Retrospective study of 540 cats with respiratory diseases in Japan (2003-2020).

BACKGROUND: Few epidemiological studies on respiratory medicine and the relationship between clinical signs and various respiratory diseases in cats have been reported. OBJECTIVES: This retrospective study aimed to investigate the prevalence and breed predisposition to feline respiratory diseases in Japan and determine the association between clinical signs, duration and type of respiratory diseases. METHODS: The medical records of cats with feline respiratory diseases were examined to obtain information on age, sex, breed, final diagnosis, clinical signs and duration. The odds ratios (ORs) and 95% confidence intervals were calculated to evaluate breed predispositions. Mann-Whitney U, Kruskal-Wallis and Dunn's tests were used to assess the duration of clinical signs. RESULTS: This study included 540 cats with 615 respiratory diagnoses. The American Shorthair breed was predisposed to bronchopneumonia (BP; OR: 5.0) and pulmonary tumour (PT; OR: 3.6), while the Russian Blue breed exhibited a predisposition to inflammatory lower airway diseases (OR: 3.4), BP (OR: 6.1) and interstitial lung diseases (OR: 11.1). Similarly, the Scottish Fold breed displayed predisposition to PTs (OR: 5.8). The duration of clinical signs among nasal diseases, nasopharyngeal diseases and lower tracheal/bronchial and pulmonary diseases differed significantly (p = 0.001, p = 0.012, p < 0.0001, respectively). CONCLUSIONS: The results suggest that some popular breeds in Japan are predisposed to feline respiratory diseases, especially the American Shorthair, Russian Blue and Scottish Fold breeds. The characteristics of occurrence, clinical signs and duration of each disease will aid in diagnosing, treating, preventing and elucidating the pathophysiology of feline respiratory disease.

Construction of diagnostic prediction model for canine nasal diseases using less invasive examinations without anesthesia.

Advanced imaging techniques under general anesthesia are frequently employed to achieve a definitive diagnosis of canine nasal diseases. However, these examinations may not be performed immediately in all cases. This study aimed to construct prediction models for canine nasal diseases using less-invasive examinations such as clinical signs and radiography. Dogs diagnosed with nasal disease between 2010 and 2020 were retrospectively investigated to construct a prediction model (Group M; GM), and dogs diagnosed between 2020 and 2021 were prospectively investigated to validate the efficacy (Group V; GV). Prediction models were created using two methods: manual (Model 1) and LASSO logistic regression analysis (Model 2). In total, 103 and 86 dogs were included in GM and GV, respectively. In Model 1, the sensitivity and specificity of neoplasia (NP) and sino-nasal aspergillosis (SNA) were 0.88 and 0.81 in GM and 0.92 and 0.78 in GV, respectively. Those of non-infectious rhinitis (NIR) and rhinitis secondary to dental disease (DD) were 0.78 and 0.88 in GM and 0.64 and 0.80 in GV, respectively. In Model 2, the sensitivity and specificity of NP and SNA were 0.93 and 1 in GM and 0.93 and 0.75 in GV, respectively. Those of NIR and DD were 0.96 and 0.89 in GM and 0.80 and 0.79 in GV, respectively. This study suggest that it is possible to create a prediction model using less-invasive examinations. Utilizing these predictive models may lead to appropriate general anesthesia examinations and treatment referrals.

Retrospective study of feline tracheal mass lesions.

