Spiral penile deviation

Keywords: penis, bovine, corkscrew, anatomy, infertility

This image shows severe spiral ("corkscrew") deviation of the penis of a three year Polled Limousin bull. As is typical, the bull had produced calves from his first breeding season but during his third year of life and second breeding season, the owner had observed spiral deviation during the bull's attempts to breed.

 

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The image was taken during stimulation with an electroejaculator. Pre-ejaculate accessory fluid can be seen dripping from the penis.

Notes:
Under certain conditions spiral deviation can be considered normal; about half of the bulls in one study (where a transparent artificial vagina was used) showed slight to pronounced spiral deviation during ejaculation. However, the problem arises when pronounced spiral deviation occurs before penetration, preventing penetration itself. The incidence of that situation varies considerably, but in a large study in New Zealand, just over 10% of the tested bulls showed this problem. It is interesting and potentially important to note that there have been at least two independent observation (one Australian and the other North American) where spiral deviation was more common in polled than horned bulls. This suggests that the condition has a heritable nature; something to bear in mind when considering corrective surgery.

One may ask why it is that even normal bovine penises have a tendency to spiral when fully erect. After reading Ashdown and Smith's paper, the author dissected the terminal portion of a bulls penis to assess its peculiar anatomy first-hand. The image below is the product of that dissection, some 31 years ago! It has been sharpened and annotated for clarification.  The anatomy of the bovine penis is not symmetrical. The apical ligament widens out distally from its origin, about 20 cm proximal from the glans. Strangely, it is attached firmly to the left side of the corpus cavernosum but on the right, its attachment could be described as "flimsy".  Ashdown had a more elegant description and also described an asymmetric arrangement of collagen fibers in the tunica albuginea of the corpus cavernosum itself.

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In the image of the author's dissection, the dotted green line (A) indicates the firm and thick attachment of the apical ligament to the tunica albuginea on its left side. The dashed black line (B) marks the approximate dorsal center line of the penis. The apical ligament itself (C) is shaded green. The thin and rather flimsy attachment of the apical ligament to the tunica albuginea on its right side is marked by the red dotted line (D).

During erection, the blood pressure in the corpus cavernosum penis increases to about 200 kPa  or (~30psi, close to the pressure in a car tire) or higher, expanding it distally. As the corpus cavernosum expands maximally, it pushes against the thin and loosely attached right side of the dorsal ligament. This allows the corpus cavernosum to "break away" and move sideways and distally from the sturdy, linear attachment of the ligament on the left side. That part of the ligament therefore provides an axis for a spiral deviation to form. This is further explained in  the diagram below.

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As mentioned, some degree of spiraling is normal but when the right-sided attachment between the corpus cavernosus and the dorsal ligament is stretched beyond its normal limits, the penis begins to spiral prematurely, preventing penetration.

Several surgical approaches have been described to treat excessive, premature spiraling. One of these (braiding of the dorsal ligament) aims to strengthen the attachment between the apical ligament and the dorsal section of the tunica albuginea through fibrous tissue formation. Autogenous transplants of fascia lata to this area have the same outcome but introduce additional tissue strength as well. Carbon fiber implants merely strengthen the dorsal and right side of the area of attachment between the apical ligament and the tunica albuginea.  Although success (return to breeding) has been reported with all methods, they have not been compared in controlled studies. Also, the rate of relapse has not been well documented.  Because the potentially heritable nature of spiral deviation (recessive, dominance or penetrance)  it is probably prudent to avoid surgery in these cases.

References:

Anderson, D.E. 2008. Surgery of the Prepuce and Penis. Vet. Clin. North America: Food Animal Practice. 24: 245-251

Ashdown, R.R. and Smith, J.A. 1969.The anatomy of the corpus cavernosum penis of the bull
and its relationship to spiral deviation of the penis. J. Anat. 104:153-159

Becket, S.D et al 1974. Corpus cavernosum penis pressure and penile muscle activity in the bull during coitus. Am. J. Vet. Research 35: 761-764

de Blockey, M.A.B. and Taylor, E.G. 1984. Observations on spiral deviation of the penis in beef bulls. Australian. Vet. J. 61:141-145

Lewis, J.E. et al. 1968. Blood pressure within the corpus cavernosum penis of the bull. J.Reprod. Fert. 17:155-156

McDiarmid, J.J. 1981 "Corkscrew penis" and other breeding abnormalities in beef bulls
 N. Zealand. Vet. J. 29:35-36

Mobini, S. 1982. An experimental evaluation of the response of the bull penis to carbon fiber implants Cornell Vet. 72:350-360

Pearson, H. 1974. Corkscrew penis: relapse in a bull after surgical correction, Corkscrew penis: relapse in a bull after surgical correction. Vet. Record. 94:225

Seidel, G.E. and Foote, R.H. 1969 Motion picture analysis of ejaculation in the bull. J. Reprod. Fert. 20: 313-317

Whitsell, D. 1969. Deviations of the bovine penis Iowa State University Veterinarian. 31. Article 5. 25-28.

