In current animal production systems, the reproduction of species on farms is the basis for obtaining economically satisfactory results from an entrepreneurial point of view.

Thus, infertility problems, mainly represented by infectious abortions, constitute a key issue impacting the productivity of farms.

Abortion outbreak: huge economic issue

Indeed, if we consider the ovine species, the onset of abortion outbreaks affecting a high percentage of pregnant ewes represents a very serious economic problem for the farmer.

In addition to the loss of lambs there is also milk production, and the possible onset of complications which can be cause for the animals’ future infertility.

It is estimated that the cost of an abortion in sheep at the end of pregnancy, which occurs with a high percentage of infectious abortions, exceeds €300, not just as a consequence of direct losses. 

Also, due to the costs of maintenance and unproductivity for more than six months, the time required for animals to recover and become pregnant again in order to be productive.

 

| The cost of 1 abortion can exceed €300

The percentages of 3-4% of abortions in the flock, which is usually related to management, is considered normal and economically feasible on intensive farms.

The problem arises when these rates significantly increase as a result of causes not to do with management, like that which occurs when abortions of an infectious nature occur.

There are many infectious agents that can cause abortive diseases in sheep livestock, classified as viral, bacterial, parasitic and fungal.

Infectious agent in sheep abortions

 

• In terms of viral agents, these include border disease or bluetongue disease.
  
   
• Bacterial agents include Chlamydia abortus (agent causing ovine enzootic abortion), Coxiella burnetii (causing Q fever), Salmonella Abortusovis (responsible for paratyphoid abortion), Brucella melitensis, and others with a lower incidence such as Listeria monocytogenes, Campylobacter fetus and Leptospira spp.
  
   
• The parasites include protozoans Toxoplasma gondii and, to a lesser extent, Neospora caninum.
  
   
• Fungal infections occur less frequently, although they can induce sporadic abortions in some species of relatively ubiquitous genera such as Aspergillus, Absidia, Mucor and Rhizopus.

It is important to consider that in some of these infections, in addition to their veterinarian interest from a health and economic point of view, their zoonotic nature must be highlighted, such as in the case of brucellosis, Q fever, toxoplasmosis and chlamydiosis.

 

| Some abortive diseases are zoonosis and therefore, high risk for human health

The majority of prevalence data come from private veterinary laboratories dedicated to laboratory diagnosis.

Official data from each country are difficult to obtain. Despite all this, in a large number of studies reported, ovine enzootic abortion, caused by Chlamydia abortus, is the main cause of abortion in Europe.

<sup>REFERENCES:

Due to the extensive bibliography used in the writing of this article, the references have not been included in the text. If the reader would like further information about any aspect of this monograph, please direct your questions to the authors at the following email address: jsalinas@um.es</sup>