Clinical Commentary: Atypical myopathy associated with Box Elder in EuropeKnowles, E.J. and Piercy, R.J.The Royal Veterinary College, Royal College Street, LondonThe case report by Jahn et al (REF when available) describes a case of Atypical Myopathy in Europe caused by ingestion of the protoxin hypoglycin A (HGA) from Box Elder seedlings. This is an important report. It reminds clinicians in Europe that trees other than The European Sycamore (Acer pseudoplatanus) may contain HGA and of the potential for other unfamiliar plant species to cause pasture-associated toxicities.After many years of research, the pathogenesis of Atypical Myopathy, also known as Seasonal Pasture Myopathy, is now well understood. The severe myopathy results from ingestion of the seeds or seedlings of European Sycamore (Acer pseudoplatanus) in Europe and the Box Elder (Acer negundo) in the USA (Westermann et al. 2008, Valberg et al. 2013). The seeds, seedlings and leaves of these trees contain the protoxin HGA, and to a lesser extent its analogue methylenecyclopropylglycine (MCPrG) (Bochnia et al. 2019a). These protoxins are metabolised to the active toxins Methylenecyclopropylacetyl-CoA (MCPA-CoA) and MCPrG-CoA respectively at tissue-specific rates and primarily in skeletal muscle (Sander et al. 2023). The toxic effects mainly occur in the highly-oxidative ‘slow-twitch’ type I muscle fibres such as the postural muscles, masseters, diaphragm and cardiac muscle (Cassart et al. 2007). The primary toxin, MCPA-CoA inhibits acyl-CoA dehydrogenase enzymes involved in the beta-oxidation of fatty acids and catabolism of branched-chain amino acids resulting in failure of mitochondrial energy generation and subsequently muscle cell death (Westermann et al. 2008). Inhibition of Acyl-CoA dehydrogenase enzymes causes an accumulation of their acyl-CoA substrates and the carnitine and glycine conjugates of those substrates in serum and urine, a characteristic metabolic profile known as multiple acyl-CoA dehydrogenase deficiency (MADD) (Westermann et al. 2008). The accumulation of acylcarnitines together with the protoxins (HGA and MCPrG) and the carnitine conjugates of the toxins (MCPA-carnitine and MCPF-carnitine) can be detected in serum by liquid-chromatography-mass-spectometry (LCMS) (Valberg et al. 2013, Bochnia et al. 2019, González-Medina et al. 2021).In many cases a diagnosis of Atypical Myopathy can be made relatively confidently based on the characteristic clinical signs, serum biochemical changes, the seasonal occurrence and, in Europe, the presence of Sycamore (Acer psuedoplatanus) seeds or seedlings on the pasture (González-Medina et al. 2017, Dunkel et al. 2018). Detection of serum HGA or MCPA-carnitine by LCMS may be useful to confirm the diagnosis and may be particularly useful to identify sub-clinically affected cases, or those with less-severe or unusual presentations or when a toxic (tree) source cannot readily be identified.HGA or MCPA-carnitine has been detected in the serum of horses co-grazing with affected cases (Baise et al. 2016, Bochniaet al. 2018, Renaud et al. 2024). Whilst these co-grazing horses were apparently healthy it is unknown whether clinical signs would have been apparent if they had undertaken higher levels of exercise or if they could have been precipitated by a greater negative energy balance, requiring a greater reliance on metabolism of stored fats. It is therefore plausible that HGA could affect the exercise performance of a much greater number of horses than those with overt clinical signs.Identification of serum HGA or MCPA-carnitine can also be useful in cases such as the case described by Jahn et al (REF when available) in which Box Elder but not Sycamore trees were present on the pasture. Whilst the presence of Box Elder had been reported on one European pasture grazed by an AM affected horse previously, Sycamore was also present