Reproduction

Question 1

What is the hypothalamic pituitary gonadal axis?

Answer 1

1. Hypothalamus → GnRH
2. GnRH → Anterior Pituitary → FSH or LH
   3a. FSH or LH → Ovary → Progestins, Estrogens
   3b. FSH or LH → Testes → Androgens

Question 2

Gonadotropin Releasing Hormone

1. Where is it produced
2. Where does it act? What does it cause?
3. What is the negative feedback for this hormone?

Answer 2

1. Hypothalamus
2. Anterior pituitary → FSH and LH
3. Negative feedback via steroid hormones

Question 3

Follicle Stimulating Hormone

1. Where is it produced?
2. Where does it act? What does it do?
3. What is the negative feedback for this hormone?

Answer 3

1. Pituitary gland
   2a. Ovarian GRANULOSA CELLS → stimulate follicular development
   2b. Testicular SERTOLI CELLS → aid spermatogenesis
2. Negative feedback via steroid hormones and inhibin

Question 4

Luteinizing Hormone

1. Where is it produced?
2. Where does it act? What does it do?
3. What is the negative feedback for this hormone?

Answer 4

1. Pituitary Gland
2. a. Acts on multiple ovarian cells → stimulate steroid hormone synthesis; OVARIAN GRANULOSA CELLS → stimulate ovulation
   2b. Testicular LEYDIG CELLS → stimulate steroid hormone synthesis
3. Negative feedback via steroid hormones* and inhibin
   * However there is a time after a certain point of estrogen increase, that estrogen will create a positive feedback loop with LH

Question 5

What are the 3 broad roles of estrogen?

Answer 5

1. Fertilization
2. Pregnancy preparation and pregnancy
3. Long term effects on physiology → female secondary sex characteristics

Question 6

How do estrogens influence fertilization?

Answer 6

1. Increase estrous behavior in some species
2. Increase uterine contractility
3. Opens cervix to admit sperm

Question 7

How do estrogens influence pregnancy preparation and pregnancy?

Answer 7

1. Stimulates endometrial development
2. Increases uterine progesterone receptors
3. Increase GnRH → LH surged → ovulation

Question 8

What are the 3 broad roles of progestins?

Answer 8

1. Fertilization
2. Preparation for pregnancy and pregnancy
3. Lactation

Question 9

What are the effect of progestins on fertilization?

Answer 9

1. Decrease uterine contractility
2. Closes cervix
3. Decrease FSH secretion

Question 10

What are the effect of progestins on preparation for pregnancy and pregnancy?

Answer 10

1. Increase uterine musculature

2. Increase endometrial gland secretions

Question 11

What are the effect of progestins on lactation?

Answer 11

1. Stimulates development of mammary alveolar cells

2. Inhibits milk production

Question 12

What are the 3 broad roles of androgens?

Answer 12

1. Spermatogenesis
2. Fertilization
3. Long term effects on physiology

Question 13

What are the effects of androgens on spermatogenesis?

Answer 13

1. Actions on SERTOLI cells
2. Maintenance of efferent ductular system
3. Maintenance of accessory sex glands

Question 14

What are the effects of androgens on fertilization?

Answer 14

1. Promote sexual behavior

Question 15

What are the effects of androgens on long term effects of physiology

Answer 15

1. Male secondary sex characteristics

2. Anabolic effect (promotes growth)

Question 16

Prolactin

1. Where is it produced?
2. What does it do?
3. What does it inhibit?

Answer 16

1. Anterior pituitary
2. Promotes lactation and maternal behavior
3. Inhibits follicular development

Question 17

Oxytocin

1. Where is it produced?
2. What does it do?

Answer 17

1. Produced in hypothalamus but released from pituitary

2. Involved in parturition

Question 18

Inhibin

1. Where is it produced?
2. What does it do?

Answer 18

1. Produced by GRANULOSA and Sertoli cells
2. Selectively inhibit FSH
   * DOES NOT INHIBIT LH*

Question 19

Prostaglandins

1. Where is it produced?
2. What does it do (in reproduction)?

Answer 19

1. Produced in many tissues by arachidonic acid cascade

2. In reproduction, most often considered in the context of luteolysis

Question 20

What are the different components of the follicular phase of reproduction? What is the dominant hormone during this phase?

