Hypospadias is rarely reported in dogs. In this study we pre-sent 2 novel cases 
of this disorder of sexual development and, in addition, a case of hereditary 
sex reversal in a female with an enlarged clitoris. The first case was a male 
Moscow watchdog with a normal karyotype (78,XY) and the presence of the SRY 
gene. In this dog, perineal hypospadias, bilateral inguinal cryptorchidism and 
testes were observed. The second case, representing the Cocker spaniel breed, 
had a small penis with a hypospadic orifice of the urethra, bilateral 
cryptorchidism, testis and a rudimentary gonad inside an ovarian bursa, a normal 
female karyotype (78,XX) and a lack of the SRY gene. This animal was classified 
as a compound sex reversal (78,XX, SRY-negative) with the hypospadias syndrome. 
The third case was a Cocker spaniel female with an enlarged clitoris and 
internally located ovotestes. Cytogenetic and molecular analyses revealed a 
normal female karyotype (78,XX) and a lack of the SRY gene, while histology of 
the gonads showed an ovotesticular structure. This case was classified as a 
typical hereditary sex reversal syndrome (78,XX, SRY-negative). Molecular 
studies were focused on coding sequences of the SRY gene (case 1) and 2 
candidates for monogenic hypospadias, namely MAMLD1 (mastermind-like domain 
containing 1) and SRD5A2 (steroid-5-alpha-reductase, alpha polypeptide 2). 
Sequencing of the entire SRY gene, including 5'- and 3'-flanking regions, did 
not reveal any mutation. The entire coding sequence of MAMLD1 and SRD5A2 was 
analyzed in all the intersexes, as well as in 4 phenotypically normal control 
dogs (3 females and 1 male). In MAMLD1 2 SNPs, including 1 missense substitution 
in exon 1 (c.128A>G, Asp43Ser), were identified, whereas in SRD5A2 7 
polymorphisms, including 1 missense SNP (c.358G>A, Ala120Thr), were found. None 
of the identified polymorphisms cosegregated with the intersexual phenotype, 
thus, we cannot confirm that hypospadias may be associated with polymorphism in 
the coding sequence of the studied genes.