The bovine clitoris

Keywords: clitoris, bovine, anatomy

The bovine clitoris is the homolog of the penis in males. In cattle it is a small structure; far smaller relative to the size of a cow than the equine clitoris relative to a mare. 

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Also, unlike the situation in mares, where the clitoris has three or more deep sinuses that harbor various pathogens (including T. equigenitalis), the bovine clitoris is simple, with a shallow, partially circumferential sinus (see image) that appears to play no major role in harboring reproductive pathogens such as Campylobacter fetus and Trichomonas fetus.

In beef animals, several studies have shown that short periods of clitoral stimulation immediately after A.I. will increase fertility modestly but significantly. The physiology behind this is not well understood but it has been linked to increased motility of the uterus. It is natural to speculate that increased motility is mediated by oxytocin but that has not been shown to be the case. Instead a local neural pathway has been suggested. Nevertheless, some hormonal involvement may be involved because the LH surge and ovulation may occur earlier in stimulated than non-stimulated cows. Interestingly, data on clitoral stimulation show that beneficial effects have only been demonstrated in older cows, not heifers. In dairy cows, the value of clitoral stimulation remains controversial; it has not been shown to be valuable yet it is still practiced by some A.I. technicians

Because the clitoris is a homolog of the penis and penile size is somewhat dependent on androgens, clitoral enlargement is a valuable sentinel for illegal use of anabolic steroid use in veal calves.

References:

Randel R.D. et al. 1973. Effect of clitoral massage after artificial insemination on conception in the bovine. J. Anim. Sci. 40: 1119-1123

Short, R.E. et al. 1979. Effect of clitoral stimulation and length of time to complete AI on pregnancy rates in beef cattle J. Anim. Sci. 49:647-650

Cooper, M.D. et al. 1985 Uterine Contractions and Fertility Following Clitoral Massage of Dairy Cattle in Estrus  J. Dairy Sci. 68: 703-708

Lunstra, D.D. er al. 1983. Clitoral stimulation and the effect of age, breed, technician, and postpartum interval on pregnancy rate to artificial insemination in beef cattle.Theriogenology. 19: 555–563

Groot, M.J. and den Hartog, J.M.P 1990  Histological Changes in the Genital Tract of Female Veal Calves Implanted with Naturally Occurring Anabolic Steroidsclitoris for androgenic activity can be useful in tracing illegal anabolic treatment of female veal calves with combination preparations.

J.Vet.Med.Series A 37: 775–786 

The uterine arteries

Keywords: uterus, artery, middle, arteries, anatomy

During transrectal palpation of the pregnant bovine uterus, it is common to feel for the presence of fremitus in a uterine artery. A video of a windsock, simulating fremitus can be seen here. It shows non-linear, turbulent flow of air through a windsock; the sock is unable to constrain the airflow in a linear, orderly fashion. During pregnancy in ruminants, blood flow to the uterus increases rapidly, exceeding the ability to contain the blood flow in a linear flow. The effect is the same in both cases.

Since antiquity, this artery has been referred to by clinicians as the middle uterine artery, implying that there are several major arteries within the mesometrium. Indeed, this is clearly the case as shown below (A, B & C...perhaps more). However, the image also shows that there is only one major uterine artery (UA) from which the smaller arteries emanate. That artery should correctly be referred to as the uterine artery.

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The question arises as to which of these arteries can develop fremitus during pregnancy. Clearly the major artery is capable of doing so. Therefore if there is any doubt as to which artery one is grasping during pregnancy diagnosis, it may be most correct to refer to "fremitus in the uterine artery" rather that "fremitus in the middle uterine artery". Finally, there is clearly potential for the development of an even number of large arteries in the mesometrium, in which case there can be no middle artery. Collectively therefore, the term "middle uterine artery" is probably incorrect in many instances of transrectal palpation. In the absence of clinical evidence to show otherwise, the term "uterine artery" should  be used.

The recto-genital pouch and ovariectomy in heifers

Keywords: recto-genital, spay, ovariectomy, anesthesia, anatomy

The recto-genital pouch of a cow. A ruler has been inserted into the pouch, pulling back its cranial peritoneal reflection. The pouch is perhaps, 5 to 6 cm deep at most. At its most cranial aspect, inside the vagina and below the black arrows, lies the external cervical os. This anatomy is important in a discussion on ovariectomy.

