ECAR prep Flashcards

Question 1

Q

Canine prostatic hyperplasia

Answer

A

*Benign Prostatic Hyperplasia is the most common prostate disorder in dogs. Prevalence is 90% in entire male dogs >8years; common in dogs that are 5years (>50%)

Cause: Long term exposure to Dihydrotestosterone (DHT) = metabolite of testosterone (Testosterone + 5alpha-reductase =>DHT); DHT is the androgen active at cellular level of prostate.

Clinical signs
o Older dogs
o Uniform enlargement
o Most will be asymptomatic
o Sanguineous/Serosanguineous discharge = intermittent or continuous
o Haematuria, stanguria and pollakiuria
o Incontinence or anuria uncommon
o Constipation if very enlarged
o Infertility (May be a cause; haemospermia cases; freezing: poor quality due to ROS)

Diagnosis
o Enlarged smooth symmetrical gland on digital palpation
o Not painful on digital palpation
o Very little else in terms of systemic signs
o CBC & Biochem normal
o Canine prostatic specific esterase levels of >80ng/ml
o Radiography; prostatomegaly
o Ultrasonography; diffuse, relatively symmetric involvement with multiple, diffuse, cystic structures
o Cytology after wash; haemorrhage & mild non-septic, non-neoplastic inflammation

Differential diagnoses:
o Lower urinary tract infection/neoplasia/trauma
o Prostatic neoplasia (difficult to differentiate at advanced changes)
o Prostatic cysts
o Paraprostatic cysts
o Prostatitis (Acute/chronic)
o Urinary cysts (aspirate it to check blood urea:creatinine ratio)

Treatment
o Surgical castration if not intended for breeding; involution in 6 weeks (50% reduction)
+ Cycle of medical Treatment before castration (if there is doubt of prostatic neoplasia)

o Medical treatment
(i) Osaterone acetate potent anti-androgenic activity
0.25-0.5 mg/kg, PO for 7 days; 6-8 months duration of effect
4 months should pass after administration
Reduction in spermatogenesis after administration + Abnormality in sperm morphology (++coiled tails) is described
(ii)Delmadinone acetate (another potent anti-androgen)
1-2mg/kg once SC
4 months duration of effect
(iii) Deslorelin acetate (Suprelorin implant) may be used for medical castration but will have a negative effect on fertility (will arrest spermatogenesis)
Flare-up effect (not good in severe cases)
Combine initially with osaterone acetate to block receptors and avoid overstimulation.
Long-term control of BPH to avoid continuous use of other medical treatments.
Safer than castration in terms of risk of prostatic neoplasia.
(iv) Finasteride: blocks the action of 5 alpha-reductase, blocks T to DHT
0.1–0.5 mg/kg daily for up to 4 months; stop 2 weeks (2mths 1 months then restart)
This is a human product, don’t use it as a first choice
Use in cases of liver problems

Question 2

Q

Uterine prolapse in bitches

Answer

A

Uterine prolapse in bitches is uncommon, although it can happen as a consequence of parturition. The clinical sign is the presence of a solid tubular mass protruding from the vulva, it can also be confirmed by abdominal ultrasound (the uterus will be absent). Manual repositioning of the uterus is not possible due to the size of bitches, therefore the main treatment is a surgical approach by means of laparotomy. As the mucosa of the endometrium is often damaged, ovariohysterectomy is performed.

Question 3

Q

Abortion in sheep

Question 4

Q

Structure of the testes

Answer

A

The testes are paired dense organs responsible for reproductive function in males. The testes include:
(i) testicular capsule: composed by the visceral vaginal tunic (continuation of the visceral peritoneum) and by the tunica albuginea (made of connective tissue and smooth muscle fibers that contracts in response to norepinephrine and acetylcholine, causing the testicular capsule to have a pump effect that help spermatozoa progression within the tubules system); finger-like projection from the tunica albuginea enter in the testicular parenchyma and converge in the mediastinum.
(ii) mediastinum: dense connective tissue hosting the rete tubules (= rete testis), made of thin tubules though which the spermatozoa leave the testis.
(iii) parenchyma: the testicular parenchyma is divided into
a) interstitial compartment: including blood and lymph vessels, nerves, and Leydig cells.
b) Tubular compartment: including peritubular cells, Sertoli cells, seminiferous epithelium, and developing germ cells (spermatogonia, primary and secondary spermatocytes, spermatides, and spermatozoa). Seminiferous tubules form highly convoluted loops, and each loop presents a convoluted portion (i.e., tubulus contortus, where majority of the spermatogenesis happens) and a straight portion (i.e., tubulus rectus). The tubular compartment can be divided into a basal compartment and a deep and a peripheral adluminal compartments. The peritubular cells that surround the seminiferous tubules contribute to the blood-testis barrier, together with the tight junction between Sertoli cells. This prevents WBC and immunoglobulins to reach the developing germ cells and recognizing secondary spermatocytes, spermatides, and spermatozoa (aploid germ cells with different genetics due to crossing-over during meiosis) as non-self.

Question 5

Q

What are the peculiarities of camelid reproduction?

Answer

A

Non-seasonal polyestrus.
Induced ovulators (neural stimulation is required for LH peak and ovulation to occur, in camelids mechanical stimulation is less important than biochemical stimulation by an ovulation inducing factor (GnRH-like)).
Long mating (hours).
Late puberty (around 2-3 years in Camels, 1-2 years in Llamas and Alpacas)

Question 6

Q

Types of estrous cycle

Answer

A

Polyestrous cycles (seasonal or non-seasonal), monoestrous cycles.

Non-seasonal polyestrous = cow, sow (in the wild sow are seasonal polyestrus, with reproductive season in autumn), camelids, rabbits, mice, guinea pigs, rats.

Seasonal polyestrous = ewe, doe (short day breeders), mare, queen, jill (long-day breeders).

Monoestrous = bitch.

Question 7

Q

Describe the differentiation phase of spermatogenesis

Answer

A

The differentiation phase of spermatogenesis is responsible for undifferentiated spherical spermatids becoming highly specialized spermatozoa. At the end of this process the nucleus is highly condensed, the acrosome is formed, and the spermatozoon is partially motile. The differentiation phase (also referred to as “spermiogenesis”) consists of four main phases: (i) the Golgi phase, in which the highly developed Golgi apparatus consisting of many small vesicles that fuse, gives rise to an acrosomic vesicle containing a dense acrosomic granule. In the meantime, the cetrioles migrate to the base of the nucleus.The proximal centriole will give rise to the implantation apparatus that will anchor the flagellum to the nucleus, whereas the distal centriole will give rise to the axoneme. (ii) During the cap phase, the acrosome forms a cap over the anterior part of the nucleus. The Golgi apparatus moves away towards the caudal end of the spermatid and will eventually disappear. (iii) In the acrosomal phase spermatids become deeply embedded into Sertoli cells, in the meantime, the acrosome continues to spread over the nucleus until it covers two thirds of it, and a system of microtubules (i.e., manchette) develops near the posterior nucleus attaching just posterior to the acrosome, this will form the post-nuclear cap during the (iv) maturation phase. In this phase the mitochondria cluster around the base of the flagellum assuming a spiral conformation to form the middle piece and the fibers of the flagellum are produced. Finally, the spermatozoon is released into the lumen of the seminiferous tubule by the Sertoli cell in which it was embedded (i.e., spermiation). During differentiation, the DNA of the spermatozoon becomes inert due to high kerathinization. Specifically, histones of the nucleus are replaced by protamines, which are small arginine-rich nuclear proteins with many sulphydryl groups forming disulfide bonds that create nuclear condensation. This way the DNA is not transcripted and translated and it is protected from possible damage occuring prior to fertilization. During fertilization, when the spermatozoon enters the oocyte, the glutathione of the oocyte reduces the disuphide bonds and histone proteins of the oocyte replace the proteamines, leading to nuclear decondensation and formation of the male pronucleus.

Question 8

Q

What are the characteristics of ovulation in bitches?

Answer

A

Ovulation is spontaneous, multiple follicles ovulate at the same time, ovulation occurs 48-60 h after the LH peak, the oocyte is ovulated immature (primary stage) and will then mature in the oviduct. The preovulatory LH peak lasts longer than in other species (36-55 h) and is accompained by a FSH peak (lasting 110 +/- 8 h). The delay between the LH peak and fertilization allow superfecundation (i.e., possible fertilization by different males).

Question 9

Q

What are protein kinases?

Answer

A

Protein kinases are a family of enzymes located in the cytoplasm of cells. These are important components of hormone action on target cells. Specifically, either protein or steroid hormones can bind to their membrane receptor, inducing a transformation of a G protein that will cause activation of a second messenger (adenylate cyclase) that converts ATP in cAMP. This links to the regulatory subunit of a proteine kinase, and this bond will activate the catalytic subunit in order to mediate the transformation of existing substrates into new compounds (protein hormones) or change the permeability of calcium channels (steroid hormones).

Question 10

Q

When does progesterone peak in bitches?

