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59 Cards in this Set
- Front
- Back
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Explain the difference between a breeding season and oestrus |
The breeding season is the time of optimal natural fertility (Nov-Feb). Oestrus occurs within the breeding season and is the time when oestrogen dominates and she is in the follicular phase of the oestrus cycle. She is also receptive to the stallion at this time. |
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Describe the spring transmission period of a mare |
· Lots of follicles that grow and regress · Irregular teasing patterns, long periods ofoestrous-like behaviour · No ovulation · Lasts 60-90 days · 1st ovulation marks the end of thetransition period |
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What is the difference between the physiological and imposed breeding season of the mare? |
• Physiologic breeding season: The time of optimal natural fertility, usually from Nov – Feb
• Imposed breeding season: When people want to breed horses - 1st Sept to early Dec for TBs |
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Describe the seasonal pattern of ovulation in the mare |
o Summer (DJF)- all mares ovulate and show behavioural oestrus
o Autumn (MAM) – mares begin to stop ovulation o Winter (JJA) – most mares anovulatory o Spring (SON) – many start to ovulate • Possibly 15-20% of mares cycle throughout the year |
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List 2 methods used to advance the onset of the Spring transition in the mare. Explain how each method achieves this |
Artificial Lighting • Mimic normal photoperiod to induce changes in the HPO axis. o 16 hours of daylight, 8 hours in the dark. Progestins Synthetic progesterone used to synchronise ovulation (suppresses LH use and allows it to build up). More effective for late transition management. Progesterone releasing devices may be used. |
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Describe Dioestrus of a mare |
Mare in non-receptive to stallion. It is the luteal phase and progesterone dominates. It lasts 14-15 days
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Describe the difference in teasing behaviour between a mare in oestrus and a mare in dioestrus. |
• Oestruso Quiet and calmo Ears forwardo Nuzzlingo Posturingo Leaningo Moving to Stalliono Raising tailo Urinatingo Clitoral winking
• Dioestrus o Agitated nervouso Ears backo Bitingo Kicking/pawingo Moving awayo Clamping down tailo Squealing |
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What changes would you expect to see on ultrasound in a mare that was about to ovulate? |
o Change in follicle consistency and shape
o Endometrial oedema (max 1-2 days pre-ovulation) o Uterine tone o Cervix relaxation o Follicle size >35mm o Urogenital folds are most obvious just before she ovulates |
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What two hormones are used to induce oestrus? When would you use them? |
1- Human chorion gonadotrophin (hCG): has an LH like effect and is given when follicle is >35mm, mare is teasing and there is good endometrial folds. Often give it on the day she is going to be bred (TB studs) – she will ovulate within 48 hours once given hCG but sperm remains viable til then. 2- GnRH analogue, Deslorelin: Inject when there is a >35mm follicle, teasing and endometrial folds. |
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How is maternal recognition of pregnancy achieved in the mare? |
The mechanism isn't fully understood • Movement inhibits endometrial PGF2a production - Conceptus moves around a lot. When its touching lots of parts of the uterus it inhibits PG production – stops mare coming back into season• Embryo produces antiluteolysins which are taken up by the endometrium |
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Where in the reproductive tract is conceptus fixation usually? What results from fixation? |
• D16 post-ovulation fixation in base of the horn (conceptus gets stuck in there)
Fixation results in.. o Increased size of conceptus o Increase in uterine tone o Decrease in uterine diameter |
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What's the difference between primary and secondary corpus luteums? |
• Primary CL results from ovulation of follicle that resulted in pregnancy - Maintained due to maternal recognition of pregnancy, primary CL secretes progesterone.
• Secondary CLs are formed after day 40 of pregnancy, the leftover follicles in the ovary either ovulate and luteinise or luteinise without ovulation. |
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What hormone drives the formation of secondary CLs? Where is it produced? |
Equine Chorionic Gonadotrophin (eCG)- Unique to horses. Produced by endometrial cups. |
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Why is it that if a mare aborts, she won't come back into season for 3+ months? |
Endometrial cups still secrete eCG even if foetus dies, this maintains the CLs. They keep secreting eCG for 3+ months.
