{\rtf1\mac\ansicpg10000\uc1 \deff0\deflang1033\deflangfe1033{\upr{\fonttbl{\f0\fnil\fcharset256\fprq2{\*\panose 02020603050405020304}Times New Roman{\*\falt Times New Roman};}
}{\*\ud{\fonttbl{\f0\fnil\fcharset256\fprq2{\*\panose 02020603050405020304}Times New Roman{\*\falt Times New Roman};}}}}{\colortbl;\red0\green0\blue0;\red0\green0\blue255;\red0\green255\blue255;\red0\green255\blue0;\red255\green0\blue255;
\red255\green0\blue0;\red255\green255\blue0;\red255\green255\blue255;\red0\green0\blue128;\red0\green128\blue128;\red0\green128\blue0;\red128\green0\blue128;\red128\green0\blue0;\red128\green128\blue0;\red128\green128\blue128;\red192\green192\blue192;}
{\stylesheet{\widctlpar\adjustright \cgrid \snext0 Normal;}{\s1\keepn\widctlpar\adjustright \b\ul\cgrid \sbasedon0 \snext0 heading 1;}{\*\cs10 \additive Default Paragraph Font;}{\s15\li720\widctlpar\adjustright \cgrid \sbasedon0 \snext15 Body Text 2;}{
\s16\fi360\li360\widctlpar\adjustright \cgrid \sbasedon0 \snext16 Body Text Indent 2;}}{\*\listtable{\list\listtemplateid984073\listsimple{\listlevel\levelnfc0\leveljc0\levelfollow0\levelstartat1\levelspace0\levelindent0{\leveltext
\'02\'00.;}{\levelnumbers\'01;}\fbias0 \fi-360\li360\jclisttab\tx360 }{\listname ;}\listid5}{\list\listtemplateid984073\listsimple{\listlevel\levelnfc0\leveljc0\levelfollow0\levelstartat1\levelspace0\levelindent0{\leveltext\'02\'00.;}{\levelnumbers\'01;}
\fbias0 \fi-360\li360\jclisttab\tx360 }{\listname ;}\listid6}{\list\listtemplateid984073\listsimple{\listlevel\levelnfc0\leveljc0\levelfollow0\levelstartat1\levelspace0\levelindent0{\leveltext\'02\'00.;}{\levelnumbers\'01;}\fbias0 \fi-360\li360
\jclisttab\tx360 }{\listname ;}\listid7}{\list\listtemplateid984073\listsimple{\listlevel\levelnfc0\leveljc0\levelfollow0\levelstartat1\levelspace0\levelindent0{\leveltext\'02\'00.;}{\levelnumbers\'01;}\fbias0 \fi-360\li360\jclisttab\tx360 }{\listname 
;}\listid8}{\list\listtemplateid-946446794{\listlevel\levelnfc0\leveljc0\levelfollow0\levelstartat1\levelspace0\levelindent0{\leveltext\'02\'00.;}{\levelnumbers\'01;}\fbias0 \fi-360\li720\jclisttab\tx720 }{\listlevel\levelnfc4\leveljc0\levelfollow0
\levelstartat1\levelspace0\levelindent0{\leveltext\'02\'01.;}{\levelnumbers\'01;}\fi-360\li1440\jclisttab\tx1440 }{\listlevel\levelnfc2\leveljc2\levelfollow0\levelstartat1\levelspace0\levelindent0{\leveltext\'02\'02.;}{\levelnumbers\'01;}\fi-180\li2160
\jclisttab\tx2160 }{\listlevel\levelnfc0\leveljc0\levelfollow0\levelstartat1\levelspace0\levelindent0{\leveltext\'02\'03.;}{\levelnumbers\'01;}\fi-360\li2880\jclisttab\tx2880 }{\listlevel\levelnfc4\leveljc0\levelfollow0\levelstartat1\levelspace0
\levelindent0{\leveltext\'02\'04.;}{\levelnumbers\'01;}\fi-360\li3600\jclisttab\tx3600 }{\listlevel\levelnfc2\leveljc2\levelfollow0\levelstartat1\levelspace0\levelindent0{\leveltext\'02\'05.;}{\levelnumbers\'01;}\fi-180\li4320\jclisttab\tx4320 }
{\listlevel\levelnfc0\leveljc0\levelfollow0\levelstartat1\levelspace0\levelindent0{\leveltext\'02\'06.;}{\levelnumbers\'01;}\fi-360\li5040\jclisttab\tx5040 }{\listlevel\levelnfc4\leveljc0\levelfollow0\levelstartat1\levelspace0\levelindent0{\leveltext
\'02\'07.;}{\levelnumbers\'01;}\fi-360\li5760\jclisttab\tx5760 }{\listlevel\levelnfc2\leveljc2\levelfollow0\levelstartat1\levelspace0\levelindent0{\leveltext\'02\'08.;}{\levelnumbers\'01;}\fi-180\li6480\jclisttab\tx6480 }{\listname ;}\listid171722629}
{\list\listtemplateid-554539796{\listlevel\levelnfc0\leveljc0\levelfollow0\levelstartat1\levelspace360\levelindent0{\leveltext\'02\'00.;}{\levelnumbers\'01;}\fi-360\li720\jclisttab\tx720 }{\listlevel\levelnfc4\leveljc0\levelfollow0\levelstartat1
\levelspace0\levelindent0{\leveltext\'02\'01.;}{\levelnumbers\'01;}\fi-360\li1440\jclisttab\tx1440 }{\listlevel\levelnfc2\leveljc2\levelfollow0\levelstartat1\levelspace0\levelindent0{\leveltext\'02\'02.;}{\levelnumbers\'01;}\fi-180\li2160
\jclisttab\tx2160 }{\listlevel\levelnfc0\leveljc0\levelfollow0\levelstartat1\levelspace0\levelindent0{\leveltext\'02\'03.;}{\levelnumbers\'01;}\fi-360\li2880\jclisttab\tx2880 }{\listlevel\levelnfc4\leveljc0\levelfollow0\levelstartat1\levelspace0
\levelindent0{\leveltext\'02\'04.;}{\levelnumbers\'01;}\fi-360\li3600\jclisttab\tx3600 }{\listlevel\levelnfc2\leveljc2\levelfollow0\levelstartat1\levelspace0\levelindent0{\leveltext\'02\'05.;}{\levelnumbers\'01;}\fi-180\li4320\jclisttab\tx4320 }
{\listlevel\levelnfc0\leveljc0\levelfollow0\levelstartat1\levelspace0\levelindent0{\leveltext\'02\'06.;}{\levelnumbers\'01;}\fi-360\li5040\jclisttab\tx5040 }{\listlevel\levelnfc4\leveljc0\levelfollow0\levelstartat1\levelspace0\levelindent0{\leveltext
