Dog hereditary diseases

"In the mammalian embryo, there are the beginnings of both reproductive systems – the Muller ducts, from which the female reproductive system develops, and the Wolf ducts, which give rise to the male. In males, during the period of sex determination, the development of the Muller ducts is suppressed by the anti-Muller hormone. With a genetic defect of this hormone, or its receptor (a molecule receiving a signal from the hormone), the development of the Muller ducts is not fully suppressed, which leads to the development of an organism with genotype XY and the presence of partially or fully developed genitalia of the opposite sex. In Miniature Schnauzers, a single nucleotide substitution (c.241C>T) was found in the AMHR2 gene, which encodes a receptor for anti-Muller hormone. Males with the mutation have genotype XY, two testicles and normal androgen-dependent masculinization of the internal and external genitalia. However, in addition, they have two oviducts, a uterus with a neck and a cranial part of the vagina. The nature of the inheritance of the disease is autosomal recessive. The disease develops only if both copies of the gene contain a mutation. Symptoms appear only in males, since the mutation affects the formation of only the male reproductive system. Bitches do not show symptoms, but they can be either heterozygous or homozygous for this mutation. Symptoms: The disease is detected only during instrumental examination, or when secondary complications occur. Sick males have normal male external genitalia, however, approximately 50% have one- or two-sided cryptorchidism. Males with at least one lowered testicle are fertile. Instrumental examination reveals bilateral fallopian tubes, full uterus, cervix and cranial part of the vagina. There is a strong connection between each end of the uterine horn and the caudal pole of the testicle, which prevents the lowering of the testicle and is the cause of cryptorchidism. Secondary complications of the disease are tumors of Sertoli cells (testicular cells) and pyometra (purulent inflammation of the uterus). The latter can be facilitated by a narrow communication between the vagina and the prostate part of the urethra, which allows pathogens to rise into the uterus, but prevents the outflow of pus. As a result of pyometra, polydipsia, polyuria and lack of appetite can be observed. The above symptoms develop only in males with a mutation in both copies of the gene. Male carriers and female carriers are reproductively normal."