Warning of possible adverse effects of SGLT2i on horses.

© Brian Sedgbeer Dreamstime.com

A group of veterinary experts have issued a warning regarding the potential adverse effects of sodium-glucose cotransporter 2 inhibitors (SGLT2i) in horses. In a letter published in the Veterinary Record, Bruce McGorum and clinicians from leading veterinary hospitals like the Royal (Dick) School of Veterinary Studies, Edinburgh, Rossdales Equine Hospital, the University of Liverpool, and the Royal Veterinary College expressed their concerns.

These medications, such as ertugliflozin and canagliflozin, are increasingly used to treat equine metabolic syndrome (EMS), particularly in horses with laminitis that hasn't responded to dietary adjustments. While these drugs have shown promise in reducing serum insulin concentrations, promoting weight loss, and managing laminitis related to hyperinsulinemia, concerns have been raised about significant adverse effects.

 

Minor side effects reported include increased serum triglycerides and liver enzymes, dullness, and increased drinking and urination. However, more serious cases have shown markedly elevated serum triglycerides (above 40 mmol/L), increased liver enzymes (such as GGT, GLDH, LDH), and bile acids, indicating potential liver damage or dysfunction. These biochemical changes were also accompanied by clinical signs such as dullness, loss of appetite, gastric impaction, bilateral laryngeal paralysis, hepatic encephalopathy, and, in some cases, death.

 

Due to these risks, the experts recommend that SGLT2 inhibitors be used only in horses that have not responded to adequate dietary or exercise management, or those with severe laminitis. 

 

Additionally, they advise against using these medications in horses with pre-existing liver disease or hyperlipaemia and emphasize the importance of regular monitoring of diet, liver enzymes, serum triglycerides, and bile acids. Horse owners should be educated about the signs of hyperlipaemia and the potential risks involved in the use of these drugs.

 

Further research is needed to fully understand the risk factors and adverse effects of SGLT2 inhibitors in horses. Until then, their use should be restricted to cases where other treatment options have failed.

For more details, see:

B C McGorum, J A Keen, S McCullagh, CM Marr, C MacKenzie, H Carslake, N Menzies-Gow, Bettina Dunkel, M Hewetson, J Reed, E Knowles.

Potential adverse effects of SGLT2i in horses 

Veterinary Record (2024) vol 195, 253

Navigating the Equine Breeding Season: Mares Webinar

Are you new to horse breeding or looking to expand your knowledge? Join the American Association of Equine Practitioners (AAEP) for a free, informative webinar on the equine breeding season.

The webinar is directed toward horse owners/managers either new to breeding horses or those with limited experience. It will cover the basics of reproductive biology of the horse, logistics of the breeding season and what to expect when breeding your mare. 

The presenter is Dr. Dale Kelley, board-certified reproduction specialist at Oklahoma State University, College of Veterinary Medicine.

 

Access is free, but registration is required.

 

Details:

• Date and time : 

 

(USA) Wednesday, Oct. 30, 8:00 p.m. ET

(UK) Thursday, Oct. 31, midnight (00:00) GMT

 

• To register go to:

https://aaep-org.zoom.us/webinar/register/WN_CHkvKjmpTlGOiPMbwhEtBA#/registration

 

• Submit questions in advance through the registration form.

 

If you miss the live event, a recording will be available.

Seasonal sycamore risk

 The British Equine Veterinary Association (BEVA) is reminding horse owners to keep horses away from sycamore trees as their seeds can cause fatal illness, known as atypical myopathy. 

Seeds (masts or helicopters) from the common sycamore tree (Acer pseudoplatanus) produce a toxin called Hypoglycin A, which can remain present in high concentrations in seedlings. When horses eat these, either by accident or because they are lacking other forage options, some individuals will develop severe and often fatal muscle damage, called atypical myopathy. 

 

Symptoms include muscle soreness, weakness, breathing issues, and dark urine. Immediate veterinary care is crucial, as 75% of affected horses die.

 

“With leaves still on trees now is the time to identify sycamores in the vicinity of your horse’s fields and predict the future risk,” said Lucy Grieve, Veterinary Projects Officer at BEVA “Once the leaves start to turn and then drop it will be much more difficult to spot sycamores.”