\'02\'07.;}{\levelnumbers\'01;}\fi-360\li5760\jclisttab\tx5760 }{\listlevel\levelnfc2\leveljc2\levelfollow0\levelstartat1\levelspace0\levelindent0{\leveltext\'02\'08.;}{\levelnumbers\'01;}\fi-180\li6480\jclisttab\tx6480 }{\listname ;}\listid917831826}
{\list\listtemplateid680410572{\listlevel\levelnfc0\leveljc0\levelfollow0\levelstartat3\levelspace0\levelindent0{\leveltext\'02\'00.;}{\levelnumbers\'01;}\fbias0 \fi-360\li720\jclisttab\tx720 }{\listlevel\levelnfc4\leveljc0\levelfollow0\levelstartat1
\levelspace0\levelindent0{\leveltext\'02\'01.;}{\levelnumbers\'01;}\fi-360\li1440\jclisttab\tx1440 }{\listlevel\levelnfc2\leveljc2\levelfollow0\levelstartat1\levelspace0\levelindent0{\leveltext\'02\'02.;}{\levelnumbers\'01;}\fi-180\li2160
\jclisttab\tx2160 }{\listlevel\levelnfc0\leveljc0\levelfollow0\levelstartat1\levelspace0\levelindent0{\leveltext\'02\'03.;}{\levelnumbers\'01;}\fi-360\li2880\jclisttab\tx2880 }{\listlevel\levelnfc4\leveljc0\levelfollow0\levelstartat1\levelspace0
\levelindent0{\leveltext\'02\'04.;}{\levelnumbers\'01;}\fi-360\li3600\jclisttab\tx3600 }{\listlevel\levelnfc2\leveljc2\levelfollow0\levelstartat1\levelspace0\levelindent0{\leveltext\'02\'05.;}{\levelnumbers\'01;}\fi-180\li4320\jclisttab\tx4320 }
{\listlevel\levelnfc0\leveljc0\levelfollow0\levelstartat1\levelspace0\levelindent0{\leveltext\'02\'06.;}{\levelnumbers\'01;}\fi-360\li5040\jclisttab\tx5040 }{\listlevel\levelnfc4\leveljc0\levelfollow0\levelstartat1\levelspace0\levelindent0{\leveltext
\'02\'07.;}{\levelnumbers\'01;}\fi-360\li5760\jclisttab\tx5760 }{\listlevel\levelnfc2\leveljc2\levelfollow0\levelstartat1\levelspace0\levelindent0{\leveltext\'02\'08.;}{\levelnumbers\'01;}\fi-180\li6480\jclisttab\tx6480 }{\listname ;}\listid1807895298}}
{\*\listoverridetable{\listoverride\listid917831826\listoverridecount0\ls1}{\listoverride\listid171722629\listoverridecount0\ls2}{\listoverride\listid1807895298\listoverridecount0\ls3}{\listoverride\listid5\listoverridecount0\ls4}{\listoverride\listid6
\listoverridecount0\ls5}{\listoverride\listid7\listoverridecount0\ls6}{\listoverride\listid8\listoverridecount0\ls7}}{\info{\title Group Assignments}{\author vetmed}{\operator Peter Shires}{\creatim\yr2001\mo4\dy20\hr9\min6}
{\revtim\yr2001\mo4\dy20\hr9\min6}{\version2}{\edmins1}{\nofpages7}{\nofwords3079}{\nofchars17553}{\*\company VMRCVM}{\nofcharsws21556}{\vern99}}
\widowctrl\ftnbj\aenddoc\noxlattoyen\expshrtn\noultrlspc\dntblnsbdb\nospaceforul\formshade\viewkind4\viewscale125\pgbrdrhead\pgbrdrfoot \fet0\sectd \linex0\endnhere\sectlinegrid360\sectdefaultcl {\*\pnseclvl1\pnucrm\pnstart1\pnindent720\pnhang{\pntxta .}}
{\*\pnseclvl2\pnucltr\pnstart1\pnindent720\pnhang{\pntxta .}}{\*\pnseclvl3\pndec\pnstart1\pnindent720\pnhang{\pntxta .}}{\*\pnseclvl4\pnlcltr\pnstart1\pnindent720\pnhang{\pntxta )}}{\*\pnseclvl5\pndec\pnstart1\pnindent720\pnhang{\pntxtb (}{\pntxta )}}
{\*\pnseclvl6\pnlcltr\pnstart1\pnindent720\pnhang{\pntxtb (}{\pntxta )}}{\*\pnseclvl7\pnlcrm\pnstart1\pnindent720\pnhang{\pntxtb (}{\pntxta )}}{\*\pnseclvl8\pnlcltr\pnstart1\pnindent720\pnhang{\pntxtb (}{\pntxta )}}{\*\pnseclvl9
\pnlcrm\pnstart1\pnindent720\pnhang{\pntxtb (}{\pntxta )}}\pard\plain \s1\keepn\widctlpar\outlinelevel0\adjustright \b\ul\cgrid {Group 6 Assignments
\par }\pard\plain \widctlpar\adjustright \cgrid {Case Recorder\emdash Jenn
\par Coordinator\emdash Mary
\par Learning Issues\emdash Kim/Katherine/Jenn/Mary
\par Word Document Recorder\emdash Cathy/Katherine
\par Explanation of Facts: Cathy/Pam
\par Hypotheses: 1- Kim, 2- Jenn, 3- Katherine
\par Plan of action: Pam/Mary/Cathy
\par }\pard\plain \s1\keepn\widctlpar\outlinelevel0\adjustright \b\ul\cgrid {Learning Issues
\par }\pard\plain \li360\widctlpar\adjustright \cgrid {
\par }\pard \fi360\widctlpar\adjustright {1.  Cranial Drawer signs (Jenn)\emdash  Cranial drawer test
\par }\pard \fi720\li360\widctlpar\adjustright {This test, which evaluates the cranial cruciate ligament, is performed with the animal in lateral recumbency with the affected leg facing up.  The proximal tibia is grasped in one hand (the right if the r
ight stifle is being evaluated and vice versa) with the index finger on the tibial tuberosity, the index, ring and little finger on the proximal medial tibia, and the thumb behind the fibula.  The distal femur is grasped in the other hand ( the left if th
e
