Cryptorchidism in the horse

1. Cryptorchidism in the horse Dr JE Cox Division of Equine Studies

2. Cryptorchidism in horses I apologise for the poor quality of some slides (scanned in a hurry) some pictures being missing (my set has got depleted over the years) the possibility that this may be of absolutely no help to you in the forthcoming exam BUT Good luck

3. The phenomenon of cryptorchidism in horses Temporary inguinal retention Permanent inguinal retention Incomplete abdominal retention Complete abdominal retention

4. Inguinal retention Temporary and permanent forms have same anatomy – the testis has passed through the inguinal canal but has not descended to scrotum Temporary form very common in ponies

5. Incomplete retention Epididymal tail descended but testis still in abdomen

6. Complete retention Testis and epididymal tail both in abdomen Note that there is a small vaginal process and the remains of the gubernaculum (inguinal extension…) through the inguinal canal

7. Abdominal retention Note that complete retention is more common on the left whilst complete and incomplete retention are equally represented on the right side – all to do with timing of descent of left and right testes

8. Positioning for cryptorchidectomy Penis pulled forwards; inguinal and paramedian areas prepped Dorsal recumbency; good anaesthesia

9. Inguinal exploration ALWAYS explore inguinal region surgically, even though you cannot feel anything LOOK for scars – though they only tell you someone has made a hole

10. Inguinal exploration Cut through skin where the scrotum should be – then DISCARD SCALPEL – there are large veins down there (one shown here) so continue by blunt dissection

11. Inguinal exploration You may find a stump with a muscle (the cremaster) on the outside – open it carefully. If you find, as here, blood vessels and the deferent duct, then it has been castrated (on that side at least)

12. Inguinal exploration You may find a testis inside its vaginal tunic (as here) Remove it and the animal has then been castrated on that side

13. Inguinal exploration You may find a vaginal tunic which when you cut into it, you find epididymal tail (e), deferent duct (v) and body of epididymis (b) as here. See next slide

14. Inguinal exploration You may be able to deliver the testis by traction on the epididymal body Anatomy slide shows why this works – they are attached to each other

15. Inguinal exploration You may find “inguinal extension of gubernaculum” – difficult to recognise as you may guess from this picture This is a case of complete retention See next slide

16. Inguinal exploration You then be able to identify a small vaginal process and inside it a ligament – traction on this may deliver the epididymal tail and then the testis Anatomy slide shows why this works – they are attached to each other

17. Where now ? The chart shows the options:- “Invasive via inguinal canal” are no longer recommended – they have a high rate of post-operative prolapse of gut !!!

18. Where now ? The chart shows the options “Non-invasive via inguinal canal (Adams)” is also no longer used – it was, in any case, based on a misunderstanding of the anatomy !!!!!

19. Where now ? The chart shows the options “Non-invasive via inguinal canal (Inguinal extension…)” is the one described on slide 16

20. Where now ? The chart shows the options “Invasive via body wall (flank) “ is no longer used – it has no advantage over paramedian and is more difficult if both testes are in the abdomen.

21. Where now ? The chart shows the options “Invasive via body wall (paramedian)” was originally devised in the early 1800s (pre Lister, pre chloroform !) and then lost favour until “re-discovered” at Leahurst by Prof JG Wright in the late 1950s

22. Where now ? The chart shows the options Not shown is laparoscopic removal which is gaining favour

23. Paramedian Paramedian incision parallel to opening of sheath and at that level – too far back may be easier to get testis, but there is cod-fat to cut through; too far forwards and it is difficult to exteriorise testis

24. Paramedian Below fat lies tendon of external and internal oblique combined – incise along length of incision

25. Paramedian Below tendons of external and internal oblique combined lies straight abdominal muscle (also called rectus abdominis) – split along fibres along length of incision

26. Paramedian Below straight abdominal muscle lies tendon of transverse muscle, fibres at right angles to incision – split along fibres at right angles to incision and puncture peritoneum below and enter peritoneal cavity.

27. Paramedian Put your hand in – How are you going to find the testis working completely blind ? It all follows from the anatomy shown at the beginning of this presentation See next slides

28. Paramedian Dissection of rig pig – head to right and tail to left; Gut removed; Caudal abdomen exposed; Bladder (b) reflected caudally to expose cut end of rectum (r) at entrance to pelvic canal See next slide

29. Paramedian Dissection of rig pig – head to right and tail to left; Note testis (t) and epididymal tail (e) Note ligament (= proper ligament of testis) joining testis (t) to epididymal tail (e)

30. Paramedian Note ligament going from epid tail into vaginal process AND Deferent duct going from epid tail to dorsal surface of bladder

31. Paramedian If testis does not fall into your hand (most are soft and floppy), then find the deferent duct on dorsal surface of bladder, follow to epid tail and thence to testis (By now you should know that these are connected to one another)

32. Paramedian And pull out a plum ! Use emasculator for haemostasis (ligatures rarely required)

33. Paramedian Repair transverse tendon and straight abdominal muscle in one layer as shown. (there were some cracks in the glass of the slide – hope you can work out what is crack and what is not)

34. Paramedian Then, matress sutures in combined tendon of internal and external oblique. Close dead space in fat. Suture skin (all absorbable)

35. Don’t forget ! Laparoscopic removal has been developed since I gave up doing any surgery However, failure rate of paramedian, even in inexperienced hands, is probably less than for inguinal non-invasive and laparoscopic removal.