HTBA & HVERC MIDDLE MANAGEMENT Stud Course 2010
Course Program - Day One
9.00-9.30
Registration / Introduction / Coffee
9.30 -10.30
Lecture 1
John Chopin PhD, FACVSc Mare – basic reproduction / follicular cycle Some ultrasound findings associated with the cycle
10.30 – 11.00
Coffee
11.00 – 12.00
Lecture 2
Allan Gunn, DACT Mare – Revision of the cycle Hormones involved Methods of altering and assisting cycle management Spring transition Autumn transition – shuttle mares Foal Heat ‘Lactation anoestrus’ Ultrasound finding associated with the cycle
12.00 – 13.00
Lecture 3
Jane Axon, DACVIM Neonatal Foals
13.00 – 14.00
Lunch
14.00 – 15.00
Lecture 4
Catherine Russell, FACVSc Equine Gastric Ulcer Syndrome (EGUS) EGUS on stud farms – stallions, mares, spellers, weanlings, older foals and neonates
15.00 – 15.30
Afternoon Tea
15.30 – 16.30
Lecture 5
Joan Carrick, PhD, DACVIM An update on Hendra Virus Biosecurity for known and emerging diseases Sample collection and submission to a laboratory – what stud staff can do to improve biosecurity and diagnostic outcomes.
17.00 – 17.30
Evening Drinks
17.30 – 18.00
Presentation by Kirsten Todhunter Caterpillar Abortion Status
18.00 – 20.00
BBQ and Speeches
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Course Program - Day Two 8.30 – 9.00
Breakfast
9.00 – 10.00
Lecture 6
Jim Rodger, FACVSc Stallion assessment: Libido Fertility Analysis of records Sperm analysis and the reasons for it
10.00 – 11.00
Lecture 7
Troy Butt, DACVS Laminitis: Causes, especially on stud farms How to deal with the laminitc mare Acute Chronic and associated welfare aspects
11.00 – 11.30
Coffee
11.30 – 12.30
Lecture 8
Chris O’Sullivan, DACVS Yearling radiography What do we know now? How to optimize the procedure as vendors
12.30 – 13.30
Lunch
13.30 – 14.30
Lecture 9
John Maxwell – Alpha Horse Yearlings How to handle and deal with yearlings to assist in optimizing showing for sales
14.30 – 15.00 15.00 – 15.30
Afternoon Tea End of course discussion
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intrafollicular rise in progesterone plays an important role in the activation of these enzymes. Ovulation occurs within 48 hours of the end of oestrus, but ovulation can occur anytime (even dioestrus) and the length of oestrus varies from 3 to 40 days.
Ovulation Prediction All the information gathered including teasing, examination of the cervix, rectal palpation and ultrasonography, aims to increase the efficiency of the stud farm by trying to minimise the number of services or inseminations per mare per oestrous cycle. This ensures that the stallion or semen is not wasted in a mare that is unlikely to ovulate within a reasonable time after insemination. This increases the efficiency of stallion usage and maximises the number of mares that the stallion can breed or inseminate in a season. The end point of the examination is a prediction of when the mare is most likely to ovulate.
Teasing The use of a trained teaser to determine which mares are in oestrus will limit the number of rectal examinations required. The teasing process is not exact and some flexibility might be required with mares that are unwillingly to show behavioural oestrus. Adequate exposure time for each mare is necessarily to induce oestrous behaviour. This will be facilitated by yard design to allow all mares’ access to the teaser with minimal competition or dominance from mares higher in the pecking order. The teaser needs to be gentle but determined, and “shy� mares might need individual attention from the teaser. This will necessitate facilities designed to minimise injury, but allow the teaser close contact with the mare.
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STALLION
MARE
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CORPUS LUTEUM
Ultrasonograph of previous ovulating follicles that have now formed 2 corpus luteums with central blood clots.
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Combination of management tools to predict ovulation No reliable ultrasonographical predictor of ovulation could be found by. In general the combination of softening of a large follicle, particularly when painful on palpation per rectum, and a substantial change in follicular shape can be used to predict ovulation within a 24 hour period. Ovulation prediction is difficult but there are several criteria available to help predict the timing of ovulation. 1. The dominant follicle increases in size during oestrus and becomes tense to touch. In the 24 hours prior to ovulation the follicle feels much softer. The degree of softening is the most useful criteria for predicting ovulation. The follicle should reach an adequate size ( 35mm) and a definite softening should be palpated. Softening of the follicle occurs in 40% of mares in the 12 hours before ovulation. The sizes of a preovulatory follicle in a Thoroughbred mare 72, 48 and 24 hours before ovulation are 40, 45 and 50 mm respectively. There is little variation in the range of ovulatory follicle diameter between cycles in an individual mare. The ovulating follicle is the largest follicle 6 days before ovulation in 82% of mares, and by this time the second largest follicle stops growing. The follicle stops enlarging in the 24 hours prior to ovulation. Forty one minutes prior to ovulation a break or protrusion of the follicle wall at the ovulation fossa is a consistent feature. Thirty minutes prior to ovulation the follicle diameter decreases by 13%. The collapse and extrusion of follicle contents (or ovulation) occurs in about 42 seconds. 2. Follicle shape may also indicate impending ovulation. The shape of the follicle changes from spherical to pear shaped in 85% of mares in the 24 hours before ovulation. The mare’s ovary is unusual in that there is a collagenous zone around the ovary with the germinal parenchyma in the centre of the ovary. This limits ovulation and release of the oocyte through an ovulation fossa on the ventral border. The change in shape of the ovarian follicle prior to ovulation is the follicle forming a channel to the ovulation fossa. 3. The follicular wall thickens prior to ovulation. This may occur too early in the process to be used as an indicator for the timing of ovulation. 4. The echogenicity of the follicular wall increases (100% of mares) and echogenic spots appear within the follicle prior to ovulation (54% of mares). The fluid in the follicle becomes slightly echogenic as granulosa cells are shed. This may also occur in large degenerate follicles. These changes are not consistent enough or close enough to ovulation to be useful in predicting the timing of ovulation.