 right stifle is being evaluated) with the index finger on the patella, the middle finger on the medial femoral condyle, and the thumb behind the lateral femoral condyle.  Counter-pressure is then applied to the femur while the tibia is gently pushed or r
o
cked backwards and forwards.  During the test, the joint is held firmly without any rotation, flexion or extension. Positive forward displacement of the tibia indicates cranial cruciate ligament rupture.  The degree of displacement varies according to the
 position of the joint, the amount of muscle tension, and the length of time since the injury and degree of ligament rupture. 
\par }\pard\plain \s15\fi360\li360\widctlpar\adjustright \cgrid {For best results, the animal should be sedated or anesthetized.  A negative test while the animal is awake does not rule out cranial ligament rupture. 
\par }\pard\plain \li720\widctlpar\adjustright \cgrid {
\par }\pard \fi360\widctlpar\adjustright {2.  Cushing\rquote s Disease (Kim)\emdash  How Cushing\rquote s disease may be related to lameness:
\par }\pard \fi360\li360\widctlpar\adjustright {Because this dog is overweight despite vigorous physical activity and a reasonable diet, we became suspicious of an underlying systemic disorder in additi
on to the lameness.  In the video, the dog appears to have a distended, pendulous abdomen and pencil thin limbs, both characteristics of Cushing\rquote s disease, a disease of cortisol excess.  Common clinical signs of Cushing\rquote 
s disease include: polyuria, polydipsia, \ldblquote potbelly\rdblquote 
, obesity, and muscle atrophy, especially atrophy of the limbs.  There are numerous dermatological manifestations including trunkal alopecia and thinning of the skin.  Uncommon clinical manifestations as related to this case include rupture 
of the cranial cruciate ligament.  The mechanism that may lead to rupture involves an inhibition of fibroblasts and collagen synthesis, both necessary for normal healthy ligaments.  Further diagnostics for Cushing\rquote 
s disease may want to be pursued as a possible relationship to the development of hind limb lameness in this dog.
\par }\pard \widctlpar\adjustright {
\par }\pard \li360\widctlpar\adjustright {3.  Cranial Cruciate (Katherine)\emdash 
\par }\pard \fi360\li360\widctlpar\adjustright {The clinical signs for an older, overweight dog is non or partially weight bearing lameness for a longer time, although this dog has not shown lamene
ss for that long.  There is usually bilateral hind limb leg lameness, although in this dog it is unilateral.  Meniscal injury is also seen.  Joint effusion is not a consistent finding.
\par The other type of cranial cruciate ligament problem is an active dog th
at is usually young and fit.  There is acute onset of non-weight bearing lameness during exercise.  There is accompanying capsular distention.  It has been non-weight bearing for at least a week.  The dog may use the leg more with time.  Recurring lamenes
s occurs with stress or overwork.  There may be meniscal injury in the unstable joint.
\par Meniscal injury in this dog is unlikely as there was no crepitance, clicking, popping, or \ldblquote giving away\rdblquote  noted on palpation of the stifle joint.
\par Diagnosis of a cranial cru
ciate ligament tear is a positive cranial drawer sign.  Usually more than 2 mm in extension and more than 9.5 mm in flexion is considered a full tear.  We do not know how the leg was positioned during the cranial drawer test, but it is assumed that there 
is at least a partial tear of the cranial cruciate ligament (4-5 mm positive cranial drawer sign).  Radiographs need to be taken to allow for evaluation for osteoarthritis, neoplasia, or bone problems.
\par The etiology of cranial cruciate ligament tears are hyp
erextension of the ligament occurs when a running animal abruptly fixes the tibia, as in stepping in a hole.  This is a highly likely situation in this dog since it is a very active dog, going on long walks, and uneven walks in the woods.  The tibia may t
hen be forcibly rotated internally or the animal rotates its body externally and the cruciate twists, causing the cranial cruciate ligament to tear or rupture.
\par The pathophysiology usually includes pain, intra-articular hemorrhage and effusion.  The distenti
on will soon limit joint laxity and stop the hemorrhage.  The ruptured ligament will retract and fan out (it has a mop-end appearance).  There is resulting osteophyte development and chronic instability of the joint.  Finally chronic degenerative joint di
sease may develop because of the instability and pathologic pressure in that area.
