Novel polymorphism of the canine dopamine receptor D4 gene intron II region

Various dog breeds are remarkably different from each other not only in their sizes and shapes but also in behavioral traits, suggesting that some of these characteristics are under genetic control. However, little is known about genes related to behavioral traits in canine species. In humans, it has been reported that the dopamine receptor D4 gene (DRD4) includes polymorphism at several regions that relate to personality or psychiatric disorders. In an earlier study by the authors of the present study, the polymorphisms in canine DRD4 exon III and exon I regions were reported. In the present study, a novel polymorphism in canine DRD4 intron II was found based on a 17 base pair insertion/deletion, and the two alleles detected were named P (shorter allele) and Q (longer allele). The allelic distribution in 28 breeds of dog, including a total of 1114 unrelated individuals, were then investigated. Both P and Q alleles were detected in most of the breeds investigated; however, the frequencies of P and Q differed greatly between breeds. With respect to classification based on breed origin, P and Q alleles were frequent in Occidental and Oriental breeds, respectively. Furthermore, two subspecies of wolves, the ancestors of dogs, were analyzed for the comparison of allele frequencies with dogs, and the P allele was predominant in both European and Chinese wolves.     

RADIOGRAPHIC LIVER SIZE IN PEKINGESE DOGS VERSUS OTHER DOG BREEDS

Differential diagnoses for canine liver disease are commonly based on radiographic estimates of liver size, however little has been published on breed variations. Aims of this study were to describe normal radiographic liver size in Pekingese dogs and to compare normal measurements for this breed with other dog breeds and Pekingese dogs with liver disease. Liver measurements were compared for clinically normal Pekingese (n = 61), normal non‐Pekingese brachycephalic (n = 45), normal nonbrachycephalic (n = 71), and Pekingese breed dogs with liver disease (n = 22). For each dog, body weight, liver length, T11 vertebral length, thoracic depth, and thoracic width were measured on right lateral and ventrodorsal abdominal radiographs. Liver volume was calculated using a formula and ratios of liver length/T11 vertebral length and liver volume/body weight ratio were determined. Normal Pekingese dogs had a significantly smaller liver volume/body weight ratio (16.73 ± 5.67, P < 0.05) than normal non‐Pekingese brachycephalic breed dogs (19.54 ± 5.03) and normal nonbrachycephalic breed dogs (18.72 ± 6.52). The liver length/T11 vertebral length ratio in normal Pekingese (4.64 ± 0.65) was significantly smaller than normal non‐Pekingese brachycephalic breed dogs (5.16 ± 0.74) and normal nonbrachycephalic breed dogs (5.40 ± 0.74). Ratios of liver volume/body weight and liver length/T11 vertebral length in normal Pekingese were significantly different from Pekingese with liver diseases (P < 0.05). Findings supported our hypothesis that Pekingese dogs have a smaller normal radiographic liver size than other breeds. We recommend using 4.64× the length of the T11 vertebra as a radiographic criterion for normal liver length in Pekingese dogs.     

Definitive‐intent intensity‐modulated radiation therapy for treatment of canine prostatic carcinoma: A multi‐institutional retrospective study

