Differences in normal nasal computed tomography findings in different dog breeds.

Background: Computed tomography (CT) is the gold standard for diagnosing canine nasal diseases. However, it cannot easily detect minor abnormalities in inflammatory diseases because they are not accompanied by obvious morphological changes. Aim: The present study aimed to compare the differences in normal CT findings of turbinate structure and mucosa between breeds to establish criteria for CT diagnosis of inflammatory diseases of the nasal cavity. Methods: CT data from 77 dogs of 5 breeds without nasal diseases were retrospectively studied. The nasal air percentage, which reflects the volume of the nasal turbinate structure and mucosa, was measured. The nasal turbinate mucosa was measured for contrast enhancement reflecting blood flow. Measurements were performed in the ventral and ethmoid turbinate (ET) regions. Comparisons were made between breeds and sections. Results: The air percentage in the ventral and ET regions was significantly different between breeds. Contrast enhancement was significantly different between breeds only in the ET. Moreover, different breeds had different correlations between body weight, age, nose length, and air percentage. Conclusion: In this study, reference values for normal CT findings of the nasal structure and mucosa were obtained, taking into account the breed, measurement section, and patient factors. The results showed that the volume of the turbinate structure and contrast enhancement of nasal mucosa differed depending on the breed. The measured values also differed depending on the cross-sections and patient factors.

Quantitative evaluation of middle ear radiopacity in French bulldogs using X-ray imaging.

Background: Radiographic examination of the middle ear in French bulldogs can be challenging due to their small ear cavity and thick walls. Quantifying opacity on radiographic images is required to determine normal or abnormal results. Aim: To quantify the radiographic opacity of the middle ear in French bulldogs and create a threshold for objective diagnosis. Methods: A study was conducted on 32 French Bulldogs using radiographic images. Significant difference tests were performed on the ears of patients with unilateral and bilateral middle ear filling on computed tomography. A threshold was established for detecting left-right asymmetry in the same individuals. In addition, comparisons were made between the filling and nonfilling middle ear groups to establish a threshold of pixel values that could determine single middle ear filling and nonfilling for different patient images. Results: Significant differences were observed in the left-right difference in max, left-right difference in max-ave, and left-right ratio of max-ave between unilateral and bilateral filling groups. The max-ave left-right ratio had the highest area under the curve value with a cutoff of 1.077% and 92.3% sensitivity. The item that showed a significant difference between middle ear groups with and without filling was corrected for nasopharyngeal pixel values with a cutoff of 1.028% and 85% sensitivity. Conclusion: Pixel value ratios in the middle ear region can detect asymmetries in ear densities. The max value in the region compared to the same image's nasopharyngeal region can determine the filling. Combining individual ear evaluations and symmetry improves accuracy.

Toceranib phosphate and firocoxib-mediated partial response in a dog with advanced intranasal sarcoma.

A nine-year-old, castrated male mixed-breed dog presented with a three-month history of sneezing and stertorous breathing. Computed tomography revealed a soft tissue mass in the left nasal cavity with lysis of the cribriform plate. The mass was diagnosed as intranasal sarcoma based on histopathological analysis. The tumor cells were immunohistochemically positive for KIT and platelet-derived growth factor receptor α/ß and negative for vascular endothelial growth factor receptor 2 and cyclooxygenase-2. Treatment with toceranib phosphate (TOC) and firocoxib reduced the tumor size, which was defined as partial response (PR). After PR induction, TOC alone mediated survival for 205 days. This case report suggests that the combination of TOC and possibly firocoxib may be a therapeutic option for canine intranasal sarcoma.

Perfusion computed tomographic measurements of cerebral blood flow variables in live Holstein calves.

OBJECTIVE To measure cerebral blood flow (CBF) and cerebral blood volume (CBV) by means of perfusion CT in clinically normal Holstein calves. ANIMALS 9 Holstein calves. PROCEDURES Each of the 9 calves (mean age, 20.2 days) was anesthetized and received an injection of iodinated contrast medium into the right jugular vein at a rate of 4.0 mL/s. Dynamic CT scanning of the head at a level that included the mandibular condyle was initiated at the time of the contrast medium injection and continued for 100 seconds. A deconvolution method was used as an analytic algorithm. RESULTS Among the 9 calves, the mean ± SD CBF in the cerebral cortex, white matter, and thalamus was 44.3 ± 10.3 mL/100 g/min, 36.1 ± 7.5 mL/100 g/min, and 40.3 ± 7.5 mL/100 g/min, respectively. The CBF in white matter was significantly lower than that in the cerebral cortex or thalamus. The mean CBV in the cerebral cortex, white matter, and thalamus was 6.8 ± 1.0 mL/100 g, 5.2 ± 1.0 mL/100 g, and 5.7 ± 0.7 mL/100 g, respectively. The CBV in the cerebral cortex was significantly higher than that in the white matter or thalamus. CONCLUSIONS AND CLINICAL RELEVANCE Measurement of CBF and CBV in clinically normal calves by means of perfusion CT was feasible. The data obtained may be useful as baseline values for use in future research or for comparison with findings from calves with CNS diseases. Investigations to determine the lower limit of blood flow at which brain function can still be restored are warranted.

