In vivo three-dimensional knee kinematics in goats with unilateral anterior cruciate ligament transection

Although the goat is an established animal model in anterior cruciate ligament (ACL) research, in vivo kinematics associated with ACL deficiency have not been previously described in this species. Three-dimensional knee kinematics were determined before and after unilateral ACL transection in eight goats. Fluoroscopic imaging of the knees during treadmill walking and force-platform gait analysis during over-ground walking were performed prior to ACL transection, and 2 weeks, 3 months, and 6 months after ACL transection. Transient lameness of the ACL-transected limb was noted in all goats but resolved by 3 months post-ACL transection. Increased extension of 8.7° to 17.0° was noted throughout the gait cycle in both the ACL-transected and the contralateral unaffected knees by 3 months post-ACL transection, in a bilaterally symmetric pattern. Peak anterior tibial translation increased by 3 to 6 mm after ACL transection and persisted over the 6-month study period. No changes in axial rotation or abduction angle were observed after ACL transection. Unilateral ACL deficiency in goats resulted in persistent kinematic alterations, despite the resolution of lameness by 3 months post-ACL transection.

Vascular ring anomalies in cats: 20 cases (2000-2018)

OBJECTIVE

To report the clinical characteristics, types of vascular ring anomalies (VRA), operative findings, complications, and survival after surgical treatment of cats with VRA.

STUDY DESIGN

Retrospective, multi-institutional case series.

ANIMALS

Client- or shelter-owned cats presenting to academic, referral veterinary institutions.

METHODS

Medical records of cats with VRA that underwent surgical treatment were reviewed. Signalment, relevant medical history, clinical signs, diagnostic imaging, surgical findings, complications, and survival were recorded.

RESULTS

Twenty cats with VRA were included. Vascular ring anomalies were most commonly (75% [15/20]) diagnosed in cats less than 1 year old, with no breed or sex predilection. Regurgitation was the most common clinical sign, present in 18 of 20 (90%) cats. A persistent right aortic arch was diagnosed in 17 of 20 (85%) cats, with concurrent aberrant left subclavian artery in four of the cats. Surgical treatment was associated with survival to discharge in 18 of 20 (90%) cats. Persistent clinical signs were reported in nine of 13 (69%) cats, and radiographic evidence of megaesophagus persisted in four of 13 (31%) cats, with a median follow-up of 275 days after discharge.

CONCLUSION

Persistent right aortic arch was the most commonly diagnosed VRA in cats in this series, although multiple anomalies were observed. Surgical treatment of VRA in cats was associated with a high survival to discharge, although persistence of clinical signs and megaesophagus was noted in 69% and 31% of the cats, respectively.

CLINICAL SIGNIFICANCE

Surgical treatment of VRA in cats is associated with a high survival rate; however, persistence of clinical signs is an expected outcome.

High-Grade Myxoid Liposarcoma (Round Cell Variant) in a Dog

A 10-year-old, neutered male, Basset hound had a 26 × 21 × 21 cm infiltrative mass on the left abdominal wall that did not extend into the peritoneal cavity based on radiographs and abdominal computed tomography. Cytological examination revealed moderate numbers of neoplastic round cells, which frequently contained numerous round, clear, cytoplasmic vacuoles. Histologically, the tumour was composed of two morphologically distinct cell populations forming a continuum of heterogeneously differentiated cells. The primary spindle-shaped population formed streams with abundant, lightly eosinophilic, alcian blue-positive, myxoid matrix. The second population was arranged in sheets and had a round cell appearance. Scattered within both populations were neoplastic cells containing variably sized, intracytoplasmic, osmium tetroxide-positive vacuoles (lipid). Multifocal large pools of mucin formed pseudocysts, and numerous small capillaries were present throughout the neoplasm. According to the current World Health Organization veterinary classification of liposarcomas, this neoplasm had morphological features of both the myxoid and pleomorphic variants of liposarcoma; however, it was analogous to the recently defined high-grade myxoid liposarcoma in man. Myxoid liposarcoma with round cells has not been described previously in dogs. This case highlights the need to potentially re-evaluate the current classification of liposarcomas in animals.