Effect of anthelmintics on the gut microbiome

 While anthelmintic treatments are invaluable for controlling parasitic worm infections, new research shows they can also have unintended consequences on the gut microbiota. 

Michel Boisseau and colleagues conducted a study to explore how helminths, particularly cyathostomins, interact with the gut microbiota in their host animals. 

 

The research team observed naturally infected ponies to track changes in this relationship over time, both before and after treating them with pyrantel. (Pyrantel targets adult cyathostomins without affecting larval stages in the gut wall.) 

 

They also looked at how the ponies' blood gene expression responded to the anthelmintic treatment. Their work is reported in iScience.

 

The study involved 40 naturally infected Welsh pony mares, divided into four groups based on their worm burden and whether they received pyrantel treatment. 

 

Among the high shedding ponies, the researchers identified 14 species of cyathostomins, the most abundant of which was Cylicocyclus nassatus. They found that ponies with high cyathostomin egg counts had a richer and more dynamic gut microbiota. The presence of butyrate-producing Clostridia seemed to play an important role in maintaining stability within the ecosystem, while also bolstering host tolerance towards cyathostomin infections. Genes involved in B-cell activation and IgA synthesis were upregulated in high shedding ponies.

 

The administration of anthelmintic treatment induced a dramatic shift in the gut environment and microbial community dynamics, with the population being less stable. These changes were still present 7 days after treatment, and to a lesser extent after 15days. Anthelmintic treatment only had a limited effect on the host blood gene expression.

 

The researchers conclude: “These observations highlight how anthelmintic treatments alter the triangular relationship of parasite, host, and gut microbiota and open new perspectives for adding nutritional intervention to current parasite management strategies.”

 

 

For more details, see:

 

Michel Boisseau, Sophie Dhorne-Pollet, David Bars-Cortina, Élise Courtot, Delphine Serreau, Gwenolah Annonay, Jérôme Lluch, Amandine Gesbert, Fabrice Reigner, Guillaume Sallé, Núria Mach,

Species interactions, stability, and resilience of the gut microbiota - Helminth assemblage in horses,

iScience, Vol 26, 2, (2023), 106044.

 

https://doi.org/10.1016/j.isci.2023.106044

 

Assessing the impact of blindfolding on equine handling

Blindfolding horses is thought to make them easier to handle in stressful situations. By covering their eyes, blindfolds can reduce distractions that might make them anxious, especially in new or tense environments. However, there has been limited research in this area so far.

A study conducted by Caleigh Copelin, Bryn Hayman, Renée Bergeron, and Katrina Merkies at the University of Guelph investigated this topic. Their research suggests that blindfolding might offer benefits when encountering visually intimidating stimuli, especially in situations where time constraints are not present.

 

However, in emergency situations, such as barn fire evacuations, blindfolding is likely to prolong lead time and exacerbate handling difficulties. This could impede successful rescue efforts and potentially jeopardize the safety of both humans and animals.

 

The study involved thirty-three riding school horses led through a course of obstacles, both blindfolded and unblindfolded. Parameters such as time taken, lead rope pressure, heart rate, and frequency of avoidant or resistant behaviour were recorded and compared between the two groups.

 

Overall, blindfolded horses required more time and exerted greater lead rope pressure when led from a stall compared to unblindfolded horses. They also exhibited higher frequencies of avoidant and refusal behaviours and experienced higher heart rate increases during the process. 

 

However, when navigating a visually frightening obstacle (a gate made of pool noodles that brushed their flanks), blindfolded horses needed less time, exerted less lead rope pressure, and displayed fewer avoidant or refusal behaviours, than they did when not blindfolded.

 

The researchers suggest that blindfolding may be beneficial in situations involving visually frightening stimuli and where time constraints are not a concern. Nevertheless, further research is necessary to evaluate more realistically the effectiveness of blindfolds in simulated emergency scenarios.

 

For more details, see:

 

Copelin, C, Hayman, B, Bergeron, R, Merkies, K,.

Compliance or confusion? The usefulness of blindfolding horses as a handling technique,

Applied Animal Behaviour Science, (2024)

Vol 271,106180,

 

https://doi.org/10.1016/j.applanim.2024.106180

Iron-related inflammatory markers in colic

 

Colic is a major concern for horse owners, with two main types: those treatable with medicine
and those needing surgery. Quickly identifying which cases need surgery is crucial. 

 

In the early stages of inflammation, the liver releases acute phase proteins (APPs) like haptoglobin, fibrinogen, and serum amyloid A. Recent studies propose that blood iron levels could also indicate inflammation severity in colic cases.

