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Is this foal septicemic?
Physical signs can provide early clues for veterinarian in the field


Identifying secondary sites of infection

Photo 3: Petechial hemorrhages inside the ears is a reliable clinical sign associated with septicemia.
If the innate immune system is incapable of controlling the infection as septicemia progresses, secondary sites of infection may develop. With the bloodstream serving as the conduit, essentially all tissues of the body are susceptible to secondary infection. Tissues that receive a large portion of the cardiac output and experience turbulent, slow or unique blood supplies, are targeted first and include physes, synoviae, the uveal tract, meninges, endocardium, liver, kidney and skin/muscle.

Any neonatal foal that has joint swelling, periarticular edema, lameness or prolonged recumbency should be carefully evaluated for sepsis. The cardinal signs of uveitis are blepharospasm, epiphora, miosis, aqueal flare, edema of the iris and hypopyon (Photo 5). These signs most often manifest bilaterally in septic foals, though unilateral presentation can occur.

Foals with meningitis often have an altered mental status, ataxia, seizures and a stiff, "guarded" neck and gait. Endocarditis is an infrequent complication of septicemia in foals. Tachycardia, tachyarrhythmia, lethargy, murmurs, jugular pulsation and dependent edema may be signs of endo-carditis.

Healthy neonatal foals commonly have a low-grade systolic murmur over the semilunar valves over the left heart base. However, loud murmurs over the semilunar valves, murmurs over the mitral or tricuspid valves or those that are accompanied by other signs of cardiac disease should be investigated further by echocardiography.

Hepatic, splenic and renal abscessation may occur secondary to septicemia, though secondary infection in these anatomic locations rarely cause localizing clinical signs.

Photo 4: Uveitis, characterized by cloudiness, aqueal flare or fibrin (arrow) in the anterior chamber, is a sign of advanced septicemia.
When the systemic pro-inflammatory response to infection is uncontrolled and malignant, the clinical state of shock and MODS (Multiple Organ Dysfunction Syndrome) ensue.

Septic shock is defined as hypotension accompanied by signs of hypo-perfusion (altered mental status, hypothermia, hypotension, shivering, cold extremities, mucous membrane pallor, bradycardia or tachycardia, poor capillary or jugular vein refill, poor pulse quality, oliguria and ileus) that is induced by the presence of sepsis, is the result of systemic vasodilation and persists, despite adequate fluid resuscitation.

The manifestations of MODS are vast and the signs reflect the organs that are predominantly affected. These may include mental deterioration, ataxia, seizures, oliguria, coagulo-pathy, dyspnea, tachypnea, tachycardia or bradycardia, colic and/or ileus. Ultimately, identification of clinical signs or physical findings of secondary infection, shock or MODS is significant. These conditions not only identify an advanced and improperly controlled disease state, but they also are associated with a poor prognosis.

Photo 5: Basophilic cytoplasm, vacuolization Dohle bodies (arrow) in neutrophils, are reliable signs of bacterial infection.
Finally, when evaluating a neonatal foal for any reason, consider that any primary disease can induce a state of immunosuppression and/or cause loss of integrity of local protective barriers that subsequently welcomes infection. For example, other common diseases during the neonatal period, such as neonatal isoerythrolysis, neonatal encephalopathy, uroperitoneum, neonatal asphyxia syndrome, meconium impaction, diarrhea or any cause of colic, may be complicated by concurrent infection.

Michelle Henry Barton is the Josiah Meigs Distinguished Teaching Professor at the University of Georgia's College of Veterinary Medicine, where she is a large-animal internist in academic practice. She received her DVM from the University of Illinois in 1985, her PhD in physiology at the University of Georgia in 1990 and became an ACVIM diplomate in 1990.


Source: DVM360 MAGAZINE,
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