 

To prevent atypical myopathy, she advises:

 

·      Identify sycamore trees near fields and anticipate risk before leaves fall.

·      Collect seeds or exclude horses from affected areas using electric fencing or stabling. 

·      provide supplementary forage to prevent seed ingestion.

·      Don’t fell seed-laden trees, as it may worsen contamination.

·      Monitor horses carefully even after they have been moved from affected pasture as disease can occur up to four days after exposure.

 

For further information you can download the Royal Veterinary College’s fact sheet on  Atypical Myopathy: https://www.rvc.ac.uk/Media/Default/Comparative%20Neuromuscular%20Diseases%20Laboratory/Atypical%20Myopathy%20fact%20file%20updated%202022.pdf

 

For further information visit www.beva.org.uk.

Is faecal microbiota transplantation useful for treating diarrhoea in foals?

(c) Rookie72 Dreamstime.com

 Diarrhoea is a common problem in foals under 6 months of age. 

There are many causes, or combination of causes, including infectious, managerial, and environmental factors.  

Foal diarrhoea can lead to dehydration, electrolyte imbalances, and, in severe cases, systemic infections. In such cases, it can become life-threatening.

 

Diarrhoea and Systemic Inflammatory Response Syndrome (SIRS) in foals are interconnected conditions that demand immediate attention. While diarrhoea is a frequent occurrence, it can escalate to SIRS, particularly when associated with severe infections or when significant dehydration and systemic stress occur.

 

A common contributor to diarrhoea in foals is dysbiosis, or a disruption in the normal intestinal microbiota. Could restoring this microbial balance be a potential solution for managing this potentially fatal condition? 

 

Faecal microbiota transplantation (FMT) has been used in adult horses to reduce diarrhoea and improve alpha diversity, a measure of the variety of microbial species within an individual’s gut.

 

A recent study in Australia, published in the Journal of Veterinary Internal Medicine, explored the effects of FMT in foals with diarrhoea and SIRS. The study, led by Jillian Bell, involved clinicians from three equine veterinary hospitals. It included 25 foals under six months of age with diarrhoea and SIRS who were admitted for treatment.

 

In the randomised, placebo-controlled cohort study, 19 foals were enrolled in the FMT group, while 9 were in the control group. The treatment groups received either FMT or an electrolyte solution once daily for three days. Researchers collected faecal samples from the foals on days 0 (D0), D1, D2, D3, and D7 to monitor changes.

 

The FMT solution was prepared 15 minutes prior to treatment. from fresh manure collected from healthy donor horses (previously screened for pathogenic agents). About 300 g of manure was blended with 1 L of warm chlorinated water (95°F) for 30 to 60 seconds, then strained through a wire strainer or gauze into a clean container.

 

The study found that FMT was associated with improvements in some clinical signs and certain clinicopathological parameters. FMT had no significant impact on survival rates (P = 0.3) or the resolution of diarrhoea (P = 0.4). Foals receiving FMT, however, showed a significantly lower heart rate, white blood cell (WBC) count, and packed cell volume (PCV), as well as higher serum chloride concentrations, compared to pretreatment values and the control group. Notably, on Day 3, the WBC count in the FMT group was significantly lower than in the control group (P = 0.04), and heart rate decreased over time in the FMT group.

 

Additionally, although three foals initially in the control group were later transferred to the FMT group, diarrhoea resolved in two of them after FMT treatment.

 

FMT was also associated with a greater diversity in the gut microbiota, with enrichment of beneficial bacteria such as the phylum Verrucomicrobiota, genus Akkermansia, and family Prevotellaceae. Previous studies have shown that Akkermansia is linked to the maintenance of the mucin layer in the intestines and can reduce bowel inflammation in humans. Members of the Prevotellaceae family have been associated with anti-inflammatory effects and improved intestinal health.

 

The authors concluded that FMT appears to be a safe treatment for foals with diarrhoea and can lead to some clinical and microbiota changes that suggest beneficial effects. 

 

However, further research is needed to confirm its impact on survival and long-term outcomes in affected foals.

 

For more details, see: 

 

Bell J,  Raidal SL,  Cuming RS,  Trope G,  Hughes KJ.  