on that pasture (Votion et al. 2014) and to the author’s knowledge, confirmed Box Elder related Atypical Myopathy has not been reported previously in Europe.Many clinicians in Europe will not be familiar with the Box Elder tree as an alternative source of HGA, However, given that the Box Elder has been identified as a major invasive species in forests in the European Union (Campagnaro et al. 2018) it is likely to be responsible for further cases of Atypical Myopathy in Europe in future. Clinicians should also be aware of the potential for many other trees of theAcer family to that are grown in gardens or as ornamental trees to contain HGA. HGA has been identified in the sugar maple (Acer saccharum) , Japanese maple (Acer palmatum) , trident maple (Acer buergerianum) , paperbark maple (Acer griseum), Himalayan maple (Acer oblongum), mountain maple (Acer spicatum), big leaf maple (Acer macrophyllum) , full moon maple (Acer japonicum), lime-leafed maple (Acer distylum) and Siebold’s maple (Acer sieboldianum). (Fowden and Pratt 1973, Novotná et al. 2023). Given the potential for the winged samaras of these species to spread widely in windy conditions it is plausible that cases of Atypical myopathy could occur if these species are grown in gardens adjoining paddocks.Acylcarnitine profiling combined with HGA/ MCPA-carnitine assays may also be clinically useful to identify unusual cases of Atypical Myopathy, other pasture toxicities and inborn errors of metabolism. For example, a rare case of Atypical Myopathy was diagnosed using these methods in a newborn foal in which the mare had suffered from Atypical Myopathy during pregnancy (Karlíková et al. 2018). In another case, severe clinical signs in a newborn foal resulted from suspected concurrent Atypical Myopathy with inborn metabolic disease (Sanderet al. 2021). Finally, acylcarnitine profiling was also successfully used to identify an inborn form of MADD without HGA toxicity in a paint foal (Pinn et al. 2018).Recently, acylcarnitine profiling was also used to identify cases of Marsh mallow (Malva parviflora) toxicity in which it is proposed that malvalic and/or sterculic acid inhibit very-long chain acyl-CoA dehydrogenase, thus slowing the beta-oxidation of very-long chain fatty acids (Bauquier et al. 2017). Acylcarnitine profiles have also revealed suspected disorders of fatty acid metabolism without the detection on HGA MCPA-carnitine in serum samples submitted to the authors’ laboratory (unpublished data) and there is likely that as yet unidentified pasture-associated toxicities occur in the UK and Europe.In conclusion, the interesting case report by Jahn et al (REF) is an important reminder to clinicians in Europe of the potential forAcer species other than Sycamore to cause Atypical Myopathy. Acyl-carnitine profiles and detection of HGA/ MCPA-carnitine by LCMS can be a useful diagnostic aid in myopathy cases.ReferencesBaise, E., Habyarimana, J.A., Amory, H., Boemer, F., Douny, C., Gustin, P., Marcillaud-Pitel, C., Patarin, F., Weber, M. and Votion, D.M. (2016) Samaras and seedlings of Acer pseudoplatanus are potential sources of hypoglycin A intoxication in atypical myopathy without necessarily inducing clinical signs. Equine Vet J 48 , 414–417.Bauquier, J., Stent, A., Gibney, J., Jerrett, I., White, J., Tennent-Brown, B., Pearce, A. and Pitt, J. (2017) Evidence for marsh mallow (Malva parviflora) toxicosis causing myocardial disease and myopathy in four horses. Equine Vet J 49 , 307–313.Bochnia, M., Sander, J., Ziegler, J., Terhardt, M., Sander, S., Janzen, N., Cavalleri, J.M.V., Zuraw, A., Wensch-Dorendorf, M. and Zeyner, A. (2019a) Detection of MCPG metabolites in horses with atypical myopathy.PLoS One 14 .Bochnia, M., Sander, J., Ziegler, J., Terhardt, M., Sander, S., Janzen, N., Cavalleri, J.M.V., Zuraw, A., Wensch-Dorendorf, M. and Zeyner, A. (2019b) Detection of MCPG metabolites