Effects of changes in analytic variables and contrast medium on estimation of glomerular filtration rates by computed tomography in healthy dogs.

OBJECTIVE To investigate effects of changes in analytic variables and contrast medium osmolality on glomerular filtration rate estimated by CT (CT-GFR) in dogs. ANIMALS 4 healthy anesthetized Beagles. PROCEDURES GFR was estimated by inulin clearance, and dogs underwent CT-GFR with iodinated contrast medium (iohexol or iodixanol) in a crossover-design study. Dynamic renal CT scanning was performed. Patlak plot analysis was used to calculate GFR with the renal cortex or whole kidney selected as the region of interest. The renal cortex was analyzed just prior to time of the second cortical attenuation peak. The whole kidney was analyzed 60, 80, 100, and 120 seconds after the appearance of contrast medium. Automated GFR calculations were performed with preinstalled perfusion software including 2 noise reduction levels (medium and strong). The CT-GFRs were compared with GFR estimated by inulin clearance. RESULTS There was no significant difference in CT-GFR with iohexol versus iodixanol in any analyses. The CT-GFR at the renal cortex, CT-GFR for the whole kidney 60 seconds after appearance of contrast medium, and CT-GFR calculated by perfusion software with medium noise reduction did not differ significantly from GFR estimated by inulin clearance. The CT-GFR was underestimated at ≥ 80 seconds after contrast medium appearance (whole kidney) and when strong noise reduction was used with perfusion CT software. CONCLUSIONS AND CLINICAL RELEVANCE Selection of the renal cortex as region of interest or use of the 60-second time point for whole-kidney evaluation yielded the best CT-GFR results. The perfusion software used produced good results with appropriate noise reduction. IMPACT FOR HUMAN MEDICINE The finding that excessive noise reduction caused underestimation of CT-GFR suggests that this factor should also be considered in CT-GFR examination of human patients.

Identification of the PLA2G6 c.1579G>A Missense Mutation in Papillon Dog Neuroaxonal Dystrophy Using Whole Exome Sequencing Analysis.

Whole exome sequencing (WES) has become a common tool for identifying genetic causes of human inherited disorders, and it has also recently been applied to canine genome research. We conducted WES analysis of neuroaxonal dystrophy (NAD), a neurodegenerative disease that sporadically occurs worldwide in Papillon dogs. The disease is considered an autosomal recessive monogenic disease, which is histopathologically characterized by severe axonal swelling, known as "spheroids," throughout the nervous system. By sequencing all eleven DNA samples from one NAD-affected Papillon dog and her parents, two unrelated NAD-affected Papillon dogs, and six unaffected control Papillon dogs, we identified 10 candidate mutations. Among them, three candidates were determined to be "deleterious" by in silico pathogenesis evaluation. By subsequent massive screening by TaqMan genotyping analysis, only the PLA2G6 c.1579G>A mutation had an association with the presence or absence of the disease, suggesting that it may be a causal mutation of canine NAD. As a human homologue of this gene is a causative gene for infantile neuroaxonal dystrophy, this canine phenotype may serve as a good animal model for human disease. The results of this study also indicate that WES analysis is a powerful tool for exploring canine hereditary diseases, especially in rare monogenic hereditary diseases.

Changes in respiratory function in Pembroke Welsh Corgi dogs with degenerative myelopathy.

Canine degenerative myelopathy (DM) is characterized by progressive degeneration of the spinal cord. Although atrophic changes in the intercostal muscles were previously reported in the late stage of DM in Pembroke Welsh Corgis (PWCs), changes in respiratory function have not yet been examined. In the present study, we performed an arterial blood gas analysis and measured respiratory movements over progressive disease stages to document changes in respiratory function in DM-affected PWCs. We found that respiratory dysfunction progressed during the later stages of DM and correlated with a change in respiratory movement to the abdominal breathing pattern. These results suggested that hypoventilation occurred due to dysfunctional changes in the intercostal muscles and resulted in hypoxemia in the later stages of DM.

