Case reports suggest oral cabergoline may offer alternative treatment for challenging equine PPID cases

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  The Equine Cushing's and Insulin Resistance Group Inc. (ECIR Group) has announced the publication of a new retrospective case report by Eleanor M. Kellon, VMD, examining the use of oral cabergoline as a treatment option for horses with equine pituitary pars intermedia dysfunction (PPID) that failed to respond to conventional therapy. 

PPID, commonly known as equine Cushing's disease, is most often managed with oral pergolide, which has become the standard treatment due to its high success rate in controlling clinical signs and hormone levels. However, a subset of horses either fails to respond adequately to pergolide or develops unacceptable behavioural or gastrointestinal side effects, leaving veterinarians and owners with limited therapeutic alternatives.

Until now, the primary alternative has been injectable sustained-release cabergoline. There is little published information on other oral treatment options.

Dr. Kellon's report, published in the Open Veterinary Journal, reviews the outcomes of five horses owned by ECIR Group members that were treated with daily oral cabergoline under the supervision of their attending veterinarians 

"All horses were confirmed PPID by Cornell University Vet Diagnostic Laboratory criteria, and were considered failures of mainline therapy due to inability to control ACTH and clinical signs," Dr. Kellon said. "Based on the success in a 2022 study*, members of the ECIR Group, under the direct care of their personal veterinarians, decided to try oral cabergoline as an alternative to pergolide or injectable cabergoline." 

The horses represented particularly challenging cases. All had previously failed to respond adequately to treatment with oral pergolide. Four of the five had also been treated with injectable sustained-release cabergoline, but this had been unsuccessful because of severe injection-site reactions, gastrointestinal side effects, or both. All of the horses had either longstanding PPID or rapidly progressive disease.

Despite the severity of these cases, the retrospective review found encouraging responses following the introduction of oral cabergoline. No changes were made to diet, concurrent medications, or overall management, allowing the observed improvements to be attributed to the change in therapy.

Although limited to a small number of horses, the findings suggest that daily oral cabergoline may provide a well-tolerated and effective alternative for PPID patients that cannot be successfully managed with pergolide or injectable cabergoline.

Dr. Kellon emphasised that these preliminary observations warrant further investigation. She believes additional research is needed to better understand the pharmacodynamics and pharmacokinetics of oral cabergoline in horses, establish its side-effect profile, and determine effective dosing strategies, particularly in horses with less severe disease.

While larger prospective studies will be necessary to confirm these findings, the report provides early evidence that oral cabergoline could expand treatment options for veterinarians managing some of the most difficult cases of equine PPID.

 

For more details, see:

Eleanor M. Kellon. 

Oral cabergoline for the management of equine pituitary pars intermedia dysfunction: Five cases.

Open Vet. J.. 2026; 16(6): 3818-3825.

https://doi.org/10.5455/OVJ.2026.v16.i6.52

 

*Godoy, A.F. and De La Fuentes, C.I. 

Cabergoline monotherapy in a Chilean creole horse with pituitary pars intermedia dysfunction (Cushing’s disease): a case report. 

Clin. Res. AnimSci. (2022) 2(3), 1–4

 

Shire Horse Society launches genetic study to safeguard the breed’s future

  

The Shire Horse Society is set to embark on a major scientific project in 2026 aimed at helping
secure the future of one of Britain’s most iconic native horse breeds.

Originating in England, particularly across the Midlands and Fenland regions, the Shire horse is renowned as a powerful draught breed with a history stretching back to the great horses of medieval England. Following the decline of heavy cavalry, Shires became indispensable to British agriculture and industry, ploughing heavy clay soils and hauling wagons, barges and brewery drays. The breed became a cornerstone of the Industrial Revolution, serving farms, mills and breweries throughout the country.

Today, however, the breed faces significant challenges. The Shire horse is currently classified as “At Risk” by the Rare Breeds Survival Trust, with official UK figures indicating a breeding population of fewer than 1,000 mares.

