Ontario Animal Health Network (OAHN)
Equine Expert Network
Quarterly Veterinary Report

The importance of removing chondroids in Strangles cases:

In June, Dr. Arroyo removed guttural pouch chondroids from a horse with Strangles and put those chondroids in a container in the refrigerator (not a nice warm/moist environment).

He recently retested the chondroids to see if bacteria would grow.

The results:

PCR  positive, CT of 23.84 (negative is a CT of 40 or greater)

Bacterial culture:  4+  S. equi

 

 

Read about our new OAHN S. equi research project and our request for samples here:

OAHN Equine Project: Detection of Streptococcus equi subsp. equi infections in Ontario horses – A comparative study (in progress) – Ontario Animal Health Network

 

 

Strangles and EHV-1 Resources

The OAHN Equine network has put together a list of Strangles and EHV-1 resources for veterinarians and owners. They are available at:

• Equine Strangles Resources – Ontario Animal Health Network (oahn.ca)
• Equine Herpesvirus-1 Resources – Ontario Animal Health Network (oahn.ca)

The Ontario map of facilities dealing with Strangles and EHM can be found here:

Equine Disease Tracking Network v 2.1 (arcgis.com)

Strangles and EHM alert notifications are available at:

• Ontario Equine Disease Alerts – Ontario Animal Health Network (oahn.ca)
• Outbreaks | Equine Disease Communication Center (equinediseasecc.org

BITS ‘N SNIPS (or “things we talked about on the network call”)

Equine Muldinodular Pulmonary Fibrosis (EMPF)

On the Q2 network call we discussed  the increase in hard-to-manage equine asthma cases that occurred this quarter. We also discussed a case of EMPF in the pathology section. Given that EMPF can be misdiagnosed as severe equine asthma, we thought an overview of EMPF was in order.

Equine Multinodular Pulmonary Fibrosis (EMPF) is an interstitial lung disease that affects horses, characterized by diffuse miliary or nodular pulmonary fibrosis. The condition is often associated with Equine Herpesvirus-5 (EHV-5), a gammaherpesvirus that has been detected in the majority of EMPF cases, although other viruses like Asinine Herpesvirus-5 (AHV-5) have also been implicated1,2. EMPF can be challenging to diagnose due to its overlap with other respiratory diseases, such as equine asthma, which also present with clinical signs of chronic respiratory issues.

Clinical Signs

Horses with EMPF typically present with progressive respiratory symptoms and weight loss. The main clinical signs include:

• Weight loss: Seen in 78% of cases1
• Increased respiratory effort: Noted in 72% of horses1
• Tachypnea: Present in 70% of cases1
• Fever: Occurs in 39%, but it is not always a reliable indicator¹
• Nasal discharge and respiratory distress were also noted in some cases.

Horses often exhibit a combination of these signs, which can overlap with other respiratory conditions like asthma, making differential diagnosis crucial2

Diagnosis

Radiographic and Ultrasonographic Findings

Diagnostic imaging is essential in the diagnosis of EMPF. Thoracic radiographs commonly reveal:

• Nodular (71%) and interstitial (78%) patterns, often combined¹
• Ultrasonography: Nodules were seen in 59% of cases, with pleural thickening in some¹

Bronchoalveolar Lavage Fluid (BALF) Analysis

BALF cytology can differentiate EMPF from other conditions such as asthma:

• Macrophage atypia: Detected in 67% of EMPF cases versus 8% in asthma¹
• Neutrophilia and abnormal macrophages with vacuolation were common features.

Virological Testing

The presence of EHV-5 in BALF or lung tissue via PCR testing is a key diagnostic marker:

• EHV-5 was detected in 80% of cases¹. However, AHV-5 has also been implicated in some cases².

Histopathological Examination

In some cases, a lung biopsy or necropsy is required for a definitive diagnosis, revealing interstitial fibrosis, often with accompanying pneumocyte hyperplasia and inflammation¹.

Treatment and Prognosis

Treatment of EMPF typically includes the use of corticosteroids and antiviral medications like valacyclovir. However, the prognosis remains poor:

• Only 24% of horses survive beyond 3 months after diagnosis¹.
• Horses with lower respiratory rates and higher BALF lymphocyte ratios had better outcomes.

Conclusion

EMPF should be considered in horses with persistent respiratory issues, especially when they do not respond to treatment for asthma or bacterial pneumonia. Thoracic imaging and BALF cytology, along with PCR testing for EHV-5, are crucial for diagnosis. While treatment options are limited and the prognosis is often guarded, early detection and management are key to improving short-term outcomes^{1, 2}.

References:

1. Clinical findings and outcome predictors for multinodular pulmonary fibrosis in horses: 46 cases (2009-2019).Craven A, Todd-Donato A, Stokol T, Liepman R, Glasberg I, Wilkins P, Luethy D, Wong D, Schoster A, van den Brom-Spierenburg AJ, Tomlinson JE.J Vet Intern Med. 2024 May-Jun;38(3):1842-1857 Free PMC article.
2. A case series highlighting the role of different gamma-herpesviruses in Equine Multinodular Pulmonary Fibrosis.Scheurer L, Bachofen C, Herteman N, Hilbe M, Wolfer N, Schoster A.Schweiz Arch Tierheilkd. 2020 Apr;162(4):245-256 Free article.

Pasture-associated laminitis was also a recurring topic on the call and from the quarterly survey.

