From Dog
Monorchidism in a puppy revealed during presentation for desexing

Cryptorchidism is a relatively common developmental disorder of dogs characterized by either one (monorchid) or both testes which have failed to descend into the scrotum within the first few weeks after birth.

Cryptorchidism has been associated with ambiguous genitalia (hermaphroditism[1] or persistent Müllerian duct syndrome) and in polyrchid dogs (presence of three testes, two of which were undescended)[2].

This disease is associated with genetic causes. Insulin-like 3 (INSL3) plays a prominent role in male development and is supposed to induce the growth of the gubernaculum testis, thus being directly involved in testicular descent[3].

Left untreated, cryptorchidism has an increased risk of sertoli cell tumor[4][5] and seminoma[6][7] development and testicular torsion[8].

Clinically affected cryptorchid dogs often have lower testosterone levels compared with normal and unilateral cryptorchid dogs[9].

Diagnosis is usually based on scrotal palpation, transabdominal palpation and ultrasonography[10].

Treatment requires surgical removal of the retained testicle, either via laparotomy, laparoscopy[11] or through extraction via the inguinal ring[12].


  1. Breshears MA & Peters JL (2011) Ambiguous genitalia in a fertile, unilaterally cryptorchid male miniature schnauzer dog. Vet Pathol 48(5):1038-1040
  2. Tamminen TM et al (2012) A polyorchid dog. Reprod Domest Anim 47(2):e26-8
  3. Arrighi S et al(2010) An insight into testis and gubernaculum dynamics of INSL3-RXFP2 signalling during testicular descent in the dog. Reprod Fertil Dev 22(5):751-760
  4. Hong S et al (2011) Spontaneous sertoli cell tumor with cryptorchism in a beagle dog. Lab Anim Res 27(2):177-178
  5. Laing EJ et al (1983) Spermatic cord torsion and Sertoli cell tumor in a dog. J Am Vet Med Assoc 183:879–881
  6. Miyabayashi T et al (1990) Ultrasonographic appearance of torsion of a testicular seminoma in a cryptorchid dog. J Small Anim Pract 31:401–403
  7. Metzger FL et al (1993) Hematuria, hyperestrogenemia, and hyperprogesteronemia due to a Sertoli-cell tumor in a bilaterally cryptorchid dog. Canine Pract 18:32–35
  8. Feldman EC & Nelson RW (1987) Canine and Feline Endocrinology and Reproduction. 2nd ed. Philadelphia: Saunders. pp:481–523
  9. Pathirana IN et al (2012) Plasma insulin-like peptide 3 and testosterone concentrations in male dogs: changes with age and effects of cryptorchidism. Theriogenology 77(3):550-557
  10. Quartuccio M et al (2012) Sertoli cell tumors associated with feminizing syndrome and spermatic cord torsion in two cryptorchid dogs. J Vet Sci 13(2):207-209
  11. Mayhew P (2009) Surgical views: laparoscopic and laparoscopic-assisted cryptorchidectomy in dogs and cats. Compend Contin Educ Vet 31(6):274-281
  12. Steckel RR et al(2011) Use of an inguinal approach adapted from equine surgery for cryptorchidectomy in dogs and cats: 26 cases (1999-2010). J Am Vet Med Assoc 239(8):1098-1103