Zygomatic Arch Parosteal Osteosarcoma in Dogs and a Cat.

Parosteal osteosarcoma is a rare, slow-growing tumor most commonly arising from the surface of long bones. Tissue or histological sections from 5 dogs and 1 cat with zygomatic arch masses were examined. Clinical presentations varied from chronic sneezing to facial swelling. Imaging consistently demonstrated osseous proliferation in the area of the zygomatic arch. Histologically, the masses were characterized by well-differentiated fibro-osseous and chondroid components that radiated outward from the periosteum of the zygomatic bone. Cellular atypia and mitotic figures were uncommon. Parosteal osteosarcomas have previously been reported in the skulls of dogs and cats, but only 1 has been reported on the zygomatic arch. Initially, these tumors are of low histologic low grade, but with time, they can show more aggressive behavior and invade the underlying bone.

Prevalence of mupirocin resistance in Staphylococcus pseudintermedius.

In the United States, veterinary use of mupirocin is primarily limited to the treatment of canine pyoderma caused by methicillin-resistant Staphylococcus pseudintermedius (MRSP). In this study, only 1 of 581 S. pseudintermedius isolates tested was resistant to mupirocin and carried the high-level mupirocin resistance gene, ileS2, on a plasmid.

Incidence of inducible clindamycin resistance in Staphylococcus pseudintermedius from dogs.

Clindamycin is increasingly used to treat canine pyoderma. Eight of 608 Staphylococcus pseudintermedius isolates were positive for inducible clindamycin resistance by double-disk diffusion testing and PCR detection of ermB. Staphylococcus pseudintermedius isolates that are erythromycin resistant but clindamycin susceptible by in vitro antimicrobial susceptibility testing should be tested for inducible clindamycin resistance.

Quantitative bioimaging of copper in frozen liver specimens from cats using laser ablation-inductively coupled plasma-mass spectrometry.

OBJECTIVES: The aim of this study was to assess laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) as a tool for measuring concentrations and determining accumulation of copper in frozen liver specimens from cats. METHODS: Six frozen liver specimens were evaluated by qualitative copper staining and quantitative flame atomic absorption spectroscopy. Tissue specimens were cryo-sectioned and quantitative bioimaging of copper was performed using LA-ICP-MS. Results were compared with those obtained using conventional methods. RESULTS: Of the six specimens, only one showed positive staining for copper with rhodanine. Using flame atomic absorption spectroscopy (FAAS), one specimen showed a deficient copper level (<100 µg/g dry weight), two specimens had copper within the reference interval (RI; 150-180 µg/g) and three specimens had copper concentrations above the RI. Bioimaging from LA-ICP-MS showed inhomogeneous distribution of hepatic copper. The areas with dense copper accumulation were represented as hotspots in the liver specimens. Hepatic copper quantification by LA-ICP-MS correlated well with copper quantified by FAAS (r = 0.96, P = 0.002). CONCLUSIONS AND RELEVANCE: Our findings suggest that quantitative bioimaging by LA-ICP-MS could be used to demonstrate the distribution and concentration of copper in frozen liver specimens from cats. The distribution of copper in these specimens was inhomogeneous with dense accumulation represented as hotspots on tissue sections. A positive correlation of hepatic copper concentrations determined by LA-ICP-MS and FAAS was found. Further studies to establish an RI for hepatic copper using this technique and to further determine its clinical utility are warranted.

Assessment of the intracellular distribution of copper in liver specimens from cats.

The intracellular distribution of copper in the liver has been investigated in dogs and humans. However, this has not been reported in cats. This study aimed to assess the intracellular copper distribution in liver specimens from cats with a range of hepatic copper concentrations. Twenty-nine frozen liver specimens from cats were included. Each liver specimen was divided into two pieces for overall copper quantification and tissue fractionation. The copper concentrations in liver specimens and liver fractions were measured by flame atomic absorption spectroscopy. Five specimens had copper concentrations < 100 µg/g dry weight, eight had copper concentrations between 100 and 180 µg/g, 14 had copper concentrations between 181 and 700 µg/g, and two had copper concentrations >700 µg/g. Only one specimen had positive copper staining. Regardless of the overall concentrations, copper was mostly found in the cytosolic fraction followed by the nuclear, large granule, and microsomal fractions. Our findings indicate that similarly to other species, intracellular copper is predominantly found in the cytosolic and nuclear fractions in cats. The distribution in cats with copper-loaded conditions, such as primary copper hepatopathy, was not assessed but warrants evaluation.

Medical conditions associated with gastroduodenal ulceration or erosion in 168 dogs: 2008-2018.

