Equine Disease Research Articles

Field study examining the mucosal microbiome in equine glandular gastric disease

Equine glandular gastric disease (EGGD) is a common disease among athletic horses that can negatively impact health and performance. The pathophysiology of this EGGD remains poorly understood. Previous studies using controlled populations of horses identified differences in the gastric glandular mucosal microbiome associated with disease. The objective of this study was to compare the gastric microbiome in horses with EGGD and those without across multiple barns and differing management practices. We hypothesized that alterations in the microbiome of the gastric glandular mucosa are associated with EGGD. A secondary objective was to perform a risk factor analysis for EGGD using the diet and management data collected. Microbial populations of biopsies from normal pyloric mucosa of horses without EGGD (control biopsies), normal pyloric mucosa of horses with EGGD (normal biopsies) and areas of glandular mucosal disruption in horses with EGGD (lesion biopsies) were compared. Lesion biopsies had a different microbial community structure than control biopsies. Control biopsies had a higher read count for the phylum Actinomycetota compared to lesion biopsies. Control biopsies also had an enrichment of the genera Staphylococcus and Lawsonella and the species Streptococcus salivarius. Lesion biopsies had an enrichment of the genera Lactobacillus and Actinobacillus and the species Lactobacillus equigenerosi. These results demonstrate differences in the gastric glandular microbiome between sites of disrupted mucosa in horses with EGGD compared to pyloric mucosa of horses without EGGD. Risk factor analysis indicated that exercise duration per week was a risk factor for EGGD.

Equine disease surveillance: quarterly update.

Equine disease surveillance: quarterly update.

PSVII-13 The Evaluation of Natural Vs Synthetic Vitamin E Supplementation for the Management of Alpha-Tocopherol Serum Concentrations in Morgan Horses

Abstract Vitamin E is an important lipid-soluble antioxidant that is tied to normal neuromuscular function in adult horses. Deficiency in serum vitamin E concentrations have been associated with several equine diseases such as Equine Motor Neuron Disease and Equine degenerative myeloencepalopathy. Horses with restricted access to pasture and genetic predispositions, like the Morgan Horse, can be especially susceptible to being marginally low or deficient. Two types of supplemental forms of Vitamin E are available: natural form, d-alpha-tocopherol acetate, and a synthetic form, dl-alpha-tocopherol, with the natural form being more expensive for horse owners. The objective of this study was to compare the serum vitamin E concentrations of horses on a low dose of natural (d-alpha) versus synthetic (dl-alpha) vitamin E. Eight horses with marginal/deficient serum alpha-tocopherol (0.94 – 2.3 µg/mL) were enrolled in a randomized block design study. Blocks were balanced for age, body weight and pre-study vitamin E level and were assigned to one of two treatments. 1) NATURAL – 2,000 IU powder (d-alpha-tocopherol acetate) for 16 wk. 2) SYNTHETIC – 2,000 IU dl-alpha tocopherol acetate for 16 wk. Horses were housed in box stalls with daily turnout without access to grass. Horses were fed hay at 2% of BW and 0.45 kg of concentrate daily with vitamin E feed activity of 45.5 and 1,378 IU/kg, respectively. Natural and synthetic treatments were fed once daily with the AM feeding. To ensure horses consumed the powder d-alpha-tocopherol acetate and capsules of dl-alpha-tocopherol acetate, cookies made from alfalfa powder, gelatin and d-alpha-tocopherol acetate powder were created. Serum alpha-tocopherol was assessed pre-feeding every four weeks from 0 to 16 weeks. Overall, horses supplemented with synthetic treatment had higher serum alpha-tocopherol than those supplemented with the natural treatment (2.61 vs 2.34, respectively; SE = 0.08, P = 0.05). Both treatments increased serum alpha-tocopherol concentrations to normal ranges (2.0-4.0 µg/mL) for all horses by 4 weeks and maintained the normal concentrations with the exception of week 12 for horses receiving the natural supplement compared with the synthetic (1.81 vs 2.62 µg/mL). Because of this diversion, there tended to be a week x treatment interaction (P = 0.06). The results of this study indicate the use of a synthetic, more affordable Vitamin E supplement will increase serum alpha-tocopherol concentrations similarly to natural supplements. However, further research is needed to determine how these supplements are utilized within the body.

