Table 1. Signalment data and ddPCR assay values for the sample cohort.

The table lists the owner-reported breed and sex of dogs included in the study (* indicates unknown sex), in addition to the age of the dog at the time of sample submission. The sample ID prefix UD denotes specimens in which the BRAF V595E variant was undetected, and the prefix POS denotes samples that tested positive for this variant by ddPCR analysis. For the 28 UD^V595E cases, the notation H/C after the sample name denotes that the diagnosis of UC was validated using conventional histopathology and/or cytology evaluation of tumor tissue (n = 7 cases). The notation US indicates the presence of a bladder mass on ultrasonography, with clinical signs and progression consistent with canine UC (n = 8 cases). Where detected, the VAF (from WES analysis) and FA (from ddPCR analysis) of the variant is shown as a percentage. The DT represents the lowest variant FA that was capable of being detected by the assay for each individual sample [5]. This value provides confidence that UD^V595E specimens are classified correctly down to a level of no greater than a single mutant allele among 1000 total alleles. The final two columns indicate the copy number ratio data derived using the UC CNA ddPCR assay. All 36 samples were classified as ‘positive’ for both DNA copy number signatures since they exceed the ratio threshold of 1.20 [21].

Sample code	Sex	Stated breed	Age (years)	BRAF V595E VAF (%)	BRAF V595E FA (%)	DT (%)	chr36/chr19 ratio	chr13/chr19 ratio
UD-001 U/S	FS	Border Terrier	11	UD	UD	0.04	2.95	1.64
UD-003 H/C	FS	Beagle	12	UD	UD	0.04	1.69	2.18
UD-007 H/C	FS	American Staffordshire Terrier	14	UD	UD	0.05	1.83	1.84
UD-018	FS	Labrador mix	12	UD	UD	0.04	1.80	1.80
UD-027	FS	Rat Terrier	14	UD	UD	0.03	2.05	1.54
UD-033 U/S	FS	Toy Poodle	12	UD	UD	0.04	1.51	2.11
UD-049 U/S	FS	Scottish Terrier	13	UD	UD	0.04	1.94	1.71
UD-054	FS	Beagle	8	UD	UD	0.04	1.71	1.95
UD-081 H/C	FS	Miniature Dachshund	9	UD	UD	0.08	2.31	1.68
UD-082	FS	Boston Terrier	13	UD	UD	0.04	2.26	1.71
UD-084 U/S	FS	Mix	10	UD	UD	0.05	1.70	3.10
UD-085 H/C	MN	Labrador Retriever	13	UD	UD	0.06	2.09	1.79
UD-088 H/C	MN	Fox Terrier	12	UD	UD	0.08	1.96	2.12
UD-091 U/S	FS	Great Dane	8	UD	UD	0.03	3.57	3.30
UD-092 U/S	MN	Terrier mix	11	UD	UD	0.03	3.60	2.52
UD-097	FS	Beagle	11	UD	UD	0.04	2.36	2.91
UD-098	FS	Boston Terrier	9	UD	UD	0.04	7.27	1.88
UD-099 H/C	FS	Beagle	8	UD	UD	0.04	3.15	1.88
UD-100 H/C	FS	Beagle/Terrier mix	13	UD	UD	0.05	2.12	2.07
UD-102	MN	German Shepherd mix	14	UD	UD	0.05	7.00	1.90
UD-104	FI	Bluetick Coonhound	13	UD	UD	0.05	3.23	3.46
UD-105 U/S	MN	Beagle	13	UD	UD	0.06	2.11	2.12
UD-106	FS	Golden Retriever/Collie mix	11	UD	UD	0.06	3.74	1.60
UD-108	MN	Bassett Hound	11	UD	UD	0.04	3.24	2.19
UD-109 U/S	FS	Beagle	12	UD	UD	0.05	2.62	2.38
UD-110	FS	Collie	12	UD	UD	0.06	3.96	3.03
UD-112	FS	Pomeranian	14	UD	UD	0.05	5.51	1.69
UD-113	FS	Beagle	13	UD	UD	0.06	3.58	2.45
POS-124	FS	Coton de Tulear	13	61.7	61.7	0.05	1.73	2.29
POS-125	FS	Labrador mix	9	65.1	60.2	0.11	2.90	1.82
POS-127	FS	Labrador/poodle mix	8	55.8	58.5	0.02	1.66	1.82
POS-128	FS	Miniature Schnauzer	10	55.3	55.4	0.02	2.41	1.63
POS-131	*	Labrador Retriever	12	49.5	53.0	0.03	2.52	1.63
POS-134	FS	Australian Cattle Dog	8	44.0	51.7	0.02	5.50	2.27
POS-138	FS	Mix	14	48.1	50.0	0.05	8.23	1.92
POS-2027	MN	Yorkshire Terrier/Shih Tzu mix	11	90.1	92.0	0.05	3.06	3.72