OBJECTIVES: This multicentre, retrospective observational study aimed to describe the clinical presentation, diagnostic methods, treatment and outcomes of cats with tracheal masses. METHODS: Eighteen cats from five academic or secondary/tertiary animal hospitals were included. RESULTS: The median age at diagnosis was 10.7 years (mean 9.5; range 1-17). There were nine castrated males, seven spayed females, one intact male and one intact female. Fourteen (78%) were domestic shorthairs, one (6%) was an Abyssinian, one (6%) was an American Shorthair, one (6%) was a Bengal and one (6%) was a Scottish Fold. The most common presenting complaints included chronic respiratory distress or dyspnoea (n = 14), followed by wheezing/gagging (n = 12), coughing (n = 5) and voice changes (n = 5). There was cervical tracheal involvement in 16/18, and two showed involvement of the intrathoracic trachea. The following methods were used for diagnosis: ultrasound-guided fine-needle biopsy (UG-FNB) and cytology (n = 8), bronchoscopic forceps biopsy and histopathology (n = 5), surgical resection and histopathology (n = 3), forceps biopsy via an endotracheal tube (n = 1) and histology of tissue sputtered from a cough (n = 1). Lymphoma was most often diagnosed (n = 15), followed by adenocarcinoma (n = 2) and squamous cell carcinoma (n = 1). Most lymphoma cases received chemotherapy with or without radiation according to various protocols, and partial (n = 5) or complete responses (n = 8) were noted. Kaplan-Meier survival data for cats with lymphoma revealed a median survival time of 214 days (95% confidence interval >149 days), which was significantly longer than that of other types of tumours (21 days). CONCLUSIONS AND RELEVANCE: Lymphoma was the most prevalent diagnosis, and showed a good response to chemotherapy with or without radiation therapy. Various diagnostic procedures were performed, and UG-FNB and cytology are good diagnostic procedures for cervical tracheal lesions. Owing to the variety of treatment protocols at different centres, it was impossible to compare outcomes.

Expression of DEP Domain-Containing 1B in Canine Lymphoma and Other Types of Canine Tumours.

Canine lymphoma is the most common haematological malignancy in dogs and is typically treated with multidrug chemotherapy. Most cases are at risk of relapse after several courses of chemotherapy and the oncogenic mechanism remains unknown. This study was aimed at identifying genes expressed in canine lymphoma by cDNA microarray. We found elevated expression of Dishevelled, EGL-10 and pleckstrin (DEP) domain-containing 1B (DEPDC1B) in canine lymphoma cells compared with cells and tissues from healthy dogs. Canine DEPDC1B protein was detected in 13 of 41 lymphoma specimens by immunohistochemistry, but was not detected in lymph nodes from normal dogs. Immunoreactive DEPDC1B protein was also detected in several other types of canine tumour. This is the first report documenting the association of DEPDC1B with canine cancer and the results suggest that DEPDC1B might serve as a potential marker or therapeutic target for canine malignancies.

Efficacy of chemotherapy and palliative hypofractionated radiotherapy for cats with nasal lymphoma.

Nasal lymphoma (NL) is the most common nasal tumor in cats, and radiotherapy, chemotherapy, or a combination of these treatments have been described as the treatment for this disease. However, the previous studies included various machines and protocols of radiotherapy. Therefore, we aimed to retrospectively compare the prognosis among cases treated with palliative hypofractionated radiotherapy, chemotherapy, and a combination of them with united machine and protocol of radiotherapy. When compared overall survival and progression free survival, there was no significant difference among these three groups. The data of this study suggested that similar efficacy could be achieved by palliative hypofractionated radiotherapy, chemotherapy, or a combination of them.

Measurement of the concentration of serum soluble interleukin-2 receptor alpha chain in dogs with lymphoma.

Soluble interleukin-2 receptor (sIL-2r) is released directly from the surface of lymphocytes expressing interleukin-2 receptor alpha chain (CD25), and its serum concentration has been found to reflect the prognosis of human lymphoproliferative malignancies. In this study, we demonstrated the presence of sIL-2r in canine serum and developed a specific sandwich enzyme-linked immunosorbent assay (ELISA) to quantify the concentration of canine serum sIL-2r. In the immunoprecipitation (IP) assay, CD25 protein weighing approximately 45 kDa was detected in canine serum, smaller than the membrane-bound CD25 (approximately 55 kDa). To measure the concentration of serum sIL-2r in dogs, an ELISA system was developed. Serum sIL-2r levels were significantly higher in dogs with multicentric high-grade B-cell lymphoma before therapy than that in healthy dogs. Serum sIL-2r concentration was also found to be elevated in a proportion of dogs with other types of lymphoma. Changes in serum sIL-2r levels generally paralleled the changes in mass and lymph node size in dogs with high-grade B-cell lymphoma. This study demonstrated that serum sIL-2r level would be a marker to monitor tumour growth and regression in canine lymphoma.