Answer

A

Progesterone peaks about 25 days after ovulation in bitches, then it gradually declines, reaching 1.5 ng/mL about 70 days after ovulation in non pregnant bitches, and < 2ng/mL around 62-63 days after ovulation in pregnant bitches (parturition normally starts within 24h from the drop of progesterone below 2 ng/mL).

Question 11

Q

Endometritis in cows

Answer

A

Endometritis in cows
PVD => solo PVD + <5% PMN
Clinical endometritis => PVD + > 5%PMN (Cytobrush)
Subclinical endometritis => no PVD + > 5% PMN

Vaginoscopio = fuoriuscita di pus dalla cervice
Glove hand technique = score 0-1 (non patologico)-2-3 (endometrite)
Metricheck = Stesso score

Ecografia = ispessimento endometrio, presenza di pus, eco-score 0-1-2-3

Impatto su fertilità 30-50% vacche da latte (meno da carne => 20%). Depends on breed, parity, farming system and management (nutrition), dystocia, placental retention, immunodepression

Batteri: microbiota differenze + Trueperella pyogenes, Fusobacterium, Prevotella, Porfiromonas, E.coli

Treatment: antimicrobial intrauterine (good result with probiotics LAB and ozone)

Question 12

Q

FSH (biochemical classification, source, target tissue, primary actions)

Question 13

Q

Describe the hormonal changes that occur during parturition in pigs.

Question 14

Q

Describe the blood-testis barrier

Answer

A

The blood-testis barrier has the function of preventing white blood cells and immunoglobulins to reach the developing germ cells within the adluminal compartment of the tubular compartment of the testicular parenchyma. The blood-testis barrier includes
(i) peritubular cells, surrounding the seminiferous tubule and preventing the passage of large molecules and cells from the interstitial compartment to the tubular compartment.
(ii) tight junctions between Sertoli cells, located in the basal compartment and preventing the passage of large molecules and cells from the basal to the adluminal compartment.

Question 15

Q

Functions of the increased mucus secretion under the effect of estrogens

Answer

A

Lubricate the cervix and vagina in preparation for copularion, flushes out foreing material, in cows low-viscosity mucus provides a preferential pathway for spermatozoa to traverse the cervix and enter the uterus

Question 16

Q

Explain sexual differentiation of the reproductive tract

Answer

A

Sexual differentiation of the reproductive tract starts by 20% of gestation and is completed around 33% of gestation. It depends on the presence or absence of the SRY gene. Specifically, the SRY (sex determining region) gene is found only on Y chromosome in the male (XY), whereas this is absent in females (XX). This gene controls the syntesis of the SRY protein. In the first phase of development. When the protein is synthesized by the sex cords, the sexual differentiation of the male starts. Therefore, the testes develop, including Sertoli cells producing anti-Müllerian hormone (AMH) that inhibit the development of the paramesonephric duct, thus that of the female reproductive tract and dihydrotestosterone. Moreover, the Desert Hedgehog Gene (DHH) causes the differentiation of fetal Leydig cells, leading to production of testosterone and dihydrotestosterone. The first stimulates the development of the male duct system, whereas the latter promotes the development of the penis, scrotum, and male accessory sex glands. In females, the SRY gene is not present, although sex differentiation is anyway an active process, because in the absence of the SRY protein, female genes are activated and ovaries will develop from the bulk of the genital ridge. The sex cord fragments into clusters of primitive follicular cells that will enclose one primitive germ cell per cluster. Primordial follicles forms on the surface of the ovary and this region will become the ovarian cortex (except in mares).

Question 17

Q

What are the functions of Sertoli cells in the process of spermatogenesis?

Answer

A

(i) Hormone production: Estrogens, Inhibin, Activin, Transferrin, Androgen Binding Protein (ABP), SGP1 (involved in fertility acquisition by spermatozoa) and SGP2 (detergent effect allowing sperm cells to move in the seminiferous tubules)
(ii) Tight junctions between Sertoli cells contribute to the blood-testis barrier
(iii) Determine the reproductive potential of the male as each Sertoli cell host a maximum number of developing sperm cells (more Sertoli cells = higher reproductive potential)
(iv) During the acrosomal phase of the spermiogenesis the spermatids become deeply embedded into a Sertoli cell with only the flagellum protruding towards the lumen of the seminiferous tubule. After the maturation phase, Seroli cells release the spermatozoa into the lumen of the seminiferous lumen (= spermiation). The cytoplasm of the spermatid remains as a residual body within the cytoplasm of the Sertoli cell.

Question 18

Q

IVM

Question 19

Q

What is necessary for luteolysis

Answer

A

Luteolysis is the irreversible degeneration of the corpus luteum that ends the luteal phase. In mammals, except for primates and canids, an intact uterine endometrium producing PGF2a is necessary for luteolysis. In primates PGF2a is produced by the corpus luteum, whereas in canids there is no luteolysis, but a gradual regression of the corpus luteum. Secretion of PGF2a by endometrial cells in other species is promoted by oxytocin (oxytocin is produced by the hypothalamus and stored and release by the posterior pituitary, in Ruminants oxytocin granules can also be found in the cytoplasm of large luteal cells). Therefore, to achieve luteolysis oxytocin receptors on endometrial cells, critical levels of oxytocin, and synthesis of PGF2a are needed.
Since progesterone blocks the formation of oxytocin receptors, luteolysis cannot happen in the first part of the luteal phase. When progesterone levels start decreasing, the block is removed, oxytocin receptors are synthesized and expressed by endometrial cells, oxytocin can bind the receptors activating the synthsis of PGF2a. PGF2a is secreted in pulses (e.g., 5 pulses in 24 h are needed in ewes for luteolysis to happen) and it binds to plasma membrane receptors on plasma membrane cells, acting via proteine kinases, the binding cause the opening of Ca2+ channels and a consequent Ca2+ influx that starts apoptosis of luteal cells. Moreover, the binding of PGF2a with the plasma membrane receptor on luteal cells causes the activation of proteine-kinase-c that inhibit the synthesis of progesterone. WBC are present in the CL at the moment of lutheolysis and they also play an active role by releasing cytokines that activate macrophages (phagocytosis of damaged/dead luteal cells), inhibit progesterone synthesis, and may trigger agents of apoptosis in luteal cells.

Question 20

Q

Vulvoplasty bitches

Answer

A

Vulvoplasty or episioplasty is a reconstructive procedure mainly performed to excise the excess of skin folds around the vulva, which can cause vulvar dermatitis (to be treated before surgery), recurrent vaginitis, and recurrent urinary tract infections. The bitch is placed in a perineal (sternal) position with limbs supported. A purse-string suture is performed prior to vulvoplasty to reduce the risk of contamination from feces. Beginning near the ventral vulvar commissure, a crescent-shaped incision is performed around the vulva. Afterwards, a second crescent incision is made medial and parallel to the first one. After excision of the outlined segment of skin and subcutaneous tissue, interrupted sutures are placed at 3 o’clock, 9 o’clock, and 12 o’clock positions to assess the effectiveness of the resection. The margins are brought together and suturing of the subcutaneous tissue using interrupted sutures with buried knots is performed. The skin margins are sutured either with intradermal patterns. Once the vulvoplasty is completed, the purse-string suture is removed. Post-operative management include the placement of an Elizabethan collar.

Question 21

Q

Patterns of GnRH, LH, FSH, and testosterone in males

Answer

A

GnRH pulses last a few minutes and have a frequency of 4-8 times per day (every 3-6 hours); LH and FSH have the same pulse frequency, although LH pulses last 30-75 minutes, whereas FSH pulses last longer. Finally, testosterone is produced about 30 minutes after each LH pulse and it is released for about 20-60 minutes.

Question 22

Q

Describe the approach to a case of testicular hypoplasia in a stallion.

Answer

A

Hypoplastic testis in a horse refers to a condition where the testis is underdeveloped, resulting in smaller size and reduced function compared to a normal testis.

Signalment and history
(i)Age: Testicular hypoplasia may be congenital or acquired, so knowing the age of onset is important.
(i)Breeding history: Has the stallion been used for breeding, and if so, has there been a history of poor fertility or failed pregnancies?
(i)Developmental abnormalities: Any history of abnormal development during growth.
(i)Previous illness or trauma: Any past infections, trauma, or surgeries related to the reproductive system.

2.Clinical examination
(i)Overall health and body condition of the horse, as systemic illnesses or poor nutrition can affect reproductive development.
(ii)Reproductive tract examination:
a.External palpation to evaluate both testes, paying attention to size, consistency, symmetry, and presence of pain or heat. Compare the hypoplastic testis with the contralateral testis (one is hypoplastic or the other one is enlarged?).
b.Testicular size: Hypoplastic testes are typically smaller and softer than normal testes. Measure the dimensions of both testes using a caliper.
c. Epididymis palpation: check for position and abnormalities in the epididymis, which may also be underdeveloped in the case of hypoplasia.
d. Examine the scrotal skin for signs of trauma, infection, or developmental abnormalities.
e.Penis and prepuce: Evaluate for any additional abnormalities in the external genitalia.