No standard of care is currently recognized for treatment of canine prostatic carcinoma (PC). This retrospective study assesses outcome following definitive‐intent, intensity‐modulated radiation therapy (RT) in dogs with PC. Medical records review was performed, including 18 patients from four institutions undergoing definitive‐intent intensity‐modulated radiotherapy to treat PC. Diagnosis was incidental in 7/18 (39%) patients. Five dogs (28%) had evidence of metastasis to loco‐regional lymph nodes at diagnosis. Seventeen patients received concurrent non‐steroidal anti‐inflammatory drugs; 15/18 (83%) patients received maximally‐tolerated dose (MTD) chemotherapy, with variable drugs and protocols employed. Total prescribed radiation dose ranged from 48 to 54 Gy (median 50 Gy) delivered as daily doses of 2.5‐2.8 Gy. One patient was euthanized prior to completing radiotherapy. Acute toxicity was observed in nine patients; Grade 1‐2 diarrhoea was the most common toxicity observed. Suspected late toxicity (urethral stricture, ureteral stricture and hindlimb oedema) was observed in three patients. Median event‐free survival (EFS) following RT was 220 days, and median overall survival was 563 days. Local progression occurred in seven patients at a median of 241 days. Median overall survival was significantly longer in incidentally diagnosed dogs (581 vs 220 days in symptomatic dogs, P = .042). EFS was significantly longer in patients treated with MTD chemotherapy (241 vs 25 days, P < .001), and significantly shorter in patients presenting with evidence of metastatic disease (109 days) vs those without (388 days, P = .008). These findings suggest that definitive‐intent radiotherapy is a valuable treatment option for local control of canine PC with moderate risk of toxicity.     

The canine prostate cancer cell line CHP‐1 shows over‐expression of the co‐chaperone small glutamine‐rich tetratricopeptide repeat‐containing protein α

Although androgen therapy resistance and poor clinical outcomes are seen in most canine prostate cancer cases, there are only a few tools for analysing canine prostate cancer by using a cell biological approach. Therefore, to evaluate androgen‐independent neoplastic cell growth, a new canine prostate cancer cell line (CHP‐1) was established in this study. CHP‐1 over‐expressed the co‐chaperone small glutamine‐rich tetratricopeptide repeat‐containing protein α (SGTA), which is over‐expressed in human androgen‐independent prostate cancer. The CHP‐1 xenograft also showed SGTA over‐expression. Although CHP‐1 shows poor androgen receptor (AR) signalling upon dihydrotestosterone stimulation, forced expression of AR enabled evaluation of AR signalling. Taken together, these results suggest that CHP‐1 will be a useful model for investigating the pathogenesis of androgen‐dependent and androgen‐independent canine prostate cancer.     

Immunohistochemical expression of heat shock proteins,p63 and androgen receptor in benign prostatic hyperplasia and prostatic carcinoma in the dog

This study compared heat shock proteins Hsp60, Hsp72 and Hsp73, along with p63 and androgen receptor (AR) immunoexpression between 16 cases of benign prostatic hyperplasia (BPH) and 11 prostatic carcinomas (PCa) in dogs. The proportion of Hsp60‐positive cells was higher in PCa compared with BPH (P = 0.033), whereas the frequency and intensity of Hsp73 immunostaining did not differ significantly between the two groups. Hsp72‐immunostained nuclei formed a discontinuous layer along the basement membrane in BPH, whereas cells in this layer in PCa were negative or weakly positive. Hsp72 nuclear score showed significant positive associations with both p63 (P = 0.016) and AR (P = 0.009) scores. Double immunofluorescence revealed Hsp72‐p63 and Hsp72‐AR co‐expressions in basal cell nuclei. Aberrant cytoplasmic p63 immunolabelling was observed in 3 of 11 PCa cases. These results suggest a role of the combined expression of Hsp72, p63 and AR in basal epithelial cells in canine BPH and PCa.     

T-cell-derived malignant lymphoma in the boxer breed

The boxer breed of dog is at high risk for a variety of neoplasms including lymphoma. In this observational study, tissue sections from boxer dogs with lymphoma were immunostained for T and B lymphocyte distinction, and the results compared with similar studies carried out on lymphoma tissues from temporally selected cohorts of golden retriever and rottweiler dogs. The frequency of T‐cell lymphomas was significantly (P < 0.001 for all comparisons) higher in the boxers than in the rottweilers or golden retrievers. We are unaware of other reports linking immunotype of canine lymphoma with breed; whether other brachycephalic breeds of dogs have a similar preponderance of T‐cell lymphoma awaits further study.     

