Gonadotropin releasing hormone

From Dog

Gonadotropin releasing hormone (GnRH) is a trophic peptide produced by the hypothalamus (pituitary) and causes the release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) from the anterior pituitary.

Abnormal production of GnRH can lead to disorders in sexual development[1] and this drug is often administered to induce estrus cycling in anestrus bitches[2].

Parenteral administration of GnRH is used for detection of ovarian tissue in ovariohysterectomized bitches with estrus suggestive of ovarian remnant syndrome[3].

Following GnRH administration in these dogs, a detectable rise in estradiol usually results in a rise in this hormone, indicating the presence of remnant ovarian tissue[4].

Administration of this drug in male dogs results in a predictable increase in testosterone and the number and activity of sperm[5]. It can thus be used for verification of neuter status in male dogs and hermaphroditism in female dogs[6].

Depot drugs such as deslorelin can pharmacologically suppress GnRH production and novel immunocontraception regimens have recently attempted to target GnRH as a possible target for endogenous antibody production, using anti-GnRH chemical conjugates[7]. Temporary reduction of LH and testosterone concentrations and decreased testicular volume has been reported, but effects decline after 4 - 5 months[8].

Recommended dose rate of administration of GnRH in dogs is 20 IU/kg daily, given intramuscularly.

References

  1. Buijtels JJ et al (2012) Disorders of sexual development and associated changes in the pituitary-gonadal axis in dogs. Theriogenology 78(7):1618-1626
  2. Nak D et al (2012) Comparison of the use of cabergoline and gonadotrophin to treat primary and secondary anoestrus in bitches. Aust Vet J 90(5):194-196
  3. Günzel-Apel AR et al (2012) Clinical signs, diagnostic approach and therapy for the so-called ovarian remnant syndrome in the bitch. Tierarztl Prax Ausg K Kleintiere Heimtiere 40(1):35-42
  4. de Gier J et al (2012) Effects of gonadotropin-releasing hormone administration on the pituitary-gonadal axis in male and female dogs before and after gonadectomy. Theriogenology 77(5):967-978
  5. Kawakami E et al (2012) Therapeutic effect of frequent injections of GnRH analogue in a beagle with knobbed acrosome abnormality of sperm. J Vet Med Sci 74(2):201-204
  6. Dianovský J et al (2013) Disorder of sexual development in a Yorkshire terrier (78, XY; SRY-positive). J Appl Genet 54(2):193-1939
  7. Samoylov A et al (2012) Generation and characterization of phage-GnRH chemical conjugates for potential use in cat and dog immunocontraception. Reprod Domest Anim 47(6):406-411
  8. Donovan CE et al (2012) Physiologic responses following gonadotropin-releasing hormone immunization in intact male dogs. Reprod Domest Anim 47(6):403-405