Effects of fecal microbiota transplantation on clinical outcomes and fecal microbiota of foals with diarrhea. 

J Vet Intern Med.  2024; 38(5): 2718-2728.

https://doi.org/10.1111/jvim.17185

Equine feed manufacturer announces free webinar series

 

 The SPILLERS™ Brand has announced a new series of free nutrition webinars designed to
elevate horse owners’ understanding of equine nutrition and wellbeing. 

 

The four webinars, to be held over the winter months, promise to provide valuable insights from nutrition, veterinary and welfare experts. 

 

The first webinar Forage fundamentals will be held on 24th October 2024, led by equine nutrition expert, Sarah Nelson. She will explore the role of forage in the horse’s diet, covering essential topics such as the different types of forage, their nutritional value, and how to choose the most suitable type and amount of forage for different horses and ponies. 

 

“This webinar is the perfect opportunity for horse owners to deepen their understanding of forage management and in turn, be better placed to support their horse’s digestive health and wellbeing,” said Sarah Nelson.

 

The first webinar will be followed by: 

 

Stabling horses: Can we do it better? – 21st November 2024, with Isabel Harker, head of the SPILLERS Care-Line team, and Sarah Hallsworth, Equine Behaviour Manager at Redwings Horse Sanctuary

Caring for the senior horse – 16th January 2025, with SPILLERS Nutritionist and Product Manager, Sarah Nelson, and Professor Pat Harris, a leading authority on veterinary clinical nutrition and senior horse nutrition.

Spring into action: Effective strategies to help your horse shed the pounds – 27th February 2025, with SPILLERS Nutrition Advisor, Isabel Harker, and Nicky Jarvis, Head of Veterinary and Care at Redwings Horse Sanctuary. 

 

To register visit: https://www.spillers-feeds.com/webinars

Managing thin soles in performance horses

(c) Matz et al 2024

 Thin soles and poor palmar angles are common issues in performance horses, significantly impacting their comfort, movement, and hoof health. Horses with thin soles are more prone to lameness due to increased sensitivity, pain, bruising, and a higher risk of developing solar abscesses.

Managing thin soles can be challenging for farriers and hoof care professionals. Many owners turn to protective footwear, while supplements rich in biotin, methionine, and zinc are often used to promote hoof growth. 

One potential therapy gaining attention is Pulsed Electromagnetic Frequency (PEMF) therapy. Widely used in equine therapy, PEMF promotes healing, reduces pain, and supports overall health and performance. Could it also play a role in managing thin soles?

 

A recent pilot study led by Madelyn Matz, published in the Journal of Equine Rehabilitation, explored the effect of PEMF therapy on hoof parameters in ten adult horses of various breeds. The horses were divided into a PEMF group (n=6) and a control group (n=4).

 

All horses underwent standard hoof trimming the day before the study began, with no further farriery work during the trial. Radiographs were taken before treatment and again 30 days later, measuring sole depth and palmar angles (see figure).

 

The PEMF group received treatment at a frequency of 22 Hz for ten minutes per session, applied to both hooves three times a week (on Monday, Wednesday, and Friday) over a 30-day period, while the control group received no intervention.

 

The study found no significant differences between the PEMF and control groups in terms of sole depth under the apex of the proximal phalanx or palmar angles. However, there was a trend towards increased sole depth beneath the distal processes of the right hoof in the PEMF-treated horses.

 

While this pilot study showed no significant improvement overall, the trend towards increased sole depth suggests that PEMF therapy may offer some benefit. 

 

The researchers concluded that further investigation is warranted, as PEMF therapy could become a non-invasive option for managing thin soles in horses.

 

 

For more details, see:

 

M.M. Matz, D.L. Alexander, J. Moore, C.E. Fedorka,

Evaluating the effect of pulsed electromagnetic field (PEMF) therapy on sole depth of the equine hoof: A pilot study,

Journal of Equine Rehabilitation, (2024) Vol 2,100010,

https://doi.org/10.1016/j.eqre.2024.100010

Can Horses Sniff Out Poisonous Plants?