\par }\pard \li360\widctlpar\adjustright {
\par }\pard\plain \s1\keepn\widctlpar\outlinelevel0\adjustright \b\ul\cgrid {Explanation Of Facts
\par {\listtext\pard\plain\f0 \hich\af0\dbch\af0\loch\f0 1.\tab}}\pard\plain \fi-360\li720\widctlpar\jclisttab\tx720\ls2\adjustright \cgrid {6 yr old Black Lab\emdash 
Age might suggest the occurrence of neoplasm causing lameness.  Osteosarcoma has a high prevalence in Labradors.  However the inciden
ce is most common in the proximal humerus and distal radius.  If cancer was a cause of the lameness, cancer cachexia should be seen with possible metastasic signs.
\par {\listtext\pard\plain\f0 \hich\af0\dbch\af0\loch\f0 2.\tab}Overweight dog yet on maintance diet and only gets fruit treats with excessive exercise\emdash May be indicative of Cushing\rquote 
s Disease.  Cushing Disease might be important because overweight dogs may be more prone to ligament tears.  Excessive cortisol levels may alter collagen synthesis and fibroblast proliferation.
\par {\listtext\pard\plain\f0 \hich\af0\dbch\af0\loch\f0 3.\tab}Excessive Exercise (in the woods, chasing other animals, etc.)\emdash 
May be prone to trauma.  Puncture wounds in the region of the knee may cause a septic exudates of the joint, such as Blastomycosis, E.coli, Pasterella, Streptococcus.
\par {\listtext\pard\plain\f0 \hich\af0\dbch\af0\loch\f0 4.\tab}Getting up Difficult, Walking Well\emdash excessive force on stifle joint when rising 
\par {\listtext\pard\plain\f0 \hich\af0\dbch\af0\loch\f0 5.\tab}Standing is Toe-touching/Partial wt-bearing (Lameness grade 2/3)\emdash lameness is shown when there is instability or pain in a joint.
\par {\listtext\pard\plain\f0 \hich\af0\dbch\af0\loch\f0 6.\tab}Joint Effusion of left stifle\emdash May indicate presence of inflammation (transudate) or exudate
\par {\listtext\pard\plain\f0 \hich\af0\dbch\af0\loch\f0 7.\tab}Distension of the Joint Capsule, on either side of the straight patellar ligament\emdash 
May indicate the presence of joint effusion.  Location of Distension to the area surrounding the straight patellar ligament may indicate meniscusal injury or cruciate injury.  If the animal ha
d meniscusal injury there would be popping or crepitance during manipulation.
\par {\listtext\pard\plain\f0 \hich\af0\dbch\af0\loch\f0 8.\tab}Pain on Manipulation of the stifle\emdash localizes the site of the problem
\par {\listtext\pard\plain\f0 \hich\af0\dbch\af0\loch\f0 9.\tab}Cranial draw present on left stifle only when sedated, not when awake\emdash because of the presence of muscle tensi
on, best preformed on a sedate patient.  For interpretation of cranial draw sign see learning issue #2, anatomic description under learning issue #5.
\par {\listtext\pard\plain\f0 \hich\af0\dbch\af0\loch\f0 10.\tab}Right had less the 2 mm movement in the stifle when awake and under sedation\emdash Under normal conditions we co
mpare anatomy bilaterally, that allows one to decide if it is normal in that animal.  The normal movement of the right stifle indicates that there is a problem in the left stifle. 
\par {\listtext\pard\plain\f0 \hich\af0\dbch\af0\loch\f0 11.\tab}Patella\rquote s are normally positioned and normally mobile\emdash r/o patella luxation or patellar ligament rupture/injury
\par {\listtext\pard\plain\f0 \hich\af0\dbch\af0\loch\f0 12.\tab}Collateral Ligaments are intact\emdash r/o tear in Collateral Ligaments
\par {\listtext\pard\plain\f0 \hich\af0\dbch\af0\loch\f0 13.\tab}Hip Joints no palpable laxity or pain\emdash r/o hip problems (dysplasia or trauma)
\par }\pard \li360\widctlpar\adjustright {
\par }\pard\plain \s1\keepn\widctlpar\outlinelevel0\adjustright \b\ul\cgrid {Hypothesis 1  
\par }\pard\plain \widctlpar\adjustright \cgrid {\fs26 Ligament Rupture}{:  Acute or degenerative injury of the cranial cruciate ligament resulting in partial or complete instability of the stifle joint.
\par }{\b\i Facts that support hypothesis:
\par {\pntext\pard\plain\f0 \hich\af0\dbch\af0\loch\f0 1.\tab}}\pard \fi-360\li360\widctlpar\jclisttab\tx360{\*\pn \pnlvlbody\ilvl0\ls4\pnrnot0\pndec\pnstart1\pnindent360\pnhang{\pntxta .}}\ls4\adjustright {Ligament rupture \endash 
 this could have been due to trauma and occurred acutely or could have been more of a degenerative injury from the amount 
of exercise the owner did.  This could have been a cranial cruciate ligament rupture which would result in partial or complete instability of the joint.  This could also have been caused by hyperextension of the joint during exercise.   
