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Case summary An 8-year-old neutered female domestic shorthair cat was referred with complaints of lethargy, anorexia, fever, tachypnoea and a pulmonary mass on thoracic radiography. Whole-body CT revealed the presence of a nodular lesion in the right caudal lobe of the lung. Fine-needle aspiration of the lung mass yielded purulent fluid and cytology showed a large number of mildly to moderately degenerated neutrophils with numerous cocci and bacilli, leading to the diagnosis of a lung abscess. Empirical administration of doxycycline and orbifloxacin was initiated on the day of referral. Bacterial culture and antibiotic susceptibility tests using the collected fluid sample detected two types of bacteria, which were susceptible to both antibiotics. The clinical signs of the cat improved after the initiation of treatment, and the antibiotics were discontinued 28 days later, after the lung lesions disappeared. No recurrence of lung abscess was observed until 588 days after the discontinuation of treatment. Relevance and novel information Only one case of a lung abscess has been previously reported in cats. Furthermore, while surgical resection is the most common treatment for lung abscesses in the field of veterinary medicine, this is the first report of successful treatment with antibiotic administration alone.

A new species of Demodex was detected in the earwax of a dog with otitis externa in Saitama Prefecture, Japan, in July 2010. The opisthosoma length of the mite was slightly shorter than 1/2 of its body length, which was different from the other species in domestic dogs, D. canis and D. injai, but was similar to the form of mites termed “short-bodied species”, including D. cornei. However, the stubby external form was morphologically different from those of “short-bodied species”, excluding a case without a species description reported from Greece. Among known species, the mite was similar to D. equi and D. acutipes.

Large cell gastrointestinal lymphoma (LCGIL) is the most common extranodal lymphoma in dogs, but its molecular biological backgrounds have not been clarified. In this study, we comprehensively investigated the gene mutations in LCGIL. Whole exome sequencing analysis using four dogs with LCGIL showed mutations in NACC1 gene in two dogs. Further, the six genes known to be mutated in human intestinal T-cell lymphoma, ASXL3, SOCS3, PRDM1, FYN, TET2, and ZDBF2, were found to be mutated in one dog. Then, targeted next-generation sequencing analysis was performed to validate these results using additional 31 dogs with LCGIL. As a result, the mutation in ZDBF2 genes were identified in all samples, but the same mutation was ubiquitously observed in all peripheral blood samples. As for the remaining genes, the mutations were not observed in any dogs. The targeted next-generation analysis of whole exon regions of ZDBF2 revealed the other mutations in additional three dogs. In the present study, some mutations in genes related to human intestinal T-cell lymphoma were identified, but common gene mutations were not found among most cases. These results implied the heterogeneity of molecular pathophysiology of canine LCGIL. Further studies are needed to comprehensively analyze genomic and non-genomic molecular aberrations in each canine LCGIL case.

A 7-year-old mixed-breed cat presented with subcutaneous oedema and erythema extending from the right axilla to the abdomen. Fine-needle aspiration of the subcutaneous lesion revealed large, atypical, round cells. A clonality analysis for the T-cell receptor-gamma and immunoglobulin heavy chain genes showed no clonal rearrangement. The presumed diagnosis was lymphoma and the cat was treated with prednisolone and L-asparaginase but died 78 days after initial treatment. At necropsy, an oedematous subcutaneous mass in the right axilla, hepatomegaly, splenomegaly and lymphadenopathy of the mediastinum and left axilla were observed. Histopathological examination revealed diffuse infiltration of large atypical round cells in the subcutaneous mass, liver, spleen, lymph nodes and bone marrow. Immunohistochemically, the tumour cells were strongly positive for CD56, and negative for CD3, CD20, CD79a, CD57, granzyme B and perforin. Based on these findings, the cat was diagnosed with blastic natural killer (NK) cell lymphoma/leukaemia. Here, we report the pathological and clinical findings of NK cell lymphoma/leukaemia in a cat. The antibody for human CD56, a diagnostic marker for human NK cell neoplasms, showed cross-reactivity with feline CD56 by immunohistochemistry and Western blotting analysis. The antibody could be a useful diagnostic marker for feline NK cell neoplasms.

