Horses 1 Flashcards
What are 4 important factors to consider and 6 things involved with breeding exam
Factors to consider - Value of the mare - Purpose of the examination (insurance, pre-breeding check, infertility) - Duration of infertility - Requests of referring veterinarian What is involved 1. History 2. General physical exam 3. Species reproductive exam 4. Special procedures 5. Blood samples 6. Plan of action
What are important parts of the history in breeding exam
- Age, Breed, ID
- Nutritional information
- Has the mare been presented to a veterinarian before
- Reproductive status
○ Pregnant (in foal)
○ Foal at food (wet mare)
○ Not pregnant - never been bred (maiden) or possible barren - Vaccination status (individual and herd)
- Previous breeding records, if available -> teasing records
- Previous general health problems
- Foaling history
- Breeding history
- History of reproductive problems -> abortions, retained foetal membranes, assisted delivery, dystocia
- Take note of last reproductive event - IMPORTANT
What is important to do after taking history for breeding exam
- After taking history outline diagnostic approach to the owner
○ Types of procedures
○ Cost
○ Time when results are available
Within the special reproductive exam what is involved with the external exam
○ Note any discharge on vulva and tail (more common on the tail
○ Determine perineal structures: anus, perineal body and vulva should be in a vertical line
○ Vulva should be below ischeal arch
○ Parting of vulva lips should not lead to air being sucked into the vagina -> need to create a seal
○ Take clitoral swabs, if needed -> before rectal examination contaminates the area
○ Udder
§ Symmetry, activity (lactating or dry), fibrosis, acute inflammation, ticks
Special reproductive exam what are the 2 main internal exam diagnostics
1) rectal exam - need to tule out pregnancy
2) vaginal exam - second as cannot do while pregnant - lead to abortion
Rectal exam describe what exam
§ Examine boney pelvis, ovaries, uterus and cervix by palpation and ultrasonography
§ Ovaries
□ Size, presence of ovulation fossa - make sure ovary not a faecal ball
□ Size, wall thickness and tension of follicles
□ Presence of luteal tissue (ultrasonography) - cannot feel CL in horse (unlike cows)
§ Uterus
□ Diameter
□ Tone and wall thickness
□ Contents (air, fluid, cysts, pregnancy!)
§ Cervix
□ Tone, diameter -> better checked in vaginal exam
§ Broad ligaments - checked for haematomas
§ Pelvic cavity
□ Presence of obstruction
Rectal exam what findings correlate with uterine infection and pregnancy
§ Big CL and uterine oedema -> uterine infection
§ No CL and uterine oedema -> pregnancy
Vaginal exam how to prepare and what to perform
§ Clean and dry perineum well § Use sterile glove and sterile lube § Manual exam § Speculum exam § Endometrial swabs - cytology - culture
How to use endometrial swabs
□ Guard swab with hand
□ Use double-guarded swab
1. While advancing hand, note integrity and tone of vestibulo-vaginal sphincter and cervix
2. Take two swabs (one for culture (first to prevent contamination) and one for cytology)
3. Swab for cytology should be well moistened in the uterus (red tinge is fine)
4. Roll out cytology swab on glass slide and let air-dry
5. Stain with suitable stain
Endometrial swabs cytology and culture what evaluate
□ Cytology
® Evaluate for presence of:
◊ Leukocytes
} (neutrophils - phagocytosis of bacteria should be notes
} Eosinophils - indication for pneumo- or urometra or fungal endometritis
◊ Endometrial cells
◊ Bacteria - morphology indicative of identity
◊ Fungal organisms - special stains warranted
® Diagnosis of endometritis if ratio between neutrophils and endometrial cells is > 1:10
□ Culture
® If clear cytology then don’t worry about sending in culture - dispose of
® If not clear cytology - then send away
What occurs if find vagina full or urine
not good
- Need to give urethral extension to prevent this therefore need to do a endometrial biopsy
Endometrial biopsy when should be obtained and how
- Should be obtained from all mares
○ That are valuable
○ That have been diagnosed with chronic endometritis
○ Where no specific cause of infertility can be found
○ That require expensive treatment: rectovaginal fistula repair, urethral extension - Induce biopsy punch manually into uterus, then move hand in rectum and push tissue into jaw of punch
What blood samples can take while evaluating fertility
- Serum samples for AB tests
○ EG - EVA and EIA -> common
○ Progesterone, eCG, oestrone sulphate - Heparin sample: karyotyping -> for intersex horses so if already had a foal then no
- Plasma sample: inhibin, testosterone -> diagnosis of granulosa cell tumor (GCT)
When should endometrial samples be taken and what beware of
controversy
- DIOESTRUS after day 5
○ Clear of fluid and bacteria
○ Embryo is present
○ After day 5 for
Beware
- Uterus is very susceptible to infection in dioestrus
- Potential risk of introducing an infection
- Therefore luteolysis HAS TO BE INDUCED by application of PGF2alpha which can only be done after day 5 of the cycle
what is important about interpretation of results from breeding exam
- Only comment of BREEDING SOUNDESS NOT fertility
- Breeding soundness certificate describes the mare’s chances to fall pregnant
- Determine if tubular or endocrine disorder and if it can be treated
- Discuss treatment plan and how success will be determined
What maintains pregnancy of horses and sources
- Maintaining adequate levels of progestogens to maintain pregnancy to term
Sources of progestagens- Corpus luteum