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What can you see on ultrasound at ... - Day 9-11 of pregnancy - Day 13-16 of pregnancy - Day 20-21 of pregnancy - Day 24-25 of pregnancy |
o Day 9-11 – sometimes can see things
o Day 13-16 – should be able to see things, conceptus usually fixed at the bottom of the uterine horn – spherical, fluid-filled conceptus o Day 20-21 – embryo visible o Day 24-25 – heart beat |
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When can a vet issue a pregnancy certificate? What is a pregnancy certificate used for? |
When there has been a successful pregnancy diagnosis after day 40 of pregnancy (most loses occur before day 40). A pregnancy certificate means the owner of the mare is required to pay the full stud fee (If applicable). |
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What are the pros and cons of ultrasound pregnancy scanning in mares? |
• Pros
o Early diagnosis of pregnancy o Diagnosis of twins o Accurate monitoring of embryo and foetal development or compromise and death Cons • In early stages conceptus can look like cysts - Can distinguish from cysts as conceptus grows, cysts don’t. - Plus its really f*cking hard to see anything |
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What hormones can be measured and used for pregnancy diagnosis? How are they measured? |
1- eCG: • False positives when embryo/foetal loss has occurred. Measured in serum or · Lateral flow test for urinary eCG. 2- Oestrogen Sulphate: Day 60 detected in blood. Kits (urine) can be used at100 days· Day 120 detected in faeces. 3- Progesterone: Serum or plasma. Indicate presence of luteal tissue, notpregnancy. |
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What are the outcomes for twins in late gestation in a mare? |
o 65% abort o 21% deliver 1 live foal o 14% deliver 2 live foals – but within 2 weeks ofbirth, both foals are likely to be dead |
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Under what conditions will a mare that if pregnant with twins, have two embryo's of the same size and there is no natural embryo reduction? |
If both follicles ovulate at the same time (they will be the same size). If they have bilateral fixation, then there is no more risk of reduction than with singletons. If they have unilateral fixation then there is 73% chance of reduction |
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How do you manage a mare pregnant with twins, before fixation of the embryo's? What advantages does this have? |
o Crush one twin – using fingers or US probe
Easy to separate twins Rapid, minimal compression needed Early in pregnancy – if procedure fails, can still attempt it post-fixation High success rate |
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How do you manage a mare pregnant with twins, after fixation of the embryo's but before day 30 of pregnancy?
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o Bilateral – crush one twin
o Unilateral – can be difficult to distinguish o Attempt to separate then crush one o More time-consuming and frustrating o Bounce embryonic vesicle and look for echogenic spots |
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How do you manage a mare pregnant with twins, after fixation of the embryo's and after day 20 of pregnancy?
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o 50% of the time results in abortion of both twins
o Damage/crush one twin Risk of damage to both Flunixin >25 days Best success is before day 20 o Abort both and rebreed mare Best done before day 35 o Monitor for spontaneous reduction (unilateral only) o Foetal reduction Damage to one twin with US• Day 40-60• Success unknown Inject one twin Abort• Endometrial cups Cervical dislocation day 60-110• 5/8 carried to term, 3/8 are normal size Do nothing |
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List some methods used to prevent equine Herpes virus abortion |
· Don’t mix pregnant mares with other horses –especially with young horses
· Isolate new arrivals for 3 weeks · Minimise stress · Vaccination – killed vaccine – given oncommercial studs |
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What is the most common cause of abortion in mares? What is the usual aetiology of this cause? |
Placentitis. It's usually bacterial e.g. Strep Zooepidemicus, E.Coli or Pseudomonas. |
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How would you diagnose and treat placentitis? |
Diagnosis Clinical signs- premature udder development and vulval discharge. Ultrasound - see thickened placenta Aborted foetuses are usually dried out looking - can send samples to lab Treatment Broad spectrum antibiotics - as it's usually bacterial Oral progesterone - Altrenogest (Regumate) Anti-inflammatories? |
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What's the difference between a fertile and subfertile mare? |
Sub fertile mares have the same fertilisation rates as fertile mares but there early embryonic loss is much higher (85% as opposed to 32%). Subfertile mares are also more susceptible to post-breeding endometritis. This could be due to the fact that subfertile mares have reduced levels of opsonins. |
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What factors affect the rate of embryonic loss? |