Nimustine Treatment of 11 Cases of Canine Histiocytic Sarcoma.

The objective of this retrospective study was to report treatment outcomes in dogs with histiocytic sarcoma (HS) that were treated with nimustine (ACNU). This study evaluated data from 11 dogs including 5 with macroscopic tumors that were treated in the primary setting and 6 that underwent aggressive local therapy while being treated in the adjuvant setting. The median ACNU starting dose was 25 mg/m2 (range, 20-30 mg/m2; 3- to 5-wk intervals, 1-8 administrations). The median overall survival in the primary and adjuvant settings was 120 days (median progression-free survival [PFS], 63 days) and 400 days (median PFS, 212 days), respectively. Neutropenia was observed in eight cases (grade 1, n = 1; grade 2, n = 2; grade 3, n = 2; grade 4, n = 3) with nadir neutrophil count at 1 wk after ACNU administration. Mild gastrointestinal toxicity (grade 1-2) was observed in three cases. ACNU was well tolerated and showed a similar outcome to that seen for lomustine, which is a drug commonly used to treat canine HS, in terms of overall survival and PFS in the current study population. Further investigations will need to be undertaken to definitively determine if ACNU is an appropriate alternative to lomustine for the treatment of HS.

Comparison of Canine and Feline Meningiomas Using the Apparent Diffusion Coefficient and Fractional Anisotropy.

Meningiomas are the most common intracranial tumor in dogs and cats, and their surgical resection is often performed because they are present on the brain surface. Typical meningiomas show comparatively characteristic magnetic resonance imaging findings that lead to clinical diagnosis; however, it is necessary to capture not only macroscopic changes but also microstructural changes to devise a strategy for surgical resection and/or quality of removal. To visualize such microstructural changes, diffusion-weighted imaging (DWI) and diffusion tensor imaging (DTI) have been used in human medicine. The aim of this retrospective study was to investigate the different characteristics of the apparent diffusion coefficient (ADC) from DWI and fractional anisotropy (FA) from DTI of meningioma between dogs and cats. Statistical analyses were performed to compare ADC and FA values between the intratumoral or peritumoral regions and normal-appearing white matter (NAWM) among 13 dogs (13 lesions, but 12 each in ADC and FA analysis) and six cats (seven lesions). The NAWM of cats had a significantly lower ADC and higher FA compared to dogs. Therefore, for a comparison between dogs and cats, we used ADC and FA ratios that were calculated by dividing the subject (intra- or peritumoral) ADC and FA values by those of NAWM on the contralateral side. Regarding the intratumoral region, feline meningiomas showed a significantly lower ADC ratio and higher FA ratio than canine meningiomas. This study suggested that ADC and FA may be able to distinguish a meningioma that is solid and easy to detach, like as typical feline meningiomas.

Dynamic pharyngeal collapse in three cats with different pharyngeal pathology.

Dynamic pharyngeal collapse (PC) is a rarely reported condition in cats defined as the partial or complete collapse of the pharyngeal lumen during inspiration. Herein, we report the imaging findings and clinical features of three cats with dynamic PC. Lateral radiograph of the head was insufficient to detect dynamic PC, but fluoroscopy in conscious cats revealed dynamic PC. Magnetic resonance imaging was not helpful to reveal dynamic PC and underlying diseases. We obtained biopsy samples from the irregular nasopharyngeal mucosal membrane through endoscopy in two of the three cases and high-grade B-cell lymphoma was histopathologically diagnosed. In feline cases with abnormal upper respiratory sounds, dynamic PC should be considered, and fluoroscopy is the imaging technique of choice to diagnose the condition.

Efficacy of zonisamide on interictal electroencephalography in familial spontaneous epileptic cats.