A randomized, open-label, positively-controlled field trial of a hydrolyzed protein diet in dogs with chronic small bowel enteropathy

Background: Hydrolyzed protein diets are commonly used to manage canine chronic enteropathies (CE), but their efficacy has not yet been critically evaluated. Hypothesis: A hydrolyzed protein diet is superior to that of a highly digestible (control) diet in the management of CE in dogs. Animals: Twenty‐six dogs (18 test diet, 8 control diet) referred for investigation and management of naturally occurring chronic small intestinal disease. Methods: Randomized, open‐label, positively controlled trial. After a full diagnostic investigation, which included endoscopy, dogs were assigned either to the test diet or control diet on a 2 : 1 basis (test : control). Cases were re‐evaluated 3 times (at approximately 3, 6–12 months, and 3 years). Outcome measures included response of clinical signs (complete, partial, none), change in severity of signs (based upon clinical disease activity index; canine inflammatory bowel disease activity index [CIBDAI]), change in body weight, and need for other therapy. Results: There were no significant differences in baseline characteristics (eg, signalment, body weight, and duration of clinical signs), and histopathologic severity between test and control diet groups. However, despite randomization, CIBDAI was significantly higher in the test diet group (P= .013). Most dogs had responded by first evaluation, with no difference between groups (P= .87). However, significantly more dogs on the test diet remained asymptomatic at both the second (P= .0012) and third (P < .001) re‐evaluation, and the decrease in CIBDAI was significantly greater (P= .010). Conclusions and Clinical Importance: A hydrolyzed protein diet can be highly effective for long‐term management of canine chronic small bowel enteropathy.     

The association between the signalment, common causes of canine otitis externa and pathogens

Objective : To determine whether associations exist between pathogens, allergies, conformational abnormalities, endocrinopathies and signalment in canine otitis externa (OE). Methods : Medical records of 149 dogs which met predetermined inclusion criteria were evaluated retrospectively. Correlations between pathogens and the presence of allergy, endocrinopathy, conformational abnormalities and signalment were evaluated statistically. Results : The shar‐pei, German shepherd and cocker spaniel breeds were over‐represented compared with the hospital's breed distribution (P<0·001). German shepherd dogs and cocker spaniels were statistically more prone to infection with rod‐shaped organisms and Labrador retrievers less than other breeds (P=0·034). Almost all dogs that were older than five years when diagnosed with OE had cocci (P=0·01) and also had higher levels of rods (P=0·028). The incidence of rods was higher in endocrinopathies (P=0·004), while that of Malassezia spp. tended to be higher in allergies (P=0·098). There were no statistically significant differences among the groups for all the other parameters examined. Clinical Significance : OE infection is usually not influenced by primary causes or predisposing factors. Endocrinopathies may be followed by a more severe otitis, however. OE may be more severe when it affects older dogs.     

A truncated retrotransposon disrupts the GRM1 coding sequence in Coton de Tulear dogs with Bandera's neonatal ataxia

Background: Bandera's neonatal ataxia (BNAt) is an autosomal recessive cerebellar ataxia that affects members of the Coton de Tulear dog breed. Objective: To identify the mutation that causes BNAt. Animals: The study involved DNA from 112 Cotons de Tulear (including 15 puppies with signs of BNAt) and 87 DNA samples from dogs of 12 other breeds. Methods: The BNAt locus was mapped with a genome‐wide association study (GWAS). The coding exons of positional candidate gene GRM1, which encodes metabotropic glutamate receptor 1, were polymerase chain reaction (PCR)‐amplified and resequenced. A 3‐primer PCR assay was used to genotype individual dogs for a truncated retrotransposon inserted into exon 8 of GRM1. Results: The GWAS indicated that the BNAt locus was in a canine chromosome 1 region that contained candidate gene GRM1. Resequencing this gene from BNAt‐affected puppies indicated that exon 8 was interrupted by the insertion of a 5′‐truncated retrotransposon. All 15 BNAt‐affected puppies were homozygous for the insert, whereas all other Cotons de Tulear were heterozygotes (n = 43) or homozygous (n = 54) for the ancestral allele. None of the 87 dogs from 12 other breeds had the insertion allele. Conclusions and Clinical Importance: BNAt is caused by a retrotransposon inserted into exon 8 of GRM1. A DNA test for the GRM1 retrotransposon insert can be used for genetic counseling and to confirm the diagnosis of BNAt.     