 

Paulo Canola and colleagues evaluated serum ferritin, transferrin and iron levels as acute phase inflammatory markers in horses admitted to the hospital with colic. 

 

Ferritin, which stores iron in a non-toxic form, helping to regulate iron levels in the body, is recognized as a positive inflammatory marker, increasing in the acute phase

 

Transferrin, a glycoprotein found in blood plasma that binds to iron and transports it throughout the body, decreases in acute inflammation.

 

The researchers analysed these markers alongside total protein, fibrinogen, ceruloplasmin, albumin, and haptoglobin levels in blood samples from 12 colic surgery cases and 10 healthy horses. They compared healthy horses with colic cases, small and large intestinal obstructions, and survival rates. The work is published in the Journal of Equine Veterinary Science.

 

They found higher transferrin and haptoglobin levels and lower serum iron in colic cases compared to healthy horses. Large intestinal obstruction cases had lower transferrin levels than small intestinal obstruction cases. Fibrinogen levels were higher in horses more likely to die from strangulating lesions.

 

The researchers suggest that the acute phase proteins examined in the study could be used to evaluate the acute inflammatory response in horses with colic requiring surgery. 

 

 

For more details, see: 

 

P.A. Canola, R.F. de Salles, E.R. Daneze, M.F.R. Sobreira, B.E. de Oliveira, M.L. Favero, M.L. Antonioli.

Iron-related markers of inflammation in horses with colic.

Journal of Equine Veterinary Science, (2024) vol 134, 105010,

https://doi.org/10.1016/j.jevs.2024.105010

When. to treat melanoma?

(c) Callpso88 Dreamstme.com

 A recent report suggests that a more pro-active approach to melanomas in horses could bejustified.

Melanomas are common in horses. They are usually found underneath the dock of the tail, in the anal, perianal and genital regions, and on the lips, eyelids, and sometimes around the salivary glands. Typically, they present as rounded black nodules.

 

Grey horses are far more susceptible to melanoma than horses of any other coat colour, with up to 80% of grey horses developing a melanoma at some point in their lives.

 

Despite their prevalence, our understanding of various aspects of this disease remains incomplete.

 

Prevailing attitudes among some owners and veterinarians suggest a reluctance to intervene early, guided by the belief that these tumours progress slowly, and that surgical intervention may exacerbate the horse's condition. But is this approach justified? 

 

Researchers in Portugal conducted a study to evaluate the effect of delayed excision on the clinical, histological, and immunohistochemical characteristics of equine melanoma. Their findings are published in Animals.

 

For this retrospective investigation, the research team reviewed tissue samples and clinical records of horses whose melanoma tissues had been submitted between 2010 and 2023. An analysis was conducted on data from 34 horses, encompassing a total of 42 melanomas, of which 13 were benign and 29 were malignant. The primary objective was to explore the clinical and histological variances between tumours that underwent prompt excision versus those left untreated for an extended duration.

 

The study found significant correlations between delayed excision and adverse outcomes, shedding light on the potential repercussions of postponing surgical intervention in equine melanomas.

 

Tumours excised at later stages were significantly larger than those subjected to earlier intervention. Additionally, delayed excision correlated with a higher incidence of multiple tumours, particularly among horses harbouring melanomas for over six years.

 

But more importantly, the interval between excision and diagnosis demonstrated a pronounced link with tumour malignancy, Melanomas excised at later stages were five times more likely to exhibit malignant characteristics compared to those removed earlier. 

 

These findings highlight the impact of delayed excision on the progression and severity of equine melanomas.

 

The report’s authors conclude that early intervention not only facilitates easier tumour removal but also mitigates the risk of future complications. 

 

“With this work, we provide scientific and objective evidence that time significantly influences equine melanomas, contributing to an increase in their size, number, and malignancy. As such, this work clarifies the importance of early intervention in preventing future complications caused by these tumours. This data may help clinicians in advising horse owners.”

 

 

For more details, see: 

 

Pimenta J, Prada J, Pires I, Cotovio M. 

The Impact of Excision Interval on Equine Melanoma Progression: Time Matters? 

Animals. 2024; 14(8):1244.

https://doi.org/10.3390/ani14081244

Investigating cabergoline for treating equine Cushing’s disease

 Cabergoline shows promise as a treatment option for equine Cushing’s disease, according to a recent report.

