IDENTIFICATION

Most males considered for BSE should have an accurate and lasting identification. Ear tags, collars, and recently, microchips are used to identify animals. Different brands of microchips, ear tags, and collars are available on the market. Microchips, once properly inserted, last for as long as the animal lives. They are easily inserted beneath the skin in various parts of the body. Most common places are at the base of the ear’s pinna. Sometimes, though, the microchip may be inserted at the base of the tail. Owners in the United States use specific names for their animals and usually the name refers to or is correlated to the animal’s lineage.

EXAMINATION OF THE EXTERNAL GENITALIA^1–3

Testicles are a set of paired organs within the scrotum located in the perineal area of the animal. They should be ovoid in shape and resilient to digital palpation. The scrotum is relatively small, nonpendulous, and protrudes from the body outline in a position rather similar to that seen in boars and dogs. The testicles should move freely within the scrotum. Any attachment to the scrotum may signify a previous or ongoing insult to them. The longitudinal and transverse axes of the testicles may be measured using calipers. The testicles increase in size with age (Table 116-1), represent 0.02% of the animal’s body, and mature relatively slowly. Ultrasonography of the testicles may be done with the animal in a standing position or in lateral recumbency. The echo texture of the testicle is hypoechogenic with a clear echogenic line in the middle indicating the presence of the mediastinum.

Table 116-1 Mean Testicular Size and Testosterone Concentrations by Age in Llamas and Alpacas

The epididymis may also be palpated, and head, body, and tail portions can easily be distinguished. In llamas and alpacas, the head of the epididymis is bigger than the tail, in contrast to rams and bulls in which the tail is markedly bigger than the head.

The penis has a sigmoid flexure just cranial to the scrotum, and the tip of the prepuce is directed caudally in the nonaroused state. Thus, the stream of urine is directed backward. However, during copulation and with the aroused penis, the prepuce is directed cranially. The penis may also be inspected when the animal is sedated and in lateral recumbency. For this purpose, the sigmoid flexure may be straightened by manual manipulation and the penis may be pushed toward the preputial orifice while the other hand retracts the prepuce. A second person is needed to grasp the penis with a gauze sponge and exteriorize it to check for anatomic abnormalities. In young animals, the prepuce is attached to the penis and this natural attachment disappears with time, driven by the rise in circulating testosterone at 21 to 24 months of age. The glans penis is totally free from any attachment by 3 years of age. The process of detachment begins with the distal tip of the glans.

EXAMINATION OF THE INTERNAL GENITALIA^1–4

The internal organs that may be evaluated are the prostate and the bulbourethral glands. The prostate has been examined by ultrasonography and has been described as a hypoechogenic mass of tissue located cranial to the bladder. The bulbourethral glands may be also evaluated digitally and by ultrasonography. Digitally, a gloved and lubricated finger is inserted into the rectum and is directed laterally where two well-defined and hard rounded structures are palpated. By ultrasonography, the bulbourethral glands appear as discrete, round structures with a hypoechogenic texture.