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

Bacterial gut diversity in TB foals improves future racing performance

 The composition of gut bacteria in one-month-old Thoroughbred foals can predict their future
athletic performance, according to a new study from the University of Surrey. Foals with lower bacterial diversity at 28 days old were also found to have a significantly increased risk of respiratory disease later in life.

 Researchers from Surrey's School of Veterinary Medicine and School of Bioscience, led by Professor Chris Proudman, examined the gut bacterial composition of Thoroughbred foals bred for flat racing and its impact on their long-term health and performance.

The three-year cohort study explored the interactions between early-life gut bacterial communities, health outcomes in later life, and athletic performance on the racetrack. The findings were published in Scientific Reports.

 

The study involved analysing 438 faecal samples from 52 foals, tracking their respiratory, gastrointestinal, orthopaedic, and soft-tissue health from birth to three years of age. The researchers also analysed data on race performance, including finishing positions, official ratings, and prize money earnings as measures of athletic performance.

 

Professor Chris Proudman, Professor of Veterinary Clinical Science at the School of Veterinary Medicine at the University of Surrey, said:   "Minimising the risk of disease and injury is important for the welfare of racehorses, and maximising their athletic potential is important for their owners. We have found that gut health, in particular the health of gut bacterial communities very early in life, exerts a profound and enduring impact on racehorse health and performance."

 

The study found a positive association between athletic performance and higher faecal bacterial diversity at one month old. Specifically, a higher abundance of the bacteria Anaeroplasmataceae was linked to a higher official rating, and increased levels of Bacillaceae at 28 days old were associated with better race placings.

 

The researchers concluded that the gut bacterial composition in the first months of life influences the risk of specific diseases and athletic performance up to three years old. Foals with lower bacterial diversity at one month old had a significantly higher risk of developing respiratory disease, which was also associated with a higher relative abundance of the bacteria Pseudomonadaceae.

 

Interestingly, the study revealed that foals treated with antibiotics during their first month of life had significantly lower bacterial diversity at 28 days old compared to those not treated with antibiotics. These foals also earned significantly less prize money and had a higher rate of respiratory disease later in life.

 

Professor Roberto La Ragione, co-investigator from the School of Bioscience at the University of Surrey, commented, "While antibiotics are essential for treating infections and ensuring the long-term health of foals, their use must be carefully managed. Our study demonstrates that antibiotic treatment can disrupt the gut microbiome with long-term consequences for health and performance. The next phase of our research will focus on minimizing this disruption when antibiotics are necessary."

 

Additionally, the researchers found that low gut bacterial diversity in early life is associated with an increased risk of soft-tissue and orthopaedic issues later on. They believe these health impacts are likely related to immunological priming, though the underlying reasons for the observed negative effects on racehorse performance are still not fully understood.

 

Dr. Kirsten Rausing, Chairman of the International Thoroughbred Breeders Federation and study sponsor through her ALBORADA Trust, remarked, "This ground-breaking study has identified the importance of gut health in our very young foals. As breeders, if we can get this right, we will produce foals that will be healthier, and that will grow into more successful racehorses."  

 

Ongoing research aims to develop novel probiotics to enhance foal gut health in early life and to investigate how antibiotics can be used while preserving gut health.

 

The researchers conclude: “For the first time, this study demonstrates a relationship between early-life gut bacterial communities and subsequent athletic performance that has implications for athletes of all species including humans.”

 

 

For more details, see:

 

Early-life gut bacterial community structure predicts disease risk and athletic performance in horses bred for racing

J. Leng, C. Moller-Levet, R. I. Mansergh, R. O’Flaherty, R. Cooke, P. Sells, C. Pinkham,O.  Pynn, C. Smith, Z. Wise, R. Ellis, A. Couto Alves, R. La Ragione and C. Proudman 

Scientific Reports (2024) vol 14, Article number: 17124 

https://doi.org/10.1038/s41598-024-64657-6 

Horses smarter than previously thought, study suggests

Horses are more intelligent than previously believed, according to a new study that shows how they cleverly adapted their behaviour to maximise rewards with minimal effort.  

Researchers at Nottingham Trent University sought to understand more about equine learning processes, as this knowledge could lead to more humane training methods and improved welfare for horses. A full report of the study is published in the journal  Applied Animal Behaviour Science. 

 

The study involved twenty horses, aged 11 to 22 years, including seven females and thirteen castrated males of mixed breeds. 

 

The team devised a task where horses had to touch a piece of card with their nose to receive a treat. They then made the task more challenging. Horses would not get a treat if they touched the card while a bright white “stop” light was on but would do if they touched it while the light was off.

 

 As the task was made more challenging, the horses initially struggled, indiscriminately touching the card whether a light was on or off, though they continued to receive rewards for correct responses.

 

In the final stage, a penalty was introduced: touching the card when a “stop” light was on resulted in a ten-second timeout during which no rewards could be earned. Remarkably, the horses quickly adapted, showing a significant reduction in errors and only touching the card at the correct times to receive treats.

 

The researchers suggest that rather than misunderstanding the game, the horses may have understood it all along but found a way to play that required less attention. They suggest that their findings indicate a higher level of cognitive processing than was previously thought possible, as the horses instantly switched strategies when faced with the risk of losing rewards. 

 

This approach requires the horse to think into the future, the researchers say, and is very goal directed, with horses required to focus on what they want to achieve and the steps they need to take to do this. 

This, they argue, is something which has previously been considered beyond a horse’s cognitive capacity.

“At first we found that horses would just keep touching the card over and over, as they probably realised they would still get a frequent reward with minimal mental effort,” said lead researcher Dr Carrie Ijichi. 

She said: “There was no cost for indiscriminate hitting, sometimes it paid off, sometimes it didn’t. When we introduced a cost for their errors, however, they could instantly understand and play the game properly. 

“Horses are not natural geniuses, they are thought of as mediocre, but this study shows they’re not average and are in fact more cognitively advanced than we give them credit for. 

“We now think that horses may be able to use a form of learning called ‘model-based learning’ which was thought to be too complex for them. This will now help us to understand their behaviour and capabilities much better.

“It’s fascinating because they have a very underdeveloped pre-frontal cortex which is what we typically credit with producing that type of thinking in humans. This means they must be using another area of the brain to achieve a similar result and this teaches us that we shouldn’t make assumptions about animal intelligence or sentience based on whether they are ‘built’ just like us.”

Researcher Louise Evans, based in Nottingham Trent University’s School of Animal, Rural and Environmental Sciences, said: “We were expecting horses’ performance to improve when we introduced the time-out, but were surprised by how immediate and significant the improvement was. 

“Animals usually need several repetitions of a task to gradually acquire new knowledge, whereas our horses immediately improved when we introduced a cost for errors. This suggests that the horses knew all along what the rules of the game were.” 

For more details, see:

Louise Evans, Heather Cameron-Whytock, Carrie Ijichi,

Whoa, No-Go: Evidence consistent with model-based strategy use in horses during an inhibitory task,

Applied Animal Behaviour Science, (2024) Vol 277, 106339,

https://doi.org/10.1016/j.applanim.2024.106339

Edited press release