Answer 20

1a. Proestrus → early follicular development and gamete maturation
1b. Estrus → final follicular development and sexual receptivity
2. ESTROGEN is the dominant hormone

Question 21

Ovulation

1. When does this phase occur?
2. What is it triggered by?
3. What happens?

Answer 21

1. Occurs at the end of estrus (or shortly after estrus in some species)
2. Triggered by the LH surge → which is in turn triggered by rising levels of estrogen inducing positive feedback of GnRH in the hypothalamus
3. Ovum is released into oviduct to encounter sperm for fertilization

Question 22

What are the different components of the luteal phase? What is the dominant hormone during this phase?

Answer 22

1a. Metestrus → formation of the corpus luteum → transition from estrogen to progesterone dominance
1b. Diestrus → corpus luteum is functional → produces progesterone to prepare uterine environment to be favorable to pregnancy
1c. Luteolysis → destruction of the corpus luteum and termination of luteal progesterone secretion
2. PROGESTERONE is the dominant hormone

Question 23

How do cells appear on vaginal cytology around ovulation?

Answer 23

1. Anucleate superficial epithelial cells → Cornified cells

Question 24

What % of cells should be cornified cells at ovulation?

Answer 24

1. 70-90%

Question 25

What is the MOA of finasteride?

Answer 25

Inhibits 5α reductase | *Blocks conversion of testosterone to DHT

Question 26

What is the top differential for an enlarged prostate in a castrated dog?

Answer 26

1. Prostatic carcinoma

Question 27

Acute bacterial prostatitis and prostatic abscesses are significantly associated with what?

Answer 27

1. BPH | 2. Estrogen administration

Question 28

When should breeding be attempted based on vaginal cytology?

Answer 28

When >75% of epithelial cells are anuclear

Question 29

During which phase does a pyometra occur?

Answer 29

1. Diestrus

Question 30

What are differentials for vaginal discharge thought to be a pyometra?

Answer 30

1. Lochia → should be green and non-odorous and present after whelping for up to 4 weeks 2. SIPS → persistant serosanguinous discharge up to 6 weeks after whelping, will usually resolve on its own 3. Metritis → ascending bacterial infection immediately after whelping 4. Re-entering heat

Question 31

How is Brucella canis transmitted?

Answer 31

1. Orally through bodily fluids * Large amount in vaginal fluid 4-6 weeks after abortion * Found in semen 2-3 months after infection

Question 32

What is the pathophysiology for Brucella canis infection?

Answer 32

1. Penetrates mucus membranes → replicates in local LYMPH NODES 2. BACTEREMIA within 7-30 days after exposure 3. Transport to monocyte/macrophage, prostate, uterus, and placenta

Question 33

Why does Brucella canis survive within macrophages?

Answer 33

1. Macrophages/monocytes inhibit the bactericidal myeloperoxidase-peroxide halide system by releasing 5-guanosine and adenine

Question 34

When does Brucella canis cause abortion?

Answer 34

75% of pregnancy loss is late in gestation (45-59 days)

Question 35

What are clinical signs associated with Brucella canis infection?

Answer 35

1. Abortion 2. Necrotizing vasculitis causing granulomatous lesions → causes epidydimal and testicular/prostatic pathology 3. Chronic infections → uveitis, granulomatous splenitis, discospondylitis, dermatitis, meningoencephalitis

Question 36

What diagnostic tests are used for Brucella canis?

Answer 36

1. Rapid slide agglutination test → initial test | 2. 2-mercaptoethanol modified RSAT → confirmatory

Question 37

There are (many/few) false positive with Brucella canis testing?

Answer 37

MANY

Question 38

What other antibodies will Brucella canis cross-react with?

Answer 38

1. Bordetella 2. Pseudomonas 3. Moraxella 4. Brucella ovis

Question 39

What are the hormonal characteristic of anestrus?

Answer 39

1. HIGH FSH | 2. Very LOW progesterone

Question 40

What are the cytologic characteristics of estrus?

Answer 40

1. >90% of the cells are superficial and unclear squamous cells (or have pyknotic nuclei) 2. NO WBC and occasional RBC