Pasture associated Laminitis

A major contributor to pasture-associated laminitis is the intake of high levels of nonstructural carbohydrates (NSC), including sugars, starches, and fructans from pasture grasses​¹. During photosynthesis, plants produce these carbohydrates, which are stored as energy reserves. Under specific conditions, such as cool, sunny weather, the NSC concentration, particularly fructans, can accumulate to dangerous levels in cool-season grasses, putting horses at risk for laminitis¹.

High intake of NSC, especially fructans, leads to rapid fermentation in the hindgut, causing a shift in gut microbiota, increased lactic acid production, and a drop in hindgut pH. This results in hindgut acidosis, compromising the horse’s metabolism and circulation in the feet, thus inducing laminitis​ ^1,2Furthermore, laminitis can occur when the digestive capacity for starch is overwhelmed, causing undigested starch to enter the hindgut, similar to fructans¹.

Fructans vs. Starches in Grasses

Fructans and starches are both types of NSC that accumulate in grasses, but they differ in their structures and storage patterns. Cool-season grasses (C3 plants) primarily store fructans, which accumulate in stems and vacuoles​¹. Fructans are continually stored in the stems to provide energy for growth and development. There is no self-limiting process, therefore fructans continue to accumulate¹.

Fructans are not easily digestible by enzymes in the horse’s foregut, leading to their passage into the hindgut, where they undergo rapid fermentation by bacteria, exacerbating hindgut acidosis and leading to laminitis​^{1, 2}

In contrast, starches are stored in the seeds and leaves of warm-season grasses (C4 plants) and legumes, where they serve as a more limited energy reserve. The storage of starches is self-limiting; starch production ceases once the chloroplasts become saturated.  Starches are easier to digest than fructans in the small intestine, but excess intake can still lead to undigested starch reaching the hindgut and causing similar issues as fructans​². While fructans are more dangerous due to their rapid fermentation properties, both carbohydrates must be carefully managed to avoid laminitis³.

Weather and Climate Impact on NSC Levels

Weather and climate directly influence the accumulation of NSCs in pasture grasses, with temperature, light, and water availability playing critical roles. For example, cool-season grasses (C3) accumulate fructans as storage carbohydrates, especially under cooler temperatures (5-10°C). Conversely, warmer temperatures (15-25°C) limit fructan accumulation and promote growth, reducing NSC content¹. This explains why laminitis cases peak during cooler periods, such as early spring and fall, when NSC levels in grasses are high^1,2.

Light Intensity

Photosynthesis drives the production of NSCs, with light intensity playing a key role in NSC accumulation. Under high light conditions, photosynthesis outpaces plant growth, leading to a surplus of carbohydrates. Conversely, shaded or cloudy conditions result in lower NSC levels¹. Diurnal variations in storage carbohydrates leased to concentrations rising during the morning with a maximum in the afternoon and declining overnight. Early morning often has the lowest levels of storage carbohydrates.

Water Availability and Drought

Drought conditions further exacerbate NSC accumulation. During prolonged drought, grasses produce higher fructan concentrations as a survival mechanism, storing energy in preparation for growth when water becomes available​¹. This increased NSC content raises the risk of laminitis during dry periods, especially if rainfall follows, promoting rapid grass growth that horses can consume².

Seasonal Patterns and Pasture Management

NSC concentrations vary throughout the year, being highest in late spring and early fall, corresponding to periods of cool temperatures and high light intensity^1,3. Management strategies for horses prone to laminitis should focus on these periods when NSC levels are most likely to be elevated. Veterinarians should recommend reducing grazing time during these peak periods or providing access to pastures with lower NSC content, such as warm-season grasses³.

Gut Microbiota and Laminitis

The gut microbiota plays a crucial role in the development of laminitis. Horses rely heavily on microbial fermentation of fiber in the hindgut to derive energy. A healthy gut microbiome is predominantly composed of fiber-digesting bacteria, which maintain hindgut pH and produce beneficial short-chain fatty acids (SCFAs)³. However, when excess NSC, particularly fructans or undigested starch, reach the hindgut, they promote the growth of lactic acid-producing bacteria, reducing pH and causing acidosis^2,3.

Studies have shown that transitioning horses between different types of forage can significantly alter their gut microbiota. For example, horses grazing on warm-season grasses, which have lower NSC content, have a more stable hindgut environment with fewer disruptions to their microbial population compared to those grazing cool-season grasses​³. Specific bacterial species, such as Akkermansia and Clostridium butyricum, have been identified as playing a role in mitigating negative metabolic responses and are enriched when horses graze on lower-NSC forages³. Supplementing with mannanoligosaccharides and frutooligosaccharides have led to an increased abundance of Akkermansia with an increase in insulin sensitivity.

Managing and Preventing Laminitis

To manage and prevent laminitis, a combination of pasture management and dietary strategies should be employed:

• Pasture Management: Limit grazing time during periods when fructan levels in grasses are high, such as in the morning and late afternoon during spring and autumn. Cool-season grasses accumulate fructans during sunny, cool days, especially when daytime temperatures are mild, but nighttime temperatures are low​¹. Restrict grazing to early morning and graze shaded pastures when possible. Special consideration to be given to susceptible horses (those with metabolic conditions) and those with a previous history of laminitis¹. Graze or mow pastures to keep short, leafy grass which encourages growth and utilization of NSC as opposed to storage. Avoid pastures that have gone to seed or recently harvested fields as there may be high fuctans in the stems¹.
• Grazing Systems: Rotational grazing and integrating warm-season grasses, which have lower NSC levels, can help reduce the risk³.
• Dietary Management: Horses at risk of laminitis should have controlled access to pasture and can benefit from feeding low-NSC hay or other forage sources that are high in fiber. This helps maintain a stable gut environment and reduces the risk of acidosis^2,3. Grazing muzzles restrict intake but also limits intake to the tops of leaves where NSC is lowest.

