Bovine Reproduction. Группа авторов
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tissues and assist with resorption of the edema and blood clot within the elastic tissues. If preputial prolapse is present, an emollient ointment should be applied and the protruding tissues protected with a support bandage or sling to prevent secondary trauma. The bull should have a complete BBSE prior to returning to service.
If surgery is to be performed, 5–7 days post occurrence has been shown to be the optimal timeframe [5]. Given that the owner or attendant typically may not notice this problem for 2–3 days and a 36‐ to 48‐hour fast must occur prior to surgery, surgery must be scheduled immediately in an attempt to fit that best timeframe. Timely surgical correction avoids the clot organization and fibrosis that begins to occur 10 days post injury. Once the decision is made to attempt surgical correction, antibiotic therapy is instituted if not already begun and feed is removed. The bull is fasted for 36–48 hours and water withheld overnight. General anesthesia can be utilized or regional anesthesia with heavy sedation [14]. Either way, the bull is tabled in right lateral recumbency, with the left hind leg pulled back and up and fastened securely. The surgical area is prepped and a vertical incision 20–25 cm long is made just cranial to the rudimentary teat. Careful dissection, attention to hemostasis, and manual removal of the blood clot follow. Lavage with a warm saline + Betadine Prep Solution™ aids in the removal of additional clots and, coupled with blunt dissection, identification of the lesion (Figure 19.56). Careful blunt or manual dissection is not just preferred over scalpel or scissor dissection but mandatory, as injury to the area vasculature and nerves must be avoided. Specifically, the area near the dorsal nerve of the penis must be avoided. Since identification of this area can be confusing as penile manipulation changes the anatomical context, it is useful to identify the urethra which is on the ventral aspect of the penis and thus 180° from the dorsum.
Figure 19.56 Rent in tunica albuginea.
After the tear or rent is identified, carefully lavage the area again and debride the often tattered edges of the rent. This must be minimal as excessive removal of tissue complicates closure and following healing there is the potential that the bull will have trouble extending his penis. Closure of the defect with No. 1 polyglycolic acid (PGA) in a bootlace pattern is the long‐standing recommendation and justifiably so, as there is enough wound tension to make simple interrupted suture patterns problematic. The elastic layers over the penis can be closed with 3–0 chromic gut in a simple continuous pattern. The penis is then returned to its normal position within the sheath and the surgical field is irrigated with warm 3% povidone–iodine in saline. Gently remove remaining blood clots. The subcutaneous tissues are closed with 0 chromic gut and the skin can be closed with 6‐mm Braunamid, typically with a Ford interlocking pattern. Antibiotics are continued for 5–7 days. The bull should have 60–90 days of sexual rest following surgery. Continue treatment of preputial prolapse as needed, but this condition usually resolves spontaneously within one week after surgery in B. taurus bulls. In B. indicus bulls the preputial prolapse may persist for longer than two weeks. In either case, it is wise to evaluate them for secondary damage to the prolapsed tissues. Seroma formation occurs often enough that it probably should not be considered a true complication. Complications include abscessation, suture dehiscence, shunts, permanent analgesia to the penis, and reoccurrence during the subsequent breeding seasons [2, 14]. Permanent analgesia may be the result of the original injury or an injury that occurs even following surgical resolution of the hematoma. In this later instance, the bull, having returned to service, sustains penile analgesia after breeding a few cows. Best evidence suggests that there are adhesions that surround portions of the nerves along the distal bend of the sigmoid flexure. These adhesions are not severe enough to restrict extension of the penis, but following repeated breeding they tear enough to damage the nerves [14].
Penile Deviations
Deviations of the penis may occasionally prevent intromission and coitus. Bovine penile deviations are classified as spiral (corkscrew), ventral, or S‐shaped [415–19]. Typically, bulls have had one or more successful breeding seasons prior to development of penile deviations with usually no known history of previous penile injury. Most bulls with these conditions are three or four years old and occasionally a bull over that age will develop penile deviation.
Spiral Deviation
Spiral deviation of the penis occurs more commonly than either ventral or S‐shaped deviations. One potential etiology involves malfunction of the dorsal apical ligament. The apical ligament, a thick collagen band, arises from the dorsum of the tunica albuginea about 2.5 cm proximal to the distal end of the prepuce and inserts into the tunica albuginea near the distal end of the corpus cavernosum penis (CCP). The function of this structure is to help maintain the shape of the penis during erection [17]. Historically, spiral deviations were considered to result from a short or inadequate apical ligament that slipped off to the left side of the penis at peak erection, allowing the penis to spiral and therefore preventing intromission [16–18].
However, the rapidly coordinated events leading to erection and the high maximum pressures within the CCP at ejaculation suggest that affected bulls may prematurely achieve maximum erection pressures prior to intromission. This suggestion may be supported by the fact that the penis of many normal bulls likely develops a spiral orientation in a cow's vagina during ejaculation [19]. Although the definitive cause of spiral deviations remains uncertain, apical ligament malfunction and premature achievement of high CCP pressure may be involved.
Many bulls develop spiraling of the distal penis during electroejaculation and masturbation [20]. Therefore spiral deviation should only be diagnosed as a pathologic condition when it consistently develops during natural mating (Figure 19.57) [4, 17, 21].
Figure 19.57 Spiral deviation.
Bulls with spiral deviation of the penis are most often three years old and have had a successful previous breeding season. Development of this condition may be insidious, occurring intermittently at first, then more consistently as breeding efforts continue. Therefore several test matings may be necessary to confirm the diagnosis. In B. indicus bulls the deviation may occur prior to penile extension such that the deviation remains hidden within the bull's pendulous sheath and excessive prepuce. For bulls with this sheath conformation, manual retraction of the prepuce during attempted breeding may be necessary to differentiate from erection or other causes of penile extension failure.
Ventral Penile Deviation
Ventral penile deviation occurs much less commonly than spiral deviation and the etiology is uncertain. Ventral deviations may occur as a result of altered blood flow through the ventral portion of the CCP or due to stretching or injury of the apical ligament, both of which probably result from chronic traumatic injury [1, 17, 18].
Ventral penis deviation is obvious as long gradual curvatures of the erect penis (Figure 19.58). The curvature frequently originates proximal to the junction of the sheath and prepuce [17, 18]. These conditions become more apparent as erection pressure increases. Because ventral penile deviation can be induced during electroejaculation, observation during natural breeding is recommended, especially for less obvious cases. These conditions are only considered to be pathologic when they consistently prevent intromission.