The histomorphologic characteristics and chemical composition of the crystals associated with suspected pet food-induced nephrotoxicosis in 3 dogs are described. Kidney specimens from 2 dogs, a 3-year-old Parson Russell Terrier and a 3-year-old Bernese Mountain Dog, were examined. Both developed acute renal failure after eating canned pet food on the 2007 Menu Foods recall list. The third case was a kidney specimen from a 1-year-old mixed-breed dog from a similar 2004 outbreak of canine renal failure in Taiwan, which occurred after eating a commercial dog food. Hematoxylin and eosin (HE), 72-hour Oil Red O (ORO72h), Alizarin Red S (pH 4.1-4.3), and Von Kossa stains; infrared (IR) spectroscopy; and scanning electron microscopy with energy dispersive X-ray analysis (SEM/EDXA) were performed to determine the histomorphologic characteristics and chemical composition of the crystals observed in each case. Histomorphologic findings in each case included acute, marked tubular degeneration and necrosis with many intratubular birefringent crystals, and lymphoplasmacytic interstitial nephritis. In each case, most of the crystals were rough, pale brown, and stained with ORO72h but did not stain with Alizarin Red S (pH 4.1-4.3) or Von Kossa stains; these features were consistent with a plastic or lipid. IR spectroscopy and SEM/EDXA results were consistent with melamine-containing crystals. A second crystal type identified in each case was smooth and platelike with staining characteristics and IR spectroscopy and SEM/EDXA results consistent with calcium oxalate crystals. Melamine-containing crystals have distinct light microscopic, histochemical, and SEM/EDXA characteristics that facilitate their identification in tissue.

Most feline cutaneous mast cell tumors (CMCT) are behaviorally benign; however, there is a subset of these tumors with, marked pleomorphism (previously termed poorly differentiated) that have been reported to be more aggressive. In this study, pleomorphic CMCT from 15 cats were identified from surgical biopsy submissions, and follow-up clinical data were obtained for 14 of these cats. Pleomorphic CMCT were discrete dermal nodules composed of sheets of pleomorphic round cells. Tumors from all 15 cats contained markedly cytomegalic and karyomegalic cells; 9/15 tumors (60%) contained multinucleated tumor giant cells. Typical mast cell granules were easily identified in sections stained with hematoxylin and eosin and with metachromatic stains and based on ultrastructural evaluation in cytomegalic as well as smaller tumor cells, indicating that the tumors were not poorly differentiated. The mitotic rate was very low (<1 mitosis per 10 high-power fields [hpf]) in 14 of 15 tumors (93%). Affected cats were 6-19 years old (mean age = 11.5 years), and there was no breed or sex predilection. Two cats had local recurrence. The only cat that had a pleomorphic CMCT with a high mitotic rate (1-2 mitoses/hpf) subsequently developed numerous other dermal neoplasms and was euthanatized. In this study, the large majority of feline pleomorphic CMCT were behaviorally benign. Mitotic rate is likely an important prognostic indicator of CMCT behavior.

Abstract. Feline peripheral nerve sheath tumors are uncommonly reported, and their clinical behavior has not been well documented. Fifty-nine peripheral nerve sheath tumors were collected from 53 cats. All of the tumors involved skin, subcutis, skeletal muscle, and/or mucous membranes. Histologically, the tumors were composed of compact to loosely arranged streams and fascicles of spindled cells with eosinophilic, often wavy cytoplasmic processes; small to occasionally moderate amounts of collagenous to myxoid matrix; and nuclear palisading. Immunohistochemically, all tumors were positive for vimentin and S-100 protein, 44 of 59 were positive for glial fibrillary acidic protein (GFAP), and all were negative for muscle specific actin. The tumors fell into 3 histologic categories: 34 benign tumors with Antoni A areas that were S-100 protein and GFAP positive, 9 benign tumors that lacked Antoni A areas and were S-100 protein positive and GFAP negative, and 16 tumors with features of malignancy. Seventy-five percent of these cases involved the head, neck, or limbs. Recurrent tumors were submitted or tumors were reported to have recurred in 9 cases. Tumor recurrence was reported for all 3 of the histologic subtypes. None was documented as having metastasized.

The purpose of this investigation was to compare the effects of initial resuscitation with HBOC-201 to that of lactated Ringer (LR) solution in the setting of uncontrolled hemorrhage and traumatic brain injury (TBI). Anesthetized immature swine underwent fluid-percussion TBI and liver laceration. During a 75-min "prehospital phase," the animals were resuscitated with HBOC-201, LR solution, or nothing (NON). Upon "hospital arrival," the animals were provided blood and 0.9% NaCl as needed, and the liver injury was repaired. Surviving animals were killed 6 h after injury. Brain tissue was processed for blood flow, and gross, light microscopic, and immunohistochemical analyses. Mean TBI force (2.6 +/- 0.6 atm) and blood loss (64.4 +/- 3.4 mL/kg) were similar between groups. Six-hour survival was significantly greater in HBOC-201 (8 of 13 [62%]) versus LR solution (1 of 11 [9%]) and NON (1 of 8 [3%]) animals (P < 0.02). Mean arterial pressures, cardiac indices, cerebral perfusion pressures, and brain tissue oxygen tension were significantly greater, and lactate and base deficit were lower in HBOC-201 as compared with LR solution animals. Blood transfusion requirements were reduced in HBOC-201 (3.6 +/- 0.6 mL/kg per survival hour) as compared to 7.1 +/- 1.2 mL/kg per survival hour. Severity of subarachnoid and intraparenchymal hemorrhages was statistically greater in LR solution-treated animals, but these differences were not likely to be clinically significant. There were no differences in glial fibrillary acidic protein and microtubule-associated protein 2. In this model of combined uncontrolled hemorrhage and TBI, initial resuscitation with HBOC-201 resulted in significant improvements in survival and systemic and cerebrovascular physiological parameters, as well as a reduction in transfusion requirements.

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