Cushing’s disease or Pituitary Pars Intermedia Dysfunction (PPID) is a common condition in older horses, resulting from increased activity in the intermediate lobe of the pituitary gland. This excessive activity has been attributed to nerve damage impairing its regulation, with dopamine acting as the crucial neurotransmitter. When dopamine levels are deficient, the pituitary gland becomes overactive, leading to the release of various hormones, such as adrenocorticotropic hormone (ACTH).

 

Clinical manifestations associated with PPID are well-documented and include hypertrichosis, laminitis, polyuria, polydipsia, lethargy, muscle wastage, and delayed wound healing.

 

Dopaminergic agonists, medications that mimic the action of dopamine, function by stimulating dopamine receptors in the pituitary gland. This stimulation results in the inhibition of the release of certain hormones, including ACTH, thereby mitigating clinical signs such as abnormal hair coat, muscle wasting, and laminitis.

 

Pergolide, a dopamine agonist, stands as the primary treatment for managing PPID and is approved for oral administration in equines. However, some horses may exhibit resistance to daily oral dosing. Cabergoline, another dopamine agonist like pergolide, currently is not licenced for use in horses.

 

A recent retrospective study conducted by Tania Sundra of Avon Ridge Equine Veterinary Services in Brigadoon, WA, Australia, along with colleagues, explored the efficacy of intramuscular extended-release cabergoline (ERC) injection in treating PPID. Despite being unlicensed, this treatment modality is increasingly utilized off-label in clinical practice for managing PPID. The study examined clinical records of privately-owned horses with PPID that had undergone intramuscular cabergoline treatment at Avon Ridge Equine Clinic.

 

The study examined the short-term (5–8 days) and longer-term (12 months) clinical and endocrinological responses to two doses of cabergoline: a low dose (0.005mg/kg) extended-release cabergoline (LDERC) and a high dose (0.01mg/kg) extended-release cabergoline (HDERC).

 

Results showed that although both doses of ERC led to a decrease in median ACTH concentration, the levels remained above the seasonal reference range in about half of the treated horses. However, similar responses had been noted in previous studies involving pergolide treatment for PPID.

 

Owners reported clinical improvement in 78.3% and 100% of horses treated with LDERC and HDERC, respectively. 

Common side effects of dopamine agonists, such as decreased appetite, lethargy, gastrointestinal upset, and behavioural changes, were observed. Notably, partial, self-limiting inappetence was reported in 30.0% of LDERC cases and 60% of HDERC cases, with seven horses exhibiting lethargy.

 

In cases of partial anorexia, owners noted that horses preferred long-stem forage (hay or grass) over cereal-based feeds. The clinical and endocrinological responses observed were consistent with previous reports of oral pergolide treatment.

 

The authors suggest that weekly injection of ERC may serve as an effective alternative to pergolide. The 0.005 mg/kg dose appeared to be as effective as the 0.01 mg/kg dose but with a lower risk of inappetence.

 

While cabergoline shows promise as a treatment option for PPID in horses, further research is necessary to fully establish its efficacy, safety profile, and optimal usage protocols.

 

 

For more details, see: 

 

Sundra T, Kelty E, Rossi G and Rendle D (2024) 

Retrospective assessment of the use of extended-release cabergoline in the management of equine pituitary pars intermedia dysfunction. 

Front. Vet. Sci. 11:1332337. 

https://doi.org/10.3389/fvets.2024.1332337

Research into possible markers of joint health

(c) Virgonira Dreamstime.com

 Recent research suggests that microRNAs (miRNAs) present in blood and synovial fluid may one day serve as
valuable biomarkers for evaluating joint health.  

Osteoarthritis (OA) is prevalent among horses, particularly in athletic and older individuals, characterised by the gradual deterioration of synovial cartilage, underlying bone, and the synovial membrane of joints. Inflammation significantly contributes to OA's pathogenesis.

 

MiRNAs are implicated in the onset and progression of various diseases, including OA. They participate in regulating processes such as inflammation, cartilage degradation, chondrocyte apoptosis, and extracellular matrix (ECM) remodelling. By targeting genes involved in cytokine production, such as interleukins (ILs) and tumour necrosis factor-alpha (TNF-α), miRNAs modulate inflammatory responses.

 

Chondrocytes, the primary cells in cartilage tissue, play a pivotal role in maintaining cartilage homeostasis. Dysregulation of miRNAs can disrupt chondrocyte function and induce apoptosis, thereby contributing to cartilage degradation in OA.

 

Joshua Antunes and his colleagues at the Ontario Veterinary College, University of Guelph, Canada, undertook a study comparing miRNA levels in healthy and diseased joints, with their findings published in PLoS One.