Objectives The effectiveness of zonisamide (ZNS) against spontaneous epilepsy in cats has not yet been described. The purpose of this study was to investigate the effect of ZNS on interictal paroxysmal discharges (PDs) using scalp electroencephalography (EEG) in familial spontaneous epileptic cats (FSECs). Methods Eight FSECs were evaluated (six males and two females). Scalp EEG measurements were performed once a week for 3 weeks before ZNS administration (Pre-ZNS). Thereafter, administration of ZNS was started and an adjustment period was instituted until the drug in plasma achieved the steady state. When ZNS in plasma was confirmed to be within 10-40 µg/ml, scalp EEG measurements were performed once a week for 3 weeks (Post-ZNS). The number of PDs (counts/min) were compared between Pre-ZNS and Post-ZNS treatment. Results The median number of PDs for Pre-ZNS and Post-ZNS were 0.43/min (0.13-0.82/min) and 0.28/min (0.07-0.87/min), respectively. The number of PDs Post-ZNS was significantly reduced compared with Pre-ZNS ( P = 0.02). Conclusions and relevance This study showed that ZNS, within the recommended therapeutic range suggested for use in humans and dogs (10-40 µg/ml), reduced the number of PDs recorded on EEG in FSECs that are considered a model for cats with idiopathic epilepsy. Although phenobarbital is the antiepileptic drug of choice for epileptic cats, the results of this research provide evidence to support the use of ZNS in cats with phenobarbital-resistant epilepsy or for cats that cannot use phenobarbital due to adverse side effects.

Molecular cloning and characterization of the family of feline leucine-rich glioma-inactivated (LGI) genes, and mutational analysis in familial spontaneous epileptic cats.

BACKGROUND: Leucine-rich glioma-inactivated (LGI) proteins play a critical role in synaptic transmission. Dysfunction of these genes and encoded proteins is associated with neurological disorders such as genetic epilepsy or autoimmune limbic encephalitis in animals and human. Familial spontaneous epileptic cats (FSECs) are the only feline strain and animal model of familial temporal lobe epilepsy. The seizure semiology of FSECs comprises recurrent limbic seizures with or without evolution into generalized epileptic seizures, while cats with antibodies against voltage-gated potassium channel complexed/LGI1 show limbic encephalitis and recurrent limbic seizures. However, it remains unclear whether the genetics underlying FSECs are associated with LGI family genes. In the present study, we cloned and characterized the feline LGI1-4 genes and examined their association with FSECs. Conventional PCR techniques were performed for cloning and mutational analysis. Characterization was predicted using bioinformatics software. RESULTS: The cDNAs of feline LGI1-4 contained 1674-bp, 1650-bp, 1647-bp, and 1617-bp open reading frames, respectively, and encoded proteins comprising 557, 549, 548, and 538 amino acid residues, respectively. The feline LGI1-4 putative protein sequences showed high homology with Homo sapiens, Canis familiaris, Bos taurus, Sus scrofa, and Equus caballus (92%-100%). Mutational analysis in 8 FSECs and 8 controls for LGI family genes revealed 3 non-synonymous and 14 synonymous single nucleotide polymorphisms in the coding region. Only one non-synonymous single nucleotide polymorphism in LGI4 was found in 3 out of 8 FSECs. Using three separate computational tools, this mutation was not predicted to be disease causing. No co-segregation of the disease was found with any variant. CONCLUSIONS: We cloned the cDNAs of the four feline LGI genes, analyzed the amino acid sequences, and revealed that epilepsy in FSEC is not a monogenic disorder associated with LGI genes.

A cat with suspected laryngeal metastasis with mucosal irregularity resulting from apocrine/salivary gland adenocarcinoma in the head.

A 16-year-old castrated male mongrel cat presented with swelling under the left pinna and a 3 -month history of voice change. Laryngeal endoscopy revealed circumferential oedema around the arytenoid cartilages and hypersecretion of saliva. Histopathological examination of the mass around the left ear canal was considered the primary lesion that originated from cutaneous apocrine adenocarcinoma or parotid gland adenocarcinoma, and it metastasized to the larynx, lung and medial retropharyngeal lymph nodes. This report provides new insights into feline laryngeal diseases which could result in laryngeal metastasis with slight mucosal irregularity alone and without obvious radiographic abnormalities. Therefore, histopathological examination should be performed when a cat presents clinical signs such as stridor, dysphonia or voice change without any mass-forming laryngeal lesion.

