Llama Anatomy: Female Reproductive System

Female Reproductive Anatomy

• Camelids have a bicornuate uterus, similar to cows and horses.
• The left uterine horn tends to be slightly longer than the right.
• In nonpregnant llamas, the body of the uterus is short and not clearly differentiated from the base of either horn on ultrasonography.
• The uterine horns curl ventrally and caudally when "in situ".
• The degree of the uterine horns' curl is maximal during the luteal phase and minimal during the follicular phase.
• On ultrasound, the appearance of the llama/alpaca ovary is similar to that of cows, but is generally smaller.
• The typical size of the ovary is 25 mm x 12 mm x 10 mm.
• The Ovulatory-sized follicles are ≈10mm in llamas and slightly bigger in camels.
• A mature corpus luteum is 13 mm (versus 28 mm in cows).
• Ovarian follicles are arranged in a peripheral cortex, so ovulation can take place at any spot on the surface of the ovary.
• Corpus luteum (CL) and large follicles protrude distinctly from the surface of the ovary and are readily palpable.
• The cervix has two or three irregular annular or spiral folds.
• Cervix measures between 20-50 mm long.
• The external os protrudes into the vagina.

Characteristics of Tract During Follicular and Luteal Dominance

• During the follicular phase, estrogen is the prevailing ovarian hormone.
• Estrogen influence causes the uterus to have tone/edema, the cervix to be relaxed (patent), and the vagina to be shiny, pink, and moist.
• During the luteal phase, progesterone is the prevailing ovarian hormone.
• Progesterone influence causes the uterus to be atonic/flaccid, the cervix to be tightly closed and dry, and the vagina to be dry and sticky.
• The uterine horn shape has a minimum curl during the follicular phase and a maximum curl during the luteal phase.
• During the follicular phase, the Uterine echotexture is homogeneous-gray; becoming darker during the luteal phase.
• The uterine tone is turgid during the follicular phase but flaccid during the luteal phase.
• Cervical folds are indistinct during the follicular phase and distinct during the luteal phase.

Puberty - Female

• Onset of puberty varies from 5 months to 2-3 years.
• Ovarian activity begins around 10 months.
• Sexual receptivity occurs around 12 months.
• Puberty dependent on attaining 2/3 adult body weight.
• First breeding occurs between 12 and 18 months in most females

Reproductive Cycle

• Camelids are nonseasonal breeders.
• Some Seasonality can be seen in wild types.
• Camelids have induced/reflex ovulation, so mating must occur for ovulation to occur.
• Camelids are generally mono-ovulatory.

Ovulation

• Ovulation occurs 24-30 hours post-copulation.
• Spontaneous Ovulation occasionally occurs
• Copulation leads to friction of the hooked glans penis, causing an inflammatory reaction.
• This leads to a release of LH and ovulation (neuroendocrine reflex)
• An ovulation-inducing factor is found in semen that is GnRH like.
• The ovulation-inducing factor substance is absorbed from the uterus.
• The orgling noise helps stimulate ovulation during copulation.
• Corpus luteum (CL) forms, followed by progesterone secretion.
• Progesterone rises between days 3 to 10.

LH Response and Luteolysis

• Luteolysis begins 9 days after a non-fertile mating.
• Corpus luteum (CL) regresses on day 10.
• Luteolysis is caused by prostaglandin F2 alpha (PGF2a) from the endometrium.
• Differential luteolysis: effects are horn-specific.
• The right horn affects only the right ovary, akin to cows.
• The left horn can affect both ovaries via local and systemic pathways.
• This is due to vascular differences.

Receptivity

• With high Progesterone presence, animals demonstrate nonreceptive behavior.
• Estrogen presence, in the absence of progesterone, induces receptive behavior.
• Camelids do not have estrous cycles and are induced ovulators.

Follicular Dynamics and Key Points

• A pool of small, <5 mm, follicles is always present.
• Growth occurs in waves.
• Inter-wave interval occurs about every 12 days.
• Follicular Recruitment follows this order: Selection → Dominance → Regression if no ovulation.
• Follicle Classification by size (with a single copulation):
• Small follicles (4-5 mm): No Ovulation
• Growing follicles (6-7 mm): Ovulate
• Mature follicles (8-12 mm): Ovulate
• Regressing follicles (10-7 mm): Luteinizes
• The LH response to copulation depends on follicle size and growth stage
• Ovulation only occurs when the follicle is in a growing or mature stage.
• Minimum ovulatory follicle size is 7 mm.
• Regressing follicles luteinize instead of ovulating.
• Luteinized follicles last about 5 days.
• Luteinized follicles delay the onset of a new dominant follicle for 5-7 days
• A single examination cannot determine if an animal's follicle is growing, mature, or regressing
• Spontaneous ovulation does occasionally occur (roughly 1-10% of the time)

Sexual Behavior

• Receptive females assume a "prone position".
• Non-receptive females "spit off" as a rejection behavior.