 

In this small-scale investigation, they examined synovial fluid and blood samples from five horses with osteoarthritis (OA), five with osteochondritis dissecans (OCD), and four control horses. Samples were obtained from client-owned horses undergoing joint arthroscopy for OA or OCD, while control samples came from the Arkell Equine Research Facility's herd at the University.

 

Analysis revealed 57 miRNAs with differential expression in OA versus control plasma, 45 in OCD versus control plasma, and 21 in OA versus OCD plasma. Notably, they observed higher expression of miR-140-5p in OA synovial fluid, suggesting its potential as an early protective marker against OA progression.

 

The researchers emphasize the need for larger study cohorts to validate miRNAs as joint health biomarkers before reaching definitive conclusions. 

 

They also highlight the possibility of exploring miRNA-mRNA regulatory networks in OA, potentially leading to innovative miRNA-based diagnostic tools and therapies for this debilitating condition. Additionally, they propose further investigation into the therapeutic applications of these miRNAs for both OA treatment and prevention.

 

 

For more details, see:

 

microRNAs are differentially expressed in equine plasma of horses with osteoarthritis and osteochondritis dissecans versus control horses

Joshua Antunes, Ramés Salcedo-Jiménez, Starlee Lively, Pratibha Potla, Nathalie Coté, Marie-Soleil Dubois, Judith Koenig, Mohit Kapoor, Jonathan LaMarre, Thomas Gadegaard Koch

PLOS ONE

https://doi.org/10.1371/journal.pone.0297303

Interferon as potential treatment for periocular squamous cell carcinoma

Example of SCC, before (left) and after treatment

 with INFα-2b . (c) Martabano et al. For more photos, see

https://doi.org/10.1371/journal.pone.0297366.g001 

Injecting interferon alpha-2b (INFα-2b) may provide a new treatment for periocular squamous cell carcinoma in horses according to a recent report. 

Squamous cell carcinoma (SCC) is a type of skin cancer that commonly affects horses. 

 

SCC typically appears as nodules or masses on the skin or mucous membranes. These lesions can vary in size and colour but often appear ulcerated or crusted. SCC commonly affects areas with less pigment or areas exposed to sunlight, such as the eyelids, lips, and genital regions. 

 

Various treatment options may be considered including surgical excision, cryotherapy (freezing), laser therapy, topical medications, and radiation therapy.

 

A recent clinical investigation conducted by Brittany B. Martabano and colleagues from Colorado State University explored the efficacy of intralesional interferon alpha-2b (INFα-2b) treatment in 11 horses (12 eyes) diagnosed with periarticular squamous cell carcinoma (PSCC). The comprehensive findings of this study have been published in PLOS One.

 

Before commencing treatment, all horses underwent biopsy confirmation of PSCC diagnosis and were deemed healthy otherwise.

 

The treatment regimen involved injections, under sedation, of 10 million IU of INFα-2b every two weeks for a maximum of six sessions. The research team assessed the response by measuring lesion sizes before each treatment and subsequently at one, three, and twelve months after the end of the course of treatment. A response was considered positive if there was a reduction in tumour size exceeding 50%.

 

The researchers also checked for the development of antibodies against INFα-2b and assessed their potential impact on treatment response.

 

Results indicated that five out of twelve eyes (four out of eleven horses) responded positively to the treatment, with two eyes showing complete resolution of PSCC. No systemic adverse effects were observed, although local swelling occurred in six out of eleven horses during treatment, which resolved spontaneously.

 

All horses developed serum anti-IFNα2b antibodies, with no discernible difference in antibody concentration between responders and non-responders.

 

The researchers conclude that injecting IFNα2b into PSCC was well-tolerated in horses and led to tumour regression in 42% of treated eyes. They found no association between treatment failure and the development of IFNα2b antibodies.

 

 

For more details, see:

 

Intralesional interferon alpha-2b as a novel treatment for periocular squamous cell carcinoma in horses

Brittany B. Martabano, Steven Dow, Lyndah Chow, Margaret M. V. Williams, Maura K. Mack, Rebecca Bellone, Kathryn L. Wotman

Research Article | published 21 Feb 2024 PLOS ONE

https://doi.org/10.1371/journal.pone.0297366

 

Role of in-breeding in pregnancy loss

 A recent study conducted by the Royal Veterinary College (RVC) in collaboration with Cornell University sheds light on the role of inbreeding in mid and late-term pregnancy loss (MLPL) among UK Thoroughbreds. Interestingly, while inbreeding does impact MLPL, it has little effect on early pregnancy loss (EPL).