To help protect the breed’s future, the Shire Horse Society will work with genetics specialists at Nottingham Trent University’s Medical Technologies Innovation Facility (MTIF) to undertake a comprehensive genomic analysis of the UK Shire horse population. The project will be led by Dr Adam Varney, Senior Research Fellow at MTIF, alongside Dr Andy Dell, who has already worked closely with the Society on genetic management initiatives.

The study aims to provide a detailed understanding of the breed’s genetic makeup and evaluate the effectiveness of current pedigree-based breeding programmes. By examining the breed at a genomic level, researchers hope to identify both current and potential future genetic issues, enabling breeders to make more informed decisions and helping to ensure that future generations of Shires remain healthy, diverse and fit for purpose.

The Society has already adopted the SPARKS (Single Population and Records Keeping System) breeding support programme, which helps manage genetic diversity and reduce the risk of inbreeding. SPARKS calculates the relatedness of horses within the stud book and provides guidance on suitable mare and stallion pairings. While the system has proven valuable, genomic analysis offers a far more detailed picture of genetic diversity and health.

Managing inbreeding is particularly important in rare breeds, as loss of genetic diversity can lead to increased infertility, higher foal mortality, a greater risk of inherited disorders and reduced disease resistance. By combining pedigree information with modern genomic science, the Society hopes to strengthen long-term breeding strategies.

Similar genomic projects have already been successfully completed by the Eriskay Pony Society and the Cleveland Bay Horse Society, while the Suffolk Horse Society has recently begun its own programme.

Funded entirely through a generous legacy donation, the project is open to all owners of pure-bred Shire horses registered in the UK Shire Horse Society Stud Book. Mares, stallions and geldings of all ages are eligible to participate.

Collecting samples will be straightforward, requiring only a small hair sample. Testing kits, together with instructions, will be distributed directly to owners, who can either collect the samples themselves or ask their veterinarian to assist. Samples must be returned to the Society by 30 August 2026.

Once received, the DNA will be extracted and analysed by the NTU research team. Importantly, while samples identify individual horses during collection, all data will be anonymised before analysis. The project is designed to assess the breed as a whole, rather than individual animals.

The Shire Horse Society hopes that widespread participation will provide the most complete genetic picture possible. The findings are expected to play a vital role in shaping future breeding plans and ensuring that this historic British breed can thrive for generations to come.

Study challenges assumptions about “knee chips” in Thoroughbred yearlings

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The discovery of carpal osteochondral fragments (COF), commonly known as “knee chips,” on
pre-sale radiographs has long been viewed as a red flag in the Thoroughbred industry. Horses showing these lesions are often discounted at auction because buyers assume they will be less likely to succeed on the racetrack. However, new research suggests that this long-held belief may not be as straightforward as previously thought.

A study published in the Equine Veterinary Journal by researchers at the University of Kentucky's Maxwell H. Gluck Equine Research Center is the first to directly compare sales and racing outcomes of Thoroughbred yearlings with COF against a matched population of radiographically clean horses. The findings indicate that while the presence of COF can negatively affect both sales and racing performance, arthroscopic surgery may help mitigate some of those disadvantages.

“The idea came from seeing a large number of these cases get significantly marked down in price, just because people assume a chip means the horse won’t perform,” said Bruno Menarim, one of the study’s senior authors. “That was possibly true in the ’80s and part of the ’90s, but not with current arthroscopic surgery approaches.”

Researchers reviewed clinical records from Hagyard Equine Medical Institute between 2015 and 2018 and identified 46 Thoroughbred yearlings with dorsal osteochondral fragments of the radial or intermediate carpal bones. Twenty-six horses underwent arthroscopic removal of the fragments before sale, while 20 were managed conservatively. A control group of 138 sire- and year-matched siblings without radiographic abnormalities was also assembled.

