History and General Physical Examination

General and reproductive history should cover all parameters that may have an impact on reproductive performance including age, type of animal, and breeding management system. A history of previous illnesses and treatments is important because of their possible effect on reproductive performance, and the information helps identify females with high-risk pregnancies. Complete clinical evaluation of the female, including body condition and actual weight, should be done before any manipulation of the genital tract.

Female behavior provides a relatively accurate and inexpensive means for pregnancy diagnosis.¹ The behaviors most indicative of reproductive status are spitting and attempting to escape, which are consistent with the presence of a corpus luteum.² Receptivity on the other hand is not well correlated with ovarian status.^2,3 Absence of rejection of the male (spitting) strongly suggests nonpregnancy.⁴

Per Rectum Palpation and Ultrasonography

Transrectal ultrasonography of the genital tract is performed using a 7.5-MHz or 5-MHz linear transducer. For alpacas, the transducer is mounted on a handle to allow manipulation without inserting the hand in the rectum. Ultrasonography allows a more precise evaluation of follicular and luteal activity within the ovary. In the early stage of the follicular wave, the ovary appears elliptical with several small (2 to 5 mm in diameter) follicles disposed along the periphery in a diadem fashion. Dominance is established when follicular diameter reaches 6 mm. The dominant follicle continues to grow steadily until it reaches its maximal size of 9 to 14 mm in llamas and 8 to 12 mm in alpacas.^5,6 Visualization of the corpus luteum after mating is possible within 3 days.⁵ The corpus luteum is less echogenic than the ovarian stroma. It appears as a protruding round structure, sometimes with a central cavity. In other cases, the mature corpus luteum has a dense, hyperechoic central area in the shape of a star. The diameter of the mature corpus luteum varies between 11 and 13 mm.

Pathologic changes of the ovaries detected by ultrasonography include cystic changes (anovulatory or hemorrhagic follicles), inflammation, and tumors. Hypoplastic ovaries are very small and the condition is suspected if ovaries cannot be visualized. In Camelidae, development of large anovulatory hemorrhagic follicles is common in the absence of ovulation-inducing stimulus. Periovarian cysts are not rare and should be differentiated from enlarged oviducts. Ovarian inflammation (oophoritis) is suspected when the ovarian size is normal or slightly increased and does not show clear delineation from the rest of the tissue. Ovarian tumors are suspected when the ovary is enlarged and show an abnormal echotexture with no clear follicular dynamic. The ultrasonographic appearance of the ovary depends on the type of neoplasm.

During the follicular phase, the uterus is contracted and the uterine horns are straight. The echotexture of the uterus is usually heterogeneous and shows increased edema of endometrial folds. During the luteal phase, the uterus is relaxed and homogeneous with a medium degree of echogenicity. Abnormalities can be of two types: abnormal uterine echotexture (endometritis, metritis, neoplasm) and abnormal uterine content (pyometra, mummification, maceration, embryonic death).^7,8 Evaluation of the uterine wall can be facilitated by ultrasonography while the uterus is being flushed.

Vaginal Examination

The vulva is inspected for any discharge or lesions and its size and conformation are evaluated. The size of the vulva in Camelidae is relatively small compared to other species. Females presenting increased size and edema of the vulva should be examined for recent parturition or abortion. Abnormal size and position of the vulva in maiden females may suggest presence of congenital abnormalities or intersexuality. Intersexed animals present ambiguous external genitalia sometimes with a rudimentary penis. The distance from the anal sphincter to the vulvar opening is usually increased and the animal shows urinary difficulties.⁹ Copious vaginal discharge beyond 7 days post partum is almost always pathologic. Vaginal discharge is suspected upon observation of dried material on the ventral aspect of the tail or by matting of the wool around the tail and perineal area.

Digital examination of the vestibulovaginal area should be performed on all maiden females (persistent hymen and segmental aplasia) and females with pyometra or hydrometra (vestibular or vaginal adhesions). Open-sided specula are helpful if a biopsy punch or a culture swab needs to be guided into the cervix. The most frequent abnormalities encountered in the vagina and cervix are inflammations or adhesions. Vaginal adhesions are a frequent cause of pyometra or mucometra and inability to copulate.¹ The most frequent development abnormality of the cervix in camelidae is the presence of a double cervix.¹ In some cases a thorough vaginal and cervical evaluation requires the use of a flexible endoscope.