- Placenta
What occurs with the equine source of progestagens
- The primary CL is the main progesterone horse in the equine pregnancy until about day 40 of gestation
○ Uterine progesterone - The weight of the embryonic cups increases rapidly over the first 3 weeks
- The production of ecG (produced by the cups) is closely related to the weight of the endometrial cups
- ecG initially stimulates the primary CL to produce more progesterone
○ ecG is LH-like there results in luteinization of the follicles
○ FSH-like action in other species - High circulatory ecG concentrations then lead to the luteinisation of more follicles resulting in accessory CL
○ At this point the pregnancy is considered more safe - After day 100 the placenta takes over the role for the main production of progesterone (mainly other progestagens)
○ Now considered placental progesterone -> not actually high at this point
○ Equine placenta progestagens -> 5-alpa pregnanes -> main production from the placenta
§ THEREFORE total progestagens is measured not just progesterone as they will be low while total is high
Pregnancy loss and return to oestrus what is important at what days
- Termination of pregnancy >34 to 37 days gestation (induced or natural) may not result in return to oestrus
- Persistence of endometrial cups may delay return to regular cycles for 3 to 4 months (the cups continue to function and produce eCG; they survive until the time of their normal demise)
○ No foal heat and doesn’t come back into heat
○ Diagnosing -> hysteroscopy
Artificial/supplemental light why used, and how to achieve
- Used to induce oestrus earlier in season
- Required minimum of 60 days of stimulation (16 hours/per day) until well into transition (may need 90 days to result in ovulation)
- Light has to sufficiently light whole area
- Maintain under lights until diagnosed safely in foal
- Same effects described with 1 hour of light applied exactly 9.5 hours after sunset
Equilume - Mare out in the field with light shining into one eye, attached to the face mask
- Need to ensure the light doesn’t move alignment or break -> labour intensive
Oestrus cycle average duration, standing heat, ovulation and dioestrus
- Also have average oestrus cycle of 21 days
- In standing heat for up to a week (4-8 days)
- Ovulation occurs 1-2 BEFORE END of oestrus
- Duration of dioestrus is usually 14-16 days
Suppression of oestrus when use and what use
- Generally in the horse racing, competition environment
1. Progestagen :eg. Oral regumate (once per day), longacting injectable
2. GnRH vaccines’ follicular activity might not return -> should return after a few years as antibodies decrease
○ If never return -> problem!
Prostaglandin F2alpha what leads to and why wounldn’t this occur
- Luteolysis achieved by single dose
- Standing oestrus after 3 to 6 days
UNLESS
○ Mare not in luteal phase (anoestrus, silent oestrus, transitional oestrus >35d pregnant)
○ In dioestrus, but less than 5 days ago
○ May take longer to come into heat if small/atretc follicles
§ Depends on where the horse is on its follicular waves, small follicles -> larger -> atresia (repeat)
Granulosa (theca) cell tumor (GTCT)
Combines oestrogen-progesterone treatment what are the 2 steps and who occurs
- IM injection of 150mg progesterone and 10mg of oestradiol in oil for 10 days
- PGF2alpha is given on day 10 (so inseminate 8 days after IM injection)
- Progesterone simulates dioestrus, small amounts of oestradiol suppress growth of small follicles (follicular wave activity)
○ Prevent the follicular wave activity problem for prostaglandin by itself
- At time of withdrawal all mares start with new follicular wave
- At start of treatment
○ Mares in heat: ovulate in first few days of treatment
○ Mares in early mid-dioestrus: will have responsive CL
Mares in late dioestrus: will have undergone spontaneous luteolysis
Induction of ovulation when used and fertility
- Accurately time OV in mares scheduled for breeding AI
- Part of synchronisation program
- Means of interrupting transitional oestrus - unsure
- Induced OV assumed to be fertile as spontaneous one
Human Chorionic gonadotropin hCG how produced, function what occurs and when fails
- Produced by the trophoblast cells of the human embryo placenta
- LH-like function -> luteotropic -> keeps the corpus luteum around
- Results in antibody production (probably don’t interfere with action)
- If given at right time (35mm follicle, some oedema) 85% of mare ovulate between 36 and 42 hours
- Might not work in transition when lack of LH receptors
○ Need sufficient oestrogen to produce LH receptors
GnRH analogues most common one, when use and what is important to remember
- Most commonly used deslorelin (Ovuplant)
- Ovulation between 42 to 48 hours if given as soon as largest follicle is 30mm
- Implant should be removed to prevent downregulation of GnRH receptors (commonly placed in mucosa of labia)
○ If downregulated will take longer to get back into heat if conception is not successful - More expensive than hCG
What is important in terms of the timing of ovulation induction and when to reexamine after induction
- Trade-off between sperm longevity vs uterine clearance of bacteria, debris introduced by AI
- Ideally to be done at time of insemination/breeding (except frozen semen)
- If semen stored for more than 30 hours, induce OV 24 hours before AI
When to reexamine - 48 hours later, if induced early enough
- Playing the odds: 80% of mares follow the book
- Rest might not ovulate at all that cycle
- In that case discuss if more semen is to be invested (wasted?)