Equine allogeneic tenogenic primed mesenchymal stem cells: A clinical field study in horses suffering from naturally occurring superficial digital flexor tendon and suspensory ligament injuries.

Mesenchymal stem cells are an innovative therapeutic for various equine orthopaedic diseases, including soft tissue injuries. To evaluate the safety and efficacy of tenogenic primed equine allogeneic peripheral blood-derived mesenchymal stem cells (tpMSCs) in horses with naturally occurring superficial digital flexor tendon (SDFT) and suspensory ligament (SL) injuries. Multicentre, blinded, randomised, placebo-controlled clinical trial. One hundred client-owned horses with SDFT and SL injuries were randomised to receive an intralesional tpMSC (66) or saline (34) injection. Clinical and ultrasonographic evaluation was performed before treatment and on Days 56 ± 3 and 112 ± 3 after treatment. Long-term data on re-injury was collected up to 2 years after treatment. Significantly more tpMSC-treated horses achieved improvement in fibre alignment score (FAS) (100% vs. 54.5%, p < 0.001) and echogenicity (97.0% vs. 57.6%, p < 0.001) on Day 112 ± 3, and their lesion size decreased significantly (-27.6 ± 25.91 vs. -4.6 ± 26.64 mm2, p < 0.001) compared to the placebo group. A FAS = 0 was achieved in 65% of tpMSC-treated horses, as compared to 9% of placebo-treated horses at Day 112 ± 3. The attending veterinarians reported no re-injury in 41 of 53 tpMSC and in 2 of 26 saline-treated horses available for long-term follow-up (p < 0.001). As this study consisted of client-owned horses, no samples for histology were collected. Long-term follow-up was only available for a subset of enrolled horses. The intralesional administration of tpMSCs was safe and improved the quality of healing and long-term outcomes in sports horses with naturally occurring SDFT and suspensory injuries.

Characterization of gastrointestinal inflammatory cell type in equine glandular gastric disease.

To compare small intestinal inflammation with gastric inflammation in horses with and without equine gastric glandular disease (EGGD), we evaluated endoscopic, macroscopic, and microscopic findings of the glandular stomach and microscopic findings of the small intestine. 36 horses. Horses underwent endoscopy and were scored for EGGD. After euthanasia, stomachs were collected and macroscopically evaluated. Normal pyloric mucosa, glandular lesions, and small intestinal (duodenum, mid-jejunum, and ileum) samples were collected and processed for microscopic examination. Cellular infiltrate was scored. Immunohistochemistry (CD3, CD20, and Iba-1) was performed on the ventral pylorus and small intestine of horses with mild to moderate lymphoplasmacytic infiltrate. A Spearman's correlation coefficient was used to evaluate the relationship of EGGD grade with gastric glandular inflammation, and the relationships of cellular infiltrate type and severity among glandular stomach, duodenum, jejunum, and ileum. Gastrointestinal inflammation was common, with gastric inflammatory infiltrate identified in 92%, duodenal inflammatory infiltrate in 83%, jejunal inflammatory infiltrate in 92%, and ileal inflammatory infiltrate in 92% of horses. Endoscopic evidence of gastric disease (hyperemia or EGGD grade ≥ 2/4) was not associated with the presence or severity of duodenal, jejunal, or ileal inflammation. Gastric lymphoplasmacytic inflammation grade ≥ 2 was associated with duodenal lymphoplasmacytic inflammation grade ≥ 2. This was a convenience sample of horses presenting for euthanasia. Medical history (including deworming history) was unknown. Gastric lymphoplasmacytic inflammation is associated with duodenal lymphoplasmacytic inflammation but not more distal small intestinal inflammation. Intestinal inflammation is not associated with endoscopic findings (hyperemia or EGGD grade ≥ 2/4).

European Inter-Laboratory Proficiency Test for Dourine Antibody Detection Using the Complement Fixation Test.

