Horses Flashcards
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
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 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 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
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)
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 are some signs that a mare is ready to be bred
- Ovulatory follicle: usually 30-32+/-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
What is the AI dose
AI dose
- 500 million progressively motile sperm
- Sperm count (haemocytometre)
- Motility assessment (heated phase contrast microscope) done at 37 degrees
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
Success with frozen semen and ideal insemination time
30-35%/cycle
- Best management coupled with semen from a fertile stallion can yield results, equivalent to other methods (fresh, chilled): 75% + percent first service conception rate
- Mares that conceive with frozen semen mostly do so in cycle 1 or 2
○ If not by 3rd cycle, recommend switching to fresh or chilled (often successful)
Ideal insemination time: 12 hours prior to 6 hours after ovulation
What are the steps and the days which they are done for setting up AI with ovulation induction
Day 1: 8 pm (0 hours): deslorelin - induce ovulation (follicle between 30-35mm) - CAN’T HAVE LH SURGE
Day 2 (- 24 hours): scan mare to ensure she does not look like she will ovulate on her own
Day 3: 8am (36 hours): scan mare to ensure she has not ovulated - if she has just inseminate
Day 3: 2pm (42 hours): inseminate
Day 3: 8pm (48 hours): confirm ovulation
IF she has NOT ovulated
- Owner makes decision if that cycle is to be skipped or mare must be scanned every 6 hours to be inseminated again once ovulation is detected
- Mare should not be AI’d again until at least 18 hours after 1st AI (inflammatory uterine reaction)
○ shouldn’t inseminate until the next morning at 8am
Where is semen deposited, fertilisation occurs and transport of conceptus where
- Sperm deposited into uterus
- Fertilization in ampulla of oviduct
- Transport of conceptus into uterus (5 to 6 days after OV)
- Unfertilized ova remain in oviduct
When does fixation and implantation occur and what important about these
- Fixation occurs at D 16/17
○ Stuck at the base of the horn - Implantation starts around D 35
○ When placentation starts -> attaches through endometrium - Nutrition through histiotroph (uterine milk) and yolk sac
- Embryo is very vulnerable in this phase (EED)
What is the typical schedule for equine pregnancy scanning
Day 14 post ovulation (NOT INSEMINATION) - pregnancy & twin identification - HAS TO BE BEFORE DAY 16
Day 25 - 28 post ovulation - assess foetal viability (heart beat)
Day 40 post ovulation - confirm pregnancy (stud fee is usually due around this time)
Day 60 - 70 post ovulation - foetal sexing -> visualise the genital tubercle position
○ Only done by equine vets and need a 100% success rate as based on thousands of dollars
Day 150 - transabdominally sexing - external genitalia, penis, prepuce, teats, clitoris - not commonly done
Induction of parturition indicators, risk and what are the 2 main protocols
- Very few indications -> Prepubic tendon rupture
- Inform owner about risks -> risky for both mare and mainly foal
Two protocols
1. Normal protocol
a. Give 10 IU of oxytocin IV
b. If water doesn’t break within 40min: vaginal exam
c. If straining for 10min without water breaking: incise chorioallantois
d. If straining for 10min after water has broken: check for malpresentation/-position - in stage II labour
2. Modified protocol
a. Give 2.5 IU oxytocin IV
b. If mare progresses to foal: RFB was in place
c. If mare does NOT progress: postpone induction
Helps prevent premature foals being born
Immunological castration how occurs, what used for and why not used much
- Vaccine against GnRH equity
- Only registered for use in mares NOT COLTS/STALLIONS
- 10% of male horses -> became permanently infertile, doesn’t change behaviour of all male horses
Should not use in animals intended for breeding in the fertility
What if there is male behaviour yet testes are not palpable or identified with US and castration history is unknown?