References:

1. Pasture nonstructural carbohydrates and equine laminitis.Longland AC, Byrd BM.J Nutr. 2006 Jul;136(7 Suppl):2099S-2102S. doi: 10.1093/jn/136.7.2099S.PMID: 16772510 Free article.
2. The Fibre Requirements of Horses and the Consequences and Causes of Failure to Meet Them.Ermers C, McGilchrist N, Fenner K, Wilson B, McGreevy P.Animals (Basel). 2023 Apr 20;13(8):1414. doi: 10.3390/ani13081414.PMID: 37106977 Free PMC article. Review.
3. Fecal Microbiota, Forage Nutrients, and Metabolic Responses of Horses Grazing Warm– and Cool-Season Grass Pastures.Weinert-Nelson JR, Biddle AS, Sampath H, Williams CA.Animals (Basel). 2023 Feb 22;13(5):790. doi: 10.3390/ani13050790.PMID: 36899650 Free PMC article.

Network Member Reports

Southwestern Region (Melissa McKee)	In Q2, we saw a big surge in laminitis cases. Most of the horses were predisposed though obesity or metabolic/PPID conditions however we also had a few cases in some relatively normal animals. The grass has remained unusually lush with the intense rain/sun cycle which is probably the primary explanation. This has also led to difficulty getting good hay cut and baled, so we may be seeing increased respiratory and nutritional issues later in the year. We also saw some difficult-to-manage asthma cases with some ending in euthanasia. Skin conditions related to the climatic conditions are also staying at high levels- hives, fungal/mixed bacterial infections, pastern dermatitis. Foot bruising is up also, as the feet are staying soft from the constant moisture levels and not keeping up when the ground dries and gets hard. Gas colics/displacements are the primary abdominal complaint, many require referral and intensive medical management at a referral hospital. Of those that had surgery, quite a number were euthanized on the table with small intestinal complications. There has been a drop in the number of strangles cases, we have either identified and treated most of the affected farms by now and/or people are reluctant to test now that it’s notifiable. The decline of available medications in Canada is an ongoing challenge (Predef, Special Formula, Fulvicin, anti-virals, injectable vitamins such as Hemostam, etc,).
Western Region (Tara Foy)	Nothing out of the ordinary this quarter. As with other members we also saw a number of horses with laminitis but not increased for the quarter. Many of them do have normal ACTH but we don’t test with TRH as it’s not readily available so there may be more metabolic horses than we are aware.  We saw fewer asthmatic horses then usual and that may be due to regional/climatic/ management reasons in our area of the province.  There seemed to be more broad ligament bleeds than last year but that may be related to an aging broodmare population in our area. We had one interesting case of Bordatella sp endocarditis in a foal who’s growth became stunted and it was lethargic with a persistent snotty nose and cough. We had previously dealt with an outbreak of Bordatella sp pneumonia in some of our young stock.
Eastern Ontario (John Donovan)	We examined a number of horses with asthma in Q2 as well as an increase in the number of severe and ongoing laminitis cases, many of which did not have metabolic issues.  The environmental situation (lush green pasture) is believed to be part of the problem with the laminitis cases.  We saw our typical spring colics (mainly spasmodic due to changing grass and weather situations) and most were managed on farm. We also saw a number of horse with skin conditions (generalized body dermatitis, pastern dermatitis), again likely due to the wet weather.  A number of healthy foals were born but we did see an increase in angular limb deformities some of which needed periosteal stripping, and foals with contracted tendons.  Our clinic managed a Strangles outbreak in Quebec.  We also saw a number of horses with choke from decent barns with stringent feeding protocols but all resolved uneventfully. Breeding back mares has been a challenge, again likely due to the weather, with it taking more effort to get mares settled than last year.

Ontario Veterinary College (Memo Arroyo)

In Q2, we had more asthmatic horses admitted to the hospital than usual noting that most were on appropriate medical treatment but the environment was either not being appropriately managed or it was difficult to do so (poor hay quality).  We also saw a number of neurologic horses with many typical  diagnoses such as CVM/I or wobblers.  We have heard from clinicians in the field that they are seeing a number of laminitis cases. Some of these may be due to PHF/rickettsiosis as PHF cases don’t always develop diarrhea.

AHL Pathology (Emily Ratsep)