3.Differentials:
Testicular degeneration: This could be secondary to infection, trauma, or systemic illness.
Cryptorchidism: One or both testes fail to descend into the scrotum, leading to reduced testicular size and function. Use hormonal testing (AMH or hCG stimulation) to differentiate cryptorchidism from true hypoplasia.
Testicular atrophy: Often occurs secondary to infections (e.g., orchitis), trauma, or systemic conditions like fever.
Neoplasia: Although rare, testicular tumors can alter the size and function of the testis.

4.Ultrasound
Look for parenchymal abnormalities such as reduced testicular echogenicity, abnormal architecture, or cystic areas.
Measure the testicular volume to provide a more accurate assessment of testicular size and function.
Evaluate the blood flow using Doppler ultrasound to rule out vascular issues (such as testicular torsion) that could mimic hypoplasia.

Hormonal testing
(i)Basal testosterone levels (hypoplastic testes may produce less testosterone).
(ii) hCG stimulation test:
Perform an hCG stimulation test to assess the ability of the testis to produce testosterone. After administering hCG, testosterone levels should increase in a normal horse. Failure to respond suggests testicular dysfunction.
(iii) AMH levels can help differentiate between cryptorchidism and true hypoplasia. Cryptorchid testes often produce higher levels of AMH, whereas a truly hypoplastic testis may produce very low levels.
Semen Evaluation
(i)Semen collection: if the horse is used for breeding or is of breeding age, collect semen via artificial vagina or electroejaculation.
(i)Sperm analysis:
assessment of semen volume, sperm concentration, motility, and morphology.
A hypoplastic testis may result in oligo and/or terato and/or asteno-zoospermia.
If sperm production is severely impaired, the horse may be considered subfertile or infertile.

7.Testicular biopsy
DD testicular degeneration?

8.Management
Unilateral testicular hypoplasia: the prognosis for fertility is generally fair if the contralateral testis is normal. The stallion may still be capable of producing enough sperm for natural breeding or artificial insemination.
Bilateral testicular hypoplasia: The prognosis for fertility is poor in cases where both testes are significantly hypoplastic. The horse is unlikely to be fertile, and castration may be considered for management.

Question 23

Q

Sertoli cell tumors

Question 24

Q

What are the stages of parturition in dogs, and how is normal delivery monitored?

Question 25

Q

What are the primary causes of retained placenta in cattle, and how is it managed?

Question 26

Q

Uterine prolapse in mares

Question 27

Q

Breeding soundness examination in tomcats

Question 28

Q

Luteolysis in primates

Question 29

Q

Factors influencing sperm content in the tail of the epididymis

Answer

A

Frequency of ejaculation (if increased can dramatically reduce the number of spermatozoa in the tail of the epididymis, if decreased the number of spermatozoa in the tail is at its highest, although prolonged storage time can alter the morphology and function of spermatozoa); also actions of sexual preparation (false mounting, restrain from mounting increase the amount of spermatozoa ejaculated from the tail)

Question 30

Q

Characteristics of reproductive hormones

Answer

A

Acts in minutes, relatively short half-life, binds to specific receptors, regulate intracellular biochemical receptors

Question 31

Q

How can estrus be monitored in bitches?

Question 32

Q

LH (biochemical classification, source, target tissue, primary actions)

Question 33

Q

Septicaemia in newborns

Question 34

Q

Balanopostitis

Question 35

Q

Determination time of breeding in bitches

Question 36

Q

How do glucocorticoids affect reproductive function?

Question 37

Q

How many pulses of GnRH, LH, and FSH happen in 24h in males?

Answer

A

4-8 pulses

Question 38

Q

How do you manage a mare with retained fetal membranes?

Question 39

Q

Muscles involved in penile erection

Answer

A

Blulbospongiosus (overlaps the root of the penis, covers the bulbo-urethral glands - if present - empties the extrapelvif part of the urethra), ischiocavernosum (paired muscles, relatively short, located in the area of the root of the penis. These muscles insert broadly on the lateral parts of the penis above the sigmoid flexure - if present. These muscles attach the penis to the ischiatic arc), uretralis (striated muscle surrounding the pelvic urethra, responsible for the movement of the semen.

Question 40

Q

Mastitis

Question 41

Q

Uterine prolapse in sows

Question 42

Q

Cycle manipulation in bitches

Question 43

Q

How long is the interval between estrous periods in bitches?

Question 44

Q

What are the stages of parturition in cattle, and how is normal delivery monitored?

Question 45

Q

Discuss the pathophysiology of testicular degeneration in bulls.

Question 46

Q

Which species are reflex ovulators

Question 47

Q

Describe the stages of development of ovarian follicles

Answer

A

An ovarian follicle are structures located within the ovarian cortex and containing immature oocytes. Ovarian follicles can be classified as primordial, primary, secondary, and antral (or tertiary). A dominant antral preovulatory follicle can also be refferred to as ‘Graafian follicle’. Females are born with a lifetime reserve of primordial and primary follicles. Primordial follicles are the earliest stage of development and the smallest structures. The oocyte is surrounded by a single layer of flattened squamous epithelium. These evolve into primary follicles, that are small structures in which the oocyte is surrounded by a single layer of cuboidal follicular cells. Primary follicles cannot divide into other primary follicles, but either evolve to secondary follicles or degenerate. Secondary follicles have 2 or more layers of follicular cells and the oocyte is surounded by a zona pellucida. Finally, antral follicles (or tertiary follicles) are the largest stuctures, ranging from 1 mm to some cm, these possess an antrum filled with follicular fluid. Each follicle has multiple layers. Specifically, the theca externa is made of connective tissue supporting the follicle, the theca interna is made of cells producing androgens under the influence of LH. The theca interna is divided by the granulosa cell layer by a thin basement membrane. The cells of the granulosa layer present FSH receptors and produce estrogens, inhibin, follicular fluid. Once ovulation of antral follicles occurs, small blood vessels rupture causing an hemorrage, moreover the follicular fluid is lost causing the collapse of the follicle (‘in-folding’). In this process, some theca and granulosa cells are pushed to the apex of the follicle. All this causes the formation of a ‘corpus hemorragicum’ (NB the follicular fluid of mares contains an heparin-like substance that prevents clots formation). After the formation of the corpus hemorragicum, the theca and granulosa cells differentiate into luteal cells forming the corpus luteum. Specifically, the theca cells become small luteal cells, whereas the granulosa cells become large luteal cells.

Question 48

Q

How long does the luteal phase last in bitches?

Question 49

Q

Which animals are induced ovulators?

Question 50

Q

Definition of luteal phase

Question 51

Q

Discuss the role of reproductive ultrasonography in pregnancy diagnosis in cattle.

Question 52

Q

Explain reflex ovulation

Question 53

Q

How is the dictyotene block removed?

Question 54

Q

What is the stigma?

Question 55

Q

Vaginitis

Question 56

Q

In which species is manipulation per rectum possible?

Answer

A

Cattle, Horse, Camel. In large gilts and sows it is possible to palpate the uterine artery pulse for pregnancy diagnosis after day 40 (increased tone and fremitus).

Question 57

Q

Uterine prolapse

Question 58

Q

Describe the different methods of pregnancy diagnosis in small ruminants.

Question 59

Q

Induction of parturition in sows

Question 60

Q

Discuss the role of genomic selection in modern livestock breeding programs.

Question 61

Q

Describe how neonatal septicemia is diagnosed and treated in foals.

Question 62

Q

Why is inguinal herniation common in boars?

Answer

A

Inguinal herniation is common in boars (1/200 males) because the inguinal canal is located more dorsally compared to other species. In this conditions, abdominal organs (mostly the gut) is herniated within the vaginal process, which is in direct communication with the peritoneal cavity. Usually, the visceral vaginal tunic and the parietal vaginal tunic can be sutured in order to prevent further herniation.

Question 63

Q

Maternal recognition of pregnancy in ruminants

Question 64

Q

What are the main factors affecting weaning success in piglets?

Answer 26

A

The proliferation phase is the first phase of spermatogenesis, it takes place in the basal compartment of the seminiferous tubules. It consists of mitotic divisions of spermatogonia until the stage of primary spermatocytes. The number of mitotic divisions depends on the species. In general, there are multiple generations of spermatogonia A, then spermatogonia I, and finally spermatogonia B, that will divide into primary spermatocytes, that do not divide by mitosis but immediately enter the first meiotic division, passing from the proliferation phase to the meiosis phase of spermatogenesis.

Answer 27

A

Equine ovaries present an inversion of the cortex and medulla, therefore ovulation can only take place at one location, which is the ovulation fossa (a depression located on the ventral surface of the ovary). Follicles can be palpated per rectum at the ovulation fossa. However, normally palpation of the corpus luteum is not possible as it tends to penetrate the ovarian tissue intead of protruding from the surface of the ovulation fossa.