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Ultimately, the hypothalamic surge centre produces a surge in GnRH production. This induces a LH surge, and the mature or ripened follicle ruptures. The oocyte, or egg, is released from the ovulation fossa which is unique to equids, and travels down the uterine tube to meet the sperm waiting for it, hopefully to unite and form an embryo. Formation of an early embryo is typically very successful, usually in the region of 90%. The embryo enters the uterus after about 5-6 days from ovulation. The ruptured follicle then fills up with blood. Initially this is called a corpus haemorrhgicum (CH). This matures into a CL, which starts producing P4. And the cycle goes around again.
Follicular Dynamics Illustration
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Hormonal Feedback Loops
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Figure 1. Foal nursing showing good tongue seal on teat. Foal also has an indwelling nasogastric tube through which it had been fed until it developed the good suckle.
Figure 2. Intranasal oxygen therapy utilised on a recumbent foal with lack of tongue control, a common finding in foals with HIS.
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Figure 3. Premature foal highlighting domed forehead, floppy ears, small size, and thin silky coat.
b.
a. Figure 4a and b. Radiographs of a hock and carpus from a premature foal with incomplete ossification.
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Figure 5. Foal with pale yellow mucous membranes from neonatal isoerythrolysis
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Equine Gastric Ulcer Syndrome (EGUS) Lecture Four Dr Catherine Russell, FACVSc Scone Equine Hospital
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Stallion Assessment Lecture Seven Dr Jim Rodger, FACVSc Jerry’s Plains Veterinary Hospital
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Selection of the Stallion Select Carefully For What You Need
Ability
Appearance (quality control)
Good limbs
Able to stand up to work
Laminitis is a common killer of stallions
No evidence of congenital disease
Hernia, parrot mouth, spavin, ringbone, sidebone
No evidence of neoplasia
Testicular tumours are rare
A masculine appearance with well developed genitalia is often a good indication of a stallion libido. The stallion should have sound limbs and be kept fit. Stallions that are overfed and under worked may develop problems, particularly laminitis. There should be no sign of an abnormal or inguinal hernia. Monorchid or hypoplastic testicles not likely to produce adequate sperm. Pickett(1977) maintains that semen production is related to testicular size and that the combined width should be no less than 70mm to achieve satisfactory production. There are indications that testicle size and development may be impaired under the influence of anabolic steroids (Blanchard, 1983; W.P. Howey, personal communication) and we certainly see sires with poor first season performances that later improve, although no accurate correlation has been made in these sires. Testicular neoplasms fortunately are rare. Size differences may be associated with post orchitis fibrosis. (Caron, Barber & Bailey, 1985) The penis should be a normal size and shape with no injuries. The glans penis should be examined for ulceration or habronema infection. We have had several stallions affected in this way and they need careful management. A case of penile paralysis associated with malnutrition has been described (Carr & Hughes, 1984).
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Yearling Radiography Lecture Eight Dr Chris O’Sullivan BVSc DipVCS MS Diplomate ACVS
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What do we know now? Veterinarians who view films for purchasers at sales are predominately experienced (>10yrs practice) veterinarians. The majority have either experience on the racetrack or are surgical specialists. In interpreting yearling sales films they make a judgement call on the clinical significance of lesions that are identified. The risk they may develop into a clinical problem and the impact that may have on a horses’ ability to race and subsequent performance. Their opinions are based on:
Experience: obviously veterinarians with experience treating and managing horses in race training will be biased by their individual experiences with specific problems. Also some experience regarding the purchaser or trainer will also influence the decision making.
Scientific Data: there are numerous studies which look at the impact that lesions seen in the repository have on thoroughbred race performance. There are weaknesses in this data which is inherent when looking at performance. While many of the studies look at large numbers of yearlings (n=1162 – 2773) applying the findings of these studies to specific cases is difficult.
The level of agreement on specific lesions among veterinarians is variable and dependant on the type of lesion seen or joint involved. Veterinarians seem to have better agreement on lesions of the hock particularly ‘OCD’.
What else would we like to know? Ideally we should seek as an industry data on individual lesion types over large numbers of horses with an aim to develop more standardised method of reporting. This should be based on the likelihood of a specific lesion to becoming clinical, and its subsequent impact on the horses racing career.
How to optimise the procedure as vendors? Horse preparation Well handled quiet horses will provide better quality films and improve the occupational health and safety of the radiographers. Horses should also have their feet well trimmed and be cleaned of all mud. Small balls of mud in the coat can closely resemble bone fragments on radiographs.
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