2 yo standardbred filly was diagnosed with suspect equine neuroaxonal dystrophy. She had neurologic signs; cranial nerve deficits II, V, VII, VIII, X, XII and grade 3/5 ataxia. There was multifocal axonal swelling observed in the dorsolateral tract of the spinal cord at the level of T17/18 thoracic spine. Approximately 80% of axons were swollen. These are the features of equine neuraxonal dystrophy, although the vitamin E levels in the liver were within normal limits. There are reports that normal vitamin E levels have been observed in horses with eNAD. Changes in vitamin E metabolism and genetic predisposition are suspected to be contributing factors. It is possible that this horse may have had past vitamin E deficiency that isn’t reflected in the current liver concentrations. 17 yo TB was diagnosed with liposarcoma. A non-ulcerated, movable lump on the face midway from the base of the ear to jawline was removed entirely and sent for histological diagnosis. Liposarcomas are considered rare in horses but have been reported from various sites. These neoplasms tend to be locally infiltrative, however the current mass is well demarcated and does not appear to be exhibiting any distinct infiltrative behaviour. 24 yo gelding was diagnosed with necrosing cystitis and peritonitis with bladder rupture. He presented for inability to urinate following colic on the weekend. Ultrasound showed free abdominal fluid and distended bladder. Abdominal drains were placed and catheterization was attempted but not successful. Urethroscopy showed a urolith that could not be removed. Extensive necrosis of the bladder was identified (consistent with the clinical history and gross examination) urethritis secondary to abrasion by the obstructive urolith and subsequent surgical removal was observed. Bladder necrosis was considered a consequence of pressure necrosis from urinary stasis and eventual rupture. Laminitis was observed in all limbs and suspected to reflect the systemic inflammation following peritonitis. Renal tubular distension was observed and considered secondary to the recent urinary obstruction. 20 yo mare was diagnosed with equine multinodular pulmonary fibrosis. She present with a history of chronic weight loss, coughing and lymphocytosis. Lymphoma was suspected. Lung sounds were increased bilaterally with crackles. Thoracic ultrasound revealed pleural roughening, irregularities and comet tails. The pulmonary parenchymal changes are those of equine multinodular pulmonary fibrosis (EMPF); there is no evidence of neoplastic cells. EMPF may be from infection by equine herpesvirus-5 (1). Though tissue submitted for this case was negative for EHV-5 by PCR. 2 day old SB filly was diagnosed with thyroid hyperplasia and musculoskeletal syndrome. The filly presented with severe angular limb deformity in the hind limbs and dehydration. She was diagnosed with rib fractures and significant abnormalities on blood work. She developed nystagmus,  a fever and was abnormally vocalizing. Her condition deteriorated and she died. The postmortem examination findings, as well as histopathologic hyperplasia of the thyroid gland and ovarian dysmaturity are consistent with thyroid hyperplasia and musculoskeletal syndrome. While not well-characterized, previous studies have suggested that this condition may be related to dietary iodine levels in the mare. Although arthrogryposis is classically associated with this condition, in this case tendon contractures may have affected extensor rather than flexor tendons and caused the rigid fixation of the tarsi in extension noted grossly. The histopathologic changes seen within the lung are indicative of embolic pneumonia, with additional changes in the liver most suggestive of hypoxic/ischemic injury due to a combination of sepsis and poor lung aeration. The blebs observed grossly remain incompletely explained, as embolic pneumonia does not typically produce blebs . The generalized lympholysis seen within the spleen, thymus, and lymph node is a nonspecific indicator of stress and systemic disease within foals. In this case, the foal was most likely unable to stand to nurse adequately and this could have led to failure of passive transfer and increased susceptibility to a wide array of pathogens. Evidence of mild amniotic fluid and meconium aspiration was superimposed on the embolic pneumonia and may have further contributed to poor aeration and clinical compromise.

OMAFA (Hannah Golightly & Alison Moore)

Immediately Notifiable Diseases: Case Reports to OMAFA Equine Herpesvirus-1: There were 0 facilities affected by EHM due to EHV-1 in Q2. One horse tested PCR positive when screened to enter a broodmare facility. Map of counties with facilities positive for EHV-1 (with EHM) in Q1 and Q2. Available from: Equine Disease Tracking Network v 2.1 (arcgis.com) Strangles: During Q2 there were 5 new facilities managing Strangles located in: City of Kawartha Lakes,  Peterborough County, United Counties of Prescott and Russell, Regional Municipality of Waterloo. Equine Influenza: In Q2, there was one facility in Simcoe County positive for equine influenza. There have been no West Nile virus or Eastern Equine Encephalitis virus positive horses reported in Q2. Q2 Equine Syndromic Surveillance: Graphs of disease syndromes based on samples sent for testing to the Animal Health Laboratory. This information is compiled based on the type of sample, test ordered, and key terms included in the submission history (if provided).

 

Please follow:

Outbreaks | Equine Disease Communication Center (equinediseasecc.org) for reported outbreaks!

Syndromic and AHL Laboratory Data Surveillance

Survey – Key points

• 22 Counties represented
• 63% equine, 19% equine and food animal, 6% mixed animal, 6% equine and small animal and 6% referral practice veterinarians responded.
• 23% of veterinarians reported working with pleasure/backyard horses, 23% with performance/Competition/Show horses, 14% with foals, breeding and young stock, 14% with draft horses, 13% with mules/donkeys 9% with racehorses, and 2% with buggy horses.
• Increases in Q2 were noted for (foal): septic joints/growth plates in foals >30 days or at odd ages, pneumonia (older than 3 mos), multiple “snotty noses”, upper respiratory infections, Strangles, meconium impactions, Lawsonia suspects, limb deformities. One S. zoo on tracheal wash resistant to ceftiofur.
• Increases in Q2 were noted for (adult) Equine asthma, allergic dermatitis, laminitis , anaplasmosis, slobbers, rainrot, EHV respiratory infections (2, 4, 5), colic (gas, displacements, surgical) FUO / oxytetracycline responsive fevers, suspect EDM cases, lice, uterine infections, EMS, PPID, P1 fractures

New conditions or those without a diagnosis:

• Eye related issues – look like ERU, IMMK

 

Equine Research from Ontario and Around the World

Researchers in Ontario

Reproductive Tract Microbiota of Mares. Gil-Miranda A, Macnicol J, Orellana-Guerrero D, Samper JC, Gomez DE.Vet Sci. 2024 Jul 18;11(7):324. Free PMC article.

Effect of extracorporeal shockwave therapy on the immunomodulatory and anti-inflammatory properties of cultured equine umbilical cord blood mesenchymal stromal cells. Giraldo A, Koch TG, Madan P, Lepage S, Monteith G, Alizadeh AH, Tran A, Mortagy N, Koenig JB.Can J Vet Res. 2024 Jul;88(3):87-93. Free PMC article.