(c) Victoria Shibut Dreamstime.com

Recent research from Poland suggests that horses may use their sense of smell to avoid
poisonous plants. 

Many plants are toxic to horses, potentially causing serious health issues or even death if ingested. So how do horses identify poisonous plants? 

In the wild, horses may avoid unfamiliar plants or those with bitter or unpleasant tastes. Domesticated horses may not always avoid toxic plants. Overgrazed pastures or contaminated hay can expose them to harmful species, clouding their natural foraging instincts.

 

A study by Izabela Wilk and colleagues at the University of Life Sciences in Lublin, Poland, tested whether stabled horses could distinguish poisonous plants by scent alone. The researchers presented six plants to the horses, enclosed in boxes so the horses could only smell them, not see or touch them. 

 

The plants included three poisonous species: Common Yew (Taxus baccata), Common Box (Buxus sempervirens), and Northern White-Cedar (Thuja occidentalis), as well as three non-poisonous ones: Parsley (Petroselinum crispum), Dill (Anethum graveolens), and Arugula (Eruca sativa).

 

The horses were trained to approach and investigate the boxes. Researchers observed the time they spent exploring each box and found that horses spent significantly more time investigating non-poisonous plants. This suggests that horses may be able to discriminate between novel odours and rely on olfaction to avoid toxic plants.

 

While this ability may help horses avoid danger, it is not foolproof, and their environment plays a significant role in their exposure to harmful species.

 

For more details, see

 

Izabela Wilk, Elżbieta Wnuk, Anna Stachurska, Wiktoria Janicka, Ewelina Tkaczyk, Natalia Kumanowicz, Jarosław Łuszczyński,

Explorative behaviour in horses when presented with unfamiliar poisonous and non-poisonous plants,

Applied Animal Behaviour Science, (2024) Vol 277, 106352,

 

https://doi.org/10.1016/j.applanim.2024.106352

 

Effect of PPID on egg shedding after deworming

It has been suggested that horses with hormonal disorders, such as insulin dysregulation and
Pituitary Pars Intermedia Dysfunction (PPID), may be more susceptible to worm infections. 

Horses with PPID often have a weakened immune system, which can allow worms, such as cyathostomes, to thrive more easily compared to healthy horses. These horses may also not respond as effectively to standard deworming treatments due to their altered immune function.

 

A study conducted in Australia aimed to determine whether horses with PPID had increased strongyle faecal egg counts (FEC) compared with control horses.

 

The study, led by Adelaina Horner, took place over a fourteen-week period and involved adult horses and ponies over eight years old in Victoria, Australia. All horses lived on pasture and had not been dewormed for at least three months prior to the study. A total of 45 privately owned horses and ponies met the criteria for inclusion, with 14 horses diagnosed with PPID and 31 serving as controls. PPID diagnosis was confirmed by elevated plasma ACTH concentrations (above 120 pg/mL) along with at least one clinical sign of the disorder.

 

All horses were dewormed with a standard dose of a commercially available ivermectin product. Faecal egg counts were taken before treatment and then every two weeks for 14 weeks. A FEC of 200 eggs per gram (EPG) or higher was used as the cutoff for significant worm burden.

 

The results showed that the egg reappearance period (ERP) after deworming was shorter in PPID horses, and cumulative FEC after deworming was higher in these horses. However, the researchers noted that some PPID horses consistently had no detectable eggs or low EPG (≤ 200) throughout the study, and this could not be explained by observed husbandry practices.

 

Worm eggs collected during the study were cultured in the laboratory, and examination of the larvae confirmed that all worms were cyathostomin species.

 

The researchers advise monitoring egg shedding before anthelmintic treatment in PPID horses, in line with sustainable worm management guidelines, as some PPID horses consistently showed low FEC results.

 

While hormonal disorders like PPID do not directly cause an increase in parasitic infections, they can impair the horse’s immune system and overall health, making them more vulnerable to worm infections and potentially reducing the effectiveness of treatments. Effective management of both the hormonal disorder and parasitic infections is crucial for maintaining the health of affected horses.