Male Reproductive Anatomy

• The scrotum is found at the level of the ischial arch.
• The testes are remarkably small.
• The prepuce points caudally.
• Accessory Sex Glands: Ampulla, prostate, and bulbourethral.
• No seminal vesicles.
• Fibroelastic penis: featuring a cartilaginous process that has a hook like curve at the tip
• During urination, the stream of urine is directed back between the legs.

Puberty - Male

• Fertile spermatozoa may be produced by 10-12 months.
• Penile-preputial attachments can slow fertile process.
• 8% detached by 1 year
• 70% detached by 2 years
• All detached by 3 years

Semen Collection and Characteristics

• Semen Collection
• Can be completed via Electroejaculation. – Features include variable quality, variable concentration, and requires sedation.
• Specialized Artificial Vagina (AV) using a dummy.
• Aspiration or scoop of the vagina – This method usually produces poorer quality semen.
• Semen Characteristics
• Volume= 2-10 ml
• Low concentration
• Highly viscous, leading to slow progressive motility
• Morphology >70% normal – Semen Parameter not yet clearly defined (lacks a consortium).

Mating Behavior

• Ejaculation features include directly depositing into the uterus.
• The penis gradually traverses the cervix and enters the uterine body/horns.
• Total breeding time= 10 to 50 minutes.
• Copulation occurs in sternal recumbency and lasts for 5-60 minutes.
• Semen is then deposited deep into each uterine horn.

Reproductive Problems in Males

• Testicular hypoplasia
• Cryptorchidism (uncommon)
• Hydrocoele
• Testicular degeneration
• Orchitis
• Neoplasia (rare)

Breeding Management and Strategies

• Breeding Strategies
• Pasture breeding – Advantages: Hands off. – Disadvantages: could lead to injuries if they fight, may not know when mating occurred.
• Hand or Appointment Breeding – Tease/breed once every 7 days until the female "spits off". – Start teasing 14 days post-breeding.
• If receptive and breeds, copulates, test for another 7 days for signs of rejection, and then start again until double-checked two weeks later.

Pregnancy

• Day 5-6- The embryo enters the uterus.
• Days 12 and 14- Apposition and attachment.
• Less than or equal to day 10- Recognition of Pregnancy.
• Gestation= 335-365 days (11.5 months).
• Pregnancy is established in the left horn in 95-98% of pregnancies.
• Ovulations can occur from either ovary, but the embryo will migrate to the left horn to be held.
• Pregnancy Maintenance= CL dependent.
• Twinning is rare.
• Dystocia is rare but does still occur.

Placentation

• Features a Diffuse (microcotyledonary)
• This is Epitheliochorial
• Similar to a horse in appearance

Chorioallantois & Epidermal Membrane

• The amnion lies adjacent to the chorion (similar to the cow).
• The water (allantoic fluid) will not break first.
• Crias born covered with an epidermal membrane (4th membrane)
• Newborn Alpacas do not clean off the cria.

Parturition

• Signs of impending parturition are minimal.
• There will be little change in the udder.
• There will also be slight vulvar relaxation, waxing of teats, and changes in milk calcium.
• Usually occurs between sunrise and midday.
• They appear restless, humming, more urination off feed.
• Stage one can last up to six hours; whereas, Stage two typically occurs for an hour to 90 minutes- often deliver while standing.
• Usually, the baby will come out headfirst with the four legs extended.
• Because of limited obvious signs; uterine torsions happen but can be corrected by rolling her.
• Stage Three - The placenta is expelled somewhere between 45 minutes up to three hours.
• Cria = term for baby camelid.
• Initiate therapy: antimicrobials and NSAIDs.
• Uterine prolapse with a Buhner stitch.
• Female kind of ignores the baby + retain fetal membranes, think initiate therapy more like with a horse not a cow.

Uterine Involution

• Lochia (fetal fluids and placental remains) is expelled for 7-10 days.
• Involution is complete by 3 weeks.
• Breeding can occur back at 14-21 days postpartum.
• Expect complete involution by 3 weeks & breed them if willing.

Pregnancy Diagnosis

• No return to receptivity (Spitting off)
• Progesterone>6nmol/L (blood and milk)
• Oesterone sulfate
• 21-27 days
• Only measured in the final 60 days
• Relaxin
• Ultrasound from 12-14 days is the most common/reliable