Biosecurity perceptions among Ontario horse owners during the COVID-19 pandemic.Germann JA, O’Sullivan TL, Greer AL, Spence KL.Equine Vet J. 2024 Jun 27.

Tetanus prophylaxis in horses: guidelines for New Zealand and Australia based on a critical appraisal of the evidence. Lovett AL, Riley CB, Chapman V, Bell B, Bishop B, Grierson A, Johnstone LJ, Sykes BW.N Z Vet J. 2024 Sep;72(5):241-255.

Researchers around the world

Behaviour

Horses can learn to identify joy and sadness against other basic emotions from human facial expressions. Jardat P, Menard-Peroy Z, Parias C, Reigner F, Calandreau L, Lansade L.Behav Processes. 2024 Jul 26:105081.  Free article.

Automated recognition of emotional states of horses from facial expressions. Feighelstein M, Riccie-Bonot C, Hasan H, Weinberg H, Rettig T, Segal M, Distelfeld T, Shimshoni I, Mills DS, Zamansky A.PLoS One. 2024 Jul 15;19(7):e0302893. Free PMC article.

Biomechanics

Relationship between the left-right asymmetric motor-related conformation and the orientation of facial hair whorls in Japanese Kiso horses. Onouchi S, Yoshida T, Saito S, Atoji Y.J Vet Med Sci. 2024 Jul 9. doi: 10.1292/jvms.24-0182. Online ahead of print.PMID: 38987179 Free article.

Influence of surgical intervention at the level of the dorsal spinous processes on the biomechanics of the equine thoracolumbar spine. Baudisch N, Singer E, Jensen KC, Eichler F, Meyer HJ, Lischer C, Ehrle A.Equine Vet J. 2024 Jun 27. doi: 10.1111/evj.14123. Online ahead of print.

Characterization and Association of the Missing Ventral Tubercle(s) from the Sixth Cervical Vertebra and Transpositions on the Ventral Surface of the Seventh Cervical Vertebra in Modern Equus ferus caballus. May-Davis S, Eckelbarger PB, Dzingle D, Saber E.Animals (Basel). 2024 Jun 20;14(12):1830. doi: 10.3390/ani14121830.PMID: 38929448 Free PMC article.

Effect of circle, surface type and stride duration on vertical head and pelvis movement in riding horses with pre-existing movement asymmetries in trot. Marunova E, Hernlund E, Persson-Sjödin E.PLoS One. 2024 Aug 16;19(8):e0308996. doi: 10.1371/journal.pone.0308996. eCollection 2024.PMID: 39150961 Free PMC article.

Digital video analysis reveals gait parameters that predict performance in the jumping test phase of three-day eventing.Johns LT, Smythe MP, Dewberry S, Staiger EA, Allen K, Brooks SA.J Equine Vet Sci. 2024 Aug 17:105166. doi: 10.1016/j.jevs.2024.105166.

Prevalence of movement asymmetries in high-performing riding horses perceived as free from lameness and riders’ perception of horse sidedness. Zetterberg E, Persson-Sjodin E, Lundblad J, Hernlund E, Rhodin M.PLoS One. 2024 Jul 30;19(7):e0308061. Free PMC article.

Foal Medicine

Ultrasound findings in 34 newborn foals with uroperitoneum. Bernick A, Demattio LS, Wehrend A.Vet Med Sci. 2024 Jul;10(4):e1545. doi: 10.1002/vms3.1545.PMID: 39001601 Free PMC article.

Gastroenterology

Systematic evaluation supports the use of ELISA for quantification of calprotectin in equine feces, a first step toward noninvasive quantification of intestinal inflammation in horses. Bishop RC, Graham SM, Connolly SL, Wilkins PA, McCoy AM.Am J Vet Res. 2024 Jul 9:1-10. Free article.

Changes in saliva analytes in equine gastric ulcer syndrome (EGUS) after treatment: a pilot study. Muñoz-Prieto A, Llamas-Amor E, Cerón JJ, Hansen S.Res Vet Sci. 2024 Aug;176:105346. Free article.

Measurement of Trace Elements (Zinc, Copper, Magnesium, and Iron) in the Saliva of Horses: Validation Data and Changes in Equine Gastric Ulcer Syndrome (EGUS). Muñoz-Prieto A, Cerón JJ, Tecles F, Cuervo MM, Contreras-Aguilar MD, Ayala I, Oudada-Guillén A, Pardo-Marín L, Hansen S.Animals (Basel). 2024 Jun 7;14(12):1724 Free PMC article.

Genetics

Preliminary investigation of potential links between pigmentation variants and opioid analgesic effectiveness in horses during cerebrospinal fluid centesis. Bacon EK, Donnelly CG, Bellone RR, Haase B, Finno CJ, Velie BD.BMC Vet Res. 2024 Jul 12;20(1):311 Free PMC article.

Health Management

Hoof wall masses removal in 30 standing sedated horses: Surgical technique, postoperative complications and long-term outcome.Ross C, White JM, Hibner-Szaltys M, Stephenson RS, Withers JM, Marcatili M.Vet Surg. 2024 Jul 19.

Environmental Conditions in Equine Indoor Arenas: A Descriptive Study. McGill S, Coleman R, Hayes M.J Equine Vet Sci. 2024 Aug 16:105165.

Horse Racing
Concurrent radiological and ultrasonographical findings in the forelimb proximal sesamoid bones and adjacent suspensory ligament branches in yearling and 2-year-old Thoroughbred sales horses. Peat FJ, Kawcak CE, McIlwraith CW, Berk JT, Keenan DP. Equine Vet J. 2024 Jul 22. doi: 10.1111/evj.14120.