What are the 3 main tools of determine timing for breeding
- Teasing
- Rectal exam: palpation and ultrasound
- Vaginal exam - not on all
Teasing the mare what are important principles
- Most important management tool for breeders (esp. thoroughbred studs)
- Teasing records very important to veterinarian
- Preferably done by same person every day
- Mares must be teased regularly (ideally daily) from 3 day post-partum until 60 days pregnant
- Teasing cute/wall is ideal (open front and back)
- Stallion starts at head and is then allowed to move backwards and ideally rest head on croup
- Mares have individual teasing patterns
What are some signs that a mare is ready to be bred
- Ovulatory follicle: usually +/-mm of same size each cycle; can be large individual differences between mares
○ Generally don’t look for on commercial farms as just wait till she is ready to be induced - Increasing oedema
Cervix relaxes in oestrus, open until ovulation, then it closes
Natural breeding problems
○ Stallion can only breed limited number of mares
○ Mare and stallion have to be in same location
○ Risk of diseases, injuries
○ Difficult to assess semen quality (dismount sample - can get concertation, morphology but NOT VOLUME)
§ Don’t know how much went into the mare
Artifical insemination what are 6 advantages over natural service
- More mares can be bred to single stallion
○ 500 - 800 per year - Mare and stallion do not have to be in same location
- Limiting transmission of venereal diseases
- In case of incompatibility (size, temperament, physical, disability) breeding still possible
- Minimum contamination breeding technique possible
- Stallions semen quality can be monitored
Artifical insemination how to collect, AI dose and when to AI
How to collect
- Different vagina models
- May need phantom mare/ teasing mare
AI dose
- 500 million progressively motile sperm
- Sperm count (haemocytometre)
- Motility assessment (heated phase contrast microscope) done at 37 degrees
When to AI
- Semen is best kept in the mare’s uterus
- Shipping container good for transport
- BUT semen should be inseminated as quickly as possible
- No reason to split dose over two days
Raw semen what is good about it and what important when done with AI
○ Minimize injuries
○ Assess semen quality
○ Breed multiple mares from same ejaculate
Raw semen with AI
○ “dirtiest” of all AI methods
○ Risk of iatrogenic infection especially when done in early or later oestrus
○ AI dose not dilate cervix as stallions penis would
○ Deposit desired dose into uterus w/in 30min
Fresh extended semen when use, how extended and how long last
○ When number of mares are to be inseminated with same ejaculate
○ Integral part of “minimal contamination breeding technique” for mares susceptible to endometritis
○ Collected semen extended at 1 part semen to 4 parts extender (at least 1:2)
○ Extend sample to a concentration of 25-50 million/ml
○ Centrifugation might be necessary
○ Should be used within 3 hours at room temperature
Cool extended semen goal, how occurs and success
○ Goal: breed once per cycle
○ Observe stallion collection schedule
○ Extended semen cooled to 5 degrees
○ Colling rate critical (1 degree/3mins)
○ If manual: extender and semen at 37 degrees placed in beaker with 37 degrees water, add ice
○ Commercially available shipping containers cool at ideal rate
Success with cooled extended semen
○ Varies by stallion and individual farm management
○ Not all stallions can have semen successfully shipped
○ With best management and semen from a fertile stallion, equal to other methods:
§ 75+% first service conception
What are the 2 main important stallion variations within artifical insemination
1) fertilisation capability of sperm - up to 72 hours in storage, some earlier - should be tested before chilled, extenders can be used
2) number of AI doses/ejaculate also variable - if unknown do not plan more than 5-10 insemination in 2 days
What are the 3 events of puerperium
- Uterine involution
- Shedding bacteria
- Resuming regular cyclic ovarian activity
Foal heat when present, when end, and what is the trade off
Foal heat
- Onset usually 6 to 9 days post foaling (5 to 12 days normal)
- Ends with first ovulation post-partum
- Interval becomes shorter later in season
- Higher early embryonic death rate if breed in foal heat (if OV before D10)
Trade-off between getting mare in foal as early as possible and ensuring successful outcome of pregnancy
- If breed in foal heat and successful actually gaining time (foal born earlier than last one)
- HOWEVER if breed foal heat but not successful then have to wait another 30 days to cycle again
○ Falling behind with schedule as if didn’t breed in foal heat would have short cycled her and then gotten pregnant earlier
WORSE if breed foal heat and successful but then LOSE pregnancy then you can be quite a lot of days behind
What are 2 situations to breed and 3 when don’t breed
BREED
- Normal parturition and puerperium
- Ovulation > D 10 post-partum
DON’T BREED
- Abnormal parturition and/or puerperium
- Ovulation < D10 post-partum (short cycle instead)
- Don’t induce ovulation
○ Why not induce her on day 10? -> later she ovulates the more time for puerperium so successful pregnancy
○ THEREFORE -> not ideal to breed with frozen semen or heavily booked stallions as need to induce for these
