Comparison of 18 F-sodium fluoride positron emission tomography and computed tomography for imaging of the fetlock in 25 nonracehorses

BACKGROUND

18 F-sodium fluoride (18 F-NaF) positron emission tomography (PET) has been validated as a useful imaging technique in the racehorse fetlock. The use of 18 F-NaF PET in the nonracehorse fetlock has not been reported.

OBJECTIVES

To describe 18 F-NaF PET findings in nonracehorse fetlocks, to compare with computed tomography (CT) findings and to compare PET findings between horses with and without fetlock pain.

STUDY DESIGN

Retrospective observational study.

METHODS

All horses undergoing 18 F-NaF PET and CT imaging of the fetlock between October 2016 and March 2021 were included in the study. Medical records were reviewed for associated lameness information.

RESULTS

Thirty-six fetlocks (33 front and 3 hind) from 25 horses were included. The interobserver agreement for PET [0.62 (95% confidence interval [CI] 0.59-0.65)] was higher than for CT [0.47 (95% CI 0.43-0.51)]. Increased 18 F-NaF uptake was most common in the medial subchondral bone of the proximal phalanx (23/36), the dorsomedial (20/36) and dorsosagittal (16/36) metacarpal/metatarsal distal subchondral bone, whereas sclerosis was identified on CT in these areas in 22 of 36 (p > 0.9), 33 of 36 (p = 0.001) and 23 of 36 (p = 0.15), respectively. Significant correlations were found between PET grades and both subchondral sclerosis and resorption CT grades (p < 0.001, Spearman r = 0.19 and 0.21, respectively). Abnormal 18 F-NaF uptake in the proximal sesamoid bones (PSBs) was identified in 12 of 36 of the fetlocks, which was more common than CT abnormalities (3/36, p = 0.02). Periarticular increased uptake was seen in 7 of 36 fetlocks, whereas osteophytosis was recognised on CT in 20 of 36 (p = 0.1). Maximal standardised uptake values (SUVmax) were significantly higher in painful than in nonpainful fetlocks (22.0 and 11.9, respectively, p = 0.038).

MAIN LIMITATIONS

Retrospective study and limited sample size.

CONCLUSIONS

Overall PET and CT findings follow a similar distribution in their location. PET identified more abnormalities in the PSBs than CT. SUVmax is a pertinent factor to take into consideration for the assessment of the clinical significance of findings.

Establishment of a sequential dual tracer 18 F-NaF/18 F-FDG PET protocol for imaging the equine foot

The combination of ¹⁸ F-Sodium Fluoride (¹⁸ F-NaF) and ¹⁸ F-FluoroDeoxyGlucose (¹⁸ F-FDG) for positron emission tomography (PET) imaging of the equine foot is appealing for detection of both osseous and soft tissue lesions in a single scan. As the combination of tracers could lead to a loss of information, a sequential approach, consisting in imaging with one tracer prior to injecting the second tracer, might be valuable. The goals of this prospective, methods comparison, exploratory study were to establish the order of tracer injection and timing for imaging. Six research horses were imaged under general anesthesia with ¹⁸ F-NaF PET, ¹⁸ F-FDG PET, dual ¹⁸ F-NaF/¹⁸ F-FDG PET, and CT. Proper uptake could be identified in tendon lesions as early as 10 min after 18F-FDG injection. Bone uptake was limited when 18F-NaF was injected under general anesthesia, even at 1 h after injection, when compared with ¹⁸ F-NaF injection prior to anesthesia. The sensitivity and specificity of the dual tracer scans were 0.77 (0.63 to 0.86) and 0.98 (0.96 to 0.99) respectively, to assess ¹⁸ F-NaF uptake and 0.5 (0.28 to 0.72) and 0.98 (0.95 to 0.99), respectively, for 18F-FDG uptake. These results suggest that the sequential dual tracer approach is a pertinent technique to optimize the PET data gained from a single anesthetic episode. Based on dynamics of tracer uptake, the optimal protocol consists in injecting 18F-NaF prior to anesthesia, acquire 18F-NaF data then inject 18F-FDG and start acquisition of dual tracer PET data 10 min later. This protocol should be further validated in a larger clinical study.

In Vitro Generated Equine Hepatic-Like Progenitor Cells as a Novel Potent Cell Pool for Equine Metabolic Syndrome (EMS) Treatment

Equine metabolic syndrome (EMS) is recognized as one of the leading cause of health threatening in veterinary medicine worldwide. Recently, PTP1B inhibition has been proposed as an interesting strategy for liver insulin resistance reversion in both equines and humans, however as being a multifactorial disease, proper management of EMS horses further necessities additional interventional approaches aiming at repairing and restoring liver functions. In this study, we hypothesized that in vitro induction of Eq_ASCs hepatogenic differentiation will generate a specialized liver progenitor-like cell population exhibiting similar phenotypic characteristics and regenerative potential as native hepatic progenitor cells. Our obtained data demonstrated that Eq_ASCs-derived liver progenitor cells (Eq_HPCs) displayed typical flattened polygonal morphology with packed fragmented mitochondrial net, lowered mesenchymal CD105 and CD90 surface markers expression, and significant high expression levels of specific hepatic lineage genes including PECAM-1, ALB, AFP and HNF4A. therewith, generated Eq_HPCs exhibited potentiated stemness and pluripotency markers expression (NANOG, SOX-2 and OCT-4). Hence, in vitro generation of hepatic progenitor-like cells retaining high differentiation capacity represents a promising new approach for the establishment of cell-based targeted therapies for the restoration of proper liver functions in EMS affected horses.