Answer 28

A

The flagellum consists of a middle piece, a principal piece, and a distal piece. (i) The middle piece consists of a capitulum that inserts within the implantation socket (a depression of the posterior nucleus of the spermatozoon), laminated columns (that provide flexibility during flagellar beat), and the mitochondrial helix (which is the engine allowing the motility of the flagellum). The juncture between the middle and the principal pieces is the annulus. The principal piece is formed by the axoneme, that originated from the distal centriole and is formed by a 9+9+2 arrangement of microtubules, with 9 pairs of microtubules radially arragend around two central filaments. The microtubules terminate in the (iii) distal piece.

Answer 29

A

Increased lordosis, phonation, physical activity

Answer 30

A

The oviduct (or salpinx, or Fallopian tube) is a paired hollow organ of the female reproductive tract. It is responsible for receiving the ovulate oocyte/oocytes, being the location of fertilization, and conveying the early embryo to the uterus. It can be divided into three parts. The infundibulum is the cranial end of the oviduct, it is funnel-shaped and the mucosa possessess finger-like projections (‘fimbriae’) increasing the surface area (6-10 cmq in sheeps, and 20-30 cmq in cows) and protruding towards the ovary and increasing the chances to capture the ovulated oocytes. An ostium marks the passage from the infundibulum to the ampulla, which represents more than 50% of the lenght of the oviduct and it is the site of ovulation. It presents fern-like mucosal folds with ciliated epithelium. An ampullary-ishtmic junction separates the ampulla from the caudal portion of the oviduct, which is the isthmus. The ampullary-isthmic junction is poorly defined, although in mares represents an important control point for the passage to the isthmus (only fertilized oocytes forming viable embryos producting PE2 normally pass into the isthmus). The isthmus is smaller, although presents a thicer muscolaris layer and fewer mucosal folds compared to the other parts of the oviduct. It is connected to the uterus through a utero-tubal junction which represent a control point: specifically, in cows it forma a kink when estradiol is high, the it straightens when estradiol decreases, allowing the passage of the embryo into the uterine horn. In sows, constriction of the utero-tubal junction prevents excessive amounts of spermatozoa to reach the ampulla, therefore it is a mechanism for polyspermy prevention in this species. The muscolaris of the oviduct is importat to guarantee contractions fro gamete transport in opposite directions so they can meet in the ampulla. The mucosa provides the optimal environment for oocytes, spermatozoa, and for the development of early embryos.

Answer 31

A

Hormone secretion can follow an episodic pattern (with sudden release of high levels of hormones, e.g., GnRH by the surge center of the hypothalamus). When episodic secretion of hormones follow a predictable pattern, this is defined as pulsatile. Pulsatile patterns are those of GnRH, LH, and FSH and are key to manain cyclicity. There second type of hormone secretion pattern is the basal secretion of low amoun of hormones, which blood concentraction fluctuate with low amplitude (e.g., GnRH released from the tonic center in the hypothalamus). Finally, sustained secretion is another pattern of hormone secretion. This consist of continuous production of the hormone that remain elevated for long periods (e.g., steroids, as P4 during pregnancy and diestrus).

Answer 32

A

Mesoderm (gonads, salpinx, uterus, cervic, cranial vagina, epididymis, ductus deferens, accessory sex glands); ectoderm (mammary glands, portions of the vagina and vestibule, also hypothalamus and both lobes of the pituitary)

Answer 33

A

Alpha-ferroprotein is a protein secreted by the embryonic yolk sac and later by the liver that binds estradiol and prevents it from crossing the blood-brain barrier

Answer 34

A

The mare will not show a normal response to changes in the photoperiod, whereas ewes keep exhibiting normal seasonality, indicating that environmental factors other than melatonin are involved in seasonality

Answer 35

A

Milk ejection by mammary alveoli. This involves oxytocyn produced by the paraventricular nucleus of the hypothalamus and stored in the posterior pituitary. Once sensory receptors in the nipple or tit are mechanically stimulated, an afferent sensory nerve convey the information to the spinal cord, where it synapses with an interneuron, that synapses with an efferent nerve conveying the information to the brain, making another synapsys with neurons in the hypothalamus and causing the release of oxytocyn. Oxytocin causes the myoepithelial cells of the mammary alveoli to contract. Another example is the Ferguson’s reflex, with mechanical stimulation of sensory terminals within the cervix by the fetus, leading with a similar mechanism to the release of oxytocin that will act on the myometrium causing uterine contractions. Finally, another example of neuroendocrine reflex is that leading to production of gonadotropins in the anterior pituitary.

Answer 36

A

The mesonephric ducts are paired ducts conveying the urine produced in the mesonephros (the first functional kidney of the fetus that replaces the pronephros that was not functional and that is replaced when the metanephros is developed; the metanephros will develop into the definitive kidney) to the urogenital sinus. These ducts will originate the efferent ducts system of the male reproductive tract. Specifically, the mesonephros is drained by mesonephric tubules, 5-15 of which will penetrate into the primitive gonad, connecting to the sex cord via the rete testis. The mesonephric tubules converge into a larger mesonephric duct that will originate the epididymis and ductus deferens. In females, the mesonephric ducts regress and only remnants can be found by dissecting the floor of the vestibule of the vagina in adult animals (Gartner’s ducts)

Answer 37

A

Some hormones can be orally administered (e.g., steroids), whereas others cannot (e.g., glycoproteins). Glycoproteins cannot be orally administered because they are polypeptide chains with carbohydrate moieties that are easily degraded into the digestive system.

Answer 38

A

The cremaster muscle is a striated muscle that is the continuation of the oblique internal abdominal oblique muscle and it passes within the spermatic cord, contributing to the wall of the scrotum. Being a striated muscle, is it not capable of sustained contractions, and its function is to have short rhytmic contraction pumping the venous blood back to the main circulation. However, it may be involved in short elevation of the scrotum due to fear. It is responsible for rhytmic movements of the testicles in bulls and ram during sexual excitation.

Answer 39

A

Spermatozoa maturation (acquisition of abitilty to move and fertilize), storage of spermatozoa (in the cauda), movement of spermatozoa to the ductus deferens,

Answer 40

A

Ewe, cow, sow

Answer 41

A

Mechanism: melatonin is an endogenous hormone secreted by the pineal gland and it is mainly produced at night, when the enzymes involved in the synthesis of this hormone have higher functionality. Melatonin acts on the suprachiasmatic nucleus of the hypothalamus by linking to MT1 and MT2 receptors.
In long-day breeders (e.g., cat, horse), high melatonin levels suppress kisspeptin production, inhibiting GnRH release and thus suppressing reproductive activity. Conversely, when nights are shorter, melatonin levels drop, allowing kisspeptin to increase, thereby triggering reproductive activity. The opposite pattern may be observed in short-day breeders (e.g., sheep).
Therefore, the photoperiod affects reproduction in seasonal breeders and altering light-darkness proportions may be used as a tool to control the estrus cycle in these species.

Mare: exposure of mares to a stimulatory artificial photoperiod is commonly used to anticipate the onset of the breeding season.
The duration from the onset of artificial light exposure and the first ovulation of the year is about 60-90 days. The objective should be a daily light exposure of about 15-16 hours. This works better than a 24-hour light exposure.
In Europe, the artificial photoperiod can be started at the beginning of December. Mares can be exposed to natural light from sunrise to late afternoon (before dusk), when lights are turned on to extend the exposure to 16 hours. This allows 8 hours of darkness. Minimum light intensity is approximately 100 lux.
Different approaches can be used:
- Exposure of anestrous mares to 35 days of artificial photoperiod (14.5 hours of light and 9.5 hours of dark, light intensity of 100 lux). Mares will start ovulating about 76 days after the onset of the artificial photoperiod.
- ‘Skeletal lighting’ protocol: exposure of mares to two hours of light 8-9.5 hours after the onset of darkness. This interrupts the course of melatonin exposure, thus modulating the inhibitory effect of melatonin on GnRH secretion. This has been reported to stimulate follicular development in anestrus mares.
- Blue light mask: mares can be exposed to a LED blue light with wavelength of 468 nm and intensity of 10 lux. This is normally done using a mask emitting a low-level blue glow on a single eye. Advantages of light masks include the possibility of programming it to start light exposure at a specific time and the possibility to keep the mare in external paddocks.

Queen: the minimum number of hours per day reported to stimulate follicular activity in queens is 12h. A daily dark-light cycle of 12h:12h lead to continuous cycling in queens. Light exposure can be increased to 14 h to induce estruses and were reported to be optimal to stimulate the hypothalamic-pituitary axis. However, continuous exposure for 24h per day causes a decrease in the frequency of cycles. Moreover, phases with lower light exposure (i.e., < 8 hours per day) seem to optimize the response to light exposure (> 12h).
The best protocol to induce estrus is to extend the natural photoperiod to 12-14h hours by exposing the queen to 300 lux intensity light and introduce an estrus female or a tomcat, this should cause cyclicity to start within 30-45 days.
Cats are common pets living indoor and can be exposed to artificial light with variable intensity and duration. However, majority of intact pet cats in Europe do not cycle between October and December.

Small ruminants (sheep and goat): in these species, decreasing daylight will stimulate cyclicity. This can be achieved in spring and summer either by housing the animals in daylight proof facilities or by exposing the animal to artificially longer days (e.g., 22 hours light exposure) for at least one month and then returning to natural day length.