The research specifically explores the influence of genomic inbreeding levels on late-term pregnancy loss in horses. These findings provide valuable insights for breeding practices, which can help inform mating decisions to reduce the risk of miscarriages in Thoroughbreds.

 

Inbreeding, the mating of related individuals, is a common practice in the livestock industry and can be beneficial in controlled breeding programs for consolidating desirable traits within a population. However, excessive inbreeding heightens the likelihood of producing offspring with harmful homozygous recessive genotypes. This can lead to genetic disorders, reduced fertility, and decreased overall population fitness.

 

Approximately five to ten percent of equine pregnancies result in early pregnancy loss (EPL), while seven percent are lost between Day 70 of gestation and 24 hours postpartum (MLPL). Despite this, prior to this study, there had been no genomic analysis of the correlation between inbreeding levels and pregnancy loss in horses.

 

Led by Dr. Jessica Lawson, Alborada Trust Research Fellow at the RVC, and Professor de Mestre at the Baker Institute for Animal Health at Cornell University, along with former RVC PhD student Dr. Charlotte Shilton, the research team analysed DNA samples from 189 individuals. These samples included allantochorion and foetal DNA from early pregnancy loss (EPL) cases (n=37, gestation age 14–65 days), mid and late-term pregnancy loss (MLPL) cases (n=94, gestational age 70 days–24 hours post parturition), and hair or blood samples from adult UK Thoroughbred controls (n=58).

 

The study revealed that Thoroughbred pregnancies lost in mid and late gestation (MLPL) had significantly higher inbreeding metrics compared to UK Thoroughbred adult controls. Conversely, pregnancies lost early in gestation (EPLs) showed no significant difference in inbreeding metrics compared to controls.

 

These findings emphasise the importance of informed mating decisions in the Thoroughbred breeding industry. Moreover, they stress the need for further research to identify and characterise genomic changes that may prove detrimental to pregnancy.

 

Dr Jessica Lawson, Alborada Trust Research Fellow at the RVC, said: “This research provides critical evidence showing that mating highly related individuals does have a tangible effect on our breeding operations, as there is a real risk of a mare losing her pregnancy late in gestation and failing to produce a foal at all that season. 

 

“The take home from our work should be to carefully consider breeding choices that involve mating of highly related individuals as, ultimately, this may increase the chance of the foal inheriting mutations which may not be compatible with life. We are already working on the next step, looking to identify these changes so more specific advice can be provided in the future”.

 

This research was funded by the Thoroughbred Breeders Association, Horserace Betting Levy Board, the Alborada Trust, and partial PhD studentship funding from the Royal Veterinary College's Paul Mellon Trust for Equine Research.

 

For more details, see: 

Lawson JM, Shilton CA, Lindsay-McGee V, Psifidi A, Wathes DC, Raudsepp T, de Mestre, AM.

Does inbreeding contribute to pregnancy loss in Thoroughbred horses? 

Equine Vet J. 2024.

https://doi.org/10.1111/evj.14057

 

 

Edited press release. Read the original press release:

https://www.rvc.ac.uk/equine-vet/news/new-rvc-research-finds-inbreeding-is-contributing-factor-to-mid-and-late-term-pregnancy-loss-in-thoroughbreds

Effect of punch biopsy on sarcoid growth

 The common belief that taking biopsies of suspected sarcoids could make them worse may not be justified.

 Sarcoids, are the most common skin tumour of horses. Although typically benign, they can be locally aggressive and difficult to manage. They appear in various forms, including flat, nodular, verrucous, fibroblastic, and occult types. Bovine papillomavirus (BPV) has been implicated in the development of sarcoids, although the exact mechanism is not fully understood.

 

In standard veterinary practice, biopsies are a useful diagnostic tool for identifying the nature of swellings and masses. However, the fear of inadvertently worsening the condition has led many veterinarians to avoid biopsy procedures for sarcoids.

 

A recent small-scale study investigating the impact of punch biopsies on the growth of equine sarcoids challenges this assumption. The study failed to confirm the notion that biopsies could exacerbate the aggressiveness or spread of sarcoids.

 

Lien Gysens carried out the study with her colleagues at the Department of Large Animal Surgery, Anaesthesia and Orthopaedics of Domestic Animals, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium. A full rereport of tth research is published in Veterinary Dermatology.

 

The study included six client-owned horses with a total of 11 sarcoids. These horses, all Belgian Warmbloods, presented with a range of clinical types: three occult, four nodular, two verrucous, and two fibroblastic sarcoids.

 

To qualify for inclusion in the study, the horses had to test positive for BPV-1/-2. This was determined using superficial swabs, scrapings, or fine needle aspirates (FNA), which were then subjected to quantitative PCR (qPCR).