The team then tracked sales and racing records up to June 2023, examining variables including sale price, career earnings, average earnings per start, number of starts, seasons raced, highest speed figure achieved and the highest class of race reached.

Overall, the presence of COF was associated with lower sale prices and reduced lifetime earnings, regardless of treatment. Horses in both the surgical and non-surgical groups also recorded fewer starts and raced for fewer seasons than their unaffected counterparts.

However, important differences emerged when treatment was considered. Horses whose fragments were removed arthroscopically were significantly more likely to achieve a racing career than those managed conservatively. Statistical analysis showed surgically treated horses had more than six times the odds of making it to the racetrack compared with untreated horses.

Perhaps more importantly from a commercial perspective, surgically treated horses were not significantly different from the control group in either sale price or total earnings. In contrast, untreated horses were heavily penalised at auction and earned significantly less during their racing careers.

“In other words, the gap between a surgically treated horse and a clean horse was not statistically significant,” Menarim explained. “The gap between an untreated horse and a clean horse was.”

The researchers also noted that the average difference in sale price between treated and untreated horses was nearly $2,000 - roughly equivalent to the cost of the surgery itself.

The study’s authors caution that the relatively small sample size and single-centre design limit the broader applicability of the findings. Nevertheless, the results suggest that while a history of COF can affect buyer perception, arthroscopic removal may preserve both sales appeal and future athletic potential.

For consignors and owners faced with a yearling diagnosed with a knee chip, the research offers reassurance that the lesion itself need not be career-defining - particularly when modern surgical treatment is employed.

For more details, see:

 

Daria C Debald, Victoria L Stanton, Cole B Sandow, Dwayne H Rodgerson, Michael A Spirito, Robert J Hunt, Bruno C Menarim.

Racing and sales performance in Thoroughbred yearlings after carpal osteochondral fragment removal.

Equine Vet J. 2026;58(3):682–691

https://doi.org/10.1111/evj.14532

Gothenburg Zoo horses remain calm around visitors, study finds

Dennis Björklund CC BY-SA 3.0

  

Visitors to zoos and animal parks often wonder how their presence affects the animals they
come to see. A new study from the University of Gothenburg offers reassuring news for animal keepers and visitors alike: the horses at Gothenburg's Children's Zoo appear comfortable around people, even when surrounded by groups of enthusiastic children.

Animal welfare encompasses both the physical and psychological wellbeing of animals and is a key concern for zoos and other organisations that keep animals in captivity. Understanding how animals respond to visitors is particularly important in facilities involved in conservation and breeding programmes, as stress can negatively affect health and reproduction.

To investigate whether human activity influences the welfare of horses at Slottsskogen, a large city park in Gothenburg, Sweden, researchers from the Department of Biological and Environmental Sciences, University of Gothenburg, monitored the heart rates of eight Gotland russ horses. Heart rate is widely used as an indicator of stress because it rises when animals experience physical exertion or emotional strain.

Lead researcher Isidora Dundjerovic and her colleagues fitted the horses with Polar heart rate monitors and measured their heart rates under three different conditions: while resting, during exercise, and during a playground event in which the horses stood in a paddock next to a children's play area and were petted by visitors while eating hay.

The results showed clear differences between the three situations. The horses' average resting heart rate was 42.5 beats per minute (bpm), while exercise increased it to an average of 85 bpm. During the playground event, however, the average heart rate was only 51 bpm - higher than at rest but far below the level recorded during exercise.

These findings suggest that interaction with visitors was not a significant source of stress for the horses. In fact, despite being surrounded by children and adults, the animals remained relatively calm throughout the event.

The study also provided insight into how the horses reacted to other common features of the urban park environment. During their daily walks, the horses encountered barking dogs, passing cars and other animals. None of these appeared to trigger a measurable stress response.

One exception stood out. During one playground session, an excavator unexpectedly started operating close to the paddock. The horses' heart rates rose sharply, and they quickly moved away from the machine. This reaction indicated that loud mechanical noise was stressful, unlike the presence of visitors or routine park activity.

