Contrast-enhanced computed tomographic evaluation of the deep digital flexor tendon in the equine foot compared to macroscopic and histological findings in 23 limbs

REASONS FOR PERFORMING THE STUDY

Distal deep digital flexor tendinopathy is an important cause of foot lameness in horses that is difficult to diagnose with radiography and ultrasonography. Magnetic resonance imaging is a well-accepted and validated technique for the identification of deep digital flexor tendon (DDFT) lesions, but has some practical and financial drawbacks. Contrast-enhanced computed tomography (CECT) has been proposed as a suitable alternative, but validation studies are currently lacking.

OBJECTIVE

To assess the accuracy of CECT for the identification and characterisation of deep digital flexor tendinopathy.

STUDY DESIGN

Descriptive study of CT, macroscopic and histological findings of the DDFT.

METHODS

Plain and CECT scans were acquired of 23 limbs of 16 horses with clinical lameness localised to the foot. All horses had lesions of the DDFT that were identified and characterised with CT and CECT with respect to their anatomic location and extent. All horses underwent post mortem examination and gross abnormalities were described. Samples of the DDFT were taken at specific sites (lesion and nonlesion) for histological evaluation. Macroscopic and histological outcomes were compared with CECT findings.

RESULTS

Of 67 sites in 23 DDFTs that were evaluated, 42 sites in 18 tendons had lesions on CECT images. These 42 sites also had lesions on macroscopic evaluation. There were 3 false negative and 3 false positive results identified on CECT. The sensitivity of CECT for diagnosing lesions of the DDFT in the equine foot was 93%.

CONCLUSION

CECT is an effective adjunct to the more commonly used diagnostic techniques in equine foot pain.

Acute fasting in heifers as a model for assessing the relationship between plasma and follicular fluid NEFA concentrations

It is known from epidemiological studies that negative energy balance in early lactating dairy cows is related to a depression in reproductive performance. Elevated plasma concentrations of non-esterified fatty acids (NEFA) are a typical metabolic characteristic of these animals and are proposed as the possible link. The suggestion is that NEFA might have a direct effect on the ovary, by affecting development of the oocyte or the granulosa cells. However, no data is available concerning the relationship between the concentration of NEFA in follicular fluid and plasma. Therefore, a cross-over study with 10 heifers around 15 months of age was conducted to analyze this relationship and examine the suggested effects of the negative energy balance on follicular growth. Investigation of these effects was performed on fasted heifers. The experimental treatment consisted of feeding hay with a subsequent period of fasting, to induce elevated plasma NEFA concentrations. Sampling of follicular fluid was performed using transvaginal aspiration of follicles, which were standardized using a synchronization protocol. In addition, concentrations of glucose, insulin, NEFA, and estradiol were measured in plasma. Follicular estradiol and progesterone concentrations were also measured to assess the quality of the dominant follicle. Fasting resulted in significantly lower plasma glucose (P=0.0006) and plasma insulin (P<0.0001) concentrations, higher plasma estradiol (P=0.008) and higher NEFA (P<0.001) concentrations, and smaller follicles (P=0.04) with lower estradiol:progesterone (E/P) ratios (P=0.05). Concentrations of NEFA in follicular fluid and plasma were closely related. Given this close relationship, we concluded that the presence of high plasma NEFA concentrations might link energy metabolism in early lactation with fertility.