Mitochondria transfer restores fibroblasts-like synoviocytes (FLS) plasticity in LPS-induced, in vitro synovitis model

Background

Synovitis (SI) is one of the most common and serious orthopedic diseases in horses of different age, breed and sex, which contributes to the development of osteoarthritis. The burden of SI includes economic loss and represents a real challenge for current veterinary health care. At the molecular level, fibroblasts-like synoviocytes (FLS) are recognized as major cell populations involved in SI pathogenesis. In the course of SI, FLSs are losing their protective and pro-regenerative cytological features, become highly proliferative and initiate various stress signaling pathways.

Methods

Fibroblast-like synoviocytes were treated with LPS in order to generate SI in vitro model. Mitochondria were isolated from peripheral blood derived mononuclear cells and co-cultured with FLS. After 24 h of culture, cells were subjected to RT-qPCR, western blot, cytometric and confocal microscopy analysis.

Results

Mitochondrial transfer (MT) was observed in vitro studies using confocal microscopy. Further studies revealed, that MT to LPS-treated FLS reduced cell proliferation, modulated apoptosis and decreased inflammatory response. Overall, MT Resulted in the considerable recovery of recipient cells cytophysiological properties.

Conclusions

Presented data provides evidence that mitochondria transfersignificantly modulate FLS proliferative and metabolic activity through improved mitochondrial biogenesis and dynamics in activated FLS. Obtained results for the first time demonstrate that horizontal MT might be considered as a therapeutic tool for synovitis treatment; however, further clinical studies are strongly required.

18 Fluorine-fluorodeoxyglucose positron emission tomography for assessment of deep digital flexor tendinopathy: An exploratory study in eight horses with comparison to CT and MRI

Lesions of the deep digital flexor tendon (DDFT) are a cause for foot lameness in horses. Positron emission tomography (PET) could provide valuable information regarding the metabolic activity of these lesions. The aims of this exploratory, prospective, methods comparison study were to assess the ability of ¹⁸ fluorine-fluorodeoxyglucose (¹⁸ F-FDG) PET to detect DDFT lesions and to compare the PET findings with CT and MRI findings. Eight horses with lameness due to pain localized to the front feet were included. Both front limbs of all horses were imaged with ¹⁸ F-FDG PET, noncontrast CT, and arterial contrast-enhanced CT; 11 limbs were also assessed using MRI. Two observers graded independently ¹⁸ F-FDG PET, noncontrast CT, arterial contrast CT, T1-weighted (T1-w) MRI, and T2-weighted (T2-w)/STIR MRI. Maximal standardized uptake values were measured. Lesions were found in seven of 16 DDFT on PET, 12 of 16 DDFT on noncontrast CT, six of 15 DDFT on arterial contrast CT, eight of 11 DDFT on T1-w MRI, and six of 11 DDFT on T2-w/STIR MRI. Positron emission tomography was in better agreement with arterial contrast CT (Kappa-weighted 0.40) and T2-w/STIR MRI (0.35) than with noncontrast CT (0.28) and T1-w MRI (0.20). Maximal standardized uptake values of lesions ranged from 1.9 to 4.6 with a median of 3.1. Chronic lesions with scar tissues identified on noncontrast CT or T1-w MRI did not have increased ¹⁸ F-FDG uptake. These results demonstrated that ¹⁸ F-FDG PET agreed more closely with modalities previously used to detect active tendon lesions, i.e. arterial contrast CT and T2-w/STIR MRI. ¹⁸ Fluorine-fluorodeoxyglucose PET can be used to identify metabolically active DDFT lesions in horses.

Isolation of Campylobacter fetus subspecies fetus from an abdominal abscess in an adult mare

A 12-year-old Warmblood mare was referred for evaluation of behavioral changes not explained by general physical examination or lameness evaluation. Transrectal ultrasound examination was performed to determine if the behavioral changes were related to ovarian abnormalities, and a large abscess was found near the base of the cecum. Laparoscopic-guided aspiration and lavage of the abscess cavity followed by injection of benzyl penicillin G was carried out. Culture of the lavage sample yielded Campylobacter fetus subspecies fetus, an organism not previously reported as an etiological agent in abdominal abscesses in horses. The mare was treated after surgery with an extended course of antibiotics (minocycline per os q12h for 10 days followed by enrofloxacin per os q24h for 42 days). The mare resumed work in competitive eventing 10 months after surgery, and the behavioral complaints had resolved according to the owner. Key clinical message: We describe the diagnosis and treatment of a mare with an abdominal abscess from which Campylobacter fetus subspecies fetus was cultured. This organism has not previously been reported as an etiological agent in abdominal abscesses in horses.