- > 18 months - anti-mullerian hormone produced by Sertoli cells
○ Simplest if at the right age - < 2 yo or donkey of any age HCG stimulation test
○ Testosterone baseline and 30-120mins after giving HCG -> gelding <40 pg/ml, cryptorchid >100 pg/ml - 3 yp Oestrone sulphate
○ Single blood test -> gelding <40 pg/ml, cryptorchid >400 pg/ml
What evaluating with sperm characteristics and stain used
- Vol of the ejaculate (40-200 ml) x concentration = total sperm count. ( 500mill per dose)
- Sperm cell morphology
- pH of semen - 7.2-7.9
- Bacterial cultures, e.g. for Taylorella equigenitalis(contagious equine metritis; CEM), Pseudomonas, Klebsiella spp.
- Motility analysis (motility = % moving acitvely forward), chromosomal analysis, sperm chromatin assays, acrosome reactions etc.
Stain nigrosineosin stained smear - black sperm DEAD
What are the 4 types of sarcoids and appearance
- Occult sarcoids, which are smooth, flat and usually hairless.
- Verrucous sarcoids, which have wart-like appearance.
- Fibroblastic or nodular sarcoids – these are sometimes referred to as two different types, with fibroblastic sarcoids usually being ulcerated and nodular sarcoids being lumps under otherwise normal-appearing skin. However, fibroblastic sarcoids are more likely a progression of the nodular form.
- Mixed sarcoids contain components of two or more of the above types. They most likely represent a transition between different types.
Melanoma treatment 3 options
- Surgery resection? -> anal sphincter issues
- Palliative care - intralesional chemotherapy
- Cimetidine - unsure on how works but can help
Rain scald (dermatophilosis) clinical signs, cause and how transmitted
- Significant hair loss over face, dorsum, extending ventrally
- Crusting bald/ulcerative
- Housed outdoors, recent rainfall
- No scratching/itching but painful
Cause - Dermatophilus congolensis
Required for development
1. Moisture
2. Skin abrasions
3. A carrier animal
Transmission - Flies, biting insects, fomites
Rain scald treatment and prevention
Treatment 1. Wash with benzamidine, chlorhexidine 2. Topical disinfectants 3. Get horse out of the rain Prevention - Collect ulcerations as act as carrier of the spores Keep dry with adequate shelter
Dermatophytosis (ringworm) cause, transmission
cause - trichophyton and Microsporon - Warmth and humidity
Transmission
- Contact with other infected animals or infected hair shafts
- Younger animals more susceptible - immunity after exposure
Dermatophytosis (ringworm) treatment
- Probably go away by itself but if want resolved quickly
1. Malaseb - medicated wash
2. Imaverol - systemic antifungal? - only if immunosuppressive - NOT IN PREGNANT ANIMALS
Pastern dermatitis predispoing factor and treatment
Predisposing factors
- Draft or feathered breeds
- Excess hair aids in keeping the area wet and prepetuation of bacterial growth
Also predisposed to chorioptic mange that can lead to dermatitis
Treatment
1. GET OUT OF THE MUD
2. Dry and clip the hooves
3. Topical disinfectants - dilute chlorhexidine scrub and topical ointments such as silversulfadiazine
4. Systemic antibiotics in severe cases -> procaine penicillin G
○ Should do culture and sensitivity if infection remains
Cutaneous habronemiosis what known as, cause and locations
Also known as “summer sores” due to increased occurrence during warm months
Cause
- Deposition of larvae Habronema microstoma/muscae or Draschia by flies (intermediate host) into wounds or moist skin sites rather than mouth (normally)
- Results in hypersensitivity reactions to dead and dying larvae
Locations
- Media canthus of the eye
- Third eyelids
- Distal limb
- Penis or prepuce
Cutaneous habronemiosis diagnosis, treatment and prevention
Diagnosis
Biopsy with histopathology usually revealing granulomatous inflammation
Treatment
- Ivermectin (moxidectin)
- Corticosteroids may be needed to control hypersensitivity reaction
Prevention