in horses with atypical myopathy.PLoS One 14 .Bochnia, M., Scheidemann, W., Ziegler, J., Sander, J., Vollstedt, S., Glatter, M., Janzen, N., Terhardt, M. and Zeyner, A. (2018) Predictive value of hypoglycin A and methylencyclopropylacetic acid conjugates in a horse with atypical myopathy in comparison to its cograzing partners.Equine Vet Educ 30 , 24–28.Campagnaro, T., Brundu, G. and Sitzia, T. (2018) Five major invasive alien tree species in European Union forest habitat types of the Alpine and Continental biogeographical regions. J Nat Conserv 43 , 227–238.Cassart, D., Baise, E., Cherel, Y., Delguste, C., Antoine, N., Votion, D., Amory, H., Rollin, F., Linden, A., Coignoul, F. and Desmecht, D. (2007) Morphological alterations in oxidative muscles and mitochondrial structure associated with equine atypical myopathy. Equine Vet J 39 , 26–32.Dunkel, B., Ryan, A., Haggett, E. and Knowles, E.J. (2018) Atypical myopathy in the South-East of England: Clinicopathological data and outcome in hospitalised horses. Equine Vet Educ . https://doi.org/10.1111/eve.12895Fowden, L. and Pratt, H.M. (1973) Cyclopropylamino acids of the genus Acer: Distribution and biosynthesis. Phytochemistry 12 , 1677–1681.González-Medina, S., Hyde, C., Lovera, I. and Piercy, R.J. (2021) Detection of hypoglycin A and MCPA-carnitine in equine serum and muscle tissue: Optimisation and validation of a LC-MS-based method without derivatisation. Equine Vet J 53 , 558–568.González-Medina, S., Ireland, J.L., Piercy, R.J., Newton, J.R. and Votion, D.M. (2017) Equine atypical myopathy in the UK: Epidemiological characteristics of cases reported from 2011 to 2015 and factors associated with survival. Equine Vet J 49 , 746–752.Karlíková, R., Široká, J., Mech, M., Friedecký, D., Janečková, H., Mádrová, L., Hrdinová, F., Drábková, Z., Dobešová, O., Adam, T. and Jahn, P. (2018) Newborn foal with atypical myopathy. J Vet Intern Med 32 , 1768–1772.Novotná, T., Jahn, P., Šamonilová, E., Kabešová, M., Pospíšilová, S. and Maršálek, P. (2023) Hypoglycin A in Acer genus plants. Toxicon 234 , 107271.Pinn, T.L., Divers, T.J., Southard, T., De Bernardis, N.P., Wakshlag, J.J. and Valberg, S. (2018) Persistent hypoglycemia associated with lipid storage myopathy in a paint foal. J Vet Intern Med 32 , 1442.Renaud, B., Kruse, C.J., François, A.C., Cesarini, C., van Loon, G., Palmers, K., Boemer, F., Luis, G., Gustin, P. and Votion, D.M. (2024) Large-scale study of blood markers in equine atypical myopathy reveals subclinical poisoning and advances in diagnostic and prognostic criteria. Environ Toxicol Pharmacol 110 , 104515.Sander, J., Terhardt, M. and Janzen, N. (2021) Severe Inhibition of Long-Chain Acyl-CoA Enoylhydratase (EC 4.2.1.74) in a Newborn Foal Suffering From Atypical Myopathy. Front Vet Sci 8 , 765623.Sander, J., Terhardt, M., Janzen, N., Renaud, B., Kruse, C.J., François, A.C., Wouters, C.P., Boemer, F. and Votion, D.M. (2023) Tissue Specific Distribution and Activation of Sapindaceae Toxins in Horses Suffering from Atypical Myopathy. Animals (Basel) 13 .Valberg, S.J., Sponseller, B.T., Hegeman, A.D., Earing, J., Bender, J.B., Martinson, K.L., Patterson, S.E. and Sweetman, L. (2013) Seasonal pasture myopathy/atypical myopathy in North America associated with ingestion of hypoglycin A within seeds of the box elder tree.Equine Vet J 45 , 419–426.Votion, D.-M., van Galen, G., Sweetman, L., Boemer, F., de Tullio, P., Dopagne, C., et al. (2014) Identification of methylenecyclopropyl acetic acid in serum of European horses with atypical myopathy. Equine Vet J 46 , 146–149.Westermann, C.M., Dorland, L., Votion, D.M., de Sain-van der Velden, M.G.M., Wijnberg, I.D., Wanders, R.J.A., Spliet, W.G.M., Testerink, N., Berger, R., Ruiter, J.P.N. and van der Kolk, J.H. (2008) Acquired multiple Acyl-CoA dehydrogenase deficiency in 10 horses with atypical myopathy. Neuromuscular Disorders 18 , 355–364.