 

 

For more details, see: 

 

Strongyle egg shedding and egg reappearance periods in horses with pituitary pars intermedia dysfunction

Adelaina Horner, Nicholas J. Bamford, Michael J. Stear, David Piedrafita, Abdul Jabbar, Kristopher J. Hughes, Charles M. El-Hage, Sarah Preston

Veterinary Parasitology (2024) Vol 328, 110176

 

https://doi.org/10.1016/j.vetpar.2024.110176

Chicory: a natural anthelmintic?

(C) Malsa et al CC BY-NC-ND 4.0

Recent research in France suggests that chicory shows promise as a natural anthelmintic for horses.

 

Cyathostomes (small redworms) are the most common gastrointestinal parasites in horses and are now the leading cause of parasite-related equine diseases. The larval stages of these worms can damage the large intestinal wall, leading to diarrhoea, colic, and loss of condition.

 

These parasites are also important because they are the most likely to develop resistance to the anthelmintics used to control them. Consequently, there is a shift away from regular deworming to reduce the development of anthelmintic resistance. Limiting unnecessary anthelmintic use is also important due to its environmental impact, particularly on insects that feed on horse manure.

 

Chicory (Cichorium intybus), a common forage plant, has been studied for its potential anthelmintic (anti-parasitic) properties, particularly in ruminants. Research has shown that certain compounds in chicory, such as sesquiterpene lactones, may have effects against gastrointestinal parasites.

 

Joshua Malsa and colleagues investigated the effect of horses grazing pasture containing a high proportion of chicory on faecal worm egg production and larval development. The research is reported in the International Journal for Parasitology: Drugs and Drug Resistance.

 

Twenty naturally infected 2-year-old saddle horses were used in the study. All horses were born and raised on the premises where the study took place and were naturally exposed to the same parasite populations. They had not been dewormed for 264 days before the onset of the trial. The last treatment given had been moxidectin.

 

 The horses were divided into two groups, each of ten horses, and were grazed either a field of chicory or a control field of mixed pasture

 

The researchers found a significant reduction in FEC after 16 days of grazing on chicory. By the end of the study grazing on chicory had an efficacy slightly lower than that of pyrantel treatment (85.5% vs 99.3% FECR for chicory and pyrantel respectively). 

 

The chicory diet also reduced the development of eggs into third-stage larvae in faeces and affected the diversity of the cyathostomin community.

 

They conclude: “Our study demonstrated the efficacy of grazing chicory (cv. Puna II) to reduce cyathostomins egg excretion and larval development in horses. The magnitude of this effect was almost as high as expected from synthetic drugs, although we identified differential sensitivity between species.”

 

Integrating chicory into a broader parasite management plan could be beneficial, especially in reducing reliance on chemical dewormers and combating drug resistance.

 

 However, while it might complement conventional parasite control methods, it should not yet be considered a replacement for standard anthelmintics without further research.

 

 

For more details, see:

 

Joshua Malsa, Leslie Boudesocque-Delaye, Laurence Wimel, Juliette Auclair-Ronzaud, Bertrand Dumont, Núria Mach, Fabrice Reigner, Fabrice Guégnard, Angélique Chereau, Delphine Serreau, Isabelle Théry-Koné, Guillaume Sallé, Géraldine Fleurance,

Chicory (Cichorium intybus) reduces cyathostomin egg excretion and larval development in grazing horses.

International Journal for Parasitology: Drugs and Drug Resistance, (2024) Vol 24,100523

 

https://doi.org/10.1016/j.ijpddr.2024.100523

Do haynets affect tooth wear in horses?

(c) Nigel Baker Dreamstime.com

Using haynets to feed horses has several benefits, including reducing hay waste and slowing down consumption. 

However, there are potential downsides, such as the risk of injury and unnatural feeding positions. When individual haynets are hung too high, horses may eat with their heads raised, which may lead to muscle discomfort and long-term problems. This position also increases the chance of inhaling dust or hay particles, which may cause respiratory issues.Do haynets also influence tooth wear.?

 

Michelle DeBoer and colleagues conducted a study to compare horse body weight and condition, hay consumption, tooth wear, and dental conditions between horses fed with or without hay nets. 

 

The work was presented at the Equine Science Society Symposium 2023, and a report is published in the Journal of Equine Veterinary Science.

