Is this foal septicemic?
Physical signs can provide early clues for veterinarian in the field
May 01, 2008
Septicemia, defined as the systemic reaction caused by the presence of microorganisms or their toxins in the blood, often is cited as the most common reason for illness and death in the neonatal period.
Thus, based on its definition, a positive blood culture usually is considered the gold standard of diagnostic proof of septicemia. However, the inherent delay in obtaining the results of blood culture precludes a timely diagnosis, which is vital for a successful outcome.
The purpose of this and the following article next month is to review physical findings and laboratory tests that can alert the practitioner working in the field that septicemia is likely.The physical examination
In performing the physical examination, one should specifically try to identify potential primary routes of infection, signs of a clinical response to infection and signs of advanced infection into secondary sites.
Primary sites of infection
The skin, umbilicus and digestive, respiratory and genitourinary tracts should be carefully examined as potential sites of primary bacterial invasion.
Considering that gram-negative enteric bacteria, notably Escherichia coli, account for the majority of cases of septicemia in foals, it logically follows that the gastrointestinal tract is the most common primary site of infection.
External evidence of omphalophlebitis may not be grossly apparent for several days to one to two weeks after initial infection. Occasionally, despite significant infection of the umbilical vessels or urachus interior to the body wall, there will be no obvious evidence of disease in the external umbilical stump. Clinical signs consistent with infection of the umbilical remnants include heat, swelling, patentcy, pain of the umbilical stalk or discharge or moistness from or around the stalk.
Surprisingly, even severe infection of the respiratory tract may not manifest clinical signs in neonatal foals. Often the only signs of respiratory-tract disease are the presence of unexplained tachypnea, nasal flare or dyspnea. Other localizing signs, such as nasal discharge, cough, pleurodynia or audible abnormalities, when present, are incriminating clues.
The clinical response to infection
All of these signs often are associated with the onset of fever. The cyclic nature of fever necessitates serial evaluation; otherwise it may be overlooked. As the inflammatory response to infection intensifies, other signs of systemic disease appear, including tachycardia, tachypnea, bilateral scleral injection (Photo 1), hyperemia of the coronary bands, unpigmented skin (Photo 2) and mucous membranes (Photo 3), petechial hemorrhages and edema. Petechiae in the pinnae (Photo 4) are a highly reliable indicator of sepsis in the foal and may develop as a result of either thrombocytopenia or vasculitis.