Analysis of fecal short chain fatty acid concentration in miniature dachshunds with inflammatory colorectal polyps.

Short chain fatty acids (SCFAs) play an important role in the maintenance of colonic homeostasis, and their depletion has been reported in various gastrointestinal disorders. Inflammatory colorectal polyps (ICRPs) are a recently recognized disease specific to miniature dachshunds (MDs), and fecal dysbiosis with a reduction of SCFA-producing bacteria has been reported with this disease. Therefore, this study was performed based on the hypothesis that a reduced SCFA concentration associates with the development of ICRPs. We recruited 11 ICRP-affected MDs and 25 control MDs. Their fecal SCFA concentrations and bacterial proportions were quantified using high performance liquid chromatography and quantitative real-time PCR, respectively. The feces of ICRP-affected MDs contained lower amounts of propionic acid and lower proportions of Bifidobacterium than the feces of control MDs. Furthermore, fecal proportions of Bifidobacterium, Firmicutes and Lactobacillus exhibited significant positive correlations with fecal concentrations of total SCFAs and/or propionic acid; fecal Escherichia coli proportions correlated negatively with fecal concentrations of total SCFAs, as well as acetic, propionic and butyric acid. This result indicates an association between fecal dysbiosis and fecal SCFA concentrations; these phenomena may contribute to ICRP pathogenesis in MDs. Potential therapeutic targeting of the reduced propionic acid concentration using probiotics, prebiotics or SCFA enemas merits further study.

Comparisons among MRI signs, apparent diffusion coefficient, and fractional anisotropy in dogs with a solitary intracranial meningioma or histiocytic sarcoma.

Although MRI has become widely used in small animal practice, little is known about the validity of advanced MRI techniques such as diffusion-weighted imaging and diffusion tensor imaging. The aim of this retrospective analytical observational study was to investigate the characteristics of diffusion parameters, that is the apparent diffusion coefficient and fractional anisotropy, in dogs with a solitary intracranial meningioma or histiocytic sarcoma. Dogs were included based on the performance of diffusion MRI and histological confirmation. Statistical analyses were performed to compare apparent diffusion coefficient and fractional anisotropy for the two types of tumor in the intra- and peritumoral regions. Eleven cases with meningioma and six with histiocytic sarcoma satisfied the inclusion criteria. Significant differences in apparent diffusion coefficient value (× 10-3 mm2 /s) between meningioma vs. histiocytic sarcoma were recognized in intratumoral small (1.07 vs. 0.76) and large (1.04 vs. 0.77) regions of interest, in the peritumoral margin (0.93 vs. 1.08), and in the T2 high region (1.21 vs. 1.41). Significant differences in fractional anisotropy values were found in the peritumoral margin (0.29 vs. 0.24) and the T2 high region (0.24 vs. 0.17). The current study identified differences in measurements of apparent diffusion coefficient and fractional anisotropy for meningioma and histiocytic sarcoma in a small sample of dogs. In addition, we observed that all cases of intracranial histiocytic sarcoma showed leptomeningeal enhancement and/or mass formation invading into the sulci in the contrast study. Future studies are needed to determine the sensitivity of these imaging characteristics for differentiating between these tumor types.

Fecal dysbiosis in miniature dachshunds with inflammatory colorectal polyps.