Dourine is a sexually transmitted parasitic disease affecting equids. Its causative agent is referred to as Trypanosoma equiperdum and the prescribed serodiagnosis method is the complement fixation test (CFT). In the context of our European Reference Laboratory mandate for equine diseases (excluding African horse sickness), we organised dourine CFT inter-laboratory proficiency tests (ILPTs) in 2015, 2018 and 2022 to evaluate the performance of the European Union network of National Reference Laboratories (NRLs) for dourine. ILPT panels were composed of horse sera with or without antibodies against Trypanosoma spp. originating from non-infected, immunised or experimentally infected horses. Twenty-two NRLs participated in at least one of the three sessions. In 2015, 2018 and 2022, the percentage of laboratories obtaining 100% of the expected results was 57, 90 and 80, respectively. These dourine CFT ILPTs showed the benefits of standardising the method's detection limit and underlined the constant need to evaluate NRLs to improve the network's performance. These results also argue in favour of the need for a representative bio-bank to improve the representativeness of ILPT samples and to allow the adoption of alternative serological methods for international surveillance of dourine.

Equine disease surveillance: quarterly update.

Equine disease surveillance: quarterly update.

Comparison of oral esomeprazole and oral omeprazole in the treatment of equine squamous gastric disease.

Oral omeprazole is the accepted treatment for equine squamous gastric disease (ESGD); however, it is not universally effective. Esomeprazole results in more consistent and pronounced acid suppression in men and is more effective than omeprazole in the treatment of oesophageal and gastric disease. Pharmacodynamic and pilot clinical studies have indicated esomeprazole might also be more effective than omeprazole in horses. To compare the efficacy and safety of oral esomeprazole and omeprazole pastes in the treatment of ESGD and, where present, concurrent equine glandular gastric disease (EGGD). Randomised, single-blinded controlled trial. Horses presenting with grade ≥2 ESGD lesions were randomly allocated to receive 4 mg/kg of either a buffered esomeprazole or omeprazole paste orally once daily for 28 days before gastroscopy being repeated within a further 3 days. Videos and images were anonymised and subsequently graded blind by one researcher. The severity of ESGD (and EGGD) lesions before and after treatment, and thereby treatment responses, were compared using univariable logistic regression. A higher proportion of horses had ESGD healing in response to esomeprazole treatment (63/74, 85%) than with omeprazole treatment (43/73, 59%) (odds ratio [OR]: 4.00, 95% confidence interval [CI]: 1.81, 8.82, p = 0.001). In a subset of horses that had concurrent EGGD, a greater proportion of the horses treated with esomeprazole had lesions ≤grade 1 (esomeprazole 28/51, 55%; omeprazole 6/24, 25%; OR: 3.65, 95% CI: 1.25, 10.71, p = 0.02) Using grade 0 as the benchmark for EGGD healing, the difference remained significant (OR: 4.44, 95% CI: 1.33, 14.85, p = 0.02). It may not be possible to extrapolate these results to other populations with different signalment or management. Oral-buffered esomeprazole was a more effective treatment for ESGD (and concurrent EGGD) than oral-buffered omeprazole.

Nutritional management of equine gastric ulcers

Over the last 10 years there has been increasing awareness and subsequently recorded cases of equine gastric ulcer syndrome and with this comes an increased interest in appropriate nutrition and feed management. This review presents a systematic approach to assessing the ration of a horse at risk of or diagnosed with equine gastric ulcer syndrome and demonstrates the ample evidence upon which to base nutritional recommendations for horses with equine squamous gastric disease, and to a lesser extent, equine glandular gastric disease, with an emphasis on forage. Careful selection and management of the forage ration should be the first step in designing a suitable ration, followed by selection of an appropriately low starch and sugar (less than 2 g per kg body weight per day and 1 g per kg body weight per meal) complementary feed.