 

Thirteen adult geldings were recruited for the cross-over study and divided into two groups.

 

They were housed in adjacent dry lots with access to shelter and water. Both groups were fed round hay bales in feeders, with one group of six horses receiving hay wrapped in hay nets, while the other five horses were given hay without nets.

 

The study spanned two years, with the two groups switching halfway through: the five horses that initially had their hay wrapped switched to unwrapped hay, while the six horses moved to wrapped hay.

 

The researchers tracked hay consumption and monitored dental health, including incisor length, dental abnormalities, and conditions. They also recorded horse body weight and body condition scores annually—before, during, and after the study.

 

Results showed that horses eating unwrapped hay consumed more and had higher body weight (BW) and body condition scores (BCS). No significant differences were found in incisor length, incisor bevels, or dental abnormalities.

 

The researchers concluded that hay nets do not negatively affect dental health but can reduce hay consumption and help manage horse body weight and condition.

 

 

 

For more details, see:

 

M. DeBoer, L. Keener, J. Layeux-Parks, O. Schueller, L. Johnson, K. Martinson,

Effect of hay nets on horse bodyweight, body condition score, hay usage, and dental health in mature adult horses,

Journal of Equine Veterinary Science,(2024) Vol 136,105051

 

https://doi.org/10.1016/j.jevs.2024.105051

Inflammatory marker increase after routine vaccination

 Routine vaccination can lead to a temporary increase in Serum Amyloid A (SAA), according to a recent study in the USA.

Serum amyloid A (SAA) is an acute-phase protein, meaning its levels in the blood increase rapidly in response to infection, injury, or stress. Due to its rapid increase during inflammatory conditions, SAA is often used in horses as a biomarker to assess inflammation or infection 

 

Researchers at the Department of Clinical Sciences, College of Veterinary Medicine, Kansas State University, conducted a two-part study to monitor the response to vaccination. Cassandra M. Baumgarten was the lead author of the study, which was published in the Journal of the American Veterinary Medical Association.

 

The study included a total of 36 clinically normal horses. Twenty-eight horses received routine booster vaccinations recommended for horses in the southern states of the USA (rabies, tetanus, West Nile virus, Eastern and Western equine encephalomyelitis, equine herpesvirus-1/-4, and influenza). Eight horses received placebo injections of saline.

 

The research team conducted daily clinical examinations of the horses, which included measuring their temperature and collecting blood samples to monitor serum amyloid A (SAA) levels for the first ten days after vaccination.

 

They found that, compared to the control group, vaccinated horses had higher SAA concentrations for up to ten days after vaccination, generally returning to normal by the ninth day. About 85.7% of the horses had their SAA levels return to normal within ten days of vaccination.

 

Fever (temperature >38.4°C) was observed in 78.6% of the horses after vaccination, but there was no correlation between fever and SAA concentration.

 

The authors suggest that elevated SAA levels for 10 days after vaccination and fever lasting 12 to 24 hours cannot be used as indicators of illness. They recommend that clinicians, when assessing a patient’s condition after vaccination, should not rely on just one or two clinical signs but rather evaluate the patient as a whole. They also state that measuring SAA for 10 days post-vaccination cannot reliably indicate illness.

 

Based on their findings that routine vaccination increases SAA concentrations, the authors suggest that when advising horse owners about travel or competition, practitioners should recommend a recovery period following vaccination.

 

They also suggest the need for further studies to investigate the effect of travel or competition on the antibody response.

 

 

 

For more details, see: 

 

Baumgarten, C. M., Delph Miller, K. M., Davis, E. G., Beard, L. A., Blevins, C. A., Wottowa, M., Hill, M., & Larson, R. L. (2024). 

Serum amyloid A increases following routine vaccination of healthy adult horses. 

Journal of the American Veterinary Medical Association, 262(9), 1181-1187. 

https://doi.org/10.2460/javma.24.04.0244

Adverse effect of bute on assisted reproduction in mares

(c) Zuzana Tillerova Dreamstime.com

 Phenylbutazone (“bute”) may not be as harmless for breeding animals as previously thought.

 Recent research from the USA indicates that bute can interfere with oocyte maturation and development after fertilization when assisted reproduction techniques are used.