Sow: in domesticated animals housed in breeding facilities, food availability and controlled environment suppress seasonality. However, wild pigs are seasonally anestrous. For this reason, a seasonal decrease in fertility is sometimes observed in gilts and sows in summer and autumn. This can be avoided by optimizing nutrition and light exposure. Specifically, it is advised to use a light program consisting of 16 hours of light (light intensity of 200 lux) and 8 hours of darkness in the breeding area, whereas the proportion can be inverted (8 hours of light and 16 hours of darkness) in the lactation area.

Answer 42

A

Vulva, vestibular-vaginal fold, cervix

Answer 43

A

The Gartner’s ducts are remnants of the Wollfian ducts located in the floor of the vestibule of the vagina.

Answer 44

A

The cervix is an hollow organ located between the uterus and the vagina. It is relatively thick-walled and the lumen is differently shaped among domestic species. In bitches and queens the mucosa is relatively smooth and a single fold of mucosa protrude within the cranial vagina; in cowe, ewes, sows, and mares there are multiple folds protruding within the cranial vagina. Specifically, in cows and ewes the folds form interlocking finger-like projections (i.e., cervical rings), the surface is rich in crypts and folds and mucous secretion is cospicuous depending on the stage of the cycle; in the mare there are cospicuous cervical folds protruding into the vagina, mucous production is lower, the cervical tone is increased under the influence of P4, otherwise the cervix is relatively soft in mares; in sows the mucosa forms interdigitating prominences, requiring a special conformation of the glans penis of the boar (corckscrew spiral twist; in this species the semen is ejaculated in the cervix and the high volume of 200-500 mL, causes the semen to quickly progress to the uterus). The cervix is a barrier to sperm transport in cows, ewes, bitches, queens but not in mares and sows. In all species, the mucosal epithelium is capable of secreting the mucus forming the cervical seal of pregnancy, isolating the pregnant uterine environment from the vagina and external environment, thus preventing ascenting contamination from potentinally pathogenic bacteria.

Answer 45

A

Ruminants post-scrotal, boar = pre-scrotal

Answer 46

A

Lactational anestrus is the absence of cyclicity in lactating dams, due to mechanical (suckling), auditory, visual, and olfactory stimuli associated with maternal care of newly born offspring. This happens in most domestic species, except for the mare and alpaca. Moreover, bitches do not show a proper lactational anestrus, since they would anyway be in the anestrus phase of the cycle that follows diestrus. In queens, lactational anestrus is present in some animals and not in others and cyclicity is mainly restored in 7-10 days. Sows present lactational anestrus and display estrus and ovulate 4-8 days after weaning, making time at weaning a key breeding management tool in this species. Cows normally show lactational anestrus, although newborns from dairy cows are removed from their dam immediately or few hours afrer birth, thus dairy cows do not show a proper lactational anestrus as beef cows do. Suckling seem to be a major mechanical stimulation involved in lactational anestrus and a suckling frequency of less than 2 times per day promote the increase in amplitude and frequency of LH pulses and the return to cyclicity, whereas a number equal to or higher than 3 keeps LH pulses with low amplitude and frequency, thus mantaining lactational anestrus.

Answer 47

A

A normal CL should be visible in pregnant mares up to day 45 of gestation. During early pregnancy it is important to evaluate the size of the CL, since CL smaller than normal could indicate an insufficient P4 production (in that case, P4 should be supplemented: e.g., altrenogest 0.088 mg/kg per os). Secondary corpora lutea may be identified in pregnant mares after 45-60 days of gestation, although these do not form in every pregnant mare.

Answer 48

A

Ejaculation is an example of simple neural refles involved in reproduction. When sensory terminals in the glans penis are mechanically stimulated, afferent nerves with body cells located in the spinal cord synapse with interneurons in the spinal cord that will synapse with efferent nerves and the axons of these neurons will convey the signal to muscles involved in ejaculation causing this event. Similarly, when temperature sensitive terminals on the skin of the scrotum are stimulated by a descrease in the temperature, the message is conveyied to the spinal cord via afferent nerves with body cells in the spinal cord, these will synapse with an interneuron that will synapse with an efferent neuron conveying the information to the smooth muscle of the tunica dartos causing a contraction that will bring the scrotum closer to the body.

Answer 49

A

The implantation socket is a depression within the posterior nucleus hosting the capitulum of the flagellum.

Answer 50

A

Periventricular, preoptic, arcuate

Answer 51

A

Ovariectomized bitches cannot carry a pregnancy to term, since the CL is needed to produce P4, therefore ovariectomy at any stage of pregnancy causes abortion in bitches. Many queens will abort as well. However, some queens ovariectomized after 45 dop, will carry the pregnancy to term, probably because the the placentae can produce some P4 by converting pregnenolone to P4. This matter is still controversial, and ovaries are still considered the main source of P4 in pregnant queens.

Answer 52

A

Dopaminergic substances can promote folliculogenesis by modulating GnRH producting neurons thus GnRH secretion that in turn modulare FSH and LH secretion. This is proved by iatrogenic administration of dopaminergic agenst (e.g., cabergoline and bromocriptine) during anestrus: this can stimulate GnRH production thus shortening the anestrus.

Answer 53

A

Primordial germ cells migrate by ameboid movement from the endoderm of the yolk sac to the genital ridge, where undergo replication by mitosis and locally stimulate the proliferation of the connective tissue that will form the primitive sex cords, that will push towards the mesonephros (primordial kidney). Precursors of the Sertoli cells migrate from the coelomic epithelium to the genital ridge. Precursors of the Leydig cells are formed in the mesonephros. Male mammals have a Y chromosome carryin a gene named SRY (Sex Determining Region) controlling the synthesis of the SRY protein. When the SRY protein is produced by the sex chords, the development of the male reproductive system is stimulated. This will lead to the development of the testes, in which Sertoli cells carry a Desert Hedgehog Gene (DHH) and produce AMH and dihydrotestosterone, which will cause degeneration of the paramesonephric ducts. DHH causes the differentiation of Leydig cells that will produce testosterone and dihydrotestosterone, promoting the development of the male reproductive system.

Answer 54

A

Reproductive organs develops in retroperitoneal position, they then grow pushing the peritoneum until they are completely enveloped by it and a portion of the peritoneum eventually fuses forming a double layered sheet of connective tissue named ‘broad ligament’. The broad ligament privide vascular supply, limphatics, and nerves to the reproductive organs and suspends them to the dorsal body wall. The cranial portion of the broad ligament is called mesovaium: it attaches and supports the ovary and vehiculate vessels and nerves to the organ, forming the ilus of the ovary. Most species also have a utero-ovarian ligament (also called proper ligament of the ovary) that connect the ovary to the uterus (these ligaments are not part of the broad ligament!). The thinner serous portion of the broad ligament that supports the oviduct and forms the ovarian bursa (nearly complete in bitches) is named mesosalpinx. This ligament has also the function to orient the infundibulum of the salpinx towards the ovary in order to enhance the chances that oocytes will reach the infundibulum. Finally, the largest part of the broad ligament is called ‘mesometrium’. It supports the uterine horns and body and it is continuous with the dorsal peritoneum, so that it literally hangs from the dorsal body wall. There are also intercornual ligaments (dorsal and ventral) connecting the two uterine horns.

Answer 55

A

The pituitay originate from the embryonic ectoderm. It consists of two lobes (adenohypohysis and neurohypophysis). The anterior lobe (adenohypophysis) originates from the dorsal wall of the stomodeum that forms a diverticulum named Rathke’s pouch, that grows dorsally. The posterior lobe (neurohyphysis) originate from the floor of the third ventricle of the embryonic brain (infundibulum) and grows towards the Rathke’s pouch. The posterior lobe contains the axons and nervous terminals (telodendra) of the hypothalamus. Whe the two lobes are almost completely formed, the sphenoid bone starts growing around the two lobes, that will then be contained in the sella turcica of the sphenoid bone, which works as a protective case.

Answer 56

A

Acrosome reacrion is an organized and highly specialized exocytosis allowing the release of acrosomal enzymes to penetrate the oocyte during fertilization.

Answer 57

A

Bitch, cow, mare

Answer 58

A

STAR (steroidogenic acute regulatory)

Answer 59

A

It starts at 20% of the gestation and it is completed at 33%.

Answer 60

A

Hormones can be classified based on their mode of action in the following way. (i) neurohormones: these hormones are produced by neurons and released in the blood (oxytocin, GnRH); (ii) gonadotropins: these hormones act on the gonads (FSH, LH); (iii) sexual promoters: promote sexual behavior and secondary sex characteristics (steroids); (iv) pregnancy manteinance hormones: eCG, hCG, P4; (v) lactogenic hormones (placental lactogen); (vi) general metabolic hormones (thyroxin, somatotropin); (vii) luteolytic hormones (PGF2α).

