Pregnancy loss is a common complaint in camelid practice. The general approach to diagnosis is similar to that in other species. However, camelids have several unique features of placentation and pregnancy. In nearly all pregnancies, the fetal horn is the left uterine horn, and the placenta is epitheliochorial, microcotyledonary diffuse (such as in the horse), but the allantochorion adheres to the amniotic sac.
Noninfectious causes of abortion include fetal or placental abnormalities (twinning, umbilical cord torsion, severe deformities, chromosomal abnormalities and placental insufficiency, uterine torsion), luteal insufficiency (hypoluteidism), environmental stressors (severe disease process; long, stressful trip; heat stress), or iatrogenic causes (administration of prostaglandin F2α, corticosteroids, 8-way vaccines). Recurrent loss due to luteal insufficiency has been associated with obesity and possibly hypothyroidism. Presence of large avillous areas suggest placental insufficiency. Twin conceptions are not rare, and most are reduced to singleton or lost by day 45. Abortion of twins is generally seen between 5 and 9 mo of pregnancy.
On a herd basis, severe losses may be seen with nutritional deficiencies (selenium, vitamin A, iodine), or toxicosis (copper, iodine). Lactating and very young maiden females may have an increased incidence of embryo and fetal losses.
Viral causes of abortion are dominated by bovine viral diarrhea virus (BVDV). However, abortions due to equine herpesvirus 1, equine arteritis virus, and bluetongue virus have been reported. The most common BVDV serotype that affects alpacas and llamas is noncytopathic BVDV-1b. Abortion may occur at any stage of gestation, or a weak, persistently infected (PI) cria may be born prematurely. The birth of a PI animal can have significant effects on a herd of animals. Diagnosis of BVDV infection is based on virus isolation from fetal blood, fetal tissues (lymph nodes), and placenta. Immunohistochemistry may be performed on formalin-fixed tissues. PCR on whole blood samples is commonly used to screen newborn crias.
The most commonly diagnosed infectious causes of pregnancy losses are chlamydiosis and brucellosis (in some parts of the world). Chlamydia spp have been identified as a cause of abortion and birth of weak crias in llamas. C abortus has been associated with infertility and ovarian hydrobursitis in camels.
Brucellosis (Brucella abortus and B melitensis) is a common cause of abortion in camelids in some areas of the world.
Other reported bacterial causes of abortion in camelids include leptospirosis (Leptospira interrogans serogroups Icterohaemorrhagiae and Ballum), listeriosis (Listeria monocytogenes), and campylobacteriosis (Campylobacter fetus fetus). Coxiellosis (Coxiella burnetii) abortion is suspected to occur but has not been diagnosed definitively.
Nonspecific bacterial infections (Escherichia coli, Streptococcus equi zooepidemicus) are often isolated from cases of abortion that were due to placentitis.
Reported protozoal causes of abortion in camelids include toxoplasmosis (Toxoplasma gondii), neosporosis (Neospora caninum), and sarcocystosis (Sarcocystis aucheniae and S cruzi). Trichomoniasis (Tritrichomonas foetus) has been isolated from camels, but there is no strong evidence it is involved in abortion.