CHARACTERIZATION AND GROWTH EVALUATION OF STREPTOCOCCUS EQUI IN HORSES: A PREDICTORY APPROACH TOWARDS ITS MANAGEMENT IN HERDS

Strangles is the most common infectious and contagious disease of equines that affects upper respiratory tract. It is prevalent among the horses in sub-continent from pre partitioned times, an effective study to isolate locally prevalent strains in the area and study of factors affecting their consequent growth is essential. For the said purpose, twenty nasal swab samples were collected, ten from clinically sick and ten from apparently healthy horses with the history of disease. Isolated strains were undergone identification through biochemical and lancefield testing. Maximum in-vitro growth of Streptococcus equi (S. equi) is a critical factor for its cost effective bioceutics production. Effect of different factors like composition of medium such as (Tryptic Soy Broth (TSB), Nutrient Broth, Brain Heart Infusion broth (BHI), Reinforced Clostridial Medium (RCM) and Peptone Broth, pH (5, 7, 9), gas (oxygen availability, 5% CO2, aeration), horse serum (2%, 5%, 10%) and temperature (35°C, 37°C, 39°C) on growth of S. equi was therefore carried out. Growth was expressed in form of Colony Forming Units (CFU) which was converted into log values followed by statistical analysis. TSB among media, pH 7, CO2 5% gas, horse serum 5% and incubation temperature 37°C showed optimum growth of S. equi.

Image challenge in Veterinary Pathology, answers: Equine diseases.

Image challenge in Veterinary Pathology, answers: Equine diseases.

Evaluating Trends in Strangles Outbreaks Using Temperature and Precipitation Data in the United States of America for 2018-2022.

Strangles is a highly contagious upper respiratory infection of equids that is globally distributed. The causative agent of strangles, Streptococcus equi subspecies equi, can be spread through indirect contact with infected fomites, and studies have shown this microbe to live well in varying environmental conditions. The purpose of this study was to analyze strangles case numbers across the United States of America from 2018 to 2022 to investigate potential temporal or weather patterns associated with outbreaks. Diagnosed case records were obtained from the Equine Disease Communication Center, university databases, government agencies, or veterinary diagnostic labs, and geographic information systems (GISs) were used to map cases and to acquire relevant meteorological data from outbreak areas. These data were analyzed using logistic regression to explore trends that occur between outbreaks and changes in temperature and precipitation. Initial review of weather data suggested monthly changes in strangles case numbers corresponded with changing seasons. Logistic regression indicated that changes in monthly average temperature and minimum temperature were significantly associated with increased or decreased odds of strangles outbreaks, respectively. Future analyses should focus on weather data isolated within a smaller region or state to better resolve trends in strangles outbreaks throughout the continental USA.

Cobalt Protoporphyrin Blocks EqHV-8 Infection via IFN-α/β Production.

Equid alphaherpesvirus type 8 (EqHV-8) is the causative agent of severe respiratory disease, abortions, and neurological syndromes in equines and has resulted in huge economic losses to the donkey industry. Currently, there exist no therapeutic molecules for controlling EqHV-8 infection. We evaluated the potential antiviral activity of cobalt protoporphyrin (CoPP) against EqHV-8 infection. Our results demonstrated that CoPP inhibited EqHV-8 infection in susceptible cells and mouse models. Furthermore, CoPP blocked the replication of EqHV-8 via HO-1 (heme oxygenase-1) mediated type I interferon (IFN) response. In conclusion, our data suggested that CoPP could serve as a novel potential molecule to develop an effective therapeutic strategy for EqHV-8 prevention and control.

Comparison of equine paranasal sinus trephination complications and outcome following standing computed tomography, radiography and sinoscopy guided approaches for the treatment of sinusitis.

The recent availability of standing computed tomography (CT) for equine paranasal sinus disease has enhanced diagnosis and enabled more targeted surgery compared to radiography and sinoscopy. To date, there have been no studies which have critically evaluated the benefit of preoperative CT versus radiography and sinoscopy on complications and outcome in horses undergoing sinus trephination. Retrospective study. A total of 229 equids. The medical records of equids (229) presented for sinusitis treated via trephination that had CT, radiography and/or sinoscopy at time of surgery between 2009 and 2022 were reviewed. Outcome and complications were evaluated for six different pre- and intraoperative imaging modalities. The six groups did not differ in demographics or disease category, though equids with less weight (p = .0179) and shorter disease duration (p = .0075) were more likely to have radiography and sinoscopy based surgical planning. Short-term postoperative complications occurred in 30.1% and were higher in groups using preoperative CT imaging (p = .01), with hemorrhage being the most common surgical complication. Following initial trephination surgery, 57.0% (127/223) of cases resolved and there was no difference between the imaging groups. Final resolution after follow-up medical or surgical treatment increased to 94.6% (211/223) and was not different between the imaging groups or between primary or secondary sinusitis. Additional nasal fenestrations to improve sinonasal drainage, maxillary septal bulla fenestrations and trephinations to treat nasal conchal bullae were made in the CT groups. CT provided additional diagnostic information and enabled different surgical approaches but did not improve resolution in this study population.

