Effects of magnesium with or without boron on headshaking behavior in horses with trigeminal-mediated headshaking

Sensory nerve conduction stimulus threshold measurements of the infraorbital nerve and its applicability as a diagnostic tool in horses with trigeminal-mediated headshaking

BACKGROUND

To determine whether sensory nerve conduction stimulus threshold measurements of the infraorbital nerve are able to differentiate horses with idiopathic trigeminal-mediated headshaking (i-TMHS) from healthy horses and from horses with secondary trigeminal-mediated headshaking (s-TMHS). In a prospective trial, headshaking horses were examined using a standardized diagnostic protocol, including advanced diagnostics such as computed tomography and 3-Tesla-magnetic resonance imaging (MRI), to differentiate s-TMHS from i-TMHS. Clinically healthy horses served as controls. Within this process, patients underwent general anesthesia, and the minimal sensory nerve conduction stimulus threshold (SNCT) of the infraorbital nerve was measured using a bipolar concentric needle electrode. Sensory nerve action potentials (SNAP) were assessed in 2.5-5 mA intervals. Minimal SNCT as well as additional measurements were calculated.

RESULTS

In 60 horses, SNAP could be recorded, of which 43 horses had i-TMHS, six had suspected s-TMHS, three horses had non-facial headshaking, and eight healthy horses served as controls. Controls had a minimal SNCT ≥ 15 mA, whereas 14/43 horses with i-TMHS and 2/6 horses with s-TMHS showed a minimal SNCT ≤ 10 mA. Minimal SNCT ≤ 10 mA showed 100% specificity to distinguish TMHS from controls, but the sensitivity was only 41%.

CONCLUSION

A minimal SNCT of the infraorbital nerve ≤ 10 mA was able to differentiate healthy horses from horses with TMHS. Nevertheless, a higher minimal SNCT did not exclude i-TMHS or s-TMHS and minimal SNCT does not distinguish s-TMHS from i-TMHS.

The analgesic effects of magnesium in veterinary patients: a qualitative evidence synthesis

OBJECTIVE

To perform a qualitative evaluation of the analgesic effects of magnesium in domestic animals, including its anaesthetic sparing effects.

STUDY DESIGN

All database searches were made using PubMed and Google Scholar. Studies published after 1990, evaluating the use of magnesium and reporting information on analgesia, in dogs, cats, horses, cows, goats and sheep were selected (last search in August 2023). A reference check in the selected papers was performed to identify any study which was omitted. The CERQual (Confidence in Evidence from Reviews of Qualitative research) approach was used to assess confidence and analyse the evidence.

RESULTS

A total of 20 studies relevant to the analgesic effects of magnesium in veterinary patients and two reviews were included. All were published after 2006. Of the 20, five studies provided information about analgesia in the postoperative period in dogs with heterogenous results. Magnesium added epidurally increased the duration of the sensory block in several species. Motor block was also observed when added to spinal analgesia. Results regarding volatile agents sparing effect were conflicting. Occasional moderate adverse effects were reported in dogs, such as nausea and vomiting, when administered as a bolus in conscious animals, and hypotension when administered intraperitoneally. Collapse was reported in horses after epidural administration.

CONCLUSIONS AND CLINICAL RELEVANCE

The evidence of an analgesic effect of magnesium in veterinary patients remains scarce considering the paucity and low quality of published data. Further research may be helpful to establish the efficacy and indications of magnesium in multimodal analgesia in animals.

Applications of Biodegradable Magnesium-Based Materials in Reconstructive Oral and Maxillofacial Surgery: A Review

Reconstruction of defects in the maxillofacial region following traumatic injuries, craniofacial deformities, defects from tumor removal, or infections in the maxillofacial area represents a major challenge for surgeons. Various materials have been studied for the reconstruction of defects in the maxillofacial area. Biodegradable metals have been widely researched due to their excellent biological properties. Magnesium (Mg) and Mg-based materials have been extensively studied for tissue regeneration procedures due to biodegradability, mechanical characteristics, osteogenic capacity, biocompatibility, and antibacterial properties. The aim of this review was to analyze and discuss the applications of Mg and Mg-based materials in reconstructive oral and maxillofacial surgery in the fields of guided bone regeneration, dental implantology, fixation of facial bone fractures and soft tissue regeneration.

Intravenous magnesium sulphate in standing horses: effects on physiological parameters, plasma concentration of magnesium and nociceptive threshold tests

A bolus of 50 mg kg ^-1 MgSO₄ (treatment Mg) or the same volume of saline (treatment S) was infused over 15 minutes in 5 adult healthy horses. T0 was the end of the infusion. Physiological parameters were recorded throughout the study period. Measurements of electrical, thermal and mechanical nociceptive thresholds were performed at the pelvic limbs at baseline (before T0), and at specific timepoints. Blood samples were taken at fixed timepoints before, during and until 12 hours after the infusion. For statistical analysis, the 95% confidence intervals (CI's) for the differences in nociceptive thresholds between treatments were calculated. Physiological parameters were compared using a linear mixed model (global α = 0.05, with Bonferroni correction α = 0.0125). The concentrations of ions were also compared with baseline values at specific timepoints, using a linear mixed model. The Pearson's correlation coefficient was derived between the ion concentrations. The 95% CI's of thermal, mechanical and electrical thresholds were [-1; +2]°C, [0; +3] N and [-1; +1] mA (positive differences indicate higher thresholds for treatment Mg), respectively. Heart rate was significantly higher (p < 0.0001) and non-invasive systolic arterial pressure (p < 0.0001) and respiratory rate (p = 0.0002) significantly lower after treatment Mg compared to treatment S. Additionally, non-invasive systolic arterial pressure was significantly different at T45 (p < 0.001). Although mild changes in cardiovascular parameters and plasma concentrations were seen with intravenous administration of MgSO₄, no changes in nociceptive thresholds were detected in standing non-sedated horses.

