Emma McConnell

Background
Sand enteropathy is a common disease in horses worldwide. The presence of sand does not always cause disease. The amount of sand required to cause clinical disease is not well established.

Objectives
To establish a weight-indexed cut-off for the diagnosis of clinically relevant sand enteropathy based on radiographic area.

Study design
Cross-sectional.

Methods
Abdominal radiographs were acquired from clinically normal horses and compared with horses with clinical sand enteropathy. Sand area and sand area per kilogram of body weight were calculated. A receiver operating characteristic (ROC) curve was used to differentiate groups.

Results
Seventy clinically normal horses and 57 sand enteropathy cases were included. Median sand area in control horses was 1 cm2 per 100 kg (interquartile range 0–6 cm2 per 100 kg), and in sand enteropathy horses was 118 cm2 per 100 kg (interquartile range 83–180 cm2 per 100 kg). Receiver operator characteristic (ROC) analysis revealed that using a cut-off of 21 cm2 per 100 kg had a sensitivity of 98.25% (CI 90.71%–99.1%) and a specificity of 92.54% (CI 83.69%–96.77%) for a diagnosis of clinical sand enteropathy.

Conclusions
A weight-based cut-off of >21 cm2 per 100 kg for the diagnosis of sand enteropathy was determined with excellent sensitivity and good specificity. This may aid in determining if the amount of sand accumulation in a horse is of clinical consequence.

Background
Antimicrobial resistance (AMR) is increasingly recognised in equine medicine. Antimicrobial use (AMU) is a key driver of AMR.

Objectives
To pilot a point prevalence survey (PPS), based on the Global-PPS used in human hospitals, to obtain data on antibiotic prescribing and AMR in equine hospitals and to identify targets for improvement in AMU.

Study Design
Point prevalence survey.

Methods
Eight equine hospitals located in Australia, Belgium, South Africa, the United Kingdom and the United States were recruited. Data on AMU were collected from all in-patients on antibiotic treatment at 08h00 on four selected study days throughout the study year (2022).

Results
In total, 742 patients, 310 (41.8%) surgical and 432 (58.2%) nonsurgical cases, were evaluated and 58.7% (182/310) surgical and 25.9% (112/432) nonsurgical patients were on antibiotics. The most prescribed antibiotics were penicillin, gentamicin and trimethoprim sulfonamides. In 45.2% (215/476) of prescriptions, use was prophylactic. Therapeutic use was based on a biomarker in 48.8% (127/260) of treatments. A sample was submitted for culture in 56.9% (148/260) of therapeutic treatments. A positive culture result was reported from 49.3% (73/148) of samples, with an antibiogram available for 90.4% (66/73) of the positive cultures. An antibiotic use stop/review date was not recorded in 59.5% (283/476) of uses.

Main Limitations
This PPS was a pilot study with a relatively small sample size and likely does not reflect AMU in all types of equine hospitals in all geographic locations.

Conclusions and Clinical Relevance
The PPS identified multiple ways in which antibiotic prescribing could be improved. Targets identified for stewardship interventions included empiric use of European Medicines Agency Category A and B antibiotics, the high prevalence of prophylaxis and the lack of use of a stop/review date. The survey could be used as a repeatable tool to assess stewardship interventions in equine hospitals.

Background
The natural progression of equine glandular gastric disease (EGGD) in the absence of treatment has not yet been described in the literature, nor has the prevalence in a teaching herd population been reported.

Objectives
The aims of this study were to determine the prevalence of disease in a teaching population over the study period (2019–2021) and to observe the changes over time in disease severity of naturally occurring diseases (not experimentally induced) without medical intervention.

Methods
Twenty-one horses underwent an initial gastroscopy and a repeat gastroscopy between 14 and 731 days later. Gastroscopy data were graded quantitatively and described qualitatively. Prevalence and 95% confidence intervals (CI) were calculated. The changes over time were determined by comparing initial and repeat gastroscopies.

Results
The prevalence from initial, repeat and total number of gastroscopies was 62% (95% CI: 40.8–79.3), 71% (95% CI: 50.0–86.2) and 67% (95% CI: 51.6–79), respectively. The changes over time included worsening of disease in 29% of horses (95% CI: 13.8–50.0), improvement of disease to a lower grade in 24% (95% CI: 10.6–45.1), no change in grade in 38% (95% CI: 20.8–59.1), and complete resolution of disease to grade 0 in 10% (95% CI: 2.7–28.9).

Main limitations
Limitations included a maximum of two gastroscopies per horse given COVID-19 restrictions on data collection, and highly varied interval times between initial and repeat gastroscopies.

Conclusion
In conclusion, there is a high prevalence of disease in this teaching herd. The changes over time in naturally occurring diseases without medical intervention might include worsening, improvement, no change or resolution of disease.
Main limitations

Limitations included a maximum of two gastroscopies per horse given COVID-19 restrictions on data collection, and highly varied interval times between initial and repeat gastroscopies.

Conclusion
In conclusion, there is a high prevalence of disease in this teaching herd. The changes over time in naturally occurring diseases without medical intervention might include worsening, improvement, no change or resolution of disease.

