Principles of infertility in the female

Question 1

Into which 3 broad categories can causes of infertility/subfertility be divided?

Answer 1

• Anatomical
• Physiological
• Management

Question 2

What are some anatomical causes of infertility?

Answer 2

• Congenital
  
  • Ovarian hypoplasia
  • Reproductive dysplasia
  • Free-martinism/intersex
  • Persistence of hymen (mare)
• Acquired
  
  • Adhesions (e.g. ovario-bursal)
  • Endometrial fibrosis
  • Cystic endometrial hyperplasia (bitch)
  • Reproductive tract neoplasia (uncommon)

Question 3

What are some physiological causes of infertility/subfertility?

Answer 3

• Ovarian pathology
  
  • Anovulatory anoestrus
  • Cystic ovarian disease
  • Persistent CL
• Uterine infection
  
  • Pyometra
  • Endometritis
  • Metritis
• Failure to establish pregnancy

Question 4

What are some management causes of infertility/subfertility?

Answer 4

• Nutrition
• Oestrus detection
• Genetic
• Timing/management of mating
• Expectation
• Stress

Question 5

Describe how ovarian pathology might present

Answer 5

• Oestrus not observed
• Pregnancy diagnosis
• Persistent oestrus
• Irregular oestrus cycle

(Important to understand normal reproductive expectations)

Question 6

Describe potential causes/forms of ovarian pathology

Answer 6

• Lack of follicular growth/oestradiol
• Lack of an LH surge
• Lack of GnRH/gonadotrophin
• Lack of endometrial PGF2a production

Underlying pathology might explain this e.g. severe negative energy balance, stress, prolonged prolactin, hypothyroidism

Question 7

Describe methods to diagnose ovarian pathology

Answer 7

• Hormone analysis i.e. progesterone
• Ovarian and uterine palpation
• Ovarian and uterine ultrasound (small, inactive ovaries? Enlarged follicular structures?)

Accurate diagnosis can be very difficult especially with cystic ovarian disease.

Question 8

Describe the treatment options for ovarian pathology

Answer 8

• Promote ovarian function i.e. gonadotropin via GnRH / eCG
• Mimic luteal phase (with progesterone)
• Induce luteinisation (ovulation) via GnRH / LH
• Induce luteolysis if luteal tissue is present

Remember: these cases are likely to reoccur. Consider underlying factors as if the animal is in “deep” anoestrus there will be no quick fix.

Question 9

Give some examples of ovarian pathology and what they are associated with

Answer 9

• Anovulatory anoestrus
  
  • Lack of cyclicity
  • Delayed return post-season
  • Associated with NEB
  • Seen in cows, bitches, sows, and following pregnancy failure in the mare
• Cystic ovarian disease
  
  • Follicular structure that fails to ovulate; can be persistent follicular or luteal structure
  • Seen in cows and sows
• Persistent CL
  
  • Failure to return to oestrus
  • CL persists in absence of pregnancy
  • Common in mare and cows

Question 10

What is the typical time of presentation for reproductive tract infections (endometritis/cervicitis/vaginitis)? What are the treatment options?

Answer 10

• Post-partum (associated with retained foetal membranes)
• Post-mating
• Treatment: stimulation of uterine contractions, antibiotics

Question 11

What are some infectious causes of infertility?

Answer 11

• Many commensal organisms
• Venereal pathogens
  
  • Bovine general campylobacteriosis
  • Infectious pustular vulvovaginitis (IPV/IBR)
  • Contagious equine metritis
• Systemic infections
  
  • e.g. BVD, IBR, BHV1

Question 12

Describe how nutrition can influence infertility

Answer 12

• Negative energy balance → reduced gonadotropin/IGF1 levels
• Vitamin/mineral deficiencies or toxicities
  
  • Copper
  • Molybdenum
  • Selenium
• Oestrogen substances in plants