 

 The research team examined the dynamics of tumour growth, focusing on factors such as thickness, area, and circumference, as well as viral load (VL) and Visual Analog Scale (VAS) scores in horses affected by sarcoids who underwent a single diagnostic punch biopsy.

 

The growth of each sarcoid was closely monitored on a weekly basis for nine months: from 12 weeks prior to the punch biopsy to 24 weeks following the procedure.

 

In this preliminary study, the researchers didn't find any clear trend in how sarcoids grew after a single punch biopsy. 

 

They observed significant changes in all growth parameters after the biopsy, but there wasn't a consistent direction of change – some grew larger, some smaller, and some stayed the same.

Drawing definite conclusions is challenging due to the limited number of tumours (11 in total) from only six horses with four different types of clinical sarcoids.

 

They conclude: “Our results indicate that post-biopsy lesion deterioration is not a general concept that applies to all sarcoids, and both deterioration or improvement are possible outcomes over a 24-week period. Further clinical studies with a larger sample size are needed before a definitive conclusion can be made.”

 

 

For more details, see:

 

Gysens L,  Martens A,  Haspeslagh M.  

Longitudinal pilot study examining the effect of punch biopsy on equine sarcoid growth dynamics. 

Vet Dermatol.  2024; 35: 148–155.

https://doi.org/10.1111/vde.13236

Collagen link to Thoroughbred fracture risk

 

Recent research conducted by the Royal Veterinary College (RVC) sheds light on the genetic factors contributing to bone fractures in Thoroughbred horses. The study reveals that horses with diminished levels of collagen type III have a higher risk of fractures.

Previously, the underlying genetic mechanisms behind these fractures had remained elusive. However, these new findings have enabled the RVC to identify a novel DNA variant associated with fractures, impacting the expression of collagen type III.

 

Bone fractures are common in Thoroughbred racehorses, due to the forces the bones can experience, and are a leading cause of euthanasia. Approximately 60 horses each year are euthanised on UK racecourses as a result. However, fracture is a complex condition, with both environmental and genetic risk factors affecting a horse’s susceptibility.

Led by Dr. Debbie Guest, Senior Research Fellow at RVC, the team developed a polygenic risk score to gauge disease susceptibility based on various genes. They were then able to use this information to select cells from horses whose risk placed them at the extreme ends of the population with either very low or very high risk. These cells were then used in laboratory studies to establish a cell model and investigate the genetic factors involved in fracture risk.

 

The research team’s findings indicate that bone cells from horses predisposed to fractures express collagen type III at reduced levels due to alterations in their DNA sequence in the region which controls how much collagen III is produced. 

This discovery provides a crucial step forward in identifying genetically high-risk horses. By understanding the genetic causes of fractures,, this research can help identify, diagnose, and manage high-risk horses, improving the health and welfare of Thoroughbreds in the racing industry.

 

Ongoing research aims to validate the risk-scoring system across different horse populations and further explore genetic factors using the established cell model.

 

For more details, see:

 

Palomino Lago, E.; Baird, A.; Blott, S.C.; McPhail, R.E.; Ross, A.C.; Durward-Akhurst, S.A.; Guest, D.J. 

A Functional Single-Nucleotide Polymorphism Upstream of the Collagen Type III Gene Is Associated with Catastrophic Fracture Risk in Thoroughbred Horses. 

Animals 2024, 14, 116. 

https://doi.org/10.3390/ani14010116 

New aid to wound healing?

Polymerisation of the synthetic
epidermis spray (c) Paindaveine et al

Recent research suggests that a synthetic skin spray could aid in wound healing by limiting the
formation of exuberant granulation tissue.  

Due to their nature, horses are prone to injuring themselves. Wounds on the lower legs are particularly likely to heal slowly, often involving exuberant granulation tissue (EGT). This excessive tissue growth, commonly known as "proud flesh," poses a significant challenge to equine wound management, as it hampers further healing by protruding from the wound site. 

 

A team of researchers based in France has been investigating the efficacy of a novel synthetic epidermis spray (SES)* in promoting wound healing. Led by Charlotte C Paindaveine from the Ecole Nationale Vétérinaire de Lyon, the researchers conducted a small-scale clinical trial to compare the healing outcomes of experimental surgical wounds treated with SES spray versus those treated with a standard bandaging technique. 

 

The study, detailed in a report published in PLoS One, involved creating standardised surgical wounds on the lower limbs of six adult Standardbred mares. These wounds were then subjected to treatment with either SES or a traditional bandaging method.