Caecal microbiota in horses with trigeminal‐mediated headshaking

Background

Trigeminal‐mediated headshaking (TMHS) in horses is a form of neuropathic pain of undetermined cause that often results in euthanasia. The role of microbiota in TMHS has not been investigated in diseased horses.

Objective

To investigate if gastrointestinal microbiota in the cecum is different in horses with TMHS compared to a control population, during a summer season with clinical manifestations of disease.

Animals

Ten castrated horses: five with TMHS and five neurologically normal controls.

Methods

All horses were sourced from our institution and kept under the same husbandry and dietary conditions. All horses were fed orchard grass hay for 30 days and then were euthanized due to chronic untreatable conditions including TMHS and orthopedic disease (control group). Caecal samples for microbiota analysis were collected within 20 min after euthanasia. Sequencing was performed using an Illumina MiSeq platform and the microbiome was analyzed.

Results

The caecal microbiota of horses with TMHS was similar to control horses in terms of diversity but differed significantly with Methanocorpusculum spp. having higher abundance in horses with TMHS. 

Conclusions and clinical importance

Methanocorpusculum spp. was more abundant in the cecum of horses with TMHS. However, its role in disease is unknown. Furthermore, it could also represent an incidental finding due to our small population size.

Research status of biodegradable metals designed for oral and maxillofacial applications: A review

The oral and maxillofacial regions have complex anatomical structures and different tissue types, which have vital health and aesthetic functions. Biodegradable metals (BMs) is a promising bioactive materials to treat oral and maxillofacial diseases. This review summarizes the research status and future research directions of BMs for oral and maxillofacial applications. Mg-based BMs and Zn-based BMs for bone fracture fixation systems, and guided bone regeneration (GBR) membranes, are discussed in detail. Zn-based BMs with a moderate degradation rate and superior mechanical properties for GBR membranes show great potential for clinical translation. Fe-based BMs have a relatively low degradation rate and insoluble degradation products, which greatly limit their application and clinical translation. Furthermore, we proposed potential future research directions for BMs in the oral and maxillofacial regions, including 3D printed BM bone scaffolds, surface modification for BMs GBR membranes, and BMs containing hydrogels for cartilage regeneration, soft tissue regeneration, and nerve regeneration. Taken together, the progress made in the development of BMs in oral and maxillofacial regions has laid a foundation for further clinical translation.

Pharmacokinetics of magnesium and its effects on clinical variables following experimentally induced hypermagnesemia

The objectives of this study were to describe pharmacokinetic and pharmacodynamic changes as a result of a single intravenous administration of magnesium sulfate (MgSO₄ ) to healthy horses. MgSO₄ is a magnesium salt that has been used to calm horses in equestrian competition and is difficult to regulate because magnesium is an essential constituent of all mammals. Six healthy adult female horses were administered a single intravenous dose of MgSO₄ at 60 mg/kg of body weight over 5 min. Blood, urine, and cerebrospinal fluid (CSF) samples were collected, and cardiovascular parameters were monitored and echocardiograms performed at predetermined times. Noncompartmental pharmacokinetic analysis was applied to plasma concentrations of ionized magnesium (Mg²⁺ ). Objective data were analyzed using the Wilcoxon rank-sum test with p < .05 used as a determination for significance. Plasma concentrations of Mg²⁺ increased nearly fivefold, ionized calcium (Ca²⁺ ) decreased by nearly 10%, and the Ca²⁺ to Mg²⁺ ratio declined more than 3.5-fold and remained different than baseline until 24 hr (p < .05). Significant changes were seen with urinary fractional excretion of electrolytes, cardiovascular parameters, and echocardiographic measurements. No changes were detected in CSF electrolyte concentrations. The decrease in Ca²⁺ result of hypermagnesemia supports the interaction between these cations. Alterations detected in plasma electrolyte concentrations and urinary fractional excretion of electrolytes may serve as biomarkers for regulatory control for the nefarious administration of MgSO₄ .

Effects of magnesium with or without boron on headshaking behavior in horses with trigeminal-mediated headshaking

Background

Oral administration of magnesium and boron might have a beneficial effect on headshaking behavior in horses.

Objective

Evaluate the effects of oral magnesium alone or in combination with boron on headshaking behavior in affected horses.

Animals

Twelve geldings (6 healthy controls and 6 affected).

Methods

Prospective randomized controlled dietary trial over 42 days in 12 horses (6 horses diagnosed with trigeminal‐mediated headshaking and 6 unaffected healthy controls). All horses received a hay diet and were randomized into 3 treatment groups: pelleted feed combination (PF), pelleted feed combination with magnesium (M), and pelleted feed combination with magnesium‐boron (MB) with a week washout of hay only between treatments. Headshaking behavior and biochemical blood variables were assessed at baseline (hay only) and then after each week of supplementation.

Results

All 3 diet interventions increased blood ionized and total magnesium. Groups M and MB further increased Mg²⁺ when compared to PF. Horses receiving treatments had a significant reduction in headshaking behavior, as measured by incidence rate ratio (IRR), when compared to unsupplemented hay diet (44% for PF, IRR, 0.558; CI, 0.44, 0.72; P < .001; 52% for M, IRR, 0.476; CI, 0.37, 0.62; P < .001; and 64% for MB, IRR, 0.358; CI, 0.27, 0.48; P < .001).

Conclusions and Clinical Importance

Magnesium in combination with boron had the greatest decrease in headshaking. Oral supplementation with magnesium or magnesium in combination with boron should be considered in horses affected with headshaking.