\par {\pntext\pard\plain\f0 \hich\af0\dbch\af0\loch\f0 2.\tab}}\pard \fi-360\li360\widctlpar\jclisttab\tx360{\*\pn \pnlvlbody\ilvl0\ls4\pnrnot0\pndec\pnstart1\pnindent360\pnhang{\pntxta .}}\ls4\adjustright {Another possibilit
y could have been due to the possibility of Cushings disease which could also affect the cranial cruciate, as well as causing weight gain.  Indications of possible ligament rupture:
\par {\pntext\pard\plain\f0 \hich\af0\dbch\af0\loch\f0 3.\tab}}\pard \fi-360\li360\widctlpar\jclisttab\tx360{\*\pn \pnlvlbody\ilvl0\ls4\pnrnot0\pndec\pnstart1\pnindent360\pnhang{\pntxta .}}\ls4\adjustright {Capsular distension (thickened)
\par {\pntext\pard\plain\f0 \hich\af0\dbch\af0\loch\f0 4.\tab}}\pard \fi-360\li360\widctlpar\jclisttab\tx360{\*\pn \pnlvlbody\ilvl0\ls4\pnrnot0\pndec\pnstart1\pnindent360\pnhang{\pntxta .}}\ls4\adjustright {Partial weight bearing left hind limb
\par {\pntext\pard\plain\f0 \hich\af0\dbch\af0\loch\f0 5.\tab}}\pard \fi-360\li360\widctlpar\jclisttab\tx360{\*\pn \pnlvlbody\ilvl0\ls4\pnrnot0\pndec\pnstart1\pnindent360\pnhang{\pntxta .}}\ls4\adjustright {(+) Cranial drawer sign under sedation
\par {\pntext\pard\plain\f0 \hich\af0\dbch\af0\loch\f0 6.\tab}}\pard \fi-360\li360\widctlpar\jclisttab\tx360{\*\pn \pnlvlbody\ilvl0\ls4\pnrnot0\pndec\pnstart1\pnindent360\pnhang{\pntxta .}}\ls4\adjustright {Older, overweight
\par {\pntext\pard\plain\f0 \hich\af0\dbch\af0\loch\f0 7.\tab}}\pard \fi-360\li360\widctlpar\jclisttab\tx360{\*\pn \pnlvlbody\ilvl0\ls4\pnrnot0\pndec\pnstart1\pnindent360\pnhang{\pntxta .}}\ls4\adjustright {Very active dog, occurred during exercise outing

\par {\pntext\pard\plain\f0 \hich\af0\dbch\af0\loch\f0 8.\tab}}\pard \fi-360\li360\widctlpar\jclisttab\tx360{\*\pn \pnlvlbody\ilvl0\ls4\pnrnot0\pndec\pnstart1\pnindent360\pnhang{\pntxta .}}\ls4\adjustright {Favors left leg, difficulty climbing stairs
\par {\pntext\pard\plain\f0 \hich\af0\dbch\af0\loch\f0 9.\tab}}\pard \fi-360\li360\widctlpar\jclisttab\tx360{\*\pn \pnlvlbody\ilvl0\ls4\pnrnot0\pndec\pnstart1\pnindent360\pnhang{\pntxta .}}\ls4\adjustright {Trouble rising
\par {\pntext\pard\plain\f0 \hich\af0\dbch\af0\loch\f0 10.\tab}}\pard \fi-360\li360\widctlpar\jclisttab\tx360{\*\pn \pnlvlbody\ilvl0\ls4\pnrnot0\pndec\pnstart1\pnindent360\pnhang{\pntxta .}}\ls4\adjustright {
Breed predilection for Labs (CCL) and female predominate sex
\par {\pntext\pard\plain\f0 \hich\af0\dbch\af0\loch\f0 11.\tab}}\pard \fi-360\li360\widctlpar\jclisttab\tx360{\*\pn \pnlvlbody\ilvl0\ls4\pnrnot0\pndec\pnstart1\pnindent360\pnhang{\pntxta .}}\ls4\adjustright {Joint effusion (although not always a sign)
\par {\pntext\pard\plain\f0 \hich\af0\dbch\af0\loch\f0 12.\tab}}\pard \fi-360\li360\widctlpar\jclisttab\tx360{\*\pn \pnlvlbody\ilvl0\ls4\pnrnot0\pndec\pnstart1\pnindent360\pnhang{\pntxta .}}\ls4\adjustright {
Seems to be lethargic, this could be due to pain and not wanting to rise
\par }\pard \widctlpar\adjustright {
\par }{\b\i Pathophysiology:}{ There are several facts gathered from this case that lead us to believe that the cause of lameness may be due to injury to the cranial cruciate ligament.  
These facts include: large breed dog, overweight, active, 6 years old, positive cranial drawer sign of left stifle, lameness, and joint effusion with distension of capsule.  This injury to the cranial cruciate ligament may either be due to acute trauma or
 
chronic degenerative changes.  Acute trauma can result in excessive internal rotation of the tibia and subsequent twisting of the ligament or possibly hyperextension of the stifle joint.  These situations can arise when the animal turns sharply and the ti
b
ia is excessively rotated internally, and in the latter case if the animal catches their limb in a hole while running or trapping the hind limb in the top of a fence or gate.  Both of these situations may result in excessive strain on the cranial cruciate
 ligament and cause either a partial or complete tear and subsequent lameness.
\par }\pard \fi720\widctlpar\adjustright {In the case of degeneration, it is speculated that the cruciate ligament may undergo progressive weakening with age and hence become more likely to rupture.  A minor injury or si
mply a sprain that occurred during normal activity may accelerate this process.  It has been reported that degenerative changes in dogs over 5 years old and increasing body size may be a factor that exacerbates degeneration of the ligament. 
\par }\pard \widctlpar\adjustright {Once damage ha
s been done to the cranial cruciate ligament, a series of steps in the pathophysiology usually occur.  First, there is pain and hemorrhage and effusion within the stifle joint.  The distension that occurs will then limit joint laxity.  The ruptured ligame
n
t then retracts and fans out. Soon, there will be osteophyte development around the margins of bone involved.  The ultimate result is chronic instability that leads to chronic degenerative joint disease. Signs associated with chronic stifle joint instabil
ity include thickening of the medial aspect of the joint, prominence of the tibial crest, muscle atrophy, and osteoarthritic changes along the trochlea.  