 

Hypergranulation and exudation of
the lateral wounds (right leg) treated
with bandaging, compared with wounds 
on left leg treated with spray.
(c) Paindaveine et al 

For the SES treatment, the spray, which comprised  ultraviolet polymerizable methacrylate monomers, comonomers, crosslinker and a photoinitiator was applied to the wound. The researchers explain that this layer was then polymerised using a 395 nm, 20 x 30 cm, 40 mW/cm2 UV light for 60 seconds at a distance of approximately 30 cm (Fig 1). They repeated the same procedure to fix a second layer of the product. The SES was only applied on day 0. No further application was made.

 

The control treatment consisted of a nonadherent permeable dressing secured with conforming cotton gauze and held in place with a cohesive bandage, which would be a common treatment of choice for superficial wounds in a field setting. The control treatment was repeated every 4 days until the end of the study to mimic field veterinary follow-up.

 

Wounds were assessed daily for the SES treatment group, and every 4 days for the control / bandaged group.

 

The researchers report that the synthetic epidermal spray allowed healing without the production of EGT but it did not reduce the median wound healing time compared to a standard bandaging technique.

 

They add that the exuberant granulation tissue observed in the control group that did not receive the SES decreased without any trimming procedure during the 60-day period.

 

They conclude: “The SES is potentially an interesting alternative for the management of secondary intention wound healing of superficial and non-infected distal limb wounds in adult horses because of its economical and practical aspects. 

 

*Novacika®, Cohesive S.A.S, France

 

 

 

For more details, see: 

 

Charlotte C. Pandaveine, Benoit Bihin, Olivier M. Lepage (2024) 

The effects of a synthetic epidermis spray on secondary intention wound healing in adult horses. PLoS ONE 19(3): e0299990. 

https://doi.org/10.1371/journal.pone.0299990

Effect of antibiotics on gut microbiome

Recent research has shown that even a short course of antibiotics can affect the microorganisms in the
gastrointestinal tract of horses. 

While antibiotics play a vital role in combating infectious ailments, their potential misuse has come under scrutiny, primarily due to concerns surrounding the emergence of antibiotic resistance. Consequently, there's a growing consensus to restrict antibiotic usage to essential cases.

 

Moreover, there's a growing recognition of the susceptibility of the equine gut microbiota to antibiotic-induced disturbances, which can lead to adverse, and occasionally severe, consequences. Although instances of severe, life-threatening diarrhoea in horses post-antibiotic treatment have been infrequent, they highlight the potential risks.

 

Now recent work has shown that even short-term courses of commonly prescribed antibiotics can bring about detectable changes in the gut microbiome.

 

A study conducted by Joseph L Parker from the Gluck Equine Research Center, College of Agriculture, Food, and Environment, University of Kentucky, in collaboration with colleagues, aimed to explore the impact of antibiotic administration on the gut microbiome of healthy horses. They evaluated this impact through assessments of faecal consistency, bacterial population counts, and qPCR panel analysis to detect specific disease-associated organisms.

 

Twenty-four healthy horses, comprising 12 mares and 12 geldings, with no prior exposure to antibiotics or anthelmintic treatment within the preceding three months, were selected for participation in the study. They were grouped into four treatment cohorts, one serving as a control while the others underwent a brief course of distinct antibiotic regimens: potassium penicillin/gentamicin via intravenous injection, ceftiofur via intramuscular injection, and trimethoprim sulphamethoxazole orally.

 

The research team collected faecal samples before treatment began,  on the day after treatment finished, and at 10, 14, 21, and 28 days after the start of treatment. 

 

They found that the response to antibiotic administration varied among the horses. However, all horses administered antibiotics had notably softer faeces compared to the control group. One horse developed severe diarrhoea and was consequently withdrawn from the study.

 

Bacterial population counts revealed that Lactobacillus spp. levels showed a marked reduction in all samples collected from horses the day after antibiotic treatment finished

Furthermore, horses subjected to antibiotic treatment demonstrated a significantly higher likelihood of testing positive for C. difficile or C. perfringens via faecal qPCR analysis.

 

The researchers suggest that more work is needed to explore the consequences of antibiotic-microbiota interactions in the horse.

 

 

For more details, see: 

 

J.L. Parker, A. Page, O. Jacob, V. Stanton, B. Davis, M. Flythe, E.N. Adam,

Equine fecal microbiota response to short term antibiotic administration,

Journal of Equine Veterinary Science (2024) 133, 104993

https://doi.org/10.1016/j.jevs.2023.104993

Advances in endocrinology take centre stage in latest EVJ

The endocrine system plays an essential role in balancing the horse's health. Unfortunately, it is
prone to malfunction.