Answer 61

A

Multiple ovulations producting multiple follicles in one estrus and allowing to fertilizations from different matings

Answer 62

A

The uterus is the organ of pregnancy. Its primary functions are: luteolysis and control of cyclicity (in some species); sperm transport to the oviduct, where fertilization happens (ampulla); environment for embryo attachment; maternal contribution to the placenta; expulsion of the fetus and fetal annexes at the end of pregnancy.

Answer 63

A

Hormones can be classified based on the tissue of origin as follows (i) hypothalamic (GnRH); (ii) pituitary (FSH, LH, PRL); (iii) gonadal (female: estrogens, progesterone, inhibin, testosterone, oxytocin, relaxin; male: testosterone, other androgens, estrogens, inhibin); uterine and placental (PGF2α, estrogens, P4, eCG, hCG).

Answer 64

A

Biochemically, hormones can be classified as (i) peptides (chains of amino acids). These can be relatively small, as GnRH that is a decapeptide, or larger as prolactin (198 amino acids) and relaxin (two polypeptide chanins connected by disulfide links). (ii) glycoproteins: these are polypeptide chains with carbohydrate moieties. These guarantee protection to the hormone because only glycosilation sites are damaged. The higher the glycosilation, the longer the half-life of the hormone. Normally, glycoproteins are made of two chains. For instance, glycoproteins produced by the anterior pituitary within one species (including the gonadotropins FSH and LH) share the same structure of the alpha chain, that is connected (by hydrogen bonds and van der Waals forces) to a beta chain that is characteristic of the specific hormone. Other glycoproteins are inhibin (alpha and two typer of beta chains (A and B) with similar biological activity), activin (two beta chains), and follistatin. (iii) steroid hormones are synthetized from cholesterol and they all share a nucleus of cyclopentanoperhydrophenanthrene. Finally, (iv) prostaglandins are lipids consisting of 20 carbon-unsaturated hydroxy fatty acids synthetized from arachidonic acid. They have extremely short half-life (seconds, for instance PGF2α is completely removed in one pass thorugh the pulmonary circulation in about 30 seconds). There are at least six prostaglandins and several biologically active metabolites. The most important are PGF2α and PE2.

Answer 65

A

The acrosome is a membrane-bound lysosome containing enzymes such as acrosin, esterases, zona lysin, hyaluronidase, and acid hydrolases that are needed to digest and penetrate the zona pellucida of the oocyte during fertilization.

Answer 66

A

Canids, felids (rudimentary), primates (e.g., spider monkey), mustelids (ferret, skunk, otter, weasel), bears, raccons, bats, squirrels, mole, hedgehogs, shrews, guinea pig, rats, mice, hamsters, decu, gerbils, chichilla

Answer 67

A

Hormones with short half-life are prostaglandins (seconds to minutes, almost all PGF2α disappears after one complete passage in the pulmonary circulation - about 30 seconds), also gonadotropins such as LH and FSH have relatively short half-lives (ranging from 20 to 120 minutes depending on the hormone and species), whereas other glycoproteins such as eCG and hCG have longer half-life (hours to days) and steroids have even longer half-lives (days to weeks).

Answer 68

A

LH has a basal pulsatile pattern during anestrus, with pulses of low frequency and low amplitude. Frequency and amplitude start increasing at the end of anestrus and beginning of proestrus, under the effect of GnRH, which has increased pulse frequency and amplitude itself. The surge center, under the positive effect of estradiol produced by the developing follicles, produces a peak in GnRH that causes a peak in LH obout 24h after a peak in estradiol. In bitches the LH peak lasts longer compared to other species (mean 36 +/- 55h). About 48-60h after the peak in LH ovulation occurs. In metestrus LH has a pulsatile pattern characterized by higher amplitude and frequency compared to anestrus.

Answer 69

A

Proliferation, meiosis, differentiation

Answer 70

A

Paraventricular nucleus (oxytocin), surge center (mainly in the preoptic area = medial preoptic nucleus and anteroventeal periventricular nucleus), tonic center (arcuate nucleus and median eminence); also the periventricular nucleus, preoptic nucleus (contains neurons that secrete GnRH and kisspeptin), and arcuate nucleus (contains neurons that secrete GnRH and kisspeptin) can influence reproduction by secreting kispeptins which act on the surge and tonic centers of the hypothalamus.

Answer 71

A

Primary spermatocytes are the cells with the longest life-span (e.g., in bulls it is 18-19 days over 61 days of spermatogenesis). Secondary spermatocytes have a shorter life-span between 1.1 and 1.7 days, depending on the species.

Answer 72

A

Lactational anestrus is a period of absence of cyclicity associated with lactation in most domestic species. Specifically, it is associated with mechanical (suckling), olfactory, visual, and auditory stimuli associated with the presence of the offspring. It is present in cows, sows, small ruminants, sometimes in queens (variable), it is not detectabe in bitches as they woudl anyway be in anestrus following diestrus. It is not present in mare and alpaca. Dairy cows do not display lactational anestrus as the calf is removed immediately or a few hors after birth.

Answer 73

A

The menstrual cycle differs from the estrus cycle in the following ways: (i) the follicular phase is 50% of the cycle, whereas it is only 20% in domestic species; (ii) as a consequence, the luteal phase is 50% of the menstrual cycle, whereas it is 80% of the estrous cycle; (iii) sexual receptivity is homogeneous throughout the cycle (it is not affected by progesterone), while it is displayed only during estrus of the estruous cycle; (iv) ovulation happens halfway through the menstrual cycle, whereas it is the beginning of the estrous cycle; (v) the fertile period is 18% of the menstrual cycle, whereas on average, it is 5% of the estrous cycle; (vi) follicular depletion lead to the interruption of the menstrual cycle (menopause), this does not happen in animals displaying an estrous cycle.

Answer 74

A

Half-life, receptor density, pattern and duration of the secretion, receptor-hormone affinity

Answer 75

A

It may indicate an insufficient P4 production. It may be necessary to supplement P4.

Answer 76

A

The hymen is a remnant of tissue of the Müllerian ducts fusing with the urogenital sinus, it is therefore located at the vestibular-vaginal junction

Answer 77

A

From the outer to the inner: serosa (simple squamous cells layer; in the uterus it is called perimetrium); muscolaris (outer longitudinal layer, inner circular layer; in the uterus it is called myometrium); submucosa (conncetive tissue, vases, lymphatics and nerves); mucosa (epithelial layer with different characteristics based on the tract of the reproductive system. e.g., columnar ciliated within the salpinx, columnar and highly secretory in the cranial part of the vagina, stratified squamous in the vestibulum of the vagina); the uterine mucosa and submucosa are named emndometrium, with different cellular characteristics based on the stage of the estrus cycle.

Answer 78

A

Continuous supply of male gametes, providing genetic diversity, maximize reproductive success by producing spermatozoa daily, provide an immunological privileged site for germ cells development

Answer 79

A

Freemartinism is a sex differentiation condition affecting heifers twins of a bull. Specifically, if two bovine embryos are conceived and they have genetically different sexes, the sex differentiation process in the male causes abnormalities in that of the female, because the two embryos will share the same chorion and cotyledons, thus the same blood and hormone milieu. Sex differentiation in males start around 40 days of gestation in males, whereas in females this process starts later. In males, the sertoli cells of the testes produce anti-Müllerian hormone, inhibiting the development of the paramesonephric ducts, hence the formation of the female reproductive organs and the development of germ cells that are likely to produce abdonrmally high amounts of testosterone and androstenedione. The heifer calf is therefore sterile, whereas the bull is fertile. Therefore, freemartin heifers often presents with incomplete cavitation of the reproductive organs, abnormally developed ovaries, and male sex characteristics and behavior.

Answer 80

A

Pituitary gonadotropins have a half-life that range from 20 to 120 minutes depending on the hormone and species.

Answer 81

A

Stallion and boar (higher than a pregnant mare or sow), however these molecules have low biological activity

Answer 82

A

> Fetometry (ICC and OUD outer uterine diameter until 30 dop) at least 3 fetuses. CRL crown-rump length (from the most rostral part of the head to the base of the tail), BPD, BD body diameter (two transverse diameters at the level of stomach-liver = widest), DPTV deep portion of the diencephalo-telencephalic vesicle, FL femur-length, GD gastric diameter.

Answer 83

A

Defeminization of the hypothalamus is a process happening during fetal and early neonatal life, leading to inactivation of the GnRH surge center in the hypothalamus. This is caused by testosterone crossing the hemato-encephalic barrier and being aromatised to estradiol within the brain of the male. Therefore, defeminization itself is mainly caused by estradiol and happens in males due to higher levels of testosterone that can reach the brain, cross the hemato-encephalic barrier and be converted in estradiol. In females, although blood concentrations of estradiol are higher, defeminization of the hypothalamus does not take place, as estradiol cannot cross the hemato-encephalic barrier due to the action of the alpha-ferroprotein, which binds estradiol. Alpha-ferroprotein is produced both in males and females, earlier by the embryonic yolk sac, later by the liver. Early post-natal exposure to androgens is important to complete the process of defeminization of the hypothalamus, as it has been reported that it is still possible to stimulate high GnRH pulses from the surge center of bulls castrated immediately after birth.