BACKGROUND: Many medical conditions are thought to cause gastroduodenal ulceration or erosion (GUE) in dogs. However, evidence for the association between many of these conditions and GUE in dogs is lacking. OBJECTIVE: To identify medical conditions associated with GUE in dogs. ANIMALS: One hundred and sixty-eight dogs with GUE and 168 randomly selected control dogs without evidence of GUE identified on necropsy between January 2008 and September 2018. METHODS: Patient signalment, blood urea nitrogen (BUN) and serum creatinine concentrations, recently administered ulcerogenic drugs, as well as necropsy findings were recorded. The association between these findings and presence of GUE was assessed by univariable and multivariable analysis. RESULTS: In the final multivariable model, the following factors were associated with GUE: Nonsteroidal anti-inflammatory drug (NSAID) administration (odds ratio [OR], 6.3; 95% confidence interval [CI], 2.3-17.4; P = .0004), glucocorticoid administration (OR, 3.0; 95% CI, 1.5-5.9; P = .001), gastrointestinal neoplasia (OR, 13.5; 95% CI, 1.7-108.0; P = .01) and gastrointestinal mechanical disease (foreign bodies, gastric dilatation, and volvulus; OR, 4.8; 95% CI, 1.2-19.7; P = .03). Additionally, working dog breeds were predisposed to GUE compared to mixed breed dogs (OR, 2.8; 95% CI, 1.1-7.4; P = .04). Insufficient clinical data was available to either support or refute a role of other putative risk factors evaluated. CONCLUSION AND CLINICAL IMPORTANCE: Administration of NSAID or glucocorticoid and gastrointestinal neoplasia or mechanical disease were associated with GUE in dogs. The potential predisposition of working breed dogs for GUE requires further investigation.

Assessment of copper accumulation in archived liver specimens from cats.

OBJECTIVES: The aim of this study was to assess hepatic copper concentrations and zonal distribution in cat liver specimens. METHODS: For this study, 121 archived, formalin-fixed, paraffin-embedded liver specimens from cats were used. Tissue sections were stained for copper with rhodanine and scored from 0 (no copper accumulation) to 5 (panlobular copper accumulation). The tissue specimens were then deparaffinized and hepatic copper concentrations were measured using flame atomic absorption spectroscopy. RESULTS: Tissue samples were categorized into four groups based on histopathologic findings: (1) no significant histopathologic hepatic changes (n = 66); (2) hepatic steatosis (n = 18); (3) inflammatory or infectious disease (n = 24); and (4) neoplasia (n = 13). Of the 121 specimens, 13 (11%) stained positive for copper, with three having a score ⩾3. Thirty-seven specimens (31%) had copper concentrations above the reference interval ([RI] <180 µg/g dry weight liver). Copper concentrations in cats with hepatic inflammatory or infectious disease were significantly higher than cats with hepatic steatosis (P = 0.03). Copper-staining score and concentration were positively correlated (rs = 0.46, P <0.001). CONCLUSIONS AND RELEVANCE: Despite the fact that 31% of specimens had copper concentrations above the RI, only 11% showed positive copper staining and only 2.5% had a score ⩾3. Our findings suggest that hepatic copper concentrations greater than the upper limit of the RI are relatively common in cats. Further studies to determine the factors that influence hepatic copper staining in cats and to establish contemporary RIs for hepatic copper in healthy cats are warranted.

Effects of osteoarthritis on radiographic measures of laxity and congruence in hip joints of Labrador Retrievers.

OBJECTIVE- To determine effects of hip joint osteoarthritis on radiographic measures of hip joint laxity and congruence. DESIGN- Longitudinal study. ANIMALS- 40 Labrador Retrievers. PROCEDURES- Dogs were assigned to 2 groups based on radiographic evidence of osteoarthritis. Dogs in the osteoarthritis group were free of osteoarthritis at initial radiographic evaluation (t(1)) and developed osteoarthritis by a subsequent radiographic evaluation (t(2)). Dogs in the nonosteoarthritis group had no radiographic osteoarthritis at either evaluation. Hip joint laxity was quantified by use of the distraction index (DI) from a distraction radiographic view and use of the Norberg angle (NA) from a ventrodorsal hip-extended radiographic view. The compression index (CI) from a compression radiographic view was used as a measure of joint congruence (concentricity). RESULTS- Hip joint laxity (NA or DI) did not change over time in the nonosteoarthritis group. Mean hip joint laxity (NA and DI) for the osteoarthritis group was greater at t(1) than for the nonosteoarthritis group. With the onset of osteoarthritis, mean NA decreased significantly and mean CI increased significantly, but mean DI remained unchanged. CONCLUSIONS AND CLINICAL RELEVANCE- No radiographic evidence for compensatory hip joint tightening associated with osteoarthritis was detected. Hip-extended radiography revealed that hip joints got looser with osteoarthritis and NA decreased. Hip joint laxity (DI) on distraction radiographs was unchanged by the onset of osteoarthritis and remained constant in the osteoarthritis and nonosteoarthritis groups at both evaluations. However, the CI increased with osteoarthritis, as reflected in nonzero indices (incongruence). The CI may be a valid marker for early hip joint osteoarthritis.