Breed-specific pro-inflammatory cytokine production as a predisposing factor for susceptibility to sepsis in the dog

Objective: To determine whether 2 dog breeds with a high risk for parvoviral enteritis, a disease associated with sepsis, produce stronger pro‐inflammatory cytokine responses to a stimulus than dogs with a lower risk. Design: Blinded comparison. Setting: University outpatient clinic. Animals: Healthy, unrelated, purebred Doberman Pinschers (n=10) and Rottweilers (n=9) with age‐matched mixed‐breed dogs (n=7). Interventions: Heparinized, whole‐blood samples were collected from each dog and incubated for 6 hours with lipopolysaccharide. Plasma was collected, and bioassays were used to determine the concentrations of TNF‐α and IL‐6. The mean values obtained from the high‐risk breeds were compared with the mean obtained from the mixed‐breeds. Measurements and main results: The mean TNF‐α production from dogs with a high risk for parvoviral enteritis (1321±161 pg/mL; Doberman Pinscher and Rottweiler) was greater (P<0.05) than that from lower risk, mixed‐breed dogs (674±186 pg/mL). There were no differences in TNF‐α levels between Doberman (1128±247 pg/mL) and Rottweiler (1563±pg/mL) breeds or between any breeds with regard to IL‐6 production. Conclusions: The magnitude of TNF‐α production by peripheral blood monocytes was the greatest in the dogs with breed‐related risk for parvoviral enteritis. However, additional studies are needed to prove a causal relationship between high TNF and predilection for parvoviral enteritis. Regardless, breed appears to be a predisposing factor for variations in cytokine production that could impact the host response to infection and other inflammatory insults.     

Population structure and genetic differentiation of livestock guard dog breeds from the Western Balkans

Livestock guard dog (LGD) breeds from the Western Balkans are a good example of how complex genetic diversity pattern observed in dog breeds has been shaped by transition in dog breeding practices. Despite their common geographical origin and relatively recent formal recognition as separate breeds, the Karst Shepherd, Sarplaninac and Tornjak show distinct population dynamics, assessed by pedigree, microsatellite and mtDNA data. We genotyped 493 dogs belonging to five dog breeds using a set of 18 microsatellite markers and sequenced mtDNA from 94 dogs from these breeds. Different demographic histories of the Karst Shepherd and Tornjak breeds are reflected in the pedigree data with the former breed having more unbalanced contributions of major ancestors and a realized effective population size of less than 20 animals. The highest allelic richness was found in Sarplaninac (5.94), followed by Tornjak (5.72), whereas Karst Shepherd dogs exhibited the lowest allelic richness (3.33). Similarly, the highest mtDNA haplotype diversity was found in Sarplaninac, followed by Tornjak and Karst Shepherd, where only one haplotype was found. Based on F_ST differentiation values and high percentages of animals correctly assigned, all breeds can be considered genetically distinct. However, using microsatellite data, common ancestry between the Karst Shepherd and Sarplaninac could not be reconstructed, despite pedigree and mtDNA evidence of their historical admixture. Using neighbour‐joining, STRUCTURE or DAPC methods, Sarplaninac and Caucasian Shepherd breeds could not be separated and additionally showed close proximity in the NeighborNet tree. STRUCTURE analysis of the Tornjak breed demonstrated substructuring, which needs further investigation. Altogether, results of this study show that the official separation of these dog breeds strongly affected the resolution of genetic differentiation and thus suggest that the relationships between breeds are not only determined by breed relatedness, but in small populations even more importantly by stochastic effects.     