Ultrasonography of the suspensory ligament branches in yearling and 2-year-old Thoroughbred sales horses: Prevalence, progression of findings and associations with racing performance. Peat FJ, Kawcak CE, McIlwraith CW, Berk JT, Keenan DP, Selberg KT, Ojeda A.Equine Vet J. 2024 Jul 15

Histological and Histopathological Features of the Third Metacarpal/Tarsal Parasagittal Groove and Proximal Phalanx Sagittal Groove in Thoroughbred Horses with Racing History. Lin ST, Foote AK, Bolas NM, Sargan DR, Murray RC.Animals (Basel). 2024 Jun 30;14(13):1942. doi: 10.3390/ani14131942.PMID: 38998057 Free PMC article.

Heritability of sudden cardiac death in Thoroughbred racehorses. Kapusniak A, Nath L, Hebart M, Franklin S.Equine Vet J. 2024 Jul 10.

Athletic prognosis following arthroscopic removal of osteochondral fragments of the proximal dorsal sagittal ridge of the fetlock in Thoroughbreds intended for flat racing. Luick ML, Khouzam NA, Pérez-Nogués M.Vet Surg. 2024 Aug;53(6):980-987..

Early-life gut bacterial community structure predicts disease risk and athletic performance in horses bred for racing. Leng J, Moller-Levet C, Mansergh RI, O’Flaherty R, Cooke R, Sells P, Pinkham C, Pynn O, Smith C, Wise Z, Ellis R, Couto Alves A, La Ragione R, Proudman C.Sci Rep. 2024 Aug 7;14(1):17124. doi: 10.1038/s41598-024-64657-6.PMID: 39112552 Free PMC article.

Comparison of radiography and computed tomography for identification of third metacarpal structural change and associated assessment of condylar stress fracture risk in Thoroughbred racehorses. Irandoust S, O’Neil LM, Stevenson CM, Franseen FM, Ramzan PHL, Powell SE, Brounts SH, Loeber SJ, Ergun DL, Whitton RC, Henak CR, Muir P.Equine Vet J. 2024 Aug 14

Immune Response
Serum amyloid A increases following routine vaccination of healthy adult horses. Baumgarten CM, Delph Miller KM, Davis EG, Beard LA, Blevins CA, Wottowa M, Hill M, Larson RL.J Am Vet Med Assoc. 2024 Jul 3:1-7

Infectious Disease

Evaluation of Non-Invasive Sampling Techniques for the Molecular Surveillance of Equid Herpesviruses in Yearling Horses. Khan A, Olajide E, Friedrich M, Holt A, Goehring LS.Viruses. 2024 Jul 7;16(7):1091. Free PMC article.

Investigation of the Use of Environmental Samples for the Detection of EHV-1 in the Stalls of Subclinical Shedders.Pusterla N, Lawton K, Barnum S.Viruses. 2024 Jul 3;16(7):1070 Free PMC article.

Taylorella equigenitalis in Icelandic intact males compared with other horse breeds using natural cover. Grabatin M, Fux R, Zablotski Y, Goehring LS, Witte TS.Equine Vet J. 2024 Jun 21

Metabolic disease

Prevalence of insulin dysregulation in the non-obese stock-type horse and relationship with morphometric neck measurements. Heaton CP, Cavinder CA, McClure EN, Smith T, Smith WB, Liburt N, Krotky A, Harris P.J Equine Vet Sci. 2024 Jul 26:105151.

Sodium-glucose transport protein 2 inhibitor use in the management of insulin dysregulation in ponies and horses. Menzies-Gow NJ, Knowles EJ.J Vet Pharmacol Ther. 2024 Jul 10

Plasma concentration of serum amyloid A and lipopolysaccharide binding protein in horses with laminitis resulted from hindgut acidosis. Safaee Firouzabadi MS, Paidar Ardakani A.Vet J. 2024 Jul 1;306:106190.

Myopathy

Large-scale study of blood markers in equine atypical myopathy reveals subclinical poisoning and advances in diagnostic and prognostic criteria. Renaud B, Kruse CJ, François AC, Cesarini C, van Loon G, Palmers K, Boemer F, Luis G, Gustin P, Votion DM.Environ Toxicol Pharmacol. 2024 Jul 18;110:104515.

Characterisation of phenotypic patterns in equine exercise-associated myopathies. Lindsay-McGee V, Massey C, Li YT, Clark EL, Psifidi A, Piercy RJ.Equine Vet J. 2024 Jul 5.

Neurology

Use of a poll-mounted accelerometer for quantification and characterisation of equine trigeminal-mediated headshaking. Pickles KJ, Marlin DJ, Williams JM, Roberts VLH.Equine Vet J. 2024 Jul 17

Beyond the surface: how ex-vivo diffusion-weighted imaging reveals large animal brain microstructure and connectivity.Behroozi M, Graïc JM, Gerussi T.Front Neurosci. 2024 Jun 26;18:1411982. Free PMC article

Ophthalmology

Causes, treatment, and outcome of hyphema, fibrin, and vitreal hemorrhage in horses: 219 cases (2012-2023). Gould J, Wells M, de Linde Henriksen M, Gilger B.J Am Vet Med Assoc. 2024 Jul 24:1-8

Equine Corneal Wound Healing Using Mesenchymal Stem Cell Secretome: Case Report. Casado-Santos A, González-Cubero E, González-Fernández ML, González-Rodríguez Y, García-Rodríguez MB, Villar-Suárez V.Animals (Basel). 2024 Jun 21;14(13):1842. Free PMC article.

