suggests that radiographic djd cannot be diagnosed with certainty using palpation or goniometry. however, negative findings with respect to pain, crepitus, effusion and thickening, tend to predict radiographically normal joints. increased rom measurements were associated with decreased odds of there being radiographic djd present, and therefore rom may be of value in helping to rule out djd. 
however, the extent of the discrepancy between clinical and radiographic signs of oa in companion animals has not been described in detail. however, negative findings tend to predict radiographically normal joints. radiographs of appendicular joints and the axial skeleton were made under sedation. radiographic djd cannot be diagnosed with certainty using palpation or goniometry. available information suggests a mismatch between radiographic and orthopedic examination findings in cats with djd. this study aimed to evaluate the relationship between orthopedic examination findings, joint goniometry, and radiographic signs of djd in cats, in a prospective observational design.
 available information suggests a mismatch between radiographic and orthopedic examination findings in cats with djd. however, the extent of the discrepancy between clinical and radiographic signs of oa in companion animals has not been described in detail. this study aimed to evaluate the relationship between orthopedic examination findings, joint goniometry, and radiographic signs of djd in cats, in a prospective observational design. cat temperament, pain response to palpation, joint crepitus, effusion and thickening were graded. radiographs of appendicular joints and the axial skeleton were made under sedation. joint motion was measured by use of a plastic goniometer before and after sedation. associations between radiographic degenerative joint disease and examination findings were assessed to determine sensitivity, specificity and likelihood estimations.  pain response to palpation was elicited in 0-67% of the joints with djd, with a specificity ranging from 62-99%; crepitus was detected in 0-56% of the joints and its specificity varied between and 99%; for effusion, values ranged between and 38%, and thickening, 0-59%. joints with djd tended to have a decreased range of motion. the presence of pain increased the odds of having djd in the elbow; the presence of pain in the lower back increased the odds of spinal djd being present.  radiographic djd cannot be diagnosed with certainty using palpation or goniometry. however, negative findings tend to predict radiographically normal joints. palpation and goniometry may be used as a tool to help to screen cats, mostly to rule out djd. paindegenerative joint diseaseosteoarthritisfelinegoniometryorthopedicjoint 