Uterine Cytologic Examination and Culture

Endometritis is a common cause of infertility in Camelidae. It is confirmed by uterine cytology and culture. Samples should be taken from the uterine cavity using a double guarded swab. Swabs are examined routinely for aerobic and anaerobic bacteria, Ureaplasma, Mycoplasma, and fungus.¹⁰ The bacteria responsible for endometritis in camelids are essentially those found in the equine and bovine species. Uterine culture may be negative in many cases of chronic endometritis. In the experience of the author, endometrial samples for cytologic examination are best obtained using a cytobrush instead of a swab.

Uterine Biopsy

Uterine biopsy is used to detect inflammatory, degenerative, or neoplastic changes in the endometrium.¹¹ The technique is similar to that used in the equine. The cervix can be opened by administration of estradiol (0.5 mg) 6 to 8 hours before biopsy. Larger doses of ECP may produce excessive edema and are often counter-productive. The author prefers to perform all manipulation requiring bypassing the cervix without the use of estrogens. This can be accomplished if examination is done when the female has a preovulatory follicle. Evaluation of the specimen should be done by a person familiar with the normal histologic features of the camelid endometrium. Degenerative changes are mainly due to the presence of periglandular or perivascular fibrosis. In severe cases, nesting with cystic dilation of the endometrial glands or lymphatic cysts is observed. A classification of lamoid endometrial biopsies has been proposed.¹¹

Endocrinologic Evaluation

Determination of progesterone levels in blood is pro-bably the most widely used hormone assay in Camelidae.¹² Progesterone levels above 1.5 ng/ml indicate the presence of a functional corpus luteum or luteinized anovulatory follicle. The assay is commonly used to determine occurrence of ovulation in bred females. Pregnancy is suspected if progesterone level remains high in a second sample taken 2 to 3 weeks after breeding. This method of pregnancy diagnosis is relatively precise if breeding history is accurate. Plasma estrogens levels above 10 pg/ml in plasma indicate presence of follicular activity.

Hysteroscopy

Hysteroscopy is easily performed using a 9-mm diameter flexible videoendoscope. The cervical canal and uterine cavity can be evaluated for the presence of adhesions, cystic dilation, or abnormal content. Targeted biopsy may be performed during hysteroscopy.^1,13 The papilla at the uterotubal junction is prominent and easily identified. The most common lesions seen at this level are cysts and inflammation of the papillae.

Laparoscopy and Laparotomy

Laparoscopy is an invaluable technique for the confirmation of lesions suspected by ultrasonography or palpation (ovarian hypoplasia, hydrosalpinx, segmental aplasia, periuterine adhesions, etc.), particularly in alpacas.^1,14–16 Selected cases for these procedures include alpacas with suspected ovarian hypoplasia, ovarian masses, hydrosalpinx, pyosalpinx, ovarian and uterine adhesion, and segmental aplasia of the uterus and uterine tubes. Laparotomy is indicated for oviductal flushing to verify the patency of the uterine tube.

Cytogenetic Evaluation

All Camelidae have the same number of chromosomes (n = 74). Abnormal karyotype has been associated with different forms of reproductive problems in Camelidae. Cytogenetic studies should be considered when external sexual characteristics are ambiguous or when there is extreme aplasia of the ovary or genitalia. Cytogenetic abnormalities described in camelids include XO, XXX, XXY, XX/XY, and XX sex reversal.^1,9 A minute chromosome has been described in several lamoids, but its significance in infertility is not yet known (L. Buoen and A. Weber, personal communication).

Lack of Receptivity to the Male

Female reluctance to breed may be due to pregnancy (first rule-out). Behavioral problems are relatively common and may be associated to dominance or sexual differentiation disorders. Reluctance to breed may be caused by pain during mating.

Persistent corpora lutea are rare in the female Camelidae. However, the condition has been suspected in llamas on the basis of prolonged periods of high progesteronemia without pregnancy.^1,18 Many of these conditions may not be truly “persistent corpora lutea” but rather persistent luteinized hemorrhagic follicle. These structures may respond to prostaglandin F (PGF_2α), but injection may need to be repeated.

Lack of ovarian activity (anestrus or ovarian hypoplasia) does not necessarily translate to lack of receptivity, as many females with these conditions may continuously accept the male.