Real-time PCR genotyping assay for canine progressive rod-cone degeneration and mutant allele frequency in Toy Poodles, Chihuahuas and Miniature Dachshunds in Japan.

Canine progressive rod-cone degeneration (PRCD) is a middle- to late-onset, autosomal recessive, inherited retinal disorder caused by a substitution (c.5G>A) in the canine PRCD gene that has been identified in 29 or more purebred dogs. In the present study, a TaqMan probe-based real-time PCR assay was developed and evaluated for rapid genotyping and large-scale screening of the mutation. Furthermore, a genotyping survey was carried out in a population of the three most popular breeds in Japan (Toy Poodles, Chihuahuas and Miniature Dachshunds) to determine the current mutant allele frequency. The assay separated all the genotypes of canine PRCD rapidly, indicating its suitability for large-scale surveys. The results of the survey showed that the mutant allele frequency in Toy Poodles was high enough (approximately 0.09) to allow the establishment of measures for the prevention and control of this disorder in breeding kennels. The mutant allele was detected in Chihuahuas for the first time, but the frequency was lower (approximately 0.02) than that in Toy Poodles. The mutant allele was not detected in Miniature Dachshunds. This assay will allow the selective breeding of dogs from the two most popular breeds (Toy Poodle and Chihuahua) in Japan and effective prevention or control of the disorder.

Real-time PCR genotyping assay for feline erythrocyte pyruvate kinase deficiency and mutant allele frequency in purebred cats in Japan.

Erythrocyte pyruvate kinase (PK) deficiency is an inherited glycolytic erythroenzymopathy caused by mutations of the PKLR gene. A causative mutation of the feline PKLR gene was originally identified in Abyssinian and Somali cats in the U.S.A. In the present study, a TaqMan probe-based real-time PCR genotyping assay was developed and evaluated for rapid genotyping and large-scale screening for this mutation. Furthermore, a genotyping survey was carried out in a population of four popular purebred cats in Japan to determine the current mutant allele frequency. The assay clearly displayed all genotypes of feline PK deficiency, indicating its suitability for large-scale survey as well as diagnosis. The survey demonstrated that the mutant allele frequency in Abyssinian and Somali cats was high enough to warrant measures to control and prevent the disease. The mutant allele frequency was relatively low in Bengal and American Shorthair cats; however, the testing should still be carried out to prevent the spread of the disease. In addition, PK deficiency should always be considered in the differential diagnosis of anemia in purebred cats in Japan as well as worldwide.

Real-time PCR genotyping assay for GM2 gangliosidosis variant 0 in toy poodles and the mutant allele frequency in Japan.

GM2 gangliosidosis variant 0 (Sandhoff disease, SD) is a fatal, progressive neurodegenerative lysosomal storage disease caused by mutations of the HEXB gene. In canine SD, a pathogenic mutation (c.283delG) of the canine HEXB gene has been identified in toy poodles. In the present study, a TaqMan probe-based real-time PCR genotyping assay was developed and evaluated for rapid and large-scale genotyping and screening for this mutation. Furthermore, a genotyping survey was carried out in a population of toy poodles in Japan to determine the current mutant allele frequency. The real-time PCR assay clearly showed all genotypes of canine SD. The assay was suitable for large-scale survey as well as diagnosis, because of its high throughput and rapidity. The genotyping survey demonstrated a carrier frequency of 0.2%, suggesting that the current mutant allele frequency is low in Japan. However, there may be population stratification in different places, because of the founder effect by some carriers. Therefore, this new assay will be useful for the prevention and control of SD in toy poodles.

High frequency of a single nucleotide substitution (c.-6-180T>G) of the canine MDR1/ABCB1 gene associated with phenobarbital-resistant idiopathic epilepsy in Border Collie dogs.

A single nucleotide substitution (c.-6-180T>G) associated with resistance to phenobarbital therapy has been found in the canine MDR1/ABCB1 gene in Border Collies with idiopathic epilepsy. In the present study, a PCR-restriction fragment length polymorphism assay was developed for genotyping this mutation, and a genotyping survey was carried out in a population of 472 Border Collies in Japan to determine the current allele frequency. The survey demonstrated the frequencies of the T/T wild type, T/G heterozygote, and G/G mutant homozygote to be 60.0%, 30.3%, and 9.8%, respectively, indicating that the frequency of the mutant G allele is extremely high (24.9%) in Border Collies. The results suggest that this high mutation frequency of the mutation is likely to cause a high prevalence of phenobarbital-resistant epilepsy in Border Collies.