Ligand-binding characteristics of feline insulin-binding immunoglobulin G

Polyclonal immunoglobulin (Ig) G autoantibodies against insulin have been identified in sera of healthy cats. We purified and fractionated insulin-binding IgGs from cat sera by affinity chromatography and analyzed affinity of insulin-binding IgGs for insulin and their epitopes. Following the passing of fraction A, which did not bind to insulin, insulin-binding IgGs were eluted into two fractions, B and C, by affinity chromatography using a column fixed with bovine insulin. Dissociation constant (KD) values between insulin-binding IgGs and insulin, determined by surface plasmon resonance analysis (Biacore™system), were 1.64e⁻⁴ M for fraction B (low affinity IgGs) and 2e⁻⁵ M for fraction C (high affinity IgGs). Epitope analysis was conducted using 16 peptide fragments synthesized in concord with the amino acid sequence of feline insulin by an enzyme-linked immunosorbent assay. Fractions B and C showed higher absorbance (affinity) of the peptide fragment of 10 amino acid residues at the carboxyl-terminal of the B chain (peptide No. 19), followed by peptide fragments of 6 to 15 amino acid residues of the B chain (peptide No. 8). Fraction C showed a higher absorbance to 7 to 16 amino acid residues of the B chain (peptide No. 5) compared with the absorbance of fraction B. Polyclonal insulin-binding IgGs may form a macromolecule complex with insulin through the multiple affinity sites of IgG molecules. Feline insulin-binding IgGs are multifocal and may be composed of multiple IgG components and insulin.     

An outbreak of rabbit hemorrhagic disease (RHD) caused by Lagovirus europaeus GI.2/rabbit hemorrhagic disease virus 2 (RHDV2) in Ehime, Japan

A total of ten 1–2-year-old rabbits died within 2 weeks at a facility in Ehime prefecture in May 2019. Necropsy revealed liver discoloration and fragility, hemorrhage of some organs and blood coagulation failure. On histopathologic examination, necrotizing hepatitis was a common finding, together with fibrin thrombi in the small vessels and hemorrhage in some organs. Rabbit hemorrhagic disease (RHD) virus gene was detected in liver samples, and viral particles of approximately 32 nm in diameter were found in the cytoplasm of degenerated hepatocytes by electron microscopy. Phylogenetic analysis based on the partial VP60 gene sequence classified it as Lagovirus europaeus GI.2/RHDV2. This is the first confirmed outbreak of RHD caused by globally emerging GI.2/RHDV2 in Japan.     

Relationship between anti-insulin antibody production and severe insulin resistance in a diabetic cat

A 5-year-old castrated male domestic shorthair cat was diagnosed with diabetic ketoacidosis and severe insulin resistance. Although the conventional treatment for diabetic ketoacidosis was provided, the cat required frequent hospitalization because of severe dehydration and repeated diabetic ketoacidosis. We detected anti-insulin antibodies for human in this cat. Serum insulin-binding IgG levels were markedly elevated compared with those in healthy cats and other diabetic cats. We initiated prednisolone to suppress the effects of anti-insulin antibodies. After initiation of prednisolone, the cat was gradually recovered with increasing activity and appetite. Furthermore, satisfactory glycemic control was achieved with combined subcutaneous injection of insulin detemir and insulin degludec.     

Experimental hyperlipemia induces insulin resistance in cats

The effect of experimental hyperlipemia on insulin sensitivity was evaluated in seven healthy cats. Serum triglyceride and free fatty acid concentrations were significantly (P<0.05) higher when lipid-heparin was administered (2,894 ± 1,526 mg/dl and 4.54 ± 0.70 mEq/l, respectively) than when saline was administered (70 ± 42 mg/dl and 0.22 ± 0.08 mEq/l, respectively). A glucose clamp test revealed that the mean glucose infusion rate when lipid-heparin was administered (5.80 ± 0.67 mg/kg/min) was significantly (P<0.05) lower than when saline was administered (8.52 ± 1.83 mg/kg/min). These results suggest that experimental hyperlipemia induced insulin resistance in the healthy cats.     

A case of protein-losing enteropathy treated with methotrexate in a dog

A 9-year-old female Pug was presented to us with chronic diarrhea. Hematologic findings indicated severe hypoproteinemia and hypoalbuminemia, and endoscopy revealed severe edema of the duodenal mucosa. Based on these results and on additional histopathological findings, we made a diagnosis of protein-losing enteropathy caused by lymphocytic-plasmacytic enteritis with lymphangiectasia. The dog was initially treated with prednisolone and cyclosporine. This treatment regimen was not effective. However, when methotrexate was substituted for cyclosporine, progress was obtained and the diagnosis was confirmed.     

Pericardial mesothelioma in a neonatal calf

We encountered an extremely rare tumor, a pericardial mesothelioma, in a neonatal calf. The patient calf showed severe abdominal distention, and died immediately after birth. The thoracic cavity was contained a huge heart with a large amount of pericardial fluid. A number of granular and cobblestone-like nodules were dispersed over the epicardium and pericardium. The nodules consisted of papillary proliferations of neoplastic cells, and the neoplasm occasionally showed mesenchymal proliferations. Immunohistochemistry revealed that they had the characteristics of mesothelial cells (cytokeratin-and vimentin-positive), and the neoplasm was diagnosed as mesothelioma.     

Enterolithiasis in a cat

An 8-year-old female Persian cat was brought in for evaluation of chronic vomiting. The presence of opaque enteric foreign bodies and intestinal obstruction along with azotaemia, hyperphosphataemia, moderate anaemia and peritoneal fluid were revealed following appropriate diagnostic work-up. Exploratory laparotomy confirmed jejunoileal dilation, ileocaecal stenosis, and numerous foreign objects in the jejunoileum. These foreign objects and ileocaecal stenosis were surgically removed, and intestinal resection and anastomosis was performed. The patient recovered favourably. Analysis revealed that the foreign objects were composed of calcium phosphate and calcium carbonate. Intestinal inflammation and stenosis secondary to enterolithiasis may have developed following ingestion of cat litter or a previous unrelated surgical intervention. We were unable to delineate the inciting pathogenesis in this particular case.     

Pedigree analysis of factor XI deficiency in Japanese black cattle

Using a DNA-based diagnostic test for factor XI deficiency in Japanese black cattle, we surveyed 123 cattle (42 sires and 81 dams) in Gifu and Hyogo prefectures, and calculated gene frequencies. In sires, we drew up the pedigree network of the cattle with the factor XI deficiency. Results showed that the mutated allele of factor XI deficiency was retroactive in at least 6 or more generations of sires. Frequencies of the mutant gene were higher at 26.4% in total, and at 33.3% in sires. All 7 cattle with the homozygote of mutated allele were clinically normal, and showed no bleeding episodes. The mutated allele of factor XI deficiency might be widespread among Japanese black cattle.     

Computer tomography diagnosis of meningoencephalocele in a calf

A 24-day-old female Holstein calf had a soft, painless fluctuating swelling on the median plane in the frontal region, but did not show any clinical symptoms including neurological signs. Computer tomography (CT) distinctly showed the cyst filled with fluid and part of the encephalon. Hence, this swelling was diagnosed as meningoencephalocele, but not meningocele. The meningoencephalocele was successfully repaired surgically. Meningoencephalocele can thus be easily recognised by CT in a calf.