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meniscal injury. These are longitudinal tears (parallel to the circular orientation of the collagen fibres) named as the inner part of the meniscus is axially displaced resembling the handle of
a bucket. Probing with a meniscal probe may
be necessary to “unmask” a bucket handle
tear. When probing it is important to remember that in the normal medial meniscus passage
of the probe dorsally and ventrally over the meniscus will not cause damage or separation and that (other than at the area of the caudal meniscotibial ligament) the probe can not be passed caudally beyond the meniscus due to the close attachment of the joint capsule to the medial meniscus. (This is NOT the case with the lateral meniscus where the probe passes freely dorsally and ventrally). Multiple bucket handle tears can be present in the caudal horn and careful probing is necessary.
Peripheral capsular detachment is similar
to a large bucket handle tear with complete detachment of the caudal pole of the meniscus from the joint capsule.
Radial or transverse tears are full thickness tears radiating from the inner concave (axial) border.
Partial meniscectomy (removal of only the damaged part of the meniscus) is strongly preferable to total meniscectomy.
Axial partial meniscectomy is the removal of the “bucket handle” part of a bucket handle tear. This leaves the periphery of the meniscus intact and, unless the bucket handle is very large, preserves some of the load bearing capacity of the meniscus.
Caudal pole hemimeniscectomy is the removal of the entire caudal pole of a detached medial meniscus. While this is necessary in cases where the entire caudal horn is detached it inactivates the shock absorbing capacity of the meniscus and increases the severity of subsequent osteoarthritis similar to total meniscectomy.
WSV18-0268
GASTROENTEROLOGY / LIVER
GALL BLADDER MUCOCOELE: AN UPDATE
P. Watson1
1Department of Veterinary Medicine, University of Cambridge, UK
Pathophysiology
A gall bladder mucocoele describes cystic mucinous hyperplasia of the gall bladder wall with accumulation
of thick mucus. A mucocele can be subclinical and an incidental finding on diagnostic imaging but can cause obstruction of the biliary tract secondary to the thick mucus and when it becomes very large, it can also stretch the gall bladder wall and cause pressure necrosis and rupture.
Gall bladder mucoceles were first reported in dogs in 1995. They are uncommon but appear to be increasing in frequency.
The underlying cause of gall bladder mucoceles
remains poorly understood, but there does appear
to be a strong association with hypertriglyceridemia
and hypercholesterolemia in dogs. Other proposed associations include biliary tract infection; distruption
to gall bladder motility and drainage and genetic mutations. A very interesting recent study has suggested an association with neonicotinoid (imidacloprid)
use particularly in Shelties – which is an attractive explanation for the apparent sudden appearance of this new disease. Studies repeatedly report an increased incidence in small breed dogs with a strong over-lap with breeds reported to suffer from familial hyperlipidemia:
for example, Aquirre et al 2007 report gall bladder mucocele in 38 Shetland sheepdogs and Malek et al 2013 report gall bladder mucocele in 43 dogs including 10 cocker spaniels; 5 Shetland sheepdogs and 4 miniature schnauzers. A Japanese case-control study of gall bladder mucocele showed a significant association with increased cholesterol or triglycerides and miniature schnauzers were one of the breeds predisposed to mucocele.
Aguirre et al 2007 proposed an association between gall bladder mucocele and ‘dyslipidemia’ with an increase
in serum triglycerides and/or cholesterol reported
in all cases in which they were measured. Six out of
38 of their cases had hyperadrenocorticism, 5 had hypothyroidism and one had diabetes mellitus. Malek at el 2013 also reported dogs with hyperadrenocorticism, diabetes mellitus and hypothyroidism and a study of 30 dogs with gall bladder mucocele included seven dogs with hyperadrenocorticism and two dogs on long term steroid therapy. Another retrospective case-control study of gall bladder mucocele found a very significant association with hyperadrenocorticism but questioned
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