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Feedlot heifers are sometimes ovariectomized to prevent weight loss (through increased activity) and injury from mounting. The cost of the procedure and the lower weight gain and feed conversion in ovariectomized heifers are negative aspects of ovariectomy. Nevertheless, ovariectomized heifers appear to have an improved response to growth implants when compared to intact heifers. (U. Minnesota extension services data). Also, ovariectomized heifers are not considered to be breeding animals, therefore their movement out of TB zones is not restricted in the US.  Consequently, ovariectomy is still an important part of feedlot management.

Ovariectomy is usually performed via colpotomy (a per vagina incision); seldom via flank incision. Commonly, a Meagher ovary flute, Kimberling-Rupp or Willis (drop) spay instrument is used. It is the tip of Willis drop instrument that is shown in the image below. It is so named because the ovaries are not retrieved, but allowed to drop into the peritoneal cavity. 

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Whichever instrument is used, its tip is passed from through the dorsal wall of the vagina (adjacent to the fornix of the cervix) and into the peritoneal cavity as shown. This means that it penetrates the peritoneum in the cranial portion of the recto-genital pouch. The ovaries are then removed as described for each instrument.

In the author's experience with mares (where ovariectomy is performed for different reasons) the cranial vagina does not appear to be sensitive to cutting but is well-endowed with stretch-pain receptors. Strangely, mares do not respond if a scalpel incision is made in the fornix of the cranial vagina (beyond the cranial extent of caudal epidural anesthesia when used) but stretching and penetration through the peritoneum definitely cause discomfort. In addition, stretching of the mesovarian ligaments and the use of an ecraseur to remove the ovary are both painful. Therefore, flushing of these structures with local anesthetic is required to proceed humanely. Even under general anesthesia in bitches that are being ovariectomized, traction on the ovarian ligaments can cause pain and tachycardia. Ovariectomy in feedlot heifers is usually done in the complete absence of anesthesia. In this author's opinion, humane aspects of ovariectomy in heifers should be addressed more progressively than they are. 

At present, the policy of the American Veterinary Medical Association (AVMA) in this regard is as follows: 

"When ovariectomy is deemed necessary the procedure should be performed using appropriate restraint and aseptic technique. Research leading to new or improved techniques that reduce or eliminate pain and discomfort associated with ovariectomy, or development of viable alternatives to ovariectomy, is encouraged." 

The bovine infundibulum

Keywords: anatomy, bovine, ovary, infundibulum

The complex flower-like appearance of a bovine infundibulum suspended in water. A key to this image appears below it.

The macroscopic complexity of the bovine infundibulum may exceed that the equine infundibulum. The functional significance of this is open to debate. Also remarkable is the sculpted, frilly margin of the mesopsalpinx i.e. the margin of the ovarian bursa. The bright pink appearance of the uterine tube is striking as well.  It is important to note that no color adjustments were used in the processing of this image. It was however photographed with LED lighting at 5000K, perhaps explaining why these colors are so vivid and unexpected.

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Key:

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Normal postpartum bovine uterus.

Keywords: postpartum, suckling, beef, dairy, lochia, involution, uterus, estrus, ovulation

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A normal completely-involuted bovine uterus. Note to the typical Y-shaped structure with a short body and two long horns. In the left ovary, a follicle approximately 2 cm in size can be seen developing. In the contralateral (right) ovary, there appeared to be no significant structures. This is typical of a postpartum reproductive tract in a suckled beef cow.. Cows (milk but not suckled) may ovulate as soon as 10 or 14 days after calving, long before the uterus has even involuted.

Species placentation

Keywords: placentation, placenta, species, comparative, anatomy

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An amalgam of images showing the gross anatomy of the placentas of various domestic species.  All of these occur in the domestic animals but many other forms occur in other animals. For example, primates and humans have a discoid type of placentation; more intimate than any in domestic animals.

In image A, a multiplex type placenta is illustrated. In this case, it is the placenta of a ewe; similar to that of a cow (seen in image B) with subtle differences.

Image C from a neonatal calf, shows that the sites of the caruncles are established very early in the life.

Image D shows the zonary placenta of a dog; similar to that of a cat, shown in image E.

The placentas in F, G and H are all diffuse in character: Image F shows the placenta of a piglet, G the placenta of a foal and H, the placenta of a Llama, a new world camelid. Interestingly (although they are similar to ruminants) all of the camelids have diffuse placentas, not the multiplex type of placentas that one finds in domestic ruminants.