Background Lymphoma with Mott cell change, or Mott cell lymphoma (MCL), is an uncommon variant of canine lymphoma. Because of its rare occurrence, there has been no comprehensive study describing the disease so far. Miniature dachshunds, a popular breed in Japan, sometimes experience MCL. Objectives To investigate the clinical characteristics and outcomes of MCL in miniature dachshunds. Methods Medical records were retrospectively reviewed to identify miniature dachshunds diagnosed with MCL and other types of lymphoma. Data on clinical and laboratory findings, treatments and outcomes were collected. Survival times were compared between miniature dachshunds with MCL and other types of lymphoma. Results Of the 87 miniature dachshunds diagnosed with lymphoma, 9 (10%) had cytological characteristics of MCL. All 9 miniature dachshunds with MCL were categorised as having alimentary lymphoma (small and/or large intestine, 6 dogs; mesenteric lymph node, 3 dogs). The median age was 3.1 years (range, 2.0–9.4 years). All nine dogs were treated with chemotherapeutic protocols used for large cell lymphoma or alkylating agents such as melphalan or chlorambucil. The overall response rate to initial chemotherapy was 78%, and the median progression‐free survival was 105 days. Overall survival in these nine dogs ranged from 6 to >1513 days (median, 240 days), which was significantly longer than in 29 miniature dachshunds with alimentary large cell lymphoma other than MCL (median, 57 days; p = 0.0491). Conclusions MCL in miniature dachshunds can be recognised as a peculiar type of B‐cell lymphoma occurring in relatively young dogs as an alimentary form and has a longer survival compared with typical alimentary large cell lymphoma. The present retrospective study described the clinical characteristics and outcomes of lymphoma with Mott cell change, or Mott cell lymphoma (MCL) in miniature dachshunds. The response rate to initial chemotherapy was 78%, and the median overall survival was 240 days, showing a better prognosis than that of large cell alimentary lymphoma in this study population. MCL in miniature dachshunds can be recognized as a peculiar type of lymphoma which appears to be prevalent in the breed.

Cover caption: The cover image is based on the Original Article Clinical characteristics and outcomes of Mott cell lymphoma in nine miniature dachshunds by Aki Ohmi et al., https://doi.org/10.1002/vms3.975.

Cover caption: The cover image is based on the Original Article Clinical characteristics and outcomes of Mott cell lymphoma in nine miniature dachshunds by Aki Ohmi et al., https://doi.org/10.1002/vms3.975.

Background Transgenic (Tg) mice are widely used in biomedical research, and they are typically generated by injecting transgenic DNA cassettes into pronuclei of one-cell stage zygotes. Such animals often show unreliable expression of the transgenic DNA, one of the major reasons for which is random insertion of the transgenes. We previously developed a method called “pronuclear injection-based targeted transgenesis” (PITT), in which DNA constructs are directed to insert at pre-designated genomic loci. PITT was achieved by pre-installing so called landing pad sequences (such as heterotypic LoxP sites or attP sites) to create seed mice and then injecting Cre recombinase or PhiC31 integrase mRNAs along with a compatible donor plasmid into zygotes derived from the seed mice. PITT and its subsequent version, improved PITT ( i -PITT), overcome disadvantages of conventional Tg mice such as lack of consistent and reliable expression of the cassettes among different Tg mouse lines, and the PITT approach is superior in terms of cost and labor. One of the limitations of PITT, particularly using Cre -mRNA, is that the approach cannot be used for insertion of conditional expression cassettes using Cre- LoxP site-specific recombination. This is because the LoxP sites in the donor plasmids intended for achieving conditional expression of the transgene will interfere with the PITT recombination reaction with LoxP sites in the landing pad. Results To enable the i -PITT method to insert a conditional expression cassette, we modified the approach by simultaneously using PhiC31o and FLPo mRNAs. We demonstrate the strategy by creating a model containing a conditional expression cassette at the Rosa26 locus with an efficiency of 13.7%. We also demonstrate that inclusion of FLPo mRNA excludes the insertion of vector backbones in the founder mice. Conclusions Simultaneous use of PhiC31 and FLP in i -PITT approach allows insertion of donor plasmids containing Cre- loxP -based conditional expression cassettes.