Parasitology

Unravelling the Effectiveness of Anthelmintic Treatments on Equine Strongyles on Irish Farms. Elghryani N, Lawlor A, McOwan T, de Waal T.Animals (Basel). 2024 Jul 2;14(13):1958Free PMC article.

The effect of anthelmintic treatment and efficacy on the faecal microbiota of healthy adult horses. Bell J, Raidal SL, Hughes KJ.Vet Parasitol. 2024 Aug;330:110241. Free article.

Occurrence of fenbendazole resistance in Parascaris spp. on breeding farms in Sweden. Martin F, Halvarsson P, Alm YH, Tydén E.Vet Parasitol. 2024 Jul 22;331:110272. Free article.

Pharmacology

Endocannabinoid system and phytocannabinoids in the main species of veterinary interest: a comparative review.Di Salvo A, Chiaradia E, Sforna M, Della Rocca G.Vet Res Commun. 2024 Aug 20

Equine Pergolide Toxicity: A Case Series. Ebeling-Koning NE, Fowler JT Jr, DelBianco JD, Surmaitis RM.Cureus. 2024 Jul 10;16(7):e64265. Free PMC article.

Reproduction

Platelet-Rich Plasma Proteome of Mares Susceptible to Persistent-Breeding-Induced Endometritis Differs from Resistant Mares. Novello G, Souza FF, Canisso IF.Animals (Basel). 2024 Jul 18;14(14):2100Free PMC article.

An Overview of Infectious and Non-Infectious Causes of Pregnancy Losses in Equine. Li L, Li S, Ma H, Akhtar MF, Tan Y, Wang T, Liu W, Khan A, Khan MZ, Wang C.Animals (Basel). 2024 Jul 2;14(13):1961. Free PMC article.

Untargeted Metabolomic Analysis Reveals Plasma Differences between Mares with Endometritis and Healthy Ones. Zhang X, Gao Y, Mai Z, Li Y, Wang J, Zhao X, Zhang Y.Animals (Basel). 2024 Jun 29;14(13):1933 Free PMC article.

A scoping review on intraoperative and postoperative surgical castration complications in domesticated equids. Rodden EBK, Suthers JM, Busschers E, Burford JH, Freeman SL.Equine Vet J. 2024 Jul 12

Use of regenerative medicine in the treatment of endometritis in mares: A systematic review and meta-analysis.Del Prete C, Montano C, Cocchia N, de Chiara M, Gasparrini B, Pasolini MP.Theriogenology. 2024 Oct 1;227:9-20.  Free article.

In mares resistant to endometrial infection, periovulatory treatment with ecbolic drugs does not influence uterine clearance or luteal development. Khan Y, El-Shalofy A, Kaps M, Gautier C, Aurich C.Anim Reprod Sci. 2024 Aug;267:107548. Free article.

Diagnostic Approach to Equine Testicular Disorders. Waqas MS, Arroyo E, Tibary A.Vet Sci. 2024 May 29;11(6):243.  Free PMC article.

Respiratory 

The Most Common Environmental Risk Factors for Equine Asthma-A Narrative Review. Mańkowska A, Witkowska D.Animals (Basel). 2024 Jul 14;14(14):2062 Free PMC article.

An updated description of bacterial pneumonia in adult horses and factors associated with death. Hallowell KL, Hepworth-Warren KL, Dembek K.J Vet Intern Med. 2024 Jul 15.  Free article.

Aspergillus fumigatus binding IgA and IgG1 are increased in bronchoalveolar lavage fluid of horses with neutrophilic asthma. Jentsch MC, Keilhaue A, Wagner B, Rhyner C, Lübke S, Karagulyan M, Arnold C, Lohmann KL, Schnabel CL.Front Immunol. 2024 Jun 17;15:1406794. Free PMC article.

Long-term follow-up of laryngeal Rhinosporidium seeberi diagnosed by PCR and treated with laser ablation and voriconazole nebulization in a retired thoroughbred polo horse (in Alberta). Toner S, Leguillette R, Israel J, Legge C, Samani ARE, Kavanagh M, Goodmanson M.Can Vet J. 2024 Jul;65(7):667-674.

Jugular venous thrombosis as a risk factor for exercise-induced pulmonary hemorrhage in thoroughbred racehorses. Shawaf T.Open Vet J. 2024 May;14(5):1111-1116. Free PMC article.

Lipids in Equine Airway Inflammation: An Overview of Current Knowledge. Mönki J, Mykkänen A.Animals (Basel). 2024 Jun 18;14(12):1812. Free PMC article.

The amount of hyaluronic acid and airway remodelling increase with the severity of inflammation in neutrophilic equine asthma.Höglund N, Rossi H, Javela HM, Oikari S, Nieminen P, Mustonen AM, Airas N, Kärjä V, Mykkänen A.BMC Vet Res. 2024 Jun 25;20(1):273Free PMC article.

Science-in-brief: The 6th Havemeyer Workshop on Rhodococcus equi-A decade-long journey in advancing research into a major equine pathogen (2012-2023). Havemeyer Workshop on Rhodococcus equi Scientific Advisory Committee.Equine Vet J. 2024 Sep;56(5):838-841

Steamed hay and alfalfa pellets for the management of severe equine asthma. Symoens A, Westerfeld R, Vives BM, André V, Moulon L, Collomb M, Richard H, Juette T, Bédard C, Leclère M.Equine Vet J. 2024 Aug 20.