Protein-losing enteropathy in dogs is associated with decreased fecal proteolytic activity

Background: Measurement of proteolytic activity in feces is a traditional method for the diagnosis of exocrine pancreatic insufficiency (EPI). A drawback of this method is the occurrence of falsely low results that may lead to a false‐positive diagnosis of EPI. We hypothesized that intestinal loss of serum proteinase inhibitors in protein‐losing enteropathy (PLE) may inhibit fecal proteolytic activity and be a potential source of false low results. Objective: The objective of this study was to determine the effect of PLE on fecal proteolytic activity in dogs. Methods: Fecal proteolytic activity was measured using a radial diffusion casein digestion assay in 12 samples from 4 clinically healthy control dogs and 30 samples from 16 dogs with PLE. Gastrointestinal protein loss was assessed using an ELISA to determine fecal canine α₁‐proteinase inhibitor concentration. The relationship between the concentration of canine α₁‐proteinase inhibitor in the feces and the diameter cleared in the casein digestion assay was determined. The mean clearing diameter was compared between control dogs and dogs with PLE. Results: A significant negative correlation was observed between fecal canine α₁‐proteinase inhibitor concentration and casein clearing diameter (P < .001, Pearson r=—.6317, r 2 =.3999). Mean clearing diameter was significantly lower in dogs with PLE than in control dogs (12.63 vs 16.83 mm, P < .001, two‐tailed Student's t‐test). Conclusion: Increased fecal loss of α₁‐proteinase inhibitor in dogs with PLE is associated with a significant decrease in fecal proteolytic activity and may result in a false positive diagnosis of EPI.     

Canine breeds at high risk of developing inflammatory bowel disease in the south-eastern UK

Genetics are an important factor in the development of human inflammatory bowel disease (IBD); however, there is very little information available regarding the role of genetics in canine IBD. The purpose of this study was to gather information about which canine breeds in the south-eastern UK are at a high risk for developing IBD. Determination of such breeds may help further genetic research in this complex disease. The computer medical records at the Queen Mother Hospital for Animals, Royal Veterinary College dating from August 1, 2003 to December 31, 2009 were retrospectively searched for cases diagnosed with IBD. Five hundred and forty-six dogs with IBD were identified, representing 86 different breeds. The comparison group consisted of all dogs from these same 86 breeds without IBD admitted to the hospital during the same period that amounted to 27,463 dogs. The breeds at significantly higher risk of developing IBD compared with mixed-breed dogs consisted of weimaraner (odds ratio [OR]=3.6797, 95 per cent confidence interval [CI]=2.0167 to 6.7141, P<0.0001), rottweiler (OR=2.9697, 95 per cent CI=1.7569 to 5.0196, P<0.0001), German shepherd dog (GSD) (OR=2.4101, 95 per cent CI=1.5826 to 3.36705, P<0.0001), border collie (OR=1.9936, 95 per cent CI=1.1655 to 3.4101, P=0.0118) and boxer (OR=1.6961, 95 per cent CI=1.0441 to 2.755, P=0.0328). This study demonstrates for the first time canine breeds in the south-eastern UK that are highly susceptible to developing IBD. Identification of such breeds may allow for a more focused investigation of genetic mutations associated with canine IBD.     

The effects of dog breed development on genetic diversity and the relative influences of performance and conformation breeding