"Horses have lived alongside humans for thousands of years," says Dundjerovic. "We now know a little more about how they are affected by being in an environment with lots of people, which is important for ensuring their welfare."

The findings are encouraging for the staff responsible for caring for the animals at the Children's Zoo. According to zoologist Linda Thelin, animal welfare is monitored closely through a variety of methods, and physiological studies such as this help identify sources of stress that may not be obvious from behaviour alone.

As zoos continue to balance conservation, education and public engagement, studies like this provide valuable evidence to guide management decisions. For the horses at Gothenburg's Children's Zoo, it appears that friendly human attention is not a problem - but noisy construction equipment is another matter entirely.

 

For more details, see:

Dundjerovic, I., and L. U. Sneddon. 2026.

Heart Rate as an Indicator of Stress in Gotland's Russ Horses.

 Zoo Biology 45: 293-299.

https://doi.org/10.1002/zoo.70052

New genetic discovery explains fatal neurological disease in Quarter Horse foals

   

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Researchers at the UC Davis School of Veterinary Medicine have identified the genetic cause of Equine Juvenile Spinocerebellar Ataxia (EJSCA), a recently recognised and fatal neurological disease affecting American Quarter Horse foals. The discovery not only provides breeders with a genetic test to prevent affected foals from being born, but also advances scientific understanding of neurological disease in both horses and humans.

EJSCA is an inherited neurological disorder that affects foals within the first few weeks of life. Clinical signs typically develop between one and five weeks of age and progress rapidly. Affected foals initially appear uncoordinated and exhibit proprioceptive ataxia, meaning they have difficulty determining the position of their limbs in space. Within days, many develop severe weakness of the hind limbs, become unable to stand without assistance, and eventually require euthanasia on welfare grounds.

The disease results from degeneration of axons, the long nerve fibres that connect neurons and allow communication between the brain, spinal cord and limbs. As these pathways deteriorate, the nervous system can no longer accurately transmit information about movement and body position. Consequently, affected foals lose balance and coordination despite appearing normal at birth.

The first recognised case of EJSCA was identified in 2020 in a Quarter Horse filly known as “Curly Sue.” Veterinarians initially suspected another neurological condition, equine neuroaxonal dystrophy (eNAD), but further investigations revealed that the foal was suffering from a previously unrecognised disease.

To identify the genetic cause, researchers at UCDavis performed whole-genome sequencing on seven affected foals and compared their DNA with that of unaffected relatives and unrelated control horses. The investigation identified an 82-kilobase region on chromosome 11 that contained several candidate genetic variants. Further molecular studies demonstrated that the causative mutation was located within a non-coding region of the ferredoxin reductase (FDXR) gene.

Unlike many disease-causing mutations that alter the protein-coding sequence of a gene, this mutation affects how the gene is processed into messenger RNA. The variant causes the insertion of a cryptic exon - a segment of genetic material that is not normally included in the final RNA transcript. As a result, affected foals produce lower amounts of functional FDXR protein.

This finding is significant because FDXR plays an important role in cellular energy metabolism and nervous system function. Analysis of spinal cord and liver tissues showed that affected foals had substantially reduced FDXR protein concentrations compared with healthy controls. Importantly, mutations in the human FDXR gene are known to cause neurological disease, making EJSCA a potentially valuable natural model for studying similar disorders in people.

The researchers determined that EJSCA follows an autosomal recessive pattern of inheritance. This means that affected foals inherit two copies of the mutation, one from each parent. Horses carrying only one copy remain clinically normal but can pass the variant to their offspring. When two carrier horses are bred together, there is a 25% chance of producing an affected foal.

Screening of more than 1,000 Quarter Horses identified 25 carriers, indicating that the mutation currently occurs at a relatively low frequency within the breed. It has not yet been detected in other horse breeds. Because all known affected foals trace back to a single influential sire, researchers believe the mutation may have arisen relatively recently.

