Research into possible markers of joint health

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 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