Answer 84

A

Protein hormones travel in the blood stream and interstitium until they reach a target cell expressing a receptor for the hormone on the surface of its plasma membrane. Once the hormone binds to the receptor, a transformation of a G protein coupled with that receptor is induced. The transformation causes tha activation of adenylate cyclase, an enzyme promoting the conversion of ATP in cAMP. cAMP is a second messenges (the first being the hormone) that when present in the cytoplesm, binds to a proteine kinase, another enzyme consisting of two subunit. The cAMP binds to the regulatory subunit that will activate the catalytic subunit that will promote the conversion of existing substances to new products.

Answer 85

A

The hypothalamo-hyphophyseal portal system allows circulation of hormones from the hypothalamus to the anterior pituitary before dilution into the systemic blood stream. It consist of a superior hypohyseal artery, dividing in small capillaries and forming a primary portal plexus at the stalk region of the pituitary. At this level, the terminals of neurons with body cells located in the hypothalamic nuclei, make contact with capillaries of the plexus and hormones are secreted in the blood stream of these capillaries. Then the blood circulates in a second portal plexus in the anterior pituitary and finally exit the organ through venous blood vessels.

Answer 86

A

The testicular artery (originating from the abdominal aorta and directed to the testicle) convey blood at body temperature (about 39°C) to the testicle. However, in most species, testicular temperature must be 4-6° below that of the body in order to have successful spermatogenesis. The arterial blood is therefore cooled by a countercurrent heaht exchange. Specifically, the venous blood in the testes contained in the scrotum has a temperature of about 33°C. Venous vessels form finger-like wrappings around the testicular artery (pampiniform plexus). Therefore, the arterial blood has a decreased temperature when it reaches the testicle. Moreover, the testicular artery becomes convoluted (loos of pulse pressure). The intimate relationship between the pampiniform plexus and the testicular artery also guarantee some testosterone to be recirculated within the testes (passed from the vanous blood to the arterial blood). The pampiniform plexus and the testicular artery pass in the spermatic cord.

Answer 87

A

Insuline-like 3 is a factor secreted by the islets of the pancreas and by Leidyg cells with various functions. Among these, INSL-3 and its receptor (Lgr8) control the transabdominal phase of the testes descent to the scrotum.

Answer 88

A

Countercurrent heath exchange, which is also favored by the contractions of the cremaster muscle that pumps venous blood of the pampiniform plexus, moreover the tunica dartos can operate sustained contractions to keep the scrotum closer to the body. The skin of the scrotum is also important becouse has terminations of thermal sensory nerves that convey information to the thermosensitive neurons within the hypothalamus. If T°C is increased a signal from the hypothalamus increases the activity of sweat glands on the scrotal skin and relax the tunica dartos so the testes are moved away from the body. Moreover, the hypothalamus sends signals to the respiratory center so respiratory rate increases if the testicular T°C is increased.

Answer 89

A

Macroscopic: color, volume
Microscopic: concentration (manual using Burker’s chamber, Makler’s chamber, or Toma’s chamber, or automated systems as the Nucleocounter), motility (subjective evaluation or Computer-Assisted-Sperm-Analyzers = CASA), morphology (evaluation of at lease 200 sperm per slide, on eosin-nigrosine stained smears).

Answer 90

A

1)Cycle length: 21 days in all species, except ewe (17 days).
2)Estrus length: shorter in cows (average 15 h), ewes 30 h, sows 48 h, longer in mares (7 days).
3) Cows and sows have non-seasonal polyestrous cycle (although sows would have seasonality in the wild, with fertility in autumn); Ewes and mares have a seasonal polyestrous cycle, ewes are short-days breeders, whereas mares are long-days breeders.
4) Cows, mares, ewes have follicular waves, whereas sows have no follicular waves.

Answer 91

A

Obesity can impact fertility and reproductive success.
1. Hormonal Imbalances
Leptin Dysregulation: Leptin, a hormone produced by fat cells, plays a critical role in regulating appetite and energy balance but also affects reproductive hormones. Obesity leads to leptin resistance, which can disrupt the hypothalamic-pituitary-gonadal axis and impair reproductive hormone secretion, leading to:
Reduced Gonadotropin Release: Impaired secretion of luteinizing hormone (LH) and follicle-stimulating hormone (FSH), essential for normal reproductive function. Consequently, the secretion of estrogens, pregesterone, and testosterone is affected as well.

Reduced Fertility
Females:
(i)Failure to ovulate and Irregular Estrous Cycles: Obesity can lead to hormonal imbalances, particularly affecting estrogen, progesterone, and leptin levels. This can result in irregular estrous cycles, failure to ovulate or prolonged periods of anestrus (absence of heat cycles).
(ii)Dystocia: Obese animals, particularly females, are at increased risk of dystocia due to excess body fat around the pelvic region, fat deposits may reduce the space available for passage through the birth canal.
Males:
(i)Lower Sperm Quality: In obese males, there can be reduced sperm motility and morphological abnormalities in sperm. This results from hormonal imbalances, including decreased testosterone levels and increased estrogen production from adipose tissue.
(ii)Decreased Libido: Obesity can lead to reduced interest in mating due to lethargy and hormonal imbalances.
Increased Risk of Gestational Diabetes: Excessive body fat can predispose females to gestational diabetes, which can result in poor pregnancy outcomes and may affect fetal development.
Postpartum Problems: Obese females may have reduced lactation capacity and can be prone to complications like uterine infections or mastitis postpartum.
Poor Neonatal Health
Offspring born to obese mothers may be at risk for low birth weight, neonatal death, or developmental problems. Obesity may affect placental function, limiting nutrient supply to the fetus, or cause metabolic disturbances that negatively affect the fetus.
Increased Risk of Reproductive Cancers
Females: Obesity has been linked to an increased risk of reproductive cancers such as mammary tumors in dogs and cats, especially if they are intact (not spayed). This risk is compounded by high levels of circulating estrogen due to excess body fat.
Males: Obese males may be more prone to testicular tumors or prostate disease, partly due to hormonal imbalances and the inflammatory effects of obesity.
Difficulty in Spaying or Neutering
Obesity makes surgical procedures such as spaying (ovariohysterectomy) The excess fat can obscure anatomical landmarks, increase surgical time, and heighten the risk of complications like infections or poor wound healing.

Answer 92

A

Pseudopregnancy is a paraphysiologic condition in bitches. The cycle of the bitch is characterized by a long luteal phase (about 70 days). Progesterone is produced by the corpus luteum and its blood concentrations increase until day 25 after ovulation, from that moment, in non pregnant bitches, it starts decreasing. The decline in P4 is associated with a rise in prolactin. Bitches can show clinical or non-clinical pseudopregnancy. The latter may be characterized just by the presence of slight mammary enlargment and modest lactogenesis, whereas the clinical condition is also associated with behavioral signs (nervousness, anorexia, nursing of inanimate objects, nesting, aggressiveness, mock parturition) and heavier lactogenesis. This condition is self-limiting, however the clinical presentation can lead to mastitis. Therefore, medical treatment using Cabergoline, bromocriptine, metergoline is possible.

Answer 93

A

Glycoprotein hormones are polypeptide chains with carbohydrate meioties. This group of hormones includes LH, FSH, eCG, hCG, inhibin, activin, follistatin.

Answer 94

A

Effective management of neonatal diarrhea in lambs requires prompt treatment to address dehydration, the underlying cause, and supportive care. Preventive measures such as proper colostrum management, sanitation, and vaccination are critical to reduce the incidence of diarrhea in lambs.
Causes = infectious or non-infectious
1.Infectious agents:
(i) Bacteria: E. coli, Salmonella, Clostridium perfringens.
(ii)Viruses: Rotavirus, Coronavirus.
(iii)Protozoa: Cryptosporidium parvum, Eimeria spp. (coccidia).
2.Non-infectious causes
(i)Nutritional causes (overfeeding, sudden changes in diet, poor-quality milk replacers or inadequate nutrition from the ewe).
(ii)Environmental causes: cold or unsanitary environments increase the risk of diarrhea.