- Good fly control - with prompt removal and disposal of manure containing larvae and insect repellent application to affected and at-risk horses
Culicoides hypersensitivity “queensland itch” what results from, where located and age of onset in what climates
- Hypersensitivity reaction to midge saliva proteins
○ May be a hereditary predisposition for developing hypersensitivity (most likely type 3 - antibody/antigen mediated)
○ Nature of the hypersensitivity response to unknown - Present mainly over the base of the mane, neck, dorsum and ventral midline
- Age of onset usually 2-4 years and more common in warm, tropical climates - where midges are
Lice treatment what medications and how many applications
- Most only kill lice and NOT EGGS -> 2-3 treatment administered 2 weeks apart
○ In order to kill emerging nymphs and adults from pre-existing eggs
1. Ivermectin - administered systemically for SUCKING LICE ONLY
2. Topical insecticides may be used FOR BOTH TYPES - fipronil and pyrethroids spray - Single application include imidacloprid (advantage)
○ Kill the larvae and adults
ALL in-contact horses should also be treated
Atopic skin disease problem list
- Severe pruritus -> due to antibodies cross-link mast cells, causing degranulation and release of inflammatory mediators
○ May not be present - Mild patchy alopecia
- Seasonal
- Secondary pyoderma may develop
- Urticaria - “wheals” - transient focal swelling that result of dermal oedema arising from vasodilation
○ Found on the neck and cranial third of the body but may be diffuse over the body
○ Size variable from 1-10cm in diameter
○ Resolve if left untreated
Mites what are the 3 main ones, can they live off host, other animals infect and diagnosis
1) chorioptes bovis (leg mange) - can live off host, cattle, goats, skin scrape
2) psoroptes equi (body mange) - reportable disease, ear infestations, intense pruritis, skin scrape
3) sarcoptes scabiei (scabies or head mange) - rare, intense, burrow deep so may not on skin scapre may need biopsy
Mites treatment what are the 3 main steps and what NOT TO USE
- Shave their legs -> clip the feathers
- Ivermectin or moxidectin administered every 2 weeks for 2-3 treatments
○ Eggs will not be killed so need to do again (Same as lice)
○ Systemic Ivermectin and moxidectin may not eliminate all live mites - resistance possible - Topical treatment - fibronil (frontline spray -administered once weekly for 1 month), lime sulphur, malathion
- ALL in contact horses should be treated as well as DECONTAMINATION of fomites in the environment
- NOTE -> Amitraz - DO NT USE IN HORSES
○ May cause ileus in horses that may be IRREVERSIBLE
If in early stages -> alpha2 antagonists
Acute uveitis primary and secondary causes and treatment
- Primary - equine recurrent uveitis
- Secondary - to other ocular diseases
Treatment - Treat primary cause
- Timely anti-inflammatory therapy, corticosteroids, NSAIDS
- Atropine
Poor treatment = loss of vision
What are the 3 stages of wound healing and which are poor in distal limbs and therefore 3 reasons wounds break down in this area
Stages of wound healing;
1. Cellular debridement**
2. Proliferation/angiogenesis (granulation tissue)
3. Contraction/Epithelialisation
- ** poor in horse distal limbs
THEREFORE
1. Poor cellular debridement /infection
- Horses > ponies
- Distal limb
2. Movement: Tension at suture lines
3. Orientation of skin vs blood supply - Upside down flap get tension in suture and will break down
Proud flesh treatment what are the 3 main ones
1) Trim with blade - no nerve supply ○ Level with skin and distal ○ WILL BLEED ○ Removes superficial contamination/inflammation mediators ○ Keep doing it time and time again until healthy and will close up 2) Topical treatments ○ Corticosteroids ○ Yellow lotion - Zinc sulphate 3) Movement prevention ○ Bandages provide stability and promotes healthy granulation tissue ○ Cast is optimal ○ Bandage cast easier in the field