Current and Future Advances in the Detection and Surveillance of Biosecurity-Relevant Equine Bacterial Diseases Using Loop-Mediated Isothermal Amplification (LAMP).

Horses play an important role throughout the world, whether for work, culture, or leisure, providing an ever-growing significant contribution to the economy. The increase in importation and movement of horses, both nationally and internationally, has inevitably allowed for the global equine industry to grow. Subsequently, however, the potential for transmission of fatal equine bacterial diseases has also escalated, and devasting outbreaks continue to occur. To prevent such events, disease surveillance and diagnosis must be heightened throughout the industry. Current common, or "gold-standard" techniques, have shown to be inadequate at times, thus requiring newer technology to impede outbreaks. Loop-mediated isothermal amplification (LAMP) has proven to be a reliable, rapid, and accessible tool in both diagnostics and surveillance. This review will discuss equine bacterial diseases of biosecurity relevance and their current diagnostic approaches, as well as their respective LAMP assay developments. Additionally, we will provide insight regarding newer technology and advancements associated with this technique and their potential use for the outlined diseases.

West Nile Virus Lineage 2 in Free-Living Corvus cornix Birds in Poland.

The summer temperatures recorded in Poland in 2022 were among the highest in over 30 years and, combined with higher-than-expected rainfall, gave the impression of an almost tropical climate. Such climatic conditions were ideal for the transmission of vector-borne zoonotic diseases such as West Nile fever. In northeastern Poland, in the Mazowieckie region, the Polish event-based surveillance network reported increased fatalities of free-living hooded crows (Corvus corone cornix). West Nile virus (WNV) lineage 2 was identified for the first time as the etiological agent responsible for the death of the birds. WNV was detected in 17 out of the 99 (17.17%) free-living birds tested in this study. All the WNV-infected dead birds were collected in the same area and were diagnosed in September by the NVRI and confirmed by the EURL for equine diseases, ANSES, in October 2022. Unnaturally high temperatures recorded in Poland in 2022 likely favored the infection and spread of the virus in the avian population. A nationwide alert and awareness raising of blood transfusion centers and hospitals was carried out to prevent human infections by WNV.

Equine Brucellosis: Current Understanding and Challenges.

Brucellosis in equines, including horses, donkeys, and mules, is characterized by abscesses in tendons, bursae, and joints. Reproductive disorders, which are common in other animals, are rare in both males and females. Joint breeding of horses, cattle, and pigs was found as the main risk factor for equine brucellosis, with the transmission from equines to cattle or among equines possible, although unlikely. Hence, evaluation of the disease in equines can be considered an indirect indicator of the effectiveness of brucellosis control measures employed for other domestic species. Generally, the disease in equines reflects disease status in the sympatric domestic species, mainly cattle. It is important to note that in equines, the disease has no validated diagnostic test, which limits the interpretation of available data. Finally, it is important to mention that equines also represent significant Brucella spp. infection sources for humans. Considering the zoonotic aspect of brucellosis, the significant losses due to infection, and the representativeness of horses, mules, and donkeys in the society, as well as the continuous efforts to control and eradicate the disease in livestock, in this review, we covered the various aspects of brucellosis in equines and compile the sparse and diffuse information on the subject.

Evaluation of the effects of medium-term (57-day) omeprazole administration and of omeprazole discontinuation on serum gastrin and serum chromogranin A concentrations in the horse.

