Racing performance of juvenile Thoroughbreds with femoropatellar osteochondrosis at auction: A retrospective case-control study

BACKGROUND

Osteochondrosis dissecans (OCD) is common in the femoropatellar joint in Thoroughbred yearlings for sale at auction and there is no consensus on the effect on racing outcomes.

OBJECTIVES

Describe femoropatellar OCD in juvenile Thoroughbreds and compare the racing performance of affected Thoroughbred horses to siblings and unaffected horses from the same sale.

STUDY DESIGN

Retrospective case-control study of juvenile horses born 2010-2016.

METHODS

Radiographic reports from 27 Thoroughbred auctions of weanling (5-11 months of age) and yearling (12-22 months of age) horses were reviewed to identify femoropatellar OCD. Age and sex of cases and controls were obtained from the sales catalogue. Racing performance was obtained from an online database. Correlation between lesion characteristics and racing performance were assessed using Pearson and Spearman correlations for continuous and ordinal/categorical variables respectively. Racing performance was compared between cases and sibling controls and age- and sex-matched sale number controls from the same sale with Poisson distribution and log link. Significance level of alpha = 0.05 was used.

RESULTS

Femoropatellar OCD was identified in 429 horses with North American race records. OCD was present on 519 lateral trochlear ridges and 54 medial trochlear ridges. There were more males in the case group (70%) than in the sibling control group (47%). Case racing performance was compared to 1042 sibling and 757 hip controls. There were significant but small decreases in racing metrics of cases and increases in males for years raced, total starts, starts for 2-5 years of age, total placings, and placings at 2-4 years of age. Analysis of specific lesion metrics revealed weak correlations for performance outcomes (positive and negative) resulting in an inability to draw firm conclusions.

MAIN LIMITATIONS

Retrospective study where case management was unknown.

CONCLUSIONS

Femoropatellar OCD in juvenile Thoroughbreds for sale at auction decreases some racing outcomes.

Equine heel bulb lacerations: 62 cases (2004–2018)

OBJECTIVE

To characterize clinical findings and outcomes for horses with heel bulb lacerations.

ANIMALS

Medical records of a teaching hospital were reviewed to identify horses treated for heel bulb lacerations between February 2004 and October 2018. Long-term outcome was assessed by telephone communication with owners. Results were analyzed to determine association with clinical outcome.

RESULTS

31 mares and 31 geldings of various ages, breeds, and uses were evaluated. Thirty-six horses had a wound of 0 to 2 days’ duration, and 17 horses had a wound of > 2 days’ duration. Horses with a wound duration of < 2 days had a significantly greater likelihood of a higher outcome score (P = .025; OR = 7.08; 95% CI = 1.28% to 39.08%). Synovial communication with the wound was confirmed in 21 of 62 (33.9%) horses. One synovial structure was involved in 17 horses, and > 1 synovial structure was involved in 4 horses. Fifty-nine horses survived to discharge, and follow-up information was available for 18 (30.5%) horses. Of the horses available for follow-up, 78% returned to the previous level of work (14/18). Degree of lameness at presentation, degree of wound contamination, treatment prior to presentation, treatment with foot casting, and involvement of synovial structures were not found to be significantly associated with clinical outcome.

CLINICAL RELEVANCE

Results suggest that horses with heel bulb lacerations have a good prognosis for survival and a favorable prognosis for return to work. Clinical application of additional findings needs further investigation before clinical relevance can be ascertained.

Synovial butorphanol concentrations and mechanical nociceptive thresholds after intravenous regional limb perfusion in standing sedated horses

OBJECTIVE

To determine synovial butorphanol concentrations and mechanical nociceptive threshold (MNT) changes after butorphanol intravenous regional limb perfusion (IVRLP).

STUDY DESIGN

Experimental ANIMALS: Six adult horses.

METHODS

Cephalic IVRLP was performed with 10 mg butorphanol in sedated horses with a wide rubber tourniquet and a total volume of 30 mL. Radiocarpal synovial fluid and serum concentrations along with MNT were evaluated prior to and 0.5, 1, 2, 4, and 6 hours after IVRLP. Butorphanol concentrations were determined with liquid chromatography coupled to tandem mass spectrometry positive electrospray ionization.

RESULTS

Butorphanol concentrations reached mean (SD) peak concentrations of 9.47 ng/mL (±12.00) in synovial fluid and 3.89 ng/mL (3.29) in serum 30 minutes after IVRLP. Concentrations remained above baseline for 4 hours in synovial fluid (P ≤ .017) and for 2 hours in serum (P ≤ .016). The only difference in MNT was detected 1 hour after IVRLP, when MNT were higher in controls than in treated horses (P = .047).

CONCLUSION

Butorphanol IVRLP seemed well tolerated and resulted in measurable levels of butorphanol in the radiocarpal synovial fluid of five of six horses.

CLINICAL SIGNIFICANCE

Intravenous regional limb perfusion appears to be a viable alternative to administer butorphanol, but additional investigation is required to evaluate the dose and local concentrations required for analgesia.