This study reports the spatial and temporal distribution of ascarid and strongylid nematodes in Thoroughbred horses by age category across different climatic zones in Australia over an 18-month period. Faecal samples ( = 2046) from individual horses were analysed using the modified McMaster technique for faecal egg counts (FECs). Strongylids were identified using PCR-directed next-generation sequencing of the second internal transcribed spacer (ITS-2) of the nuclear ribosomal DNA. Yearlings had the highest prevalence (82%) of strongyle eggs followed by weanlings (79%), foals (58%), wet mares (49%) and dry mares (46%). For Parascaris spp., foals had the highest prevalence (35%) followed by weanlings (21%) and yearlings (10%). The highest mean FECs for Parascaris spp. were observed in foals (525 eggs per gram [EPG] of faeces) while those for strongyles were in yearlings (962 EPG). Among horses that were classified as adults at the time of sampling, 77% (860 of 1119) of mares were low (i.e., <250 EPG) strongyle egg-shedders. Mean strongyle FEC counts were highest in the Mediterranean (818 EPG) followed by summer (599 EPG), winter (442 EPG), and non-seasonal (413 EPG) rainfall zones. Twenty-six nematode species were detected, with Cylicostephanus longibursatus (26.5%), Cylicocyclus nassatus (23.7%) and Coronocyclus coronatus (20.5%) being the most frequently detected species. Their richness and relative abundance varied with horse age, season and climatic zone. In addition, Strongylus equinus and Triodontophorus spp. (T. brevicauda and T. serratus) were also detected. This comprehensive study elucidates spatial (climatic zone) and temporal (i.e., seasonal) trends in prevalence and burdens of intestinal nematodes in Australian horses using non-invasive conventional and molecular methods. The information presented in this study is crucial for developing integrated management strategies to control horse parasites in farmed horses.

This study quantified the extent of anthelmintic resistance (AR) in ascarid and strongylid nematodes against commonly used anthelmintics in Australian Thoroughbred horses. Faecal egg count reduction tests (FECRTs, n = 86) and egg reappearance period (ERP) tests were conducted on 22 farms across Australia. Faecal egg counts (FECs) were determined using the modified McMaster technique, and percent faecal egg count reduction (%FECR) was calculated using the Bayesian hierarchical model and hybrid Frequentist/Bayesian analysis method. The results were interpreted using old (published in 1992) and new (2023) research guidelines of the World Association for the Advancement of Veterinary Parasitology (WAAVP). The species composition of strongylid nematodes was detected utilising a DNA-metabarcoding method using pre- and post-treatment samples. Resistance was observed in strongylid nematodes to commonly used single-active and combination anthelmintics, including ivermectin (IVM %FECR range: 82%-92%; 95% lower credible interval (LCI) range: 80%-90%), abamectin (ABM: 73%-92%; 65%-88%), moxidectin (MOX: 89%-91%; 84%-89%), oxfendazole (OFZ: 0%-56%; 0%-31%) and its combination with pyrantel (OFZ + PYR: 0%-82%; 0%-78%). Resistance in Parascaris spp. was observed to IVM (10%-43%; 0%-36%), ABM (0%; 0%) and MOX (0%; 0%). When the new thresholds recommended by the WAAVP were used, AR was detected in six additional FECRTs for strongylids and three more tests for Parascaris spp., introducing resistance to OFZ and OFZ + PYR in the latter. Shortened ERPs (4-6 weeks) of strongylids were observed in 31 FECRTs in which AR was not detected at 2 weeks post-treatment for all the anthelmintics tested. Among cyathostomins, Cylicocyclus nassatus, Cylicostephanus longibursatus and Coronocyclus coronatus were the most prevalent species at 2 weeks post-treatment, whereas the main species appearing at five weeks following treatments with macrocyclic lactones were Cylicocyclus nassatus, Cylicostephanus longibursatus and Cylicocyclus ashworthi. After treatment with OFZ + PYR, the latter three, plus Coronocyclus coronatus and Cyathostomum catinatum, were detected at 5 weeks post-treatment. Overall, the study highlights the prevalence of AR in both ascarids and strongylid nematodes against commonly used anthelmintic products to control worms in Australian horses. The results indicate that ML combination products provided acceptable efficacy at 2 weeks. However, ERP calculations suggest that products work less effectively than previously measured. It is suggested to regularly monitor the efficacy of the anthelmintics and consider changing the worm control practices to better manage worms and AR in Australian horses.

A 3-year-old Thoroughbred filly presented with a several-month history of weight loss, polydipsia and polyuria, intermittent diarrhoea and behavioural changes and intermittently uncoordinated gait. Neurological examination revealed hyperexcitability, bilaterally reduced pupillary light reflexes and quadrilateral ataxia with proprioceptive deficits more obvious in the forelimbs than in the hindlimbs. A multifocal neurological lesion was suspected. The laboratory finding of a persistent hyperchloraemia and an apparent negative anion gap prompted measurement of serum bromide concentration and subsequently confirmed bromide intoxication. Further questioning of the trainer revealed that the filly had been administered oral potassium bromide for behavioural modification over several months. Clinical signs of bromide intoxication resolved within 20 days following the last bromide administration, without specific medical intervention. This case report describes the risk of inadvertent bromide overdosing in horses and highlights the need for control of bromide use in the equine industry.

This report describes two cases of unilateral traumatic injury to the parotid salivary gland or duct and the subsequent development of severe ipsilateral peripheral dental caries. Ultrasonographic examination of the parotid salivary gland and duct was indicative of parotid glandular atrophy in one case and demonstrated parotid duct obstruction in the second case. To the authors’ knowledge, the effects of the loss of function of the parotid salivary gland on the horse's dentition has not been documented and should be considered as a potential side effect of surgical ablation of the parotid salivary gland.