Rebound gastric hyperacidity (RGH) secondary to hypergastrinemia has been suggested to contribute to the rapid recurrence of equine squamous gastric disease (ESGD) in horses after discontinuation of omeprazole. To evaluate changes in serum gastrin and chromogranin A (CgA) concentrations in response to medium-term (57-day) omeprazole treatment and after omeprazole discontinuation. Fourteen mature Thoroughbred racehorses in simulated race training. Horses received 2.28 g of oral omeprazole PO q24h for 57 days within a 61-day period, excluding a withholding period applied mid-protocol during which treatment was stopped as part of a concurrent study. Serum samples were collected on day 0 before omeprazole treatment, on day 1 of each week of the treatment period, and for an additional 5 weeks after discontinuation of treatment. Serum gastrin and CgA concentrations were analyzed using radioimmunoassay (RIA) and ELISA, respectively. Median serum gastrin concentrations increased 2.5-fold from baseline to day 7 (P < .001) but did not increase further during the omeprazole treatment period. Median serum gastrin concentrations returned to baseline within 2 to 4 days after administration of the last dose of omeprazole. No effect of treatment or discontinuation was seen in serum CgA concentrations. Serum gastrin concentrations increased in response to omeprazole treatment but returned to baseline within 2 to 4 days after the last dose of omeprazole. No effect of treatment or discontinuation was seen in serum CgA concentrations. Our results do not support the use of tapering protocols in horses.

Clinical effects of a combination of phenylbutazone and omeprazole on chronic lameness in Mongolian horses.

Phenylbutazone (PBZ) is the most commonly used drug to treat symptoms of lameness in horses; however, it is associated with adverse effects such as gastric ulcer syndrome (EGUS). Interestingly, many practitioners prescribe omeprazole (OME) concurrently with PBZ to prevent the development of EGUS. However, the efficacy and safety of this practice in Mongolian horses with chronic lameness remain unknown. To evaluate the clinical effects of a combination of PBZ and OME on chronic lameness in Mongolian horses. Randomised block experimental design. Eighteen Mongolian horses with lameness score was ≥3 points, were divided into three treatment groups, with six horses in each group: placebo (CON), PBZ (4.4 mg/kg PO q. 24 h), or PBZ plus OME (4 mg/kg PO q. 24 h; PBZ + OME) in a randomised block design based on the initial lameness score. The horses were treated for 15 days. During this period, weekly gastroscopy, and physiological and biochemical tests were performed. Both PBZ (median 1.0, interquartile range [IQR]: 0.8-1.3; p = 0.01) and PBZ + OME (median 1.0, IQR: 1.0-1.0; p = 0.01) significantly decreased the lameness score compared with before administration. In addition, PBZ significantly increased the equine glandular gastric disease (EGGD) score (3.0 ± 0.6, p < 0.001), GT-17 content (293.4 ± 21.8 pg/mL, p < 0.001), and pepsinogen-1 (PG1) content (295.3 ± 38.3 ng/mL, p < 0.001) compared with CON or PBZ + OME. However, it significantly reduced the total protein (53.6 ± 1.5 g/L, p < 0.05) and albumin (25.5 ± 1.8 g/L, p < 0.05) contents. Nevertheless, compared with PBZ, PBZ + OME significantly decreased the EGGD score (0.3 ± 0.5, p < 0.001) and significantly increased the gastric fluid pH (7.3 ± 0.5, p < 0.001), total protein content (62.5 ± 4.6 g/L, p = 0.009), and albumin content (29.4 ± 1.1 g/L, p = 0.004). Meanwhile, they significantly diminished the gastrin 17 (GT-17) (162.0 ± 21.0 pg/mL, p < 0.001) and PG1 (182.4 ± 22.5 ng/mL, p < 0.001) contents. Individual differences in horses were larger, but the sample size was small. There was larger interval between observations for each index. Compared with PBZ alone, PBZ + OME had no therapeutic effect on chronic lameness; however, it reduced the occurrence of EGGD in Mongolian horses. Horses may be protected against chronic lameness and PBZ-induced EGGD by increasing the pH value, decreasing serum PG1 and GT-17 content, and preventing the reduction of myeloperoxidase content.

Room for improvement? The use of antimicrobials in equine respiratory disease

No conflicts of interest have been declared.