public DogNavigationViewModel(
            IDogLookupDataService DogLookupDataService,
            IEventAggregator eventAggregator,
            IDialogService dialogService) : base(eventAggregator, dialogService)
        {
            Int64 startTicks = Log.CONSTRUCTOR("Enter", Common.LOG_APPNAME);

            _DogLookupDataService = DogLookupDataService;

            InitializeViewModel();

            Log.CONSTRUCTOR("Exit", Common.LOG_APPNAME, startTicks);
        }
        public CombinedNavigationViewModel(
            ICatLookupDataService CatLookupDataService, IDogLookupDataService DogLookupDataService,
            IEventAggregator eventAggregator,
            IDialogService dialogService) : base(eventAggregator, dialogService)
        {
            Int64 startTicks = Log.CONSTRUCTOR("Enter", Common.LOG_CATEGORY);

            _CatLookupDataService = CatLookupDataService;
            _DogLookupDataService = DogLookupDataService;

            InitializeViewModel();

            Log.CONSTRUCTOR("Exit", Common.LOG_CATEGORY, startTicks);
        }