Chronic gastrointestinal disease is associated with the alteration of gastrointestinal microbiota. Inflammatory colorectal polyps (ICRPs) are commonly observed in miniature dachshunds (MDs) in Japan and are characterized by multiple polyps that are restricted in the colorectal mucosa with severe neutrophil infiltration. This study was aimed to compare the fecal microbiota of ICRP-affected MDs with that of healthy MDs. High-throughput sequencing of amplicons derived from the V3-V4 region of the 16S rRNA gene was applied using the Illumina MiSeq system. Principal coordinates analysis revealed that fecal microbiota of ICRP-affected MDs was significantly altered compared with that of healthy MDs. Proportions of Fusobacteriaceae, Helicobacteraceae, Porphyromonadaceae, and Turicibacteraceae were significantly more abundant in ICRP-affected MDs, while those of Lachnospiraceae were significantly less abundant in ICRP-affected MDs compared with healthy MDs. These results suggest that the dysbiosis is associated with ICRPs and is a potential therapeutic target, though further investigations are needed.

Regulation of p16 gene expression by histone H3 acetylation in canine lymphoid tumor cell lines.

In order to investigate whether suppression of the p16 gene is mediated by histone H3 acetylation in 4 canine lymphoid tumor cell lines, the gene's acetylation status was examined. In 2 canine lymphoid tumor cell lines with low p16 mRNA expression (GL-1 and UL-1), the acetylation level was lower than that in CL-1 cells with high p16 mRNA expression. The expression of the p16 gene in these 2 cell lines was markedly restored after culture in the presence of a histone deacetylase inhibitors trichostatin A, indicating that p16 was inactivated by hypoacetylation. Findings obtained this study will add new insights and lead to the better understanding of the disease pathogenesis and future development of epigenetic therapeutic strategies.

Expression profile of circulating serum microRNAs in dogs with lymphoma.

Serum microRNAs (miRNAs) are mediators of cell-to-cell communication and alter the cellular microenvironment; they are stable for hours under certain conditions in body fluids despite the presence of RNases. Certain miRNAs have been found to be altered in the serum or plasma of humans with various cancers and may represent promising, non-invasive biomarkers for various diseases in humans and animals. The objective of this study was to determine the expression profile of circulating miRNAs in the serum of dogs with lymphoma. Serum samples were obtained from 61 dogs with lymphoma and 40 control dogs, and real-time reverse transcription-polymerase chain reaction was used for miRNA measurement. In order to select candidate genes, a comprehensive expression analysis was undertaken prior to validation of several candidate miRNAs. Of 277 miRNAs, five (let-7b, miR-223, miR-25, miR-92a, and miR-423a) were selected as candidates. The expression levels of four miRNAs (let-7b, miR-223, miR-25, miR-92a) were significantly reduced in the lymphoma group, whereas miR-423a levels were significantly increased compared to the controls. When the lymphoma cases were categorized into high- or low-grade as well as into their anatomic form, miR-25 levels were lower in the serum samples from the lymphoma group compared to those from the control group. Although the biological function of serum miRNAs still remains unclear, determining their functional roles in serum and tissues will contribute not only to the identification of potential biomarkers but also to the elucidation of the pathogenesis of canine lymphoma.

Construction of a multicolor GeneScan analytical system to detect clonal rearrangements of immunoglobulin and T cell receptor genes in canine lymphoid tumors.

Polymerase chain reaction (PCR) amplification to detect immunoglobulin heavy chain (IgH) and T cell receptor γ-chain (TCRγ) gene rearrangements has recently become widely used as part of the diagnostic strategy for lymphoid tumors in dogs. In this study, we constructed a multicolor GeneScan analytical system to improve the sensitivity and resolution of the clonality analysis of antigen receptor gene rearrangements in dogs. We used 7 reactions per sample, with 2 PCR conditions, to amplify IgH/TCRγ and control genes. By using multicolor-labeled primers, these 7 PCR products could be combined into 3 tubes before capillary electrophoresis. Clonal rearrangement of the IgH/TCRγ genes was detected in 93.3% of dogs with multicentric lymphoma and 84.6% of dogs with gastrointestinal lymphoma. Detection sensitivity of the clonally expanded cells in the background of normal peripheral blood mononuclear cells was 1-10%. The multicolor GeneScan analytical system developed here may prove to be helpful for the diagnosis of lymphoid tumors in dogs.

Polymorphisms of nucleotide-binding oligomerization domain 2 (NOD2) gene in miniature dachshunds with inflammatory colorectal polyps.

