Non-surgical castration in male dogsPossibility, availability and humanity SuppawiwatPonglowhapan DVM (Hons), MS, MSc, PhD Department of Obstetrics Gynaecology and Reproduction, Faculty of Veterinary Sciences Chulalongkorn University
Introduction Dr. Patricia N Olson
Introduction • 1970’s First awakening to pet over population at animal care & control facilities • “ … hundreds of dogs seems to have been euthanized due to some horrific diseases that was not one we have been taught about in veterinary school !” and “most of them are young and look healthy”.
Introduction • “ How would the veterinary community respond to a disease that resulted in the death of between 10-25% of all dogs and cats each year? ” a vet student asked.
Introduction • In USA, over half of all households own a dog or cat (1:3 in UK,1:4 in BKK) • The human society of the United Stated estimated • 8-10 millions dogs and cats enter shelters each year • 4.5 millions of them are euthanized
Introduction • How many stray dogs in Mexico city? • 1962: 460,000 dogs • 1974: 900,000 dogs • 2006: 3,000,000 dogs
Introduction • How many stray dogs in Bangkok?
Introduction • In some countries, such as Sweden and Norway, pet overpopulation is not a problem and neutering pets is UNCOMMON. • Pet owners: responsibilities > rights
Pet overpopulation www.spayusa.com
Pet overpopulation • Social problem • Hygiene problem • Health problem: zoonosis • Texas (1977): stray dogs can produce 94,950 gallons of urine and 38.6 tons of feces per day.
Control of pet overpopulation • The complexity of pet overpopulation • Human-animal bond • Pet owner responsibility • Animal sterilization/neutering • Non purpose-bred dogs must be neutered!
Neuter • Neuter (Latin) = Neither (neither masculine or feminine) • adjective = The German word for 'book', 'das Buch', is neuter. • verb = Has your dog been neutered? • Neutering is the removal of an animal's reproductive organ, either all of it or a considerably large part. It is the most drastic surgical procedure with sterilizing purposes. (Wikipedia) • Sterilizing • (sterilize = to perform a medical operation on someone in order to make them unable to have children) • Female; spaying (removal of the ovaries) • ovariectomy / ovariohysterectomyOVH • Male; neutering, castration (removal of the testicles)
Castration Surgical VSNon-surgical (Permanent VS temporary)
Surgical Castration • Traditional neutering of male dogs • Surgical removal of the testicles of a male animal or human • Removing or inhibiting the function or development of the testes Spermatozoa Testosterone Dog testicles
Surgical Castration Spermatozoa Testosterone Sterility Loss of testosterone- dependent characteristics libido, roaming, urine spraying, aggression, etc.
Vasectomy • Cooper (1930) : first experimental vasectomy on a dog • Vasectomy & Castration
Surgical Castration • Not all owners prefers to have their pets surgically sterilized. • In Brazil (Soto et al., 2005) • 56.5% of owners (adopted shelter dogs) against surgical sterilization • Compassion (58.1%) • Unnecessary procedure (11.4%) • Cost (9.5%) • Behavioral change (4.8%)
Surgical Castration • In Thailand (Swangchan-uthai et al., 2005) • 38.3% against contraception in dogs and/or cats (170/446) • Breeding purpose • Able to confine male dogs • Not necessary to have males neutered • Behavioral and physical change, i.e. obesity • Unsafe procedure • กลัวว่าตัวเองหรือแฟนจะเป็นหมัน ... บาป !!! • 61.7% prefer to have their pets neutered (276/446) • 13.7% males, 39.8% females, 46.5% both • 72.5% orchiectomy, 19.8% vasectomy, 7.7% reversible hormone implant
Non-Surgical Castration • No scalpel castration • Chemical castration
Non-Surgical Castration • Hormonal treatment • Progestogens, Androgens, GnRH analogues (agonist/antagonist) • Intratesticular/intraepididymal injection • Immunocontraception • Ultrasound testicular ablation