Treatment:
1. Supportive care
Neonatal diarrhea ==> dehydration, electrolyte imbalances, and acidosis = fatal if not addressed promptly.
(i)Fluid therapy:
Oral rehydration solutions (ORS)(commercial electrolyte solutions designed for livestock or prepare a homemade solution - e.g., NaCl + bicarbonate + glucose). For mild to moderate dehydration, give 50-100 mL/kg of oral electrolyte solution every 6-8 hours until the lamb improves. In cases of severe dehydration = intravenous fluids.
(ii). Warmth:
Heat lamps or blankets. NB cold lambs may not be able to suckle properly, which worsens dehydration.
(iii). Nutritional Support:
Continue feeding colostrum in the first 24-48 hours of life. Colostrum should be given within 1-2 hours of birth if possible, at about 50 mL/kg body weight. Avoid overfeeding.
2.Specific Treatments
(i)Antibiotics if bacterial infection (e.g. E. coli). Broad-spectrum antibiotics such as amoxicillin, trimethoprim-sulfamethoxazole, or neomycin may be used especially for septicemia.
(ii)For protozoal infections like Cryptosporidium or coccidiosis, use specific anti-parasitic drugs:
Cryptosporidium: Halofuginone lactate.
Coccidiosis: Toltrazuril or sulphamides.
Probiotics:

Preventive Measures:
(i). Proper Colostrum Management:
high-quality colostrum soon after birth to provide passive immunity.
Dose: 50 mL/kg body weight within the first 2 hours of life, and every 6 hours for the first day (at least 200 mL/kg in the first 24 hours).
(ii). Hygiene and Sanitation:
Maintain a clean, dry, and warm environment for the lambing area.
Avoid overcrowding.
(iii). Nutrition: avoid overfeeding or sudden changes in diet.
Ensure that ewes are properly fed during gestation and lactation, as poor maternal nutrition can result in weak lambs that are more prone to infections.
(iv). Vaccination:
Vaccination of ewes during late pregnancy (with multivalent vaccines) can protect lambs through maternal antibodies, particularly against pathogens like Clostridium perfringens (which causes enterotoxemia) and E. coli.

Answer 95

A

Ovaries are paired dense paired organs responsible for female gametes and hormones production. Each ovary is surrounded by tunica albuginea (connective tissue) covered by a single layer of cuboidal cells referred as ‘ germinal epithelium’ (although the name is misleading as this is not involved in gamete production!). Underneath the tunica albuginea, there is the ovarian cortex (except in mares). This contains the oocyte population and the cells surrounding the oocytes that forms follicles at different stages of development. The cortex also contains the corpus luteus/corpora lutea and the corpora albicantia (which are degenerated corpora lutea enriched in connective tissue from previous estrus cycles). The inner part of the ovary is referred as medulla that consists mainly of connective tissue and hosts blood and lymphatic vessels and nerves. In mares the cortex and medulla are inverted and ovulation can only take place at the ovulation fossa (random location in any part of the cortex in other species), which is a depression on the ventral border of the ovary and it is not covered by the tunica albuginea.

Answer 96

A

Because germ cells are connected by intercellular bridges that guarantee the communication between the cytoplasm of cells belonging to the same cohort.

Answer 97

A

Noakes chapter 4

Answer 98

A

When produced by gonadal cells, steroid hormones exit the cell by diffusion (as they are lipo soluble), although they to bind with transport protein to travel within the blood circulation and in the interstitium. When they reach target cells, they unbind from the transport protein and can act in two different ways. (i) steroid can enter the target cell, diffusing through the plasma membrane and the nuclear memebrane to bind with nuclear receptors within the nucleus. The bind between the hormone and the nuclear receptor is a transcription factor that will promote the synthesis of mRNA that will then exit the nucleus, reach the ribosomes and promote the synstesis of specific proteins. This mechanism takes long time (hours to days). An example is the effect of estradiol on the cell of the cervix, causin the production and secretion of mucous; another example is the progesterone causing increased endometrial secretion using the same mechanism (ii) steroid can also bind to plasma membrane receptors. The bond causes the transformation of a G protein that will activate adenylate cyclase, which is an enzyme that converts ATP to cAMP. cAMP will then bind to the regulatory subunit of a proteine kinase enzyme that will cause the activation of the catalytic subunit of the same enzyme. This will cause a change in permeability of the calcium channels. This mechanism is faster (seconds to minutes). Examples are the effect of estradiol on myometrial cells, causing a change in permeability of calcium channel that favors myometrial contraction; conversely, progesterone has a similar mode of action, although inhibiting myometrial contractions.

Answer 99

A

The meiosis phase of spermatogenesis takes place in the adluminal compartment of the seminiferous tubule. It starts when primary spermatocytes enter the first meiotic division, that guarantee genetic heterogeneity, meaning that each secondary spermatocyte and then spermatid will have unique genetic material. This is possible thanks to the formation of tetrads after complete DNA replication. Tetrads fuse at random spots (i.e., chiasmata) and crossing-over takes place, allowing segments of chromosomes to cross-over to the homologous chromosome. At the end of meiosis, secondary spermatocytes are formed.

Answer 100

A

Metaestrus is the phase of the estrus cycle that follow the estrus. In this phase, progesterone levels start rising as the corpus luteum develops.

Answer 101

A

The excurrent duct system is part of the male reproductive system responsible for the transport, maturation, and storage of sperm after they leave the testis and before they are ejaculated through the urethra.
It includes the efferent ducts (transporting the sperm from the rete tesis to the head of the epididymis), the epididymis (where spermatozoa acquire motility and fertilizing capacity and is stored until ejaculation occurs; the epididymis is divided in three regions: head, body, and tail) the ductus deferens (a muscular tube that convey the sperm to the urethra during ejaculation).

Answer 102

A

Bovine: Male 11 months (7-18), Female 11 months (9-24)

Ovine: Male 7 months (6-9), Female 7 months (4-14)

Caprine: Male 7 months (6-9), Female 7 months (4-14)

Equine: Male 12-18 months, Female 12-24 months

Swine: Male 7 months (5-8), Female 6 months (5-7)

Canine: Male 9 months (5-12), Female 12 months (6-24)

Feline: Male 9 months, Female 8 months (4-15, depending on the month of birth)

Camel: Male 3-5 years, Female 3 years

Llama and Alpaca: Male 2-3 years, Female 1 year

Rat: 4-8 weeks (both male and female)

Mouse: Male 30-42 days, Female 24-28 days

Hamster: 6-12 weeks (both male and female)

Rabbit: Male 4-8 months, Female 4-6 months

Answer 103

A

Vertical vulva, with 70-80% of the vulva located below the pelvic birm (otherwise predisposition to uterine infections)

Answer 104

A

The paramesonephric ducts are ducts that develop parallelly to the mesonephric ducts (ducts connecting the mesonephros to the urogenital sinus in the early fetus). The female reproductive system (oviducts, uterus, cervix, cranial part of the vagina) develops from the paramesonephric ducts, whereas in males these ducts regresses. The paramesonephric ducts have a cranial opening and caudally connect with the dorsal wall of the urogenital sinus, the cranial vagina will originate from the caudal part of the paramesonephric ducts, whereas the vestibule will originate from the urogenital sinus. During development of the fetus, the two paramesonephric ducts will merge medially. The degree of fusion between the two ducts will determine the type of uterus of the animal. The degree of fusion is the highest in species with simplex uteurs (one vagina, one cervix, one uterine body, no uterine horns), it is variable in species with bicornuate uterus (from the highest to the lowest degree of fusion: mare, cow and small ruminants, sow, bitch and queen), and it is the lowest in species with duplex uterus (e.g., marsupials and rabbits).

Answer 105

A

Rfamide Related Protein 3 is a peptide involved in in regulation of kiss neurons. Specifically, when melatonin decreases due to increase of the photoperios, RFRP-3 increases determining either a stimulation of kiss neurons in producing kisppeptin-10 (in long-days breeders) or an inhibition of these neurons (in short-day breeders). For this reason, in long-day breeders, when kisspeptin-10 is increased, it stimulates GnRH-producing neurons to release more GnRH that will then stimulate the release of LH and FSH from the anterior pituitary, leading to cyclicity. In short-day breeders, low kisspeptin-10 lead to low GnRH and seasonal anestrus.

Answer 106

A

It may indicate an insufficient P4 production. It may be necessary to supplement P4.

Answer 107

A

Based on the degree of fusion of the paramesonephric ducts:
- Simplex: highest degree of fusion of the paramesonephric ducts. One uterine body, no/rudimental uterine horns. Humans.
- Bicornuate:
a) High degree of fusion of the paramesonephric ducts = short uterine horns = Mare.
b) Intermediate degree of fusion of the paramesonephric ducts = Cow, Ewe, Doe
c) Low degree of fusion of the paramesonephric ducts = long uterine horns = Bitch, Queen, Sow
- Duplex = two uterine bodies, either two cervical canal and two vaginal canals (opossum) or two cervical canals and one vagina (rabbit)

Answer 108

A

Elephant, sloth, armadillo, whale, dolphin, birds

Answer 109

A

It can cause abdominal descent of the ovaries

Answer 110

A

An increase in androstenedione and testosterone

Answer 111

A

Pulsatile GnRH, LH receptors on the Leydig cells, high concentration of testosterone in the seminiferous tubules, low concentration of testosterone in the systemic circulation (100-500 times lower than in the seminiferous tubules, otherwise high systemic testosterone concentrations would cause a downregulation of the GnRH/LH system and would remove the negative feedback on FSH, that guarantees stimulation of Sertoli cells). Moreover, a pulsatile secretion of LH optimize the number of LH-receptors on the Leydig cells, as a continuous secretion would cause the Leydig cells to become refractory.

Answer 112

A

It is important to detect, map, and measure endometrial cysts before breeding a mare, in order not to confuse them with an embryonic vesicle. Cyst do not move and do not grow. If there is doubt for pregnancy diagnosis between endometrial cyst and embryo => re-scan around day 25 of gestation to check for the heartbeat.

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