Uterine infection and abortion are major complaints in camelid veterinary practice.Rates of abortion caused by infectious diseases vary from 10% to > 70% in some areas (1).
Leptospirosis, toxoplasmosis, and chlamydiosis have been diagnosed as the major causes of abortion in llamas and alpacas. In camels, brucellosis and trypanosomiasis are the major causes of infectious abortion in the Middle East and Africa.
The general approach to diagnosing causes of abortion in camelids is similar to that in other species. However, camelids have several unique features of placentation and pregnancy:
In 98% of cases, pregnancy is carried in the left uterine horn (2).
The placenta is epitheliochorial, microcotyledonary diffuse (as in horses); however, the allantochorion adheres to the amniotic sac.
The corpus luteum is the only source of progesterone throughout gestation.
The mechanism of maternal recognition of pregnancy is still unknown.
Noninfectious Causes of Abortion in Camelids
Noninfectious causes of abortion in camelids include the following:
fetal or placental abnormalities (twinning, umbilical cord torsion, severe deformities, chromosomal abnormalities, placental insufficiency, and uterine torsion)
luteal insufficiency (hypoluteidism)
environmental stressors (severe disease process; long, stressful trip; heat stress)
iatrogenic causes (administration of prostaglandin F2alpha, corticosteroids, eight-way vaccines).
Poor luteal function is often observed in very obese animals, and hypothyroidism is suspected to be a predisposing factor (3).
The presence of large avillous areas suggest placental insufficiency. Twin conceptions are not rare, and most are decreased to a singleton or lost by day 45. Abortion of twins generally occurs between 5 and 9 months of pregnancy.
On a herd basis, abortion can be the result of nutritional deficiencies (selenium, vitamin A, iodine) or toxicoses (copper, iodine). Lactating and very young maiden females can have an increased incidence of embryo and fetal losses.
Bacterial Causes of Abortion in Camelids
The most commonly diagnosed infectious causes of pregnancy losses in camelids 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. Chlamydia abortus has been associated with infertility and ovarian hydrobursitis in camels.
Brucellosis (cause by Brucella abortus or Brucella 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) (1).
Coxiella burnetii, a known cause of abortions and stillbirths in small ruminants and cattle, has been detected in aborted alpacas and llamas (4).
Nonspecific bacterial infections (eg, with Escherichia coli or Streptococcus equi zooepidemicus) are often isolated in cases of camelid abortion due to placentitis.
Leptospirosis, brucellosis, chlamydiosis, and coxiellosis are zoonotic; humans can contract the disease from contact with infected urine or tissues from camelids.
Treatment, prevention, and control: Treatment of individual camelids with bacterial infections that cause abortion depends on the causative organism and on the clinical status of the dam. Antimicrobial therapy should be initiated when an active bacterial infection is suspected, with drug selection guided by culture and antimicrobial susceptibility testing whenever possible.
Treatment of an established placental infection might not prevent fetal loss, particularly when placental damage is advanced. Supportive care should be provided to systemically ill females.
Fungal Causes of Abortion in Camelids
Sporadic cases of camelid abortion due to Encephalitozoon cuniculi and Aspergillus spp have been reported (5).
Protozoal Causes of Abortion in Camelids
Reported protozoal causes of abortion in camelids include toxoplasmosis (Toxoplasma gondii), neosporosis (Neospora caninum), and sarcocystosis (Sarcocystis aucheniae and Sarcocystis cruzi).
Tritrichomonas foetus, the agent that causes trichomoniasis, has been isolated from camels; however, there is no strong evidence that it is involved in abortion.
Viral Causes of Abortion in Camelids
Viral causes of abortion in camelids 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 in camelids can occur at any stage of gestation, or a weak, persistently infected cria might be born prematurely. The birth of a persistently infected animal can have substantial effects on a herd.
Diagnosis of BVDV infection in camelids is based on virus isolation from fetal blood, fetal tissues (lymph nodes), and placenta. Immunohistochemistry may be performed on formalin-fixed tissues. PCR assay on whole blood samples is commonly used to screen neonatal crias.
References
Tibary A, Fite C, Anouassi A, Sghiri A. Infectious causes of reproductive loss in camelids. Theriogenology. 2006;66(3):633-647. doi:10.1016/j.theriogenology.2006.04.008
Barraza DE, Zampini R, Apichela SA, Pacheco JI, Argañaraz ME. Changes in mucins and matrix metalloproteases in the endometrium of early pregnant alpacas (Vicugna pacos). Acta Histochem. 2018;120(5):438-445. doi:10.1016/j.acthis.2018.05.009
Tibary A, Rodriguez J, Sandoval S. Reproductive emergencies in camelids. Theriogenology. 2008;70(3):515-534. doi:10.1016/j.theriogenology.2008.04.024
Rüfli I, Gurtner C, Basso WU, Vidondo B, Hirsbrunner G, Zanolari P. Causes of abortions in South American camelids in Switzerland—cases and questionnaire. Animals (Basel). 2021;11(7):1956. doi:10.3390/ani11071956
Webster JD, Miller MA, Vemulapalli R. Encephalitozoon cuniculi-associated placentitis and perinatal death in an alpaca (Lama pacos). Vet Pathol. 2008;45(2):255-259. doi:10.1354/vp.45-2-255
