Search

A registered female Yorkshire terrier aged 3 years was diagnosed as intersex. Molecular and cytogenetic studies were carried out to determine whether chromosomal abnormalities were involved in the development of this condition. Analysis of the testicular tissue in the gonads and PCR amplification of three canine Y chromosome-specific DNA sequences from the genomic DNA of this animal indicated that the dog had a genetic complement with a Y chromosome. An analysis of > 100 banded metaphase chromosome spreads of this intersex dog showed uniformly a 78,XY chromosome complement and confirmed that the animal might be a male to female sex-reversed dog. However, two different types of X chromosome were observed. A whole chromosome painting probe was developed by microdissection of ten X chromosomes from the intersex dog and used for fluorescence in situ hybridization experiments on metaphase chromosome spreads from a normal male dog. Hybridization signals were detected on the X chromosome and on an autosome (not yet internationally standardized) indicating that a reciprocal translocation event had occurred. The karyotype of this mosaic sex-reversed dog was designated tentatively as 78,XY/78,XYrcp (X; autosome). This is believed to be the first report of a canine intersex dog showing male to female sex reversal. Further investigations should identify the autosome and the breaking points of the chromosomal rearrangement. These investigations potentially add to our knowledge of autosomal and X-linked loci involved in sexual differentiation of mammals.

Thirty-six cats with bronchogenic carcinoma metastatic to the digit were identified. The mean age was 12.7 years, with no breed or sex predilection. Records from 19 cases were available for review. These cats presented with a primary complaint of lameness that involved primarily weight-bearing digits and the third phalanx. None had respiratory signs, despite the presence of pulmonary carcinoma. Course of disease was consistent in the 19 cases, with a mean survival time of 58 days from initial presentation. Amputation of affected digits was rarely palliative due to development of lesions in other digits and progressive nonrespiratory disease.

We are solving disputed paternities in purebred dogs using microsatellite analysis. An interesting case involved four puppies for which pedigrees were already issued by the Swiss Kennel Club. The investigation had to be carried out without a sample from the stated sire. Even though the relationship of this sire could not be determined conclusively, comparison of microsatellite alleles within this family, including an alleged half-brother of the four puppies, showed clearly that the breeder had made contradictory statements and that false recordings of matings had occurred. The pedigrees for these four puppies were withdrawn and sanctions against the breeder were imposed.

An abnormal development of the epidermis of the footpad was observed in Irish terriers. At the age of six months, the affected animals developed smooth parchment-like footpads. The pad epidermis then hardened and grew lateral cone-like protrusions of up to 5 mm in diameter. Fissures and cracks developed and these predisposed the animal to secondary infection. The repeated occurrence in subsequent generations led to the assumption of a hereditary form of hyperkeratosis. Evidence for an autosomal recessive mode of inheritance was derived from a retrospective analysis of the breeder's records. The clinical, histopathological and ultrastructural features of the disease are presented and the genetic transmission and its implications discussed.

We have developed a novel method for identifying dog chromosomes and unambiguously mapping specific clones onto canine chromosomes. This method uses a previously established red fox/dog comparative chromosome map to guide the FISH mapping of cloned canine DNA. Mixing metaphase preparations of the red fox and dog enabled a single hybridization to be performed on both species. We used this approach to map the chromosomal locations of twenty-six canine cosmids. Each cosmid contains highly polymorphic microsatellite markers currently used by the DogMap project to compile the canine linkage map. All but two cosmids were successfully assigned to subchromosomal regions on red fox and dog chromosomes. For eight cosmids previously mapped on dog chromosomes, we confirmed and refined the canine chromosomal assignments of seven cosmids and corrected an erroneous assignment regarding cosmid CanBern1. These results demonstrate that the red fox and dog comparative chromosome map can greatly improve the accuracy and efficiency of chromosomal assignments of canine genetic markers by FISH.

Nineteen further polymorphic loci were typed on the DogMap reference panel. Five new linkage groups were identified. Additionally, five markers were added to earlier defined linkage groups. Three of the new linkage groups contain markers mapped earlier to specific dog chromosomes by physical mapping. These results make a further contribution to the canine genome map and provides more linkage groups physically assigned to known chromosomes.

Each year approximately 13,000 new pedigrees for puppies are issued by the Swiss Kennel Club Except for a few cases there are no regulations to verify the paternities independently. This report describes the practical procedure for disputed paternities and summarizes the results from 35 cases which were resolved during the last three years. Most cases relate to unwanted or wanted double matings. Generally the owner of the bitch can not state the sire. For roughly half of the cases where a sire was given as the parent the information was disproven by the genetic analysis in the laboratory. These experiences confirm the need for a better pedigree control in Swiss dog breeds. Breeding without correct pedigree control is restricted to animal keeping.

The unambiguous identification of a biological specimen can deliver invaluable evidence to solve criminal cases. In this case the origin of a heart had to be clarified. Using the polymerase chain reaction technique and species-specific primer pairs for two genes it was clearly shown that this tissue was not from a human but from a pig.

Mutations in keratin genes account for a number of inherited keratodermas in humans. The groups of basic and acidic keratin genes are clustered on human chromosomes 12 and 17, respectively. The present authors have assigned the two putative keratin gene clusters to canine chromosomes using canine cosmid clones. Successful fluorescence in situ hybridization mapped the putative cluster of canine acidic genes to dog chromosome 20 and the putative cluster of basic keratin genes to a small autosome not yet included in the partial canine standard karyotype.

As the number of detected inherited diseases in dogs is increasing, linkage mapping offers an opportunity for the localisation of the responsible genes. In humans microsatellites are ideal markers for constructing high-resolution genetic maps. Twenty-five dog specific microsatellites which are highly polymorphic in mixed dog breeds, were tested by PCR in a group of unrelated Newfoundlands and Bernese Mountain dogs. The polymorphisms found in this two breeds were clearly lower than in the mixed breeds suggesting that only 40% of the markers tested would be useful for linkage analysis. In addition the allele frequencies and distributions differed among this two purebred but related breeds. Our data suggest that a selection for useful markers for each specific breed has to be performed prior to linkage analysis.

Thoracic radiographic and postmortem findings were compared in dogs with histologically confirmed hemangiosarcoma (HSA). On the basis of results of radiography, a false-negative diagnosis was made for pulmonary HSA in 10 (21.7%) of 46 dogs, and in 26 (53.1%) of 49 dogs for cardiac HSA. The incidence of false-negative radiographic diagnosis for pulmonary HSA was lower in dogs when left and right lateral views were obtained. The radiographic sensitivity was 78%, and the negative-predictive value was 74% for pulmonary HSA. The radiographic sensitivity was 47%, and the negative-predictive value was 43% for cardiac HSA.