 

While Thoroughbred mares often start breeding young, many other mares only begin breeding after a long working life. Many of these mares retire from work or start breeding due to orthopaedic problems that limit their performance and require regular NSAID treatment.

 

Researchers at the Texas A&M School of Veterinary Medicine & Biomedical Sciences (VMBS) have found that phenylbutazone, a non-steroidal anti-inflammatory drug (NSAID) commonly prescribed in horses, can affect a mare’s egg cells (oocytes), hindering their ability to mature into viable embryos, which is crucial for assisted reproduction.

 

The study, led by Dr Luisa Ramírez-Agámez and colleagues, looked at the effect of bute on the developmental competence of in vitro-matured equine oocytes subjected to Intracytoplasmic Sperm Injection (ICSI). Their findings are published in the journal Theriogenology.

 

In a press release, Ramírez-Agámez explained: “Mare’s oocytes need approximately 30 hours to mature in the laboratory once they have been collected before they can be fertilized. Then, we have to inject the eggs with sperm to induce fertilization, a process known as Intracytoplasmic Sperm Injection (ICSI).

 

“We discovered that phenylbutazone, commonly known as bute, can affect both the ability of a mare’s eggs to mature correctly when cultured and whether the fertilized eggs will develop into a viable embryo. In either of those cases, the eggs affected by bute cannot be used in assisted reproduction.”

 

In a preliminary study, the research team compared cumulus-oocyte-complexes (COCs) harvested from two mares treated with bute for 10 days before collection with those from four untreated mares. (The term "cumulus-oocyte complex" (COC) refers to an oocyte and the surrounding cumulus cells within the follicle. The cumulus cells are essential for the oocyte's development and maturation, providing nutrients and signals, and aiding in fertilization and embryo development.)

 

They found that oocyte in vitro maturation and blastocyst rates were lower in bute-treated mares compared to the control mares.

 

In the main experiment, nine healthy mares received a daily dose of bute (4.4 mg/kg, orally, once a day) for 10 days, while ten control mares received a placebo.

 

The researchers performed ultrasound-guided transvaginal oocyte aspiration (TVA) on days 3, 33, and 77 following the last dose of bute. The COCs recovered from both groups were matured in vitro and subjected to ICSI.

 

They observed that while the in vitro oocyte maturation rate was similar between the bute and control groups, oocyte recovery, cleavage, and blastocyst rates were significantly lower in the bute-treated group. However, these effects were short-lived, as by 33 and 77 days post-treatment, in vitro maturation, cleavage, and blastocyst rates were similar between the two groups.

 

“In a future study, we hope to determine an alternative to bute that supplies the same level of pain management but does not interfere with reproduction,” she added. “The good news is that bute’s effect on equine oocytes appears to wear off within a few weeks.

 

“We found that eggs collected three days after administration of bute were not able to produce embryos, but those collected at 33 days were successful. We hope to find a more exact answer in terms of how bute affects egg cell quality in a future study.”

 

 

For more details, see:

 

Ramírez-Agámez L, Hernández-Avilés C, Whitfield-Cargile CM, Coleman MC, Love CC. 

Treatment of mares with the non-steroidal anti-inflammatory drug (NSAID) phenylbutazone transiently affects in vitro maturation of equine oocytes and blastocyst development after Intracytoplasmic Sperm Injection (ICSI). 

Theriogenology (2024) 223:53-58.

https://doi.org/10.1016/j.theriogenology.2024.04.017

Promising use of stem cells for tendon injuries in flat racehorses

Research from Australia suggests that treatment with bone marrow derived mesenchymal stem cells (BM
MSCs) results in improved healing compared with a controlled exercise rehabilitation program alone. 

 Strain of the superficial digital flexor tendon (SDFT) injury is one of the most common and significant injuries in racehorses. The tendon plays a crucial role in the movement and stability of a horse's limb, particularly during high-speed activities like racing. 

 The primary treatment is rest, often for months, to allow the tendon fibres to heal. Full recovery can take over a year, but even then, the tendon may remain weaker and more prone to re-injury, especially if the horse returns to high-intensity activities. Tendons have a limited ability to regenerate, and the damaged fibres are often replaced by scar tissue, which is mechanically inferior and increases the risk of future injury. 