Genetic diversity was compared among eight dog breeds selected primarily for conformation (Standard Poodle, Italian Greyhound and show English Setter), conformation and performance (Brittany), predominantly performance (German Shorthaired and Wirehaired Pointers) or solely performance (field English Setter and Red Setter). Modern village dogs, which better reflect ancestral genetic diversity, were used as the standard. Four to seven maternal and one to two Y haplotypes were found per breed, with one usually dominant. Diversity of maternal haplotypes was greatest in village dogs, intermediate in performance breeds and lowest in conformation breeds. Maternal haplotype sharing occurred across all breeds, while Y haplotypes were more breed specific. Almost all paternal haplotypes were identified among village dogs, with the exception of the dominant Y haplotype in Brittanys, which has not been identified heretofore. The highest heterozygosity based on 24 autosomal microsatellites was found in village dogs and the lowest in conformation (show) breeds. Principal coordinate analysis indicated that conformation‐type breeds were distinct from breeds heavily used for performance, the latter clustering more closely with village dogs. The Brittany, a well‐established dual show and field breed, was also genetically intermediate between the conformation and performance breeds. The number of DLA‐DRB1 alleles varied from 3 to 10 per breed with extensive sharing. SNPs across the wider DLA region were more frequently homozygous in all pure breeds than in village dogs. Compared with their village dog relatives, all modern breed dogs exhibit reduced genetic diversity. Genetic diversity was even more reduced among breeds under selection for show/conformation.     

A 6‐bp Deletion Variant in a Novel Canine Glutathione‐S‐Transferase Gene (GSTT5) Leads to Loss of Enzyme Function

Objectives

Glutathione‐S‐transferases (GSTs) detoxify reactive xenobiotics, and defective GST gene polymorphisms increase cancer risk in humans. A low activity GST‐theta variant was previously found in research beagles. The purpose of our study was to determine the molecular basis for this phenotype and its allele frequency in pet dogs.

Methods

Banked livers from 45 dogs of various breeds were screened for low GST‐theta activity by the substrate 1,2‐dichloro‐4‐nitrobenzene (DCNB), and were genotyped for variants in a novel canine GST gene, GSTT5. Whole‐genome sequences from 266 dogs were genotyped at one discovered variant GSTT5 locus.

Results

Canine livers ranged 190‐fold in GST‐theta activities, and a GSTT5 exon coding variant 385_390delGACCAG (Asp129_Gln130del) was significantly associated with low activity (P < 0.0001) and a marked decrease in hepatic protein expression (P = 0.0026). Recombinant expression of variant GSTT5 led to a 92% decrease in V_max for DCNB (P = 0.0095). The minor allele frequency (MAF) for 385_390delGACCAG was 0.144 in 45 dog livers, but was significantly higher in beagles (0.444) versus nonbeagles (0.007; P = 0.0004). The homozygous genotype was significantly over‐represented in Pembroke Welsh corgis (P < 0.0001) based on available whole‐genome sequence data.

Conclusions

An Asp129_Gln130del variant in canine GSTT5 is responsible for marked loss of GST‐theta enzyme activity. This variant is significantly over‐represented in purpose‐bred laboratory beagles and in Pembroke Welsh corgis. Additional work will determine the prevalence of this variant among other purebred dogs, and will establish the substrate range of this polymorphic canine enzyme with respect to common environmental carcinogens.     

Holter monitoring in clinically healthy Cavalier King Charles Spaniels, Wire-haired Dachshunds, and Cairn Terriers

Background: Few reported studies describe normal values from 24‐hour ECG (Holter) recordings of small breed dogs. Objectives: To investigate influence of breed, age, sex, body weight, degree of recording artifact, and mitral valve prolapse (MVP) on Holter recordings of 3 breeds of small dogs that have differing predispositions for myxomatous mitral valve disease. The study also assessed if heart rate (HR) at clinical examination (HRex) was associated with HR during Holter monitoring and evaluated the reproducibility of Holter variables. Animals: Fifty clinically healthy, privately owned dogs of the breeds Cavalier King Charles Spaniel (CKCS), Wire‐haired Dachshund (wD), or Cairn Terrier (CT). Methods: Prospective, longitudinal observational study. Dogs were recruited for clinical examination, echocardiography, and Holter monitoring. In 8 CKCS, Holter recordings were performed twice with a 7‐day interval. Arrhythmia and heart rate variability (HRV) analysis (time and frequency domain analysis) were performed on Holter recordings. Results: Fifteen out of 27 Holter derived variables were significantly associated with breed (P < .03), but not with age (P > .7), sex (P > .2), body weight (P > .7), degree of recording artifact (P > .4), or MVP (P > .6). During Holter recording, minimum (P= .0001) and mean HR (P= .0001) were higher in CKCS compared with wD. CKCS had significantly lower values than wD, CT, or both in 10 out of 13 HRV variables (P < .03). Minimum and mean HR during Holter recording were correlated with HRex (r= 0.55, P= .0003). HR and time domain variables had a coefficient of variation <10%. Conclusions and Clinical Importance: There is an influence of breed on Holter‐derived variables in 3 breeds of small dogs. Arrhythmia and HRV analysis can be performed on 24‐hour ambulatory ECG (Holter) recordings. Arrhythmia analysis includes HR measurements and identification of arrhythmias.     