The March issue of the Equine Veterinary Journal (EVJ) highlights the latest work advancing veterinary understanding of equine endocrinology.

  

In a press release, EVJ guest editor Melody de Laat, said “Knowledge, diagnosis and treatment of equine endocrinopathies has improved dramatically over the past 25 years, with progress driven by the publication of peer-reviewed papers and the application of evidence-based medicine.” 

   

Obesity, PPID (Equine Cushing’s), insulin dysregulation (ID), thyroid disorders and the effects of corticosteroid administration are all covered. Articles include:

 

• ·     The BEVA Primary Care Clinical Guidelines provide evidence-based recommendations for the diagnosis and management of PPID, directed at equine practitioners in an ambulatory setting. The evidence review supports clinical signs such as hyperhidrosis, regional adiposity, epaxial muscle atrophy, laminitis, weight loss, recurrent infections or delayed healing, behaviour changes, or polyuria and polydipsia as prompts for moderate suspicion of PPID in animals of more than 10 years of age. The review supports the assessment of basal plasma ACTH concentrations or ACTH responses to exogenous thyrotropin-releasing hormone (TRH) administration. It also supports the use of pergolide as a therapy for PPID.

• ·   Lumbar vertebral bone density is decreased in horses with pituitary pars intermedia dysfunction explores the infrequent finding of pathological fractures in aged horses with advanced PPID.

• ·       Influence of feeding and other factors on adrenocorticotropin concentration and thyrotropin-releasing hormone stimulation test in horses and ponies and Clinical implications of imprecise sampling time for 10- and 30-minute thyrotropin-releasing hormone stimulation tests in horses stresses the importance of exact timing when these samples are collected. 

• ·      Obesity and obesity-associated metabolic disease conditions in Connemara ponies in Ireland showed a 50% prevalence of laminitis in obese ponies. 

• ·       Development of a body condition index to estimate adiposity in ponies and horses from morphometric measurements presents an alternative method for measuring adiposity.

• ·          Associations between feeding and glucagon-like peptide-2 in healthy ponies looks at the role of glucagon-like peptide-2 in the development of hyperinsulinaemia in ID.

• ·         Expression of the GCG gene and secretion of active glucagon-like peptide-1 varies along the length of intestinal tract in horses demonstrates that both the large and small intestines are sites of equine GLP-1 secretion and that the genetic coding is identical in horses with and without ID.

• ·            Relationships between total adiponectin concentrations and obesity in native-breed ponies in England and Short-term induced hyperinsulinaemia and dexamethasone challenge do not affect circulating total adiponectin concentrations in insulin-sensitive ponies show that total adiponectin is not as strongly correlated with body condition, body shape and breed as expected and inducing short-term ID does not alter total adiponectin concentrations. 

• ·            Factors associated with insulin responses to oral sugars in a mixed-breed cohort of ponies and Epidemiological investigation of insulin dysregulation in Shetland and Welsh ponies in Australia determine that the insulin response to oral sugar is associated with multiple variables but cannot be predicted from the physical appearance. 

• ·            Insulin, but not adiponectin, is detectable in equine saliva using an automated, commercial assay in a pilot study in the UK demonstrates that insulin is measurable in equine saliva, but this method is not currently a viable alternative to blood. 

• ·        The effect of pre-dosing with metformin on the insulin response to oral sugar in insulin-dysregulated horsesshows the lack of efficacy of metformin (dosed at 30 mg/kg) on the insulin response to an oral sugar test.

• ·           Intra-articular trimacinolone acetonide injection results in increases in systemic insulin and glucose concentrations in horses without insulin dysregulation shows that intra-articular triamcinolone does not result in circulating insulin concentrations likely to induce laminitis in insulin-sensitive animals. 

• ·           Diagnosis and management of thyroid disorders and thyroid hormone supplementation in adult horses and foals reviews thyroid gland pathophysiology in adult horses and foals, blood thyroid hormone concentrations and the use of T4 supplementation in equine practice. 

 

“This robust collection reflects the continual dedication of equine veterinary researchers to developing our understanding of equine endocrinology,” said Professor Celia Marr, Editor of the EVJ. “Such work is enabling the application of evidence-based medicine to improve the diagnosis, management, treatment and quality of life of animals with endocrine disorders.”

 

The March issue is available to read free:

 

https://beva.onlinelibrary.wiley.com/toc/20423306/2024/56/2