-Maternal Age influences the incidence ofpregnancy loss. An increase in early embryonic death occurs after 13 years - Uterine environment (endometritis, cysts, endometrial fibrosis) - Oviduct environment - Progesterone insufficiency - Sire effects - Embryonic defects - Malnutrition |
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In cases of infectious endometritis, when/how is bacteria introduced into the uterus |
o Breeding - big dirty horse dick
o Foaling - big baby f*cking everything up o Uterine culture, biopsy o Poor vulval conformation - like Daisy but not like Daytona |
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What would large amounts of echogenic fluid in the uterus on U/S indicate? A- Pregnancy B- Oestrus C- Endometritis D- Dioestrus |
C |
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What is a caslick and what is their purpose? |
Caslicks are used to correct poor vulval conformation. They are created by suturing up the top part of the vulva. Prevents air/sh*t going in |
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How would you treat endometritis? |
o Oxytocin o PG Return to oestrus ( high natural resistance to endometritis) o Lavage Mechanically clears the uterus Dilutes toxins Increases tone Stimulates uterine blood flow and PMNs o Antibiotics Culture and sensitivity Target B-haem Strep and E.Coli o Antiseptics and disinfectants Povidone iodine Mild irritation causes PG release and contraction – even saline causes this |
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How can you prevent endometritis? (It's a long list, like longer than you were expecting) |
• Minimum contamination technique
o Breed once, and close to ovulation o Optimal hygiene o Artificial insemination o Oxytocin, lavage • Make sure there is no endometritis pre-breeding, can lavage • Use hCG or deslorelin to induce ovulation and only reed once • AI if allowed • Examine soon after breeding • Consider corticosteroids at the time of breeding • Post breeding treatment can include o Uterine lavage and/ or infusion post-breedingo Up to day 4 post-ovulation o Oxytocin, PG +/- caslick |
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List the components of a breeding soundness exam in a mare |
• History
• General PE • Reproductive exam o Rectal palpation o Ultrasonography o Vaginal examo Direct cervical palpation o Endometrial culture and cytology o Endometrial biopsy • Evaluate database • Fix current problems and make recommendations for breeding management |
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How does a foal's umbilicus change within the first few days of life? What should you do to prevent infection of the umbilicus? |
o Umbilical stump should shrivel up over first 48 hours of life and become small, dry and non-painful
o Routinely dip the umbilicus with chlorhexidine 0.5% for the first few days post foaling o Monitor umbilicus closely for any evidence of infection |
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Is a foal with a urine specific gravity of 1.007 normal? Explain |
Yes its normal, they drink approx. 25% of their body weight in 24hours - so produce lots of dilute urine
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What is the normal behaviour of a newborn foal (including nursing habits)? |
Foals nurse for 2 mins, 5-7 times per hour (~every 10 mins)
Foals lie down to sleep o They should track the mare o When you enter the field/stable, it should get up and follow mare o Hide illness, an off-colour foal is an emergency |
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How and when can you assess a foal's passive transfer? |
• How - Blood test foal
Measure antibody levels Take from jugular • Use a Foal side test kit, there is a range of level based on colour change in test kit or Send to lab (ELISA)- May have to wait 24 hrs • When - Best time is at 18-24 hours of age |
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How would you treat a foal with failure of passive transfer? |
If foal level is not >8g/l then recommended treatment
o If less than 12 hours old – oral colostrum o If older than 12 hours – plasma IV transfusion Commercial plasma than contains antibodies is available Or can collect your own plasma – blood donor from gelding or dam• Separate plasma off from RBCs 1-2 litres needed for 50kg foal depending on baseline level For each 1 litre of plasma, there is approx. 2g/L in it Place IV catheter and monitor foal for signs of transfusion reaction Can re-check IgG level after transfusion to check enough |
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What is sepsis in a foal? |
Bacteraemia-toxin release + Systemic Inflammatory Response Syndrome (SIRS)
SIRS = Hypo/hyperthermia + Leukopenia/cytosis + Tachycardia + Tachypnoea Sepsis is very serious and can lead to septic shock and organ failure - It can develop very fast |
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What are some clinical signs of sepsis in a foal? |
Dull, lethargic, off suck Can be recumbent Injected mucous membranes Reddened schlera Petechiae on ear Red, warm coronary bands Increased HR, RR Temp either increased or decreased Acute severe lameness Hypopyon (pus in anterior chamber) Signs related to primary disease e.g. respiratory signs, umbilical discharge and swelling
