Horses Flashcards
What things should be examined in a BSE of a mare?
Externally: udder, perineum, vulva, and clitoris
Internally:
-Rectal exam: carried out first, check uterus, ovaries, cervix, broad ligs and pelvis.
-Vaginal exam: manual and speculum, endometrial swabs for cytology and culture
When in the oestrus cycle should you take endometrial samples? Why? Are there risks?
In dioestrus (after d5). This is the time when the uterus is meant to be sterile and defence systems are at their lowest. (presence of bacteria/neutrophils in oestrus could lead to a false positive). By this time the oestral oedema should have also subsided making evaluation of biopsy sample easier. Need to follow up with PGF2alpha IM to eliminate risk of iatrogenic infection
Risks:uterus is susceptible to infection at this time
What are some indications for obtaining an endometrial biopsy?
- valuable mare
- mare diagnosed with chronic endometritis
- when no specific cause of infertility can be found
- expensive reproductive treatment required
What is a hysteroscopy?
Endoscopic examination of the uterine lumen. Helpful in dx of uterine cysts and adhesions
What is a starch granule test uses for?
To test oviductal patency
How long is the equine oestrus cycle? how long is doestrus?
21.5 d
14-16 d
What happens to hormone levels one a dominant follicle becomes a CL?
Declining inhibin and oestrogen, increasing progesterone, decline in LH
What are anovulatory haemorrhagic follicles?
Follicles which fill with blood but fail to ovulate. They eventually leutenize but may persist for several months and therefore prolong the interoestrus interval
What are some signs of oestrus in a mare?
Posturing (flexed hocks and stifles, arched tail, tipped pelvis)
Winking (everting clitoris rhythmically)
Urinating
How might oestrus be suppressed in mares to advance the onset of ovulation?
- Progestagens (eg. Regumate)
- GnRH vaccines
- Marble in uterus
What are different synchronisation techniques used in mares?
- PGF2alpha
- Progestagen
- Progesterone + oestradiol
How often should mares be teased?
Every day from 3 days post-partum until 60 d preg
What are some advantages of AI?
- more mares can be bred to a single stallion
- mare stallion don’t have to be in same place
- limit disease transmission
- breeding possible in otherwise incompatible unions
- semen quality can be monitored
- min contamination technique possible
What are conditions for motility assessment of sperm?
500 million progressively motile
Assess with contrast microscope at 37 degrees
How many days post foaling is a mare likely to show foal heat?
6-9 days post foaling
What must occur following pregnancy for a mare to be able to fall pregnant again?
- Uterine involution
- Shedding of bacteria
- Resuming regular cyclic ovarian activity
Should a mare be bred on foal heat?
Yes it she had a normal parturition/ puerperium and if she has ovulated on or after day 10 post partum.
No if opposite occurrences to this.
What are some principles of the minimal contamination technique with regards to AI?
- Semen diluted with extender
- Semen extended to a conc. of 25-50 million/ml
- Mare should only be bred once per cycle and as long as possible before ovulation
What is the ideal time to inseminate a mare with frozen semen?
12 hours prior to 6 hours after ovulation (too much before that, sperm wont be good, too much after, egg quality declines)
If an AI attempt is unsuccessful, how long should you wait before trying to inseminate a mare again? Why?
At least 18 hours due to the risk of an infl. uterine reaction
What are some true indications for exogenous P4 therapy in a mare?
- Endotoxaemia
- High plasma cortisol levels
- Failure of conceptus to signal MRP
(i.e anything that might cause luteolysis)
Where does fertilization in the mare occur? How long after ovulation?
In the ampulla of the oviduct
10-12 hrs
What is and what is the role of the capsule of an embryo?
Acellular membrane between trophoblast and zona pellucida. It is retained until the third week of pregnancy.
Protects the embryo during passage through the uterotubal junction and likely has a role in uterine-embryo interactions
When does fixation of the embryo occur and what causes it?
Day 16-17
Embryo size and uterine contractions
What is eCG?
When is it detectable in the blood?
Equine chorionic gonadotrophin- a protein hormone produced by the endometrial cups between d40 and 120. It has luteotrophic properties and leads to formation of secondary CL
Day 40-100
The embryonic bulge in a mare can first be detected via palpation at what day and where? What also happens at around this time?
D20 at the utero-cornual junction
Paling of vagina and cervix
At D21 on ultrasound, a small echogenic spot appears in the ventral part of the vesicle. What is this?
The embryo
When can the heart beat of the embryo be detected by US?
d23-24
Manual embryo reduction is best done by what day? What drugs may help with this procedure?
Prior to day 16 (mobility phase)
Propantheline bromide to relax rectal and uterine walls
Flunixine meglumine to minimise PGF2alpha release as a result of trauma to the uterus
What are some DDx for infertility in the mare? (8)
- True temporary anoestrus
- True permanent anoestrus
- Ovarian tumour
- Irregular oestrus cycle
- Endometritis
- Silent oestrus
- Retention of endometrial cups
- Transitional oestrus
What is the most common ovarian neoplasia in mares? What are some DDx?
Granulosa theca cell tumour
DDx:
- teratoma
- ovarian haematoma
What are the two most commonly isolated bacteria in cases of equine endometritis?
What are some other non-bacterial causes?
Streptococcus equi sp. zooepidemicus
E. coli
iodine/ antibiotics, air, urine, idiopathic
Dioestrus in mares is characterised by compromised defences. What does this include?
- Decreased immune functions
- Closed cervix prevents drainage
- No flushing effect
- decreased muscle contractions
What are the three main barriers involved in reproductive defence?
- Vulva
- Vestibulo-vaginal sphincter
- Cervix
When should samples be taken to test for endometritis?
In dioestrus (when cervix is still open)
What is endometrosis?
