A defect in the NOG gene increases susceptibility to spontaneous superficial chronic corneal epithelial defects (SCCED) in boxer dogs

Background Superficial chronic corneal epithelial defects (SCCEDs) are spontaneous corneal defects in dogs that share many clinical and pathologic characteristics to recurrent corneal erosions (RCE) in humans. Boxer dogs are predisposed to SCCEDs, therefore a search for a genetic defect was performed to explain this susceptibility. DNA was extracted from blood collected from Boxer dogs with and without SCCEDs followed by whole genome sequencing (WGS). RNA sequencing of corneal tissue and immunostaining of corneal sections from affected SCCED Boxer dogs with a deletion in the NOG gene and affected non-Boxer dogs without the deletion were performed. Results A 30 base pair deletion at a splice site in Noggin (NOG) (Chr 9:31453999) was identified by WGS and was significantly associated (P < 0.0001) with Boxer SCCEDs compared to unaffected non-Boxer dogs. NOG, BMP4, MMP13, and NCAM1 all had significant fold reductions in expression and SHH was significantly increased in Boxers with the NOG deletion as identified by RNA-Seq. Corneal IHC from NOG deletion dogs with SCCEDs had lower NOG and significantly higher scores of BMP2. Conclusions Many Boxer dogs with SCCED have a genetic defect in NOG. NOG is a constitutive protein in the cornea which is a potent inhibitor of BMP, which likely regulate limbal epithelial progenitor cells (LEPC). Dysregulation of LEPC may play a role in the pathogenesis of RCE.

Clinical and Histopathological Features of Renal Maldevelopment in Boxer Dogs: A Retrospective Case Series (1999–2018)

Renal maldevelopment (RM) has been proposed to replace the old and sometimes misused term “renal dysplasia” in dogs. Although renal dysplasia has been described in Boxers, hereditary transmission has only been hypothesized. This study reports clinical and renal histological findings in Boxer dogs with RM, proposing a possible mode of inheritance. Medical records of 9 female Boxer dogs, older than 5 months and with a clinical diagnosis of chronic kidney disease prior to one year of age, were retrospectively reviewed. Polyuria and polydipsia (PU/PD), decreased appetite, weight loss, lethargy and weakness were described in all affected dogs. Common laboratory findings were proteinuria, diluted urine, non-regenerative anemia, azotemia, hyperphosphatemia, hypoalbuminemia and hypercholesterolemia. Histopathology of the kidneys revealed the presence of immature glomeruli in all dogs, which is consistent with RM. In 7 related dogs, the pedigree analysis showed that a simple autosomal recessive trait may be a possible mode of inheritance. Renal maldevelopment should be suspected in young Boxer dogs with a history of PU/PD, decreased appetite, weight loss, lethargy, weakness and proteinuria. Due to its possible inheritance, an early diagnosis of RM may allow clinicians to promptly identify other potentially affected dogs among the relatives of the diagnosed case.

Molecular and Phenotypic Characterization of Escherichia coli Associated with Granulomatous Colitis of Boxer Dogs

Invasive Escherichia coli is causally associated with granulomatous colitis (GC) of Boxer dogs and French Bulldogs. The virulence determinants of GC E. coli are unclear. E. coli isolated from 16 GC (36 strains) and 17 healthy control (HC: 33 strains) dogs were diverse in phylogeny, genotype, and serotype and lacked diarrheagenic genes. Genes encoding type II (gsp), IV (traC), and VI (hcp) secretion systems, long polar fimbriae (lpfA154/141), and iron acquisition (fyuA, chuA) were frequent in GC and HC. E. coli from 14/15 GC and 10/11 HC invaded Caco-2 better than non-pathogenic E. coli strain DH5α, with invasion correlated with motility and presence of chuA and colV. E. coli from all GC and 10/11 HC survived better than DH5α in J774 macrophages, with adherent-invasive E. coli (AIEC) in 60% GC and 73% HC. AIEC replicated in monocyte derived macrophages from a GC Boxer with CD48/SLAM risk haplotype but not the HC. Fluroquinolone resistant E. coli were less motile and invasive than fluoroquinolone sensitive (p < 0.05), and only 1/8 resistant strains met criteria for AIEC. In conclusion GC E. coli are diverse, resemble extraintestinal pathogenic E. coli (ExPEC), including AIEC, and can replicate in GC-susceptible macrophages. They are likely resident pathosymbionts that can opportunistically persist within macrophages of a GC-susceptible dog.

Electrocardiographic markers of myocardial conduction and repolarization in Boxer dogs

ABSTRACT: Electrocardiographic markers have been used in people to classify arrhythmogenic risk. The aims of this study were to investigate electrocardiographic markers of conduction and repolarization in Boxers and non-Boxer dogs, and compare such findings between groups. Ten-lead standard electrocardiograms of Boxer dogs and non-Boxers recorded from 2015 to 2018 were retrospectively reviewed. Dogs ≥4 years of age and weighing >20kg were included. Animals with valvular insufficiencies, congenital cardiopathies, cardiac dilation, suspected systolic dysfunction, biphasic T-wave, bundle branch blocks, and those receiving antiarrhythmics were excluded. Electrocardiographic markers of conduction, QRS duration (QRSd) and dispersion (QRSD), and repolarization (corrected QT interval, Tpeak-Tend, JT and JTpeak), as well as derived indices, were measured. Two hundred dogs met the inclusion/exclusion requirements, including 97 Boxers (8.1±2.5 years old; 30±7kg) and 103 non-Boxer (8.8±2.5 years old, 30±8kg). QRSd and QRSD, and repolarization markers in lead II and left precordial lead V4 were considered similar between groups. Dispersion of late repolarization on lead rV2, Tpeak-Tend interval, was considered longer in Boxers (45±8ms vs 38±10ms, P=0.01). The Tpeak-Tend/JTpeak and the JTpeak/JT also differed between groups. Our results indicate that the dispersion of myocardial late repolarization in lead rV2 is slower in Boxers than other dog breeds.