Evaluation of variants in the ENTPD1 and ENTPD2 genes in athletic horses with exercise-induced pulmonary haemorrhage. Leite RO, Albertino LG, Sperandio LMS, Campos F, Campos R, Borges AS, Oliveira-Filho JP.BMC Vet Res. 2024 Aug 6;20(1):346 Free PMC article.

Sports medicine

In the Eye of the Beholder-Visual Search Behavior in Equestrian Dressage Judges. Wolframm I, Reuter P, Zaharia I, Vernooij J.Animals (Basel). 2024 Jul 9;14(14):2025 Free PMC article.

Ethical issues concerning UK veterinary surgeons practicing in equine sports medicine. Allen K, King M, Anderson L, Mullan S.Equine Vet J. 2024 Jul 20.

Workload and spirometry associated with untethered swimming in horses. Leguillette R, McCrae P, Massie S, Filho SA, Bayly W, David F.BMC Vet Res. 2024 Jul 19;20(1):327. doi: 10.1186/s12917-024-04143-3.PMID: 39030565 Free PMC article.

Histological evaluation of cardiac remodelling in equine athletes. Nath LC, Saljic A, Buhl R, Elliott A, La Gerche A, Ye C, Schmidt Royal H, Lundgren Virklund K, Agbaedeng TA, Stent A, Franklin S.Sci Rep. 2024 Jul 19;14(1):16709. Free PMC article.

Determination of Equine Behaviour in Subjectively Non-Lame Ridden Sports Horses and Comparison with Lame Sports Horses Evaluated at Competitions. Dyson S, Pollard D.Animals (Basel). 2024 Jun 20;14(12):1831 Free PMC article.

Sports medicine – bone and joint

Lesion Distribution in the Metacarpophalangeal and Metatarsophalangeal Region of 341 Horses Using Standing Magnetic Resonance Imaging. Schiavo S, Beccati F, Pokora R, Lin ST, Milmine RC, Bak L, Peter VG, Murray RC.Animals (Basel). 2024 Jun 25;14(13):1866. Free PMC article.

Ultrasound-guided caudal cervical articular process arthrocentesis is accurate in live horses with and without arthropathy.Davidson EJ, Stefanovski D, Slack J, Manzi TJ. Equine Vet J. 2024 Jul 11.

Radiographic texture of the trabecular bone of the proximal phalanx in horses with metacarpophalangeal osteoarthritis.Pereira LO, DE Souza AF, Spagnolo JD, Yamada ALM, Salgado DMRA, DE Zoppa ALDV.J Equine Sci. 2024 Jul;35(2):21-28. Free PMC article.

Radiological abnormalities of the cervicothoracic vertebrae in Warmblood horses with primary neck-related clinical signs versus controls. Dyson S, Quiney L, Phillips K, Zheng S, Aleman M.Vet Radiol Ultrasound. 2024 Aug 19.

Sports medicine – soft tissue

Return to sport activity following ultrasonographic diagnosis and conservative management of spontaneous injuries of the serratus cervicis ventralis and serratus thoracis ventralis muscles in 11 endurance horses. Puccetti M, Pilati N, Beccati F, Denoix JM.J Am Vet Med Assoc. 2024 Aug 2:1-6.

Welfare

Effect of nose twitching on the pupillary dilation in awake and anesthetized horses. Mascaró Triedo CE, Karar S, Abunemeh M, Portier K.Front Vet Sci. 2024 Jul 4;11:1412755. Free PMC article.

Eye Temperature Measured with Infrared Thermography to Assess Stress Responses to Road Transport in Horses. Aragona F, Rizzo M, Arfuso F, Acri G, Fazio F, Piccione G, Giannetto C.Animals (Basel). 2024 Jun 26;14(13):1877. Free PMC article.

Globetrotting Horses: Welfare Discourses and Disciplinary Power in the Transportation of Horses by Air.Gräschke L.Animals (Basel). 2024 Jun 24;14(13):1862. Free PMC article

Should the use of omeprazole be allowed during equestrian competition? Campbell MLH, Sykes BW.Equine Vet J. 2024 Jul 12. Enhancing the Horse Grimace Scale (HGS): Proposed updates and anatomical descriptors for pain assessment. Werner LC, de Oliveira GM, Daros RR, Costa ED, Michelotto PV.Vet J. 2024 Aug 12;307:106223.

Parasympathetic tone activity, heart rate, and grimace scale in conscious horses of 3 breeds before, during, and after nociceptive mechanical stimulation. Flores JEM, Terrazas A, Lara Sagahon AV, Aleman M.J Vet Intern Med. 2024 Aug 16. doi: 10.1111/jvim.17174. Online ahead of print.PMID: 39150630 Free article.

“How long is life worth living for the horse?” A focus group study on how Austrian equine stakeholders assess quality of life for chronically ill or old horses. Long M, Grimm H, Jenner F, Cavalleri JV, Springer S.BMC Vet Res. 2024 Aug 6;20(1):347. doi: 10.1186/s12917-024-04211-8.PMID: 39107791 Free PMC article.

Owner-reported health and disease in U.S. senior horses. Herbst AC, Coleman MC, Macon EL, Harris PA, Adams AA.Equine Vet J. 2024 Aug 2.

From facial expressions to algorithms: a narrative review of animal pain recognition technologies. Chiavaccini L, Gupta A, Chiavaccini G.Front Vet Sci. 2024 Jul 17;11:1436795.  Free PMC article.

ResearchONequine.ca is a website developed by the Ontario Animal Health Network equine network to help increase research awareness and to connect researchers from academia, industry and government with the ultimate goal of improving the lives of all equines. It was supported by OAHN and the Ontario Association of Equine Practitioners.