Hormonal treatment • Steroid hormone (Progestogens, Androgens) • Non-steroid hormone (GnRH analogues) Progestogen Androgens GnRH
Hormonal treatment Exogenous hormone Down regulation Temporary suppression of fertility
Hormonal treatment • Steroid Hormone • In early 1930, isolated and determined structure of steriods • In 1937, reported progesterone inhibits ovulation in rabbits • No new products for control of reproduction in the dog and cat have been introduced during the last two decades, other than revised formulations and new brands of progestogens. • Non-steroid Hormone • GnRH agonist • Suprelorin (Deslorelin, Virbac) • Gonazon implant (Nafarelin, Intervet)
Progestogen • Clinical use in the bitch • Control of oestrus (suppression/prevention) • Pseudopregnancy • Hypoluteoidism • Clinical use in the dog • Antisocial behaviour • Epilepsy • Benign Prostatic Hyperplasia • Contraception (+/-) • Circum-anal adenoma
Progestogen: female Prevention of anoestrus Medroxyprogesterone Perlutex2.5-3 mg/kg at 5 mth interval Promone-E50 mg/bitch at 6 mth interval Proligestone Covinan10-33 mg/kg - early proestrus - a series at 3, 4 and 5 mth intervals Side effects : type of hormone, dose, duration of repeated treatment, treatment regimen, stage of oestrus cycle and age of the animal
Progestogen: female • Side effect • Selman et al., 1994 • glucose intolerance • diabetes mellitus • mammary tumors (50%) in treated OVH-bitches • Use with Cautions • Type of hormone • Route of administration • Dosage • Duration of repeated treatment • Stage of the cycle at initiation of the treatment • Age of the animal
Progestogen: male progestogen LH/FSH Spermatogenesis
Progestogen: male • England , 1997 No change in plasma LH concentration was detected as seen in females !!! The male dog appears to differ in the sensitivity of hypothalamo-pituitary response to progestogen feedback Megestrol acetate MPA; medroxyprogesterone acetate
Progestogen: male • Not recommended for contraception in the male dog • 1. ineffective • 2. adverse effects • Selman et al., 1994 • glucose intolerance • diabetes mellitus
GnRH analogues • Agonists • Suprelorin (Deslorelin, Virbac) • Gonazon implant (Nafarelin, Intervet) • Antagonists • Acyline (Merrion Pharmaceuticals)
Deslorelin implant Hypothalamus Anterior pituitary Ovary, Testis GnRH LH, FSH Oestrogen Testosterone
Deslorelin implant 15 d pre-implant recovery 15 d post-implant
Deslorelin implant • Deslorelin • Suprelorin 4.7 mg implant for dogs has been licensed in EU. • Indication: • For the induction of infertility in healthy, non-castrated, sexually mature male dogs
Deslorelin implant Castration 50% in 3rd week 70% in 9th week (Barsanti and Finco, 1995) Finasteride 40% in 16th week (Sirinarumitr et al., 2001) Deslorelin 40% in 4th week (Ponglowhapan et al., 2010)
Deslorelin implant SAMSON Golden retriever 7 years old Urination difficulty BPH Before and 14-day post treatment of Deslorelin implant
Deslorelin implant Prostatic volume [(L x W xD)/2.6] + 1.8 (Kamolpatana et al., 2000) Before = 42.0 cm3 14-d after = 38.5 cm3
Intratesticular injection • In 1953, Freund et al. Aspermatogenesis in the guinea pig induced by the testicular tissue and adjuvants. J Exp Med. 97:711-26. • Injection of sclerozing/necrotizing agents into the testes to induce aspermatogenicorchitis and tissue sclerosis resulting in infertility Local inflammatory response Autoimmone response
Different Sites of injection Vas deferen injection Intraepididymal injection Intratesticular injection
Intratesticular injection • Sclerosing agents • Zinc gluconate (Levy et al., 2008) • 20% hypertonic saline (Emir et al., 2008) • Glycerol (Immegart et al., 2000) • 1.5% chlorhexidinegluconate in 50% DMSO (Pineda et al., 1977) • Calcium chloride (Jana and Samanta, 2007)
Intratesticular injection Zinc-based solution