Prognosis for survival to discharge and racing performance in Thoroughbred foals treated for single joint septic arthritis (2009–2016)

Abstract

Background: Haematogenous septic arthritis is a major cause of morbidity and mortality in foals. Previous research has demonstrated a variable prognosis for athletic performance in foals diagnosed with septic arthritis. Objective: To determine the racing prognosis for Thoroughbred foals, 6 months of age or less with single septic joint of presumed haematogenous origin without recognised systemic sepsis or other serious comorbidity compared with a group of maternal sibling controls. Study design: Retrospective cohort study. Methods: Data were collected from Rood and Riddle Equine Hospital in-patient records from 2009 to 2016. Parameters evaluated included: diagnostic tests, therapeutic regimens, final diagnosis and outcome. Racing records were obtained from a public archive for cases and two maternal siblings. Univariable analyses of categorical variables were conducted.Results: Ninety-five cases of Thoroughbred foals 6 months of age or less were included in this study. The last measured synovial cell count prior to hospital discharge or euthanasia (OR 0.5, p value 0.002, 95% CI: 0.3-0.8) was an indicator of poor prognosis for survival to discharge. Overall, the prognosis for survival was high (93%). Total winnings per career were the only statistically significant racing performance variable between cases and paired controls (IRR 0.7, p value, 0.05, 95% CI: 0.5-0.99).Main limitations: Retrospective study, evaluation of one regional population, potential for unknown prior exclusionary treatment on farm, unknown chronicity, no data on acute phase proteins and proportion of neutrophils of synovial fluid and unknown medical records of controls.Conclusions: While total winnings were reduced compared with maternal siblings, Thoroughbred foals with single joint septic arthritis have a favourable prognosis for both survival and starting in a race.

Clinical insights: Outcomes of juvenile orthopaedic lesions

“…Interestingly, foals requiring advanced treatments to resolve the septic arthritis, which comprised of procedures such as an arthroscopy or arthrotomy, had similar outcomes in racing performance and survival to discharge. Additionally, racing performance was not affected in foals with osteomyelitis lesions concurrently with septic arthritis 5 . This is valuable information when counselling clients in the ongoing management of the more resistant cases, and it does indicate that these foals do not have hopeless prognoses.…”

“…Career earnings and racing performances were similar to the maternal sibling controls. Similarly, in 2023, a study found 70% of foals discharged from hospital raced 5 . It was pointed out that these percentages are higher when compared with Jockey Club statistics, and the authors proposed this could be related to the regional value of the horses 6 .…”

“…Similarly, in 2023, a study found 70% of foals discharged from hospital raced. 5 It was pointed out that these percentages are higher when compared with Jockey Club statistics, and the authors proposed this could be related to the regional value of the horses. 6 Further noteworthy data concluded the treated foals' total career winnings were significantly lower than the maternal sibling controls.…”

“…This is valuable information when counselling clients in the ongoing management of the more resistant cases, and it does indicate that these foals do not have hopeless prognoses. Important information to gain from these studies is the temporal shift in the bacteria cultured in these septic arthritic foals; gram positives were most commonly encountered, namely Streptococcus spp 4,5,7 . For empirical treatment of septic arthritis cases, this knowledge is pertinent.…”

Highlights of recent clinically relevant papers

“…This retrospective cohort study by Katrijn Whisenant and co‐workers in the United States aimed to determine the racing prognosis for Thoroughbred foals, 6 months of age or less with a single septic joint of presumed haematogenous origin without recognised systemic sepsis or other serious comorbidity compared with a group of maternal sibling controls .…”