 Research by Rachel O. Salz and colleagues investigated how SDFT (superficial digital flexor tendon) injuries in Thoroughbred racehorses respond to different treatments. They compared the effects of a controlled exercise recovery program alone with those of the same program combined with either autologous bone marrow-derived stem cells (BM-MSCs) or allogenic adipose-derived stem cells (A-MSCs). (Autologous stem cells are taken from the same individual receiving the treatment. Allogenic stem cells come from a donor) 

 The study analysed clinical and race records of 213 Thoroughbreds to see if stem cell treatments improved the chances of horses returning to racing compared to just using the exercise recovery program.  

One group of horses followed a controlled exercise rehabilitation program (CERP) without stem cell treatment, while another group followed the CERP with additional treatment using either BM-MSCs or A-MSCs injected into the damaged tendon. 

The study found that horses treated with intralesional bone marrow-derived mesenchymal stromal cells were three times more likely to return to racing compared to those undergoing only the controlled exercise rehabilitation program. Additionally, these horses were at least twice as likely to participate in five or more races after returning, indicating that the treatment had a lasting impact beyond just recovery. 

 In contrast, the response to adipose-derived mesenchymal stem cells (A-MSCs) was less encouraging. The analysis showed no significant increase in the likelihood of returning to racing or completing five or more races with A-MSC treatment compared to the rehabilitation program alone. However, the researchers noted that the smaller number of horses in this treatment group might have limited the ability to detect a potential effect. 

 For more details, see: 

 Treatment of racehorse superficial digital flexor tendonitis: A comparison of stem cell treatments to controlled exercise rehabilitation in 213 cases 

Rachel O. Salz, Christopher R. B. Elliott, Tomas Zuffa, Euan D. Bennet, Benjamin J. Ahern 

Equine Veterinary Journal (2023) Vol 55, pp 979-987 

https://doi.org/10.1111/evj.13922

EVJ presents growing evidence for regenerative medicine

Processing autologous conditioned serum
for intra-articular injection 
(photo courtesy of Lynn Pezzanite)

Regenerative therapies have become more widely used in equine practice over the past 20 years. They involve treatments that aim to repair or replace damaged tissues and promote healing using the body's natural regenerative capabilities. These therapies are increasingly used to treat injuries, particularly those affecting tendons, ligaments, joints, and cartilage.

 

Despite considerable advances in the field, the true efficacy of veterinary regenerative medicine is still questioned in many instances. To enable easy access to the latest knowledge on the topic, the Equine Veterinary Journal (EVJ) has published a ‘Special Collection’.

Guest edited by Lynn Pezzanite, the Special Collection contains the ‘Top 10’ recent publications from EVJ relating to regenerative therapies over the past five years which may help practitioners select one treatment over another for a specific clinical indication.

 

The term ‘regenerative therapies’ is a broad definition for innovative medical therapies that enable the body to repair, replace, restore, and regenerate damaged or diseased cells, tissues, and organs, while ‘biological products’ are those made from living material (human, animal, plant, microorganisms) used to treat or prevent disease. 

 

Options available to clinicians in equine practice include point-of-care blood or tissue derived products (autologous – derived from the same individual) including platelet rich plasma (PRP), autologous conditioned serum (ACS or interleukin receptor antagonist protein/IRAP), autologous protein solution (APS), bone marrow aspirate concentrate (BMAC or stromal vascular fraction) or cultured stromal cell-based products (autologous or allogeneic – derived from a different individual of the same species). 

 

“Equine practitioners have access to use regenerative medicine to treat joint and soft tissue disorders as well as a variety of other conditions such as wounds, ophthalmic or theriogenology indications,” said Lynn. “However, in some instances due to lack of rigour in clinical study design, lack of demonstrated consistency in product formulation and lack of regulatory oversight that would assure appropriate standards, the true efficacy of some therapies remains controversial. We aim for this special collection to bring some clarity, to aid vets in their treatment choices.”

 

To see the Special Collection, go to::

 

https://beva.onlinelibrary.wiley.com/hub/journal/20423306/homepage/regenerative-therapies-collection