\par 
\par }\pard\plain \s1\keepn\widctlpar\outlinelevel0\adjustright \b\ul\cgrid {Hypothesis 2
\par }\pard\plain \widctlpar\adjustright \cgrid {\fs26 Neoplasia
\par }{\b\i Facts that support this hypothesis:   
\par }{This is a potential hypothesis because of the age and breed of dog.  Lab, 6 year old.
\par Indications
\par {\pntext\pard\plain\f0 \hich\af0\dbch\af0\loch\f0 1.\tab}}\pard \fi-360\li360\widctlpar\jclisttab\tx360{\*\pn \pnlvlbody\ilvl0\ls5\pnrnot0\pndec\pnstart1\pnindent360\pnhang{\pntxta .}}\ls5\adjustright {Pain upon manipulating the stifle
\par {\pntext\pard\plain\f0 \hich\af0\dbch\af0\loch\f0 2.\tab}}\pard \fi-360\li360\widctlpar\jclisttab\tx360{\*\pn \pnlvlbody\ilvl0\ls5\pnrnot0\pndec\pnstart1\pnindent360\pnhang{\pntxta .}}\ls5\adjustright {Lameness as viewed on the video
\par {\pntext\pard\plain\f0 \hich\af0\dbch\af0\loch\f0 3.\tab}}\pard \fi-360\li360\widctlpar\jclisttab\tx360{\*\pn \pnlvlbody\ilvl0\ls5\pnrnot0\pndec\pnstart1\pnindent360\pnhang{\pntxta .}}\ls5\adjustright {Partially non-weight bearing in the left hind limb

\par {\pntext\pard\plain\f0 \hich\af0\dbch\af0\loch\f0 4.\tab}}\pard \fi-360\li360\widctlpar\jclisttab\tx360{\*\pn \pnlvlbody\ilvl0\ls5\pnrnot0\pndec\pnstart1\pnindent360\pnhang{\pntxta .}}\ls5\adjustright {Difficulty rising \endash 
 if there was a tumor in the stifle joint it could cause pain of flexion and distension making it difficult for the dog to rise 
\par {\pntext\pard\plain\f0 \hich\af0\dbch\af0\loch\f0 5.\tab}}\pard \fi-360\li360\widctlpar\jclisttab\tx360{\*\pn \pnlvlbody\ilvl0\ls5\pnrnot0\pndec\pnstart1\pnindent360\pnhang{\pntxta .}}\ls5\adjustright {
Joint effusion and distension on both sides, if there were a tumor it could cause the joint capsule to be displaced resulting in joint effusion and distension on both sides
\par {\pntext\pard\plain\f0 \hich\af0\dbch\af0\loch\f0 6.\tab}}\pard \fi-360\li360\widctlpar\jclisttab\tx360{\*\pn \pnlvlbody\ilvl0\ls5\pnrnot0\pndec\pnstart1\pnindent360\pnhang{\pntxta .}}\ls5\adjustright {Lethargy \endash  canc
er can cause lethargy depending on its source and whether or not it has metastasized, however because of the dogs obesity there is no sign of cancer cachexia
\par }\pard \widctlpar\adjustright {
\par }\pard \fi720\widctlpar\adjustright {\b\i Pathophysiology:}{ Osteosarcoma is the most frequently seen primary bone tumor of the dog.  Large b
reed dogs, such as Labrador retrievers, account for more than half of the cases of osteosarcoma.  The most common sites of the lesion in the appendicular skeleton are the distal radius, proximal humerus, and proximal tibia.  The age distribution for this 
tumor ranges from 1 to 17 years old, while the mean occurs around 8 years of age.  
\par General clinical signs shown in the presentation of osteosarcoma include pain, lameness, and localized swelling.   At first the swelling is often undetectable. Later in the 
disease, with an increase in the size of the lesion, the swelling becomes palpable and visible.  Also the area becomes warm and pain increases due to periosteal elevation and stretching.  At this time a limitation in the range of motion of the nearby join
t
 is often noted.  Eventually a total loss of function, accompanied by muscle atrophy, will ensue.  Because of the severe metastatic potential of osteosarcoma, the overall condition of the animal will deteriorate, and cancer cachexia will result.  Metastas
is is often seen in the lungs but can also occur in the kidneys, liver, heart, spleen and other bones, as it spreads via the blood stream.  The progression of clinical signs tends to be fairly rapid, with death occurring in as little as several weeks.  

\par Gro
ssly, changes in the long bones that are seen with osteosarcoma include invasion of the medullary cavity, destruction of the cortex, and extension to periosteal tissue by a fibrous osteoid mass.  The spongiosa, cortex, periosteum, and soft tissue may be p
a
rtially eroded or completely destroyed.  Contour expansion of the cortex can also be observed.  Periosteal changes range from a hemorrhagic swelling to firm, fibrous osteoid proliferation to hard, dense sclerotic spiculated osseous formation.  The spongio
sa is often replaced by fibrous osteoid or osseous tissue. 
\par }\pard \widctlpar\adjustright {\tab Causes of osteosarcoma are presently unknown, but the exposure to chemicals, radiation, and viruses, along with the use of metal implants to fixate fractures, are all suspected.  In addition, chro
nic low-grade bone trauma has been hypothesized.  Although breed predilections do occur, osteosarcoma does not seem to be heritable.  Instead, the breed size and the rate of maturity may be implicated as more important in the development of this bone tumo
r.
\par 
\par }\pard\plain \s1\keepn\widctlpar\outlinelevel0\adjustright \b\ul\cgrid {Hypothesis 3
\par }\pard\plain \widctlpar\adjustright \cgrid {\fs26 Osteoarthritis 
\par }{\b\i Facts that support this hypothesis:
\par }{ This is always a rule out in any lameness because of the joint involvement due to progressive deterioration of the articular cartilage.