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What's the difference between a premature foal and a dysmature one? |
Premature: Foal born at gestational age of <320 days that displays immature physical characteristics
Dysmature: A full term foal that displays immature physical characteristics |
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What are some common clinical signs of a premature/dysmature foal? |
• Low birth weight
• Short, silky hair • Floppy ears – flop down • Domed head • Weakness, prolonged time to stand • Flexor tendon laxity • Incomplete ossification of carpal and tarsal bones |
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What causes Neonatal Maladjustment Syndrome (dummy foal)? |
• Ischaemia, oedema and reperfusion injury to the foal’s brain, kidneys, intestines and other organs due to in utero hypoxiaor Interruption of oxygen supply during birth
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What are the clinical signs and treatment of Neonatal Maladjustment Syndrome (dummy foal)? |
Clinical Signs • Mild: unable to attach to mare, poor suck reflex• Medium: aimless wandering, abnormal phonation (barkers), blind • Severe: seizures, coma, respiratory depression treatment depends on the severity of the signs Treatment o Nutrition o Fluids (maintain hydration) o Intranasal oxygen o Control seizures o Prevent infection – short term antimicrobials o Anti-inflammatories |
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How do you control seizures in a foal? |
Anti-seizure medication
o Diazepam 5-20mg IV slow – try that first o Phenobarbitone 5-10mg/kg IV or PO o Maintain anti-seizure medication at 5mg/kg q12 hours (watch out for respiratory depression) Treat underlying cause |
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How does the fluid rate of foals compare to that of adults? |
Foals have a higher maintenance fluid rate compared to adults
Foal = 4ml/kg IV fluid/hour Adults= 2ml/kg IV fluids/hour |
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What 3 local anaesthetic agents are used in lameness examinations? Which one do we usually use? |
2% Lidocaine HCl 2% Mepivacaine HCl - usually use that one 0.5% Bupivacaine HCl |
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Why do we only block sensory nerves in horses during lameness examinations? Why are a2 agonists not used in these examinations? |
We only block the sensory nerves so that the horse doesn't feel pain but can still walk normally (so the lameness goes away temporarily). a2 Agonists have a analgesic effect so can cover up the pain of the lameness and we might think we have localised lameness in the coffin bone but really it's up in the stifle. |
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What does the palmar/plantar digital block desensitise? |
Everything distal to the navicular bursa and bone. |
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Where do you inject the local in a palmar/plantar digital block? |
Just axial to the neurovascular bundle which is abaxial to the flexor tendons |
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What syndromes are commonly diagnosed with a palmar/plantar digital block? |
o Navicular syndrome
o Heel pain syndrome o Wing fractures of the coffin bone o Subsolar abscess o Heel bruises o Sheared heels o Pedal osteitis |
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Where do you inject the local in an abaxial sesamoid block? |
· Performed at the level of the sesamoidPalpateneurovascular bundle as it goes over the abaxial surfaces of the proximalsesamoid bones and inject just axial to this |
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What structures are desensitised by an abaxial sesamoid block? |
Everything distal to the fetlock (not the fetlock joint itself though) |
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What syndromes are commonly diagnosed with an abaxial sesamoid block? |
o All problems blocked by PD blocko Interphalangeal joint osteoarthritis o Soft tissue injuries of pasterno Laminitis |
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Where do you inject the local in a 4-point block? |
4 injections 1- • Insert needle parallel to ground & perpendicular to the skin between the DDFT & the suspensory ligament. Insert needle to the hub, check for blood & deposit 3-5ml – median branch. 2- Withdraw the needle until it is subcutaneous on the lateral side & deposit 3-5ml – lateral branch 3- Palpate the button (distal end) of MC IV &insert needle distal to button of the splint bone 4- Repeat on medial side (MC II) |
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What structures are blocked in a 4-point block |
All structures below and including the promimal sesamoids. Includes the fetlock joint. |
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What syndromes are commonly diagnosed with a 4-point block? |
o Fetlock osteoarthritis
o Synovitis/capsulitis o Osteochondrosis o Osteochondral fractures o Sesamoid fractures |
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What joints are commonly used for intraarticular anaesthesia in a lameness examination? |
- Stifle - Fetlock - Coffin - Carpal joints - Tarsal joints |
