AHAD Lecture 10

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  • AHAD - Lecture 10 (Horses)
    • mares
      • seasonal polyoestrus (spring)
        • with periods of anoestrus (not cycling) (winter)
        • can maniplate the season with light by either putting both mare and stallion under light in winter or transporting breeders to climates where spring occurs during our winters so they never go out of oestrus
        • estrus, metestrus, diestrus, proestrus
          • estrus and proestrus are follicular phase and metestrus and diestrus are luteal phase
      • ovulation
        • high progesterone can be used to predict pregnancy
        • if pregnant, will gestate for 336 days
          • for behavioural reasons, vets can put a marble in her uterus to trick her into thinking she is pregnant, though this does not last forever
      • equid herpesvirus-1
        • late gestation
        • placenta expelled, looks like red bag (blood), emergency as foal has no oxygen
          • sometimes bladder is mistaken for this
        • infects WBC and endothelium
    • stallion
      • accessory glands: ampulla, vestibular gland, prostate, bulbourethral gland
        • this fluid transports sperm, coagulates after ejac. to plug cervix, and contains hormones, enzymes and nutrients for sperm
      • spermatogenesis in seminiferous tubules
        • cells of leydig produce testosterone
      • fertilisation occurs within the ampulla and isthmus, zygote travels down oviduct and enters uterine horn via uterotubal junction
        • zygote hatches out of zona pellucida ~d10 and maternal recognition happens ~d12-d14
      • equine arteritis virus
        • flu like, pink eye, oedema
        • shed in semen (30% for life, so no longer viable to breed)
        • abortion ~3-10 M
        • notifiable
    • foetus
      • allantochorion = definitive placenta
        • microcotyledons most prominant ~d150-term. these allows nutrients to pass and allow placenta to be classes as diffused
      • amnion, surrounds foetus and is poorly vasculated
      • umbillical cord connects allan. to foetus
      • true implantation ~d35
      • PMSG recognises foetus
    • equine herpesvirus-3
      • vesicles = ulcerated nodules on penis/*****
      • transmitted through sexual contact
      • self-limiting
      • antibiotics used
      • prevention + vaccination is crucial
        • same for all viruses
        • new horses must be quarantined for ~3 weeks
    • contagious equine metritis: inflammes endo. leading to abortion
      • females can have same swab for each area of testing but males must have separate swabs as their infected areas can be localised and using the same one spreads the infection
      • antibiotic and topical wash used
      • taylorella congenitalis
        • gram -ve coccobacilius
      • signs: subfertility, early return to oestrus, inflammed reproductive tract, discharge
        • asymptomatic carriers, check for oestrus
    • non-infectious abortions
      • umbilical cord torsion
      • twins
      • degenerated endometrium in aged mares
        • harder to hold conceptus in place
      • poor perineal conformation
        • sunken rectum leads to faeces in ***** = infections
        • also if lips arent airtight
        • caslick surgery, cuts of bit of *****, stiched shut, and re-opened week before birth

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