Clinical and clinicopathological factors associated with survival in 44 horses with equine neorickettsiosis (Potomac horse Fever).

The research article explores factors associated with survival in horses diagnosed with equine neorickettsiosis (EN), a disease commonly known as Potomac Horse Fever. The study finds that the severity of colitis, hemoconcentration, prerenal azotemia, and treatment with the antibiotic oxytetracycline are key predictors of survival.

Study Context and Methodology

• The study acknowledges that while the epidemiology of Equine neorickettsiosis (Potomac horse Fever) has been extensively studied, there is limited data about how clinical and clinicopathological factors influence the survival of naturally infected horses.
• The objective was to identify the factors that can predict survival in horses diagnosed with EN.
• The research applied a retrospective approach and used a convenience sample of 44 horses with EN admitted to two referral institutions.
• The diagnosis of EN was based on positive blood or fecal PCR (Polymerase chain reaction) – a method used to amplify the number of copies of a specific region of DNA, in order to produce enough DNA to be adequately tested.

Findings and Results

• The study identified the most common clinical signs of EN to be diarrhea, followed by fever, anorexia, depression, colic, and lameness.
• At the median, horses were hospitalized for 6 days, and 73% of them survived to be discharged.
• About 36% of the horses developed laminitis, a painful condition affecting the horse’s feet, with 88% of them affected in all their 4 feet.
• Nonsurvivors had significantly higher serum creatinine and urea nitrogen concentrations, red blood cell (RBC) count, blood hemoglobin concentration, hematocrit, band neutrophils, serum AST (Aspartate aminotransferase) activity, serum CK (Creatine Kinase) activity, and anion gap.
• On the other hand, nonsurvivors had significantly lower serum chloride and sodium concentrations, as well as a shorter duration of hospitalization.
• Analysis by logistic regression indicated independent factors associated with survival as blood hemoglobin concentration on admission and antimicrobial treatment with oxytetracycline.

Conclusions

• The researchers concluded that severity of colitis, which is reflected by electrolyte loss, hemoconcentration (increase in blood components due to loss of fluid), and prerenal azotemia (a type of kidney failure where more nitrogenous wastes are released into the blood), are indicators of survival in horses diagnosed with EN.
• Additionally, treatment with the antibiotic oxytetracycline was found to have a positive association with increased survival.