\par Indications:
\par {\pntext\pard\plain\f0 \hich\af0\dbch\af0\loch\f0 1.\tab}}\pard \fi-360\li360\widctlpar\jclisttab\tx360{\*\pn \pnlvlbody\ilvl0\ls6\pnrnot0\pndec\pnstart1\pnindent360\pnhang{\pntxta .}}\ls6\adjustright {Left limb lameness
\par {\pntext\pard\plain\f0 \hich\af0\dbch\af0\loch\f0 2.\tab}}\pard \fi-360\li360\widctlpar\jclisttab\tx360{\*\pn \pnlvlbody\ilvl0\ls6\pnrnot0\pndec\pnstart1\pnindent360\pnhang{\pntxta .}}\ls6\adjustright {Partial weight bearing
\par {\pntext\pard\plain\f0 \hich\af0\dbch\af0\loch\f0 3.\tab}}\pard \fi-360\li360\widctlpar\jclisttab\tx360{\*\pn \pnlvlbody\ilvl0\ls6\pnrnot0\pndec\pnstart1\pnindent360\pnhang{\pntxta .}}\ls6\adjustright {Joint effusion
\par {\pntext\pard\plain\f0 \hich\af0\dbch\af0\loch\f0 4.\tab}}\pard \fi-360\li360\widctlpar\jclisttab\tx360{\*\pn \pnlvlbody\ilvl0\ls6\pnrnot0\pndec\pnstart1\pnindent360\pnhang{\pntxta .}}\ls6\adjustright {Joint swelling
\par {\pntext\pard\plain\f0 \hich\af0\dbch\af0\loch\f0 5.\tab}}\pard \fi-360\li360\widctlpar\jclisttab\tx360{\*\pn \pnlvlbody\ilvl0\ls6\pnrnot0\pndec\pnstart1\pnindent360\pnhang{\pntxta .}}\ls6\adjustright {Athletic dogs at risk 
\par {\pntext\pard\plain\f0 \hich\af0\dbch\af0\loch\f0 6.\tab}}\pard \fi-360\li360\widctlpar\jclisttab\tx360{\*\pn \pnlvlbody\ilvl0\ls6\pnrnot0\pndec\pnstart1\pnindent360\pnhang{\pntxta .}}\ls6\adjustright {Obesity may predispose 
\par }\pard \widctlpar\adjustright {
\par }{\b\i Pathophysiology}{: Osteoarthritis is a disease characterized by joint pain, tenderness, limitation of movement, crepitance, variable degrees of inflammation, and occasional eff
usion.  It usually has inflammatory and degenerative changes.  There are many types of arthritis, but this hypothesis will focus on traumatic arthritis and osteoarthritis.
\par \tab Traumatic arthritis is a joint reaction produced by a single acute injury to the jo
int.  The articular damage may vary depending on the type and extent of the trauma.  There may be torn or stretched ligaments, fractures or detachment of articular cartilage, intra-articular fractures, torn or displaced menisci, lacerated joint capsule, o
r just damage to the soft tissue.  If the trauma is minor, there will probably be only limited inflammation and this is referred to as a \ldblquote sprain.\rdblquote 
\par \tab Synovitis is often a part of traumatic arthritis, with inflammation and hemorrhage occurring within the joint
 capsule.  Synovitis is characterized with hypertrophy and hyperplasia of the lining layer, with some inflammatory cells within the supporting layer.
\par }\pard \fi720\widctlpar\adjustright {\tab Osteoarthritis (aka osteoarthrosis, degenerative joint disease, hypertrophic arthritis, and chronic senes
cent arthritis), according to Whittick, is defined as a disorder of a moveable joint characterized by deterioration and abrasion of articular cartilage and by the formation of new bone at the articular margins.  Osteoarthritis is not a distinct disease, r
a
ther an end point for joint disease.  There are three forms of osteoarthritis, primary, secondary, and erosive.  Primary osteoarthritis cannot be ruled out altogether even though this is rare in dogs.  It is difficult to diagnose because things such as mi
l
d conformational abnormality or excessive activity (such as may be present in this dog) could cause the primary osteoarthritis.  It is also present in the Labrador retriever breed and the stifle is a common area for the arthritis.  However, it usually aff
ects several joints and only one seems to be affected in this case.
\par The dog in this case would probably secondary osteoarthritis, as it is most likely secondary to trauma.  The two possible types of trauma are: abnormal forces acting on normal cartilage (ex
. fracture, ruptured cranial cruciate ligament, collateral ligament damage, etc.) and normal forces acting on abnormal cartilage (ex. forces on thickened cartilage from osteochondrosis).  Obesity and excessive exercise (of which this dog has both) will te
n
d to accelerate the osteoarthritc process.  The pathophysiology of osteoarthritis is long and involved.  It usually starts with damage to the chondrocyte or cartilage matrix.  There is increased anabolic and catabolic activity of the chondrocyte, with rel
e
ase of inflammatory mediators and production of metalloproteinases.  There is then breakdown of proteoglycan and collagen and free fragments are released into the synovial fluid.  The synovial macrophages begin to clear the debris and cause the joint caps
u
le to thicken.  The thickening is thought to provide increase joint stability, unfortunately it also decreases the range of motion of that joint.  There is then increased production of hyaluronan from the increased activity of the synoviocytes.  The commo
n
 final pathway of osteoarthritis is usually inflammation.  The cartilage damage releases cytokines from the chondrocytes.  These cytokines are able to produce a wide variety of inflammatory products.  Interleukin-1 causes a decreased ability of the chondr
ocytes to produce normal proteoglycans and cartilage.  Ultimately there is a decrease in cartilage matrix from the catabolic activity within the joint.  