Effects of probiotic Lactobacillus acidophilus D2/CSL (CECT 4529) on the nutritional and health status of boxer dogs

BackgroundThe aim of the present study was to investigate the effects of Lactobacillus acidophilus D2/CSL (CECT 4529) probiotic strain on nutritional status and faecal and microbiological parameters in a group of purebred boxers.MethodsForty healthy adult boxer dogs were randomly assigned to a treated (LACTO) group receiving a commercial diet supplemented with L acidophilus D2/CSL (CECT 4529) to a final concentration of 5.0 x 109 colony-forming unit/kg of food, and a control (CTR) group receiving the same diet but without the probiotic (placebo). Nutritional status (body weight, skinfold thickness, body condition score) and faecal quality parameters were analysed.ResultsNo differences in body weight and skin thickness were found during the whole experimental period. Dogs in the LACTO group showed a significantly higher body condition score than those in the CTR group (4.86±0.55 v 4.65±0.65), and no significant differences were recorded in body weight and skinfold thickness. The LACTO group showed a significantly lower faecal moisture (in per cent) compared with the CTR group (0.67±0.007 v 0.69±0.007). Faecal hardness (in kg) was higher in the LACTO group than in the CTR group (0.86±0.047 v 0.70±0.051), and faecal score also improved in the LACTO group (3.78±0.95 v 4.25±0.91). A significant difference in total Escherichia coli counts as well as in lactobacilli counts between the CTR and LACTO groups was only detected at 28 days.ConclusionSupplementation of L acidophilus D2/CSL (CECT 4529) significantly improved the nutritional status and faecal parameters of dogs.

Prognostic value of coupling interval, prematurity index and heart rate variability in Boxer dogs

ABSTRACT: Boxer dogs with arrhythmogenic right ventricular cardiomyopathy (ARVC) can experience sudden cardiac death regardless of presence/absence of clinical signs. The aims of this retrospective study were two-fold: 1) to investigate the coupling interval (CI) and prematurity index (PI) of ventricular arrhythmias (VA), and the heart rate variability (HRV) in Boxers, and 2) to evaluate their impact on overall survival time. The first 24-hour Holter 36 client-owned Boxer dogs meeting inclusion/exclusion criteria were evaluated for the number, morphology, site of origin, complexity, CI and PI, of ventricular premature complexes (VPCs), and time domain HRV. The effect on survival was assessed, considering the presence/absence of ventricular tachycardia (VT), and syncope. All-cause mortality was considered as the end-point, with median survival times being obtained by Kaplan-Meier analyses and compared by log-rank test. Polymorphic VPCs were more common in symptomatic dogs than asymptomatic. VPCs in dogs with VT were less premature, due to the influence of heart rate on PI despite comparable CI. The PI and mean heart rate (HRme) were significantly different between VT and non-VT dogs but did not discriminate adequately between groups as standalone tests. Median survival time was shorter in Boxer dogs with VT (463 vs 1645 days, HR: 4.31, P=0.03). The HRV parameters, SDNN and SDANN, were both associated with prognosis. The CI and PI were not demonstrated to be prognostic surrogates in Boxer dogs with VA. HRme≥112bpm is 100% sensitive but only 46% specific for detecting VT in Boxers on the 24-hour Holter. Presence of VT, SDNN≤245ms, or SDANN≤134ms at the time of the first 24-hour Holter was associated with a shorter survival.

Epidemiology, clinical and cytological features of lymphoma in Boxer dogs

The aim of this study was to evaluate the epidemiology, clinical and laboratory characteristics of canine lymphomas as well as some aspects of treatment outcomes. The study was conducted on Boxer dogs with lymphoma diagnosed by cytology and immunocytochemistry (CD3 and CD79 alpha). During the study period, lymphoma was diagnosed in 63 Boxers; 86.8% were T-cell (based on the Kiel classification: small clear cell lymphoma, pleomorphic small cell lymphoma, pleomorphic mixed T-cell lymphoma, pleomorphic large T-cell lymphoma, lymphoblastic lymphoma/acute lymphoblastic leukaemia) and 13.2% were B-cell lymphomas (according to the Kiel classification: B-cell chronic lymphocytic leukaemia, centroblastic/centroblastic polymorphic lymphoma). Overall survival (OS) was significantly longer in dogs with low-grade than with high-grade lymphoma (median OS of 6.8 and 4.7 months, respectively; P = 0.024). OS was not influenced by WHO clinical stage, WHO clinical substage, presence of splenomegaly, early administration of glucocorticoids or the time from the first presentation to the beginning of chemotherapy. There are no significant differences in clinical and laboratory parameters between low-grade and high-grade lymphomas. Boxer dogs are predisposed to T-cell lymphoma, with a predominance of high-grade tumour, especially pleomorphic, mixed small and large T-cell subtype. It is possible that Boxer dogs may respond less favourably to chemotherapy than patients of other breeds.