Soluble epoxide hydrolase activity and pharmacologic inhibition in horses with chronic severe laminitis

BACKGROUND

The roles of soluble epoxide hydrolase and lipid mediators in inflammatory and neuropathic pain could be relevant in laminitis pain management.

OBJECTIVES

To determine soluble epoxide hydrolase (sEH) activity in the digital laminae, sEH inhibitor potency in vitro, and efficacy of a sEH inhibitor as an adjunct analgesic therapy in chronic laminitic horses.

STUDY DESIGN

In vitro experiments and clinical case series.

METHODS

sEH activity was measured in digital laminae from euthanised healthy and laminitic horses (n = 5-6/group). Potency of 7 synthetic sEH inhibitors was determined in vitro using equine liver cytosol. One of them (t-TUCB; 0.1 mg/kg bwt i.v. every 24 h) was selected based on potency and stability, and used as adjunct therapy in 10 horses with severe chronic laminitis (Obel grades 2, one horse; 3-4, nine horses). Daily assessments of forelimb lifts, pain scores, physiologic and laboratory examinations were performed before (baseline) and during t-TUCB treatment. Data are presented as mean ± s.d. and 95% confidence intervals (CI).

RESULTS

sEH activity in the digital laminae from laminitic horses (0.9±0.6 nmol/min/mg; 95% CI 0.16-1.55 nmol/min/mg) was significantly greater (P = 0.01) than in healthy horses (0.17±0.09 nmol/min/mg; CI 0.07-0.26 nmol/min/mg). t-TUCB as an adjunct analgesic up to 10 days (4.3±3 days) in laminitic horses was associated with significant reduction in forelimb lifts (36±22%; 95% CI 9-64%) and in pain scores (18±23%; 95% CI 2-35%) compared with baseline (P = 0.04). One horse developed gas colic and another corneal vascularisation in a blind eye during treatment. No other significant changes were observed.

MAIN LIMITATIONS

Absence of control group and evaluator blinding in case series.

CONCLUSIONS

sEH activity is significantly higher in the digital laminae of actively laminitic compared with healthy horses, and use of a potent inhibitor of equine sEH as adjunct analgesic therapy appears to decrease signs of pathologic pain in laminitic horses.

SRY negative 64,XX intersex phenotype in an American saddlebred horse

A female American saddlebred horse was presented for surgical correction of a possible pseudohermaphrodite condition. The horse had abnormal external genitalia and exhibited stallion-like behaviour. No evidence of uterine or ovarian tissue was identified on laparoscopic examination, but hypoplastic testicular-like tissue was removed, although this was found to contain no spermatogonia upon histopathological examination. A karyotype was performed and showed the normal chromosomal complement for a female horse (64,XX). Polymerase chain reaction to detect the SRY gene was negative in peripheral blood as well as the testicular-like tissue. This case represents the first report of an SRY negative XX-male sex reversal intersex phenotype, which is a potentially inherited condition, in an American saddlebred horse.

Facilitation of Asian elephant (Elephas maximus) standing immobilization and anesthesia with a sling

An Asian elephant (Elephas maximus) required general anesthesia for orthopedic foot surgery. The elephant was unable to lie down, so it was placed in a custom-made sling, administered i.m. etorphine hydrochloride in the standing position, and lowered to lateral recumbency. General anesthesia was maintained with isoflurane administered through an endotracheal tube. After surgery, the isoflurane anesthesia was terminated, with immobilization maintained with additional i.v. etorphine. The elephant was lifted to the vertical position, and the immobilizing effects of etorphine were reversed with naltrexone. The suspension system and hoist for the sling were designed specifically for the elephant house.

Comparative study on the interstitial passage of cefuroxime, cefoxitin, cefotaxime and cefoperazone in man by the suction skin blister method

A comparative study was carried out on the concentration of cefuroxime, cefoxitin, cefotaxime and cefoperazone in serum and extravascular blister fluid. The results show that cefoperazone (which has the highest protein binding capacity) has a lower and slower extravascular penetration than the other cephalosporins examined.

[Choroidal miliary tuberculosis: fluoroangiographic study (author's transl)]

The authors have followed the evolution of disseminated choroidal tuberculosis during a period of 16 months. At the beginning of the disease, fluorescein angiography showed an early 'screen effect' and later a 'focus effect'. During the later stage of the disease, the pigmented epithelium was seen to be involved as well, as demonstrated by (1) the presence of advanced pigmented chorioretinitis at the sites where the tubercles were observed at the beginning of the disease and (2) the presence of fluorescent areas early during fluorescein angiography.

Suction skin blister, skin window, and skin chamber techniques to determine extravascular passage of cefotaxime in humans

We report the results obtained in comparative study on the extravascular passage of cefotaxime, employing three different methods: suction skin blister, skin window, and skin chamber. Applying the skin blister method in two different ways, we also studied the influence that suction pressure and time lapse between blister formation and antibiotic injection had on the results obtained in order to standardize the method and establish repeatability of the results. Using the skin chamber method, we studied the influence that the different protein contents in the fluid used to fill the skin chamber had on extravascular concentrations.