The development of a genetic test by the UC Davis Veterinary Genetics Laboratory now allows breeders to identify carrier animals before breeding. By avoiding carrier-to-carrier matings, breeders can effectively prevent the birth of affected foals while maintaining valuable bloodlines. This discovery represents the first non-coding neurological genetic variant identified in horses and the first known genetic cause of a degenerative axonal disease in the species, marking an important milestone in equine genetics and neurological research.

 

For more details, see:

Brown, B. N., Dahlgren, A. R., Ghosh, S., Durbin-Johnson, B., Willis, A., Olivas, C., York, D., Grahn, R., Bellone, R. R., Cortopassi, G. A., Miller, A. D., Brown, C. T., Woolard, K., & Finno, C. J. (2026).

An intronic variant in Ferredoxin Reductase (FDXR) creates a cryptic exon in Quarter Horses with Equine Juvenile Spinocerebellar Ataxia. 

PLoS genetics, (2026). 22(5), e1012158.

https://doi.org/10.1371/journal.pgen.1012158

Pseudomonas aeruginosa in horses and other animals

  

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Pseudomonas aeruginosa is an environmentally widespread bacterium found naturally in soil and water. Although it
is often harmless in the environment, it is an important cause of disease in both human and veterinary medicine. The bacterium is particularly concerning because it possesses a high level of intrinsic resistance to many antibiotics, has a remarkable ability to adapt genetically, and can form resilient biofilms that protect it from both the host immune system and antimicrobial treatments.

 

The World Health Organisation (WHO) has designated P. aeruginosa as a "Priority Pathogen" due to its role in antimicrobial resistance. It is also one of the six bacterial species that make up the ESKAPE group (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species). These bacteria are responsible for many hospital-acquired infections worldwide and are notorious for their ability to evade antibiotic treatment.

 

In horses, P. aeruginosa is associated with several important diseases, including genital tract infections, respiratory disease and ocular infections. In mares, infection can contribute to infertility and pregnancy-related problems, making it a significant pathogen in equine breeding operations.

 

To better understand the occurrence of P. aeruginosa in animal populations, Kellie Strickland and colleagues at the University of the Sunshine Coast, Australia, conducted a large-scale epidemiological study. The researchers analysed 1,669 DNA samples collected between 2010 and 2023 from a variety of healthy and diseased animals in South-East Queensland. The study included samples from wild birds, domestic animals, livestock, kangaroos and koalas.

 

Overall, the prevalence of P. aeruginosa was relatively low, with only 1.8% of all samples testing positive. However, livestock had the highest prevalence (4.5%), largely driven by horses, which showed a prevalence of 7.4%. This was considerably higher than the rates observed in wild birds (1.5%), koalas (1.6%) and other domestic animals (1.9%). No positive samples were detected in cattle or kangaroos.

 

Of particular concern was the detection of a genetic mutation known as GyrA Thr83Ile in two horse-derived P. aeruginosa samples. This mutation has previously been associated with resistance to fluoroquinolones, a class of antibiotics commonly used to treat P. aeruginosa infections in both humans and horses. Although the researchers were unable to confirm antibiotic resistance through laboratory culture and susceptibility testing, the presence of this mutation suggests that a resistant subpopulation may be emerging within the equine population.

 

The findings highlight the importance of ongoing surveillance of antimicrobial resistance in horses. While the overall prevalence of P. aeruginosa was low, the relatively high carriage rate in horses and the detection of a clinically important resistance-associated mutation warrant further investigation.

 

For more details, see:

Prevalence of Pseudomonas aeruginosa in Australian wild birds, native wildlife, livestock and domestic animals

Kellie R. Strickland, Martina Jelocnik, Erin P. Price & Derek S. Sarovich 

Scientific Reports (2026) vol 16, Article number: 15423 (2026) 

https://www.nature.com/articles/s41598-026-43853-6