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EQUINE CRYPTORCHIDECTOMY

EQUINE CRYPTORCHIDECTOMY. Pre-operation Implications. What is Cryptorchidism?. Cryptorchidism is the failure of one or both testes to descend into the scrotum and is the most common non-lethal developmental defect of equids.

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EQUINE CRYPTORCHIDECTOMY

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  1. EQUINE CRYPTORCHIDECTOMY Pre-operation Implications

  2. What is Cryptorchidism? • Cryptorchidism is the failure of one or both testes to descend into the scrotum and is the most common non-lethal developmental defect of equids. • Cryptorchid castration is, therefore, a common procedure in an equine surgical referral practice. • Cryptorchid horses also are often referred to as rigs or ridglings. • It has been documented in all breeds, although quarter horse breeds appear to be at greatest risk.

  3. Why does Cryptorchidism Occur? • Failure of one or both testicles to descend occurs in the fetus from a position behind the kidneys, along the wall of the abdomen, and into the scrotum. The testicle usually reaches the scrotum before birth. However, the testicle can stop at any point along its descent from the abdomen to the scrotum so that it could be “retained” within the abdomen or in the inguinal canal, the passageway between the abdomen and the scrotum. The retained testicle is not as large as the descended, normal testicle, but is still a problem.

  4. TYPES OF CRYPTORCHIDISM • Complete abdominal retention- The testicle is fully retained in the abdomen, and is mobile within the abdominal cavity. Typically this testicle will be small and flabby. It is extremely unlikely that it will produce sperm. The testicle is not externally palpable.

  5. TYPES OF CRYPTORCHIDISM • Incomplete abdominal retention- the retained testicle is not mobile within the abdominal cavity, but it is usually located close to the deep inguinal ring, with portions of the testicles attached tissue passed through the vaginal ring, where they can sometimes be palpated externally with the horse standing, and often when the horse is laid down under anesthesia.

  6. TYPES OF CRYPTORCHIDISM • Permanent inguinal retention is where the testicle has descended through the deep inguinal ring, but is trapped within the inguinal canal. It is difficult or impossible to palpate, and may be palpable upon the horse being laid down under anesthesia. Caution should be used in that it is possible to mistake the results of this palpation for those of an incomplete abdominal retention. In both instances the tail of the epididymis within a vaginal process may be felt. Either testicle can be retained, with the other testicle also sometimes being retained abdominally. An animal with this condition is sometimes known as "high flankers".

  7. TYPES OF CRYPTORCHIDISM • Temporary inguinal retention-The retained testicle may be palpable within the inguinal canal with the horse standing, but will certainly be palpable with the horse laid down under anesthesia. The right testicle is the one most commonly affected (in more than three-quarters of cases). With this type of retention the testicle will usually descend of it's own volition by the time the colt is three years of age, although cases of it not descending until the horse is six have been recorded. In this type of retention, the testicle can sometimes be aided in it's descent by treating the animal with hCG (human chorionic gonadotropin), which will artificially stimulate the natural testosterone production, thereby encouraging descent.

  8. How is a Cryptorchid Diagnosed? • Horses usually retract their testicles into the inguinal canal unless sedated and so the first thing your vet may do is sedate your horse. With sedation, it may be possible to feel part or all of a testicle in the inguinal canal. If a testicle can not be felt in the inguinal canal, blood tests to confirm the presence of testicular tissue within the abdomen must be performed.

  9. How is a Cryptorchid Diagnosed? • There are two tests available: • In horses three years and older, a single blood sample can be taken for determination of a hormone called “estrogen sulphate”. Cryptorchids have levels four to five times higher than geldings. • If the horse is less than three years of age, paired blood samples are necessary to measure testosterone levels before and after an HCG injection, a drug that stimulates testosterone release from the testicles. If the level in the second blood sample (taken 60 minutes after the administration of HCG) is higher than the pre-injection sample, it confirms the presence of testicular tissue.

  10. WHY PERFORM A CRYPTORCHIDECTOMY? • The cryptorchid may not be capable of producing viable sperm, but testosterone production will not be affected. This means that once the animal reaches puberty (usually between 12 and 18 months), he will start to act in a stallion-like manner, which can be dangerous for those not familiar with it, and inconvenient for those that are. Additionally, at this stage the stallion will be capable of breeding a mare, although he may not be fertile depending upon whether one or both testes are retained. In the event that only one testicle is retained the second testicle will probably be fully functioning, and therefore any mare bred may become pregnant. As cryptorchidism is possibly a heritable trait, this situation is not desirable. From an ethical point of view, perpetuation of such a trait should not be considered. • The indication for most castrations is to reduce masculine behavior in males not intended for future breeding.

  11. PREOPERATIVE CONSIDERATIONS • In the vast majority of cases, castration is an elective procedure. We therefore want to ensure that the horse is in good health and free of concurrent illness prior to planning the operation. Maximizing the surgical candidacy of the patient will minimize the risk for potential complications. • A thorough physical examination (sometimes including bloodwork) is an imperative part of the preoperative process. Any illness discovered during preoperative assessment is successfully treated prior to scheduling orchiectomy.

  12. PROGNOSIS • With a skilled surgeon and proper surgical techniques, prognosis is good when performing a cryptorchidectomy.

  13. SEDATION/ ANAESTHESIA AND SURGICAL PREP • Laparoscopic Castration • Horses are fasted for 36 hours to reduce intestinal bulk • Horses are restrained in stocks and sedated with detomidine hydrochloride (0.01mg/kg, IV( and butorphanol tartate (0.02mg/kg, IV). • Sedation can be maintained by CRI of detomidine hydrochloride. • The surgical site is clipped and prepared aseptically.

  14. SEDATION/ ANAESTHESIA AND SURGICAL PREP Conventional Open Cryptorchidectomy (INGUINAL APPROACH) • Prior to recumbent castrations, horses are fasted for 8 hours. • Premedication with detomidine hydrochloride (0.01mg/kg, IV) and butorphanol tartate (0.02mg/kg, IV) • Induction of general anaesthesia using ketamine hydrochloride (2mg/kg, IV) and midazolam hydrochloride (0.1mg/kg, IV( and maintain with isoflurane in oxygen. • Horses are placed either in dorsal recumbency or lateral recumbency with the upper hindlimb abducted.

  15. SEDATION/ ANAESTHESIA AND SURGICAL PREP Conventional Open Cryptorchidectomy (INGUINAL APPROACH) • The inguinal area is clipped and scrubbed thoroughly, the rear limbs are draped in shrouds and a sterile drape placed over the surgical site. • Flunixin meglumine (1.1 mg/kg, IV) is given pre-operatively

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