Haplotype analysis of the MDR1 flanking region in the dog breed Elo

A deletion mutation in the canine multidrug resistance (MDR1) gene provokes drug sensitivity in several dog breeds from the Collie lineage. A haplotype of four microsatellites containing this mdr1-1Delta mutation was conserved among affected breeds. In this study, we analysed the haplotypes of the MDR1 flanking region of 177 dogs of the breed Elo which is composed of several dog breeds including the Old English sheepdog from the Collie lineage. We detected a haplotype in the Elo breed which had previously been associated with the mutant mdr1-1Delta allele in Old English sheepdogs. Using a regression analysis for the probability of the haplotype on the proportion of genes of the founder breeds, we could exclude the Old English sheepdog as origin of this haplotype for the Elo breed. The MDR1 flanking region could be traced back to the Japanese Spitz as one of the founder dog breeds of the Elo and thus, the introgression of the mdr1-1Delta mutation into the dog breed Elo through the Collie lineage is very unlikely.     

NHLRC1 repeat expansion in two beagles with Lafora disease

Lafora disease is a fatal genetic disorder characterised by neurotoxic deposits of malformed insoluble glycogen. In humans it is caused by mutation in the EPM2A or NHLRC1 genes. There is a known mutation in miniature wirehaired dachshunds which has not been documented in other dog breeds, including beagles, in which the disease is relatively commonly reported. This case report describes the causative defect in two affected beagles, namely the same massive expansion as in miniature wirehaired dachshunds of a 12‐nucleotide repeat sequence that is unique to the canine NHLRC1 gene. This is the first mutation described in beagles with Lafora disease, and so far the only Lafora disease genetic variant in dogs.     

Collie eye anomaly in Hokkaido dogs: case study

Objective To describe a Hokkaido dog, one of the traditional Japanese breeds that was affected by Collie eye anomaly (CEA), and to report the genotype of this dog and the Hokkaido dog allelic frequency of the CEA‐associated mutation. Case A nine‐month‐old intact female Hokkaido dog without any obvious visual disturbance was diagnosed ophthalmoscopically with CEA. Severe choroidal hypoplasia was observed in the bilateral temporal area adjacent to the optic nerve head, appearing as whitish areas. Therefore, the dog was suspected of possessing the CEA‐associated mutation that was previously reported as an intronic 7.8‐kilo base deletion in the canine NHEJ1 gene. Procedures SYBR Green‐based real‐time PCR with a melting curve analysis, conventional PCR with agarose gel electrophoresis, and direct DNA sequencing were carried out to determine the genotype of the dog. Furthermore, a preliminary genotyping survey was carried out in 17 Hokkaido dogs from three kennels using the real‐time PCR method, and the pedigree relationships were analyzed using their pedigree papers. Results The Hokkaido dog affected by CEA was proven to possess the CEA‐associated mutation. Of these 17 Hokkaido dogs, 12 dogs were heterozygous carriers and five dogs were affected by this mutation. The preliminary genotyping survey and pedigree analysis demonstrated that the allelic frequency of the CEA‐associated mutation is very high in Hokkaido dogs. Conclusion These data suggest that the Hokkaido breed is highly susceptible to CEA because of the known CEA‐associated mutation much like the Collie‐related breeds.