Inflammatory colorectal polyps (ICRPs) frequently occur in miniature dachshunds (MDs) in Japan, typically form multiple polyps with severe neutrophil infiltration. ICRPs are speculated as a novel, breed-specific canine inflammatory bowel disease. Pattern recognition receptors (PRRs) play an important role in the differentiation of pathogens from commensal bacteria and food antigens, and polymorphisms of various PRRs have been shown to be associated with human and canine IBD. We recently reported that the reactivity of nucleotide-binding oligomerization domain 2 (NOD2), toll-like receptor (TLR) 1/2, TLR2, and TLR2/6 are greater in ICRP-affected MDs than that in controls. Therefore, this study was aimed to investigate single nucleotide polymorphisms (SNPs) of PRRs associated with ICRPs in MDs. Mutational analysis of canine NOD2, TLR1, TLR2, and TLR6 genes was performed with six ICRP-affected MDs, five control MDs, and five healthy beagles. The mutational analysis identified 13 non-synonymous SNPs in NOD2, TLR1, TLR2, and TLR6 genes, of which six SNPs in NOD2 exon 3 were further analyzed in an association study using 63 ICRP-affected MDs, 82 control MDs, and 237 control dogs of various breeds. Four of the SNPs (A1532G, T1573C, C1688G, and G1880A of the NOD2 gene) were in Hardy-Weinberg equilibrium and in complete linkage disequilibrium in MDs, and their minor allele frequencies were significantly lower in ICRP-affected MDs than in control MDs (0.016 vs. 0.140, P=0.0002). The calculated inheritance model was an additive model (odds ratio=0.10, 95% confidence interval=0.02-0.45, P=0.0001), which indicates that the haplotype with minor alleles in these SNPs (A, T, C, and G in A1532G, T1573C, C1688G, and G1880A) possess a protective effect regarding the development of ICRPs. However, these SNPs were not specific for MDs, although the minor allele frequencies of these SNPs in control MDs were significantly lower than in other breed dogs. These results suggest that the identified four SNPs (A1532G, T1573C, C1688G, and G1880A in the NOD2 gene) may play a role in the pathogenesis of ICRPs in MDs. Because the majority of MDs and other breed dogs do not have the protective alleles, their absence may not be a specific cause of ICRPs in MDs but rather contribute to the development of inflammation.

Functional analysis of pattern recognition receptors in miniature dachshunds with inflammatory colorectal polyps.

Inflammatory colorectal polyps (ICRPs) frequently occur in miniature dachshunds (MDs) in Japan. MDs with ICRPs develop multiple polyps with severe neutrophil infiltration that respond to immunosuppressive therapy. Therefore, ICRPs are thought to constitute a novel, breed-specific form of canine inflammatory bowel disease (IBD). Pattern recognition receptors (PRRs) play a key role in the distinction of pathogens from commensal bacteria and food antigens. Dysfunction resulting from genetic disorders of PRRs have been linked to human and canine IBD. Therefore, we analyzed the reactivity of PRRs in MDs with ICRPs. Twenty-six MDs with ICRPs and 16 control MDs were recruited. Peripheral blood-derived monocytes were obtained from each dog and then stimulated with PRR ligands for 6 and 24 hr; subsequently, messenger RNA (mRNA) expression levels and protein secretion of IL-1ß were quantified using quantitative real-time PCR and ELISA, respectively. The levels of IL-1ß mRNA and protein secretion after stimulation with a nucleotide-binding oligomerization domain 2 (NOD2) ligand were significantly greater in monocytes from ICRP-affected MDs than in those from control MDs. In addition, IL-1ß protein secretion induced by toll-like receptor (TLR) 1/2, TLR2 and TLR2/6 stimulation was also significantly greater in ICRP-affected MDs. These results suggest that reactivity against NOD2, TLR1/2, TLR2 and TLR2/6 signals is enhanced in ICRP-affected MDs and may play a role in the pathogenesis of ICRPs in MDs. Additional studies of the genetic background of these PRRs should be performed.