\par }\pard \widctlpar\adjustright {\tab The changes in cartilage matrix starts with damage to the collagen fibrils.  This results in decreased
 tensile strength and an inability to constrain the hydrophilic proteoglycan molecules.  The proteoglycans are then lost from the cartilage matrix and cannot be replaced quickly enough.  The proteoglycans swell and results in swelling of the cartilage as 
a
 whole.  This abnormal cartilage is now unable to withstand normal biochemical forces, and certainly not excessive exercise.  The constant force will cause further loss of surface integrity, with development of fissures and clefts in the articular cartila
ge.  The cartilage is now unable to distribute the force of impact over a large area and causes focal increases on the remaining cartilage and subchondral bone.
\par \tab The subchondral bone responds to the excess stress by thickening and this results in decreased 
compliance of the tissue.  The remaining cartilage then receives even more stress and strain.  The bone remodels eventually and osteophytes are produced from the abnormal forces.
\par 
\par }\pard\plain \s1\keepn\widctlpar\outlinelevel0\adjustright \b\ul\cgrid {Plan of Action
\par }\pard\plain \widctlpar\adjustright \cgrid {
\par {\pntext\pard\plain\f0 \hich\af0\dbch\af0\loch\f0 1.\tab}}\pard \fi-360\li360\widctlpar\jclisttab\tx360{\*\pn \pnlvlbody\ilvl0\ls7\pnrnot0\pndec\pnstart1\pnindent360\pnhang{\pntxta .}}\ls7\adjustright {Radiographs \endash 
 these would be helpful to rule out osteoarthritis, could see joint effusion, capsular distension because of compression of infrapatellar fat pad, periarticular osteophytes and anthesiophytes
\par }\pard \fi360\li360\widctlpar{\*\pn \pnlvlcont\ilvl0\ls0\pnrnot0\pndec }\adjustright {Radiographs will show if there is an intra-articular fracture or significant damage to the ligaments (may need 
stress radiographs).  They may also show soft tissue swelling or excess fluid in the joint capsule.
\par For osteoarthrits: presence of new bone deposits; may be sclerosis of the subchondral bone; narrowing of the joint space (loss of articular cartilage); intr
a- or periarticular calcification within synovial membranes, the fibrous layer of the capsule, ligaments, tendons, or menisci; osteophytes
\par Radiographic signs seen with osteosarcoma\emdash irregular pattern of bone destruction, with or without marginal sclerosis; 
matrix patterns that are increasingly dense with either a solid or cloudy edge; periosteal reactions that vary from cortex expansion to spiculated (sunburst) densities; osteolytic lesions that extend into the epiphysis or metaphysis and with irregular, sc
alloped edges (moth-eaten) or widened bone contour; cortical lesions ranging from partial erosion to complete destruction.  If any of these signs are seen, a bone biopsy needs to be taken to confirm the diagnosis of osteosarcoma.
\par Radiographs of the thoracic cavity would be necessary if osteosarcoma is found to rule in metastatic disease.  There would be a diffuse pattern most likely.  The absence of neoplasia in the radiographs does not rule out metastatic disease.
\par }\pard \li360\widctlpar{\*\pn \pnlvlcont\ilvl0\ls0\pnrnot0\pndec }\adjustright {
\par {\pntext\pard\plain\f0 \hich\af0\dbch\af0\loch\f0 2.\tab}}\pard \fi-360\li360\widctlpar\jclisttab\tx360{\*\pn \pnlvlbody\ilvl0\ls7\pnrnot0\pndec\pnstart1\pnindent360\pnhang{\pntxta .}}\ls7\adjustright {Arthroscope \endash  to directly visualize crucia
te ligaments, menisus and other intrarticular structures.  If cranial cruciate ruptured one would expect to see a retracted ligament that has fanned out.
\par {\pntext\pard\plain\f0 \hich\af0\dbch\af0\loch\f0 3.\tab}}\pard \fi-360\li360\widctlpar\jclisttab\tx360{\*\pn \pnlvlbody\ilvl0\ls7\pnrnot0\pndec\pnstart1\pnindent360\pnhang{\pntxta .}}\ls7\adjustright {Arthrocentesis \endash 
 this would enable us to identify an intrarticular disease and identify any sepsis or immune mediated disease.  The normal appearance of synovial fluid is clear, perhaps with a brown or yellow discoloration, with normal viscosity and a normal mucin clot.

\par }\pard\plain \s16\fi360\li360\widctlpar{\*\pn \pnlvlcont\ilvl0\ls0\pnrnot0\pndec }\adjustright \cgrid {The joint tap will show if there is damage to the joint.  There may be blood.  The whit
e cell count may be elevated in number (mostly mononuclear cells). There is usually a background stain of high proteoglycan content.
\par {\pntext\pard\plain\f0 \hich\af0\dbch\af0\loch\f0 4.\tab}}\pard\plain \fi-360\li360\widctlpar\jclisttab\tx360{\*\pn \pnlvlbody\ilvl0\ls7\pnrnot0\pndec\pnstart1\pnindent360\pnhang{\pntxta .}}\ls7\adjustright \cgrid {Blood work \endash 
 should also be performed including a CBC, Complete Chemistry Profile.
\par {\pntext\pard\plain\f0 \hich\af0\dbch\af0\loch\f0 5.\tab}}\pard \fi-360\li360\widctlpar\jclisttab\tx360{\*\pn \pnlvlbody\ilvl0\ls7\pnrnot0\pndec\pnstart1\pnindent360\pnhang{\pntxta .}}\ls7\adjustright {Thyroid panel for T3 and T4 should also 
be run as well a Cushings test.   
\par }\pard \widctlpar\adjustright {
\par 
\par }{\b\ul 
\par }}