What about endometrial cysts and transluminal adhesions?
Endometrosis: irreversible damage of functional glandular tissue
Endometrial cysts= lymphatic cysts
Transluminal adhesions= end point of EM fibrosis
What are some drug options available for you to treat endometritis?
- Polyenes
- Imidazoles
- Triazoles
- Lufenuron
- Dilute vinegar solution
- Dilute providone-iodine solution
(Follow up with OT)
WHAT is it? WHERE is it? HOW do you treat? SPECIFICS?
Melanoma
WHAT: mass of melanin-forming cells
WHERE: Ventral tail, anus, perineum, external genitalia, parotid region, oeriocular region, udder and lips
HOW: surgical excision/ debulking, cimetidine, cisplatin, melanoma vaccine
SPECIFICS: grey horses (benign)
What is cimetidine?
Histamine H2 receptor antagonist
WHAT is it? WHERE is it? HOW do you treat? SPECIFICS?
Sarcoids
WHAT: fibroblastic tumours; non regressing; locally invasive
WHERE: anywhere
HOW: complete excision, caustic ointments, 5-FU, immunotherapy, chemotherapy, BCG
SPECIFICS: bovine papilloma virus 1 and 2. Dx by biopsy
WHAT is it? WHERE is it? HOW do you treat? SPECIFICS?
SCC
WHAT: tumours of skin
WHERE: Unpigmented skin (third eyelid, periorbital area, nose and genitalia)
HOW: Surgical excision and adjunctive therapy.
SPECIFICS: UV exposure
WHAT is it? WHERE is it? HOW do you treat? SPECIFICS?
Eosinophilic granuloma (nodular necrobiosis)
WHAT: non-tumour nodular skin disease. Smooth nodules, non-pruritic, haired and firm
WHERE: neck, withers, and dorsal trunk
HOW: Sub-lesional corticosteroid injection, triamcinolone, oral prednisolone or surgical excision
SPECIFICS: Insect hypersensitivity possibly
What are some DDx for ulcerated lesions on the distal limb of a horse?
Pythiosis Habronemiasis Nodular sarcoids SCCC Exuberant granulation tissue
What is pythiosis?
Protozoal disease caused by Pythium insidiosum. Aka swamp cancer or kunker. Causes a rapidly growing ulcerated lesion that develops areas of necrosis and fistualae when there is a break in skin integrity
How do you treat cutaneous habronemiasis?
Ivermectin (+/- CSs)
Insect repellant and disposal of manure
What are three conditions for dermatophilosis? Where does it usually occur?
Moisture
skin abrasions
a carrier animal
aka rain scald or greasy heel
Dorsum, and face (rain exposed areas)
How might you treat folliculitis. furunculosis?
Mild cases might not need treatment. Horses can be washed with chlorhex scrub or malaseb. Severe cases may need penicillin G or trimethoprim silfa
How do you dx ringworm in horses? What is the aetiological agent?
Trichophyton equinum and mentagrophytes and microsporon equinum.
Microsc. examination of hair shafts, skin scrapings +/- fungal culture (woodlamps not useful)
What breeds are predisposed to pastern dermatitis?
Draft/ feathered breeds
What is the typical age of onset of culicoides hypersensitivity? How might you treat it?
2-4 years (there may be a hereditary component)
Tx:
-insect repellants
-rugs/hoods
-keeping horses indoors (need ultrafine mesh)
-fans
What causes cutaneous onchocerchiasis? How does it spread? What may be used to treat it?
Filarial dermatitis caused by the microfilariae of Onchocerca cervicalis (hypersensitivity reaction). Infection transmitted between horses by Culicoides species.
Tx is with ivermectin or moxidectin
Where are the following lice more likely to cause lesions in horses?
- Damalinia (Bovicola) equi
- Haematopinus asini.
How are these treated?
D. equi- body
H. asini- base of mane and tail
Ivermectin (and mxi) for suscking lice
Fipronyl and pyrethroid sprays
(give 2-3 treatments 2 weeks apart in order to kill emerging nymphs and adults bc these tx dont kill eggs)
Imadacloprid only needs to be given once
Where do the following mites cause disease? Chorioptes bovis (state 3 things about this) Psoroptes equi Sarcoptes scabei var equi (state 2 things about this)
Chorioptes bovis= leg (sometimes perineum).
-More common in winter. Draft breeds predisposed. Mites may survive many weeks off the host.
Psoroptes equi= body mange/ ear mites.
Sarcoptes scabei var equi= head mange. Starts on head and ears but spreads. Burrows deep
How can you treat mange in a horse?
Ivermectin or moxidectin every 2 weeks for 2-3 treatments
Topical tx:
fipronyl (once a week for a month)
lime sulphur
What is urticaria? What is the gold std for testing?
Transient focal swellings= hives= wheals
Result from dermal oedema arising from vasodilation (not always itchy)
Intradermal skin testing
What drugs commonly cause urticaria?
Penicillin, sulfa drugs, NSAIDs, and phenothiazines
How can atopic skin disease be treated in horses?
Management of environmental conditions CSs (dex, pred) Antihistamines (not v useful) Hyposensitization Avoiding exposure!!
How might you treat bullous keratopathy?
- Cover cornea (temporary tarsorrhaphy)
- Keratectomy (debride devitalised cornea and conjunctival flap/ graft)
- Topical A/bs, anti-inflammatories
What are some chronic signs of uveitis? (8)
- Phthisis bulbi (shrunken, non-functional eye)
- Cataract formation
- Posterior synechia (iris adheres to the lens)
- Retinal detachment
- Hyperpigmented iris
- Vitreous opacity
- lens luxation
- Glaucoma
How much is too much blood loss in a horse?
8L/500kg
What is tranexamic acid?
It’s an anti-fibrinolytic used to control excessive bleeding