Background: There is a concern that performing routine dental floats could result in adverse pregnancy outcomes in mares. There is a paucity of data on the effect of dentistry during pregnancy in domestic species. In women, dental prophylaxis is considered safe during pregnancy. Objectives: The objective of this study was to determine if routine dental floating was associated with adverse pregnancy outcomes in Thoroughbred broodmares. Study Design: Retrospective records analysis Methods: Clinical and farm records from 2013 to 2021 were utilized. Abortion, stillbirth and placentitis was modeled using SAS GLIMMIX procedure. Time of the dental procedure was categorized in two ways, occurring when the mares were 1) open or pregnant or 2) open, during the 1st trimester (0 – 114 days), the 2 nd trimester (115 – 228 days) or the 3 rd trimester (> 229 days) of pregnancy for separate models for each outcome. Significance was set at P < 0.05. Results: Both logistic regression models examining abortion found age of mare at the time of float remained significant, while trimester of dental procedure, farm and year float was performed were not significant. Both logistic regression models examining stillbirth found the age of the mare at the time of float remained significant, with location being significant in the first model (open or pregnant) and a tendency (0.10 > P > 0.05) in the second model (open, 1 st, 2 nd, or 3 rd trimester). Other variables in the models were not significant. Farm remained significant in both logistic models of placentitis, while age of mare at the time of float, trimester of dental float and year float was performed were not significant. Main Limitations: Not a controlled study. Conclusions: Floating a mare’s teeth during each trimester of pregnancy is a safe procedure.

This case report describes a Thoroughbred broodmare presented for colic and pyrexia. The mare had a history of repeated urinary tract infections, placentitis, abortion and endotoxaemia. A diagnosis of bilateral subcapsular renal haematoma was made by ultrasonography and standing laparoscopy and confirmed on post-mortem. Trauma, clotting disorder, and neoplasia were ruled out as a cause of the bleeding. However, histopathology revealed severe, diffuse, acute fibrinosuppurative tubulointerstitial nephritis with degeneration of vascular walls, suggesting that this has caused renal bleeding and development of subcapsular hematomas.

A document by Tim Mair. Click on the document to view its contents.

Background: Established or ongoing septic arthritis requiring repeated joint flushing remains a treatment challenge with a poor survival outcome aggravated by the necessicity of controlled antimicrobial usage. Objective: To describe the outcomes and survival rates of patients with synovial sepsis treated by lavage with a 0.05% chlorhexidine solution. Study design: Clinical retrospective observational study. Methods: Patients with synovial sepsis who underwent standing needle or arthroscopic lavage under general anaesthesia with a 0.05% chlorhexidine solution, followed by Lactate Ringer Solution (LRS). Complementary systemic and regional antibiotics were used. Short (6 months) and long term (>1 year) evolution were assessed. Results: 10 horses met the inclusion criteria. Affected joints included metacarpophalangeal joints (20%), tarso-crural joint (10%), radiocarpal and intercarpal joints (20%), distal interphalangeal joints and navicular bursa (30%), distal interphalangeal joints (20 %). Time from onset to referral ranged from 1-20 days, mean 8.3 days. Eighty percent of horses survived for more than one year. Four horses were retired to the field, three returned to a light level of work and one went back to full work. Main limitations: Retrospective study of a limited group of horses initially treated by different clinicians before referral, as such, first line treatment had differences between cases. Resolution was evaluated on clinical signs rather than clinical pathology of synovial fluid due to clinical decision or difficulty in obtaining samples. Conclusion: With this series of challenging synovial sepsis cases treated by lavage with a chlorhexidine solution we provide a treatment protocol, proof of clinical concept and report patient’s short and long-term clinical evolution. Short and long term post-operative lameness should be expected despite resolution of the septic arthritis. This treatment poses a novel option for challenging cases but should be regarded as a salvage procedure due to the possibility of long term mild lameness.

This article briefly reviews the causes of unilateral nasal discharge associated with sinonasal disease in the horse. Whilst, computed tomographic and radiographic imaging are often of great diagnostic value, clinical and nasal endoscopic examinations are the initial steps in investigating these disorders. This article reviews the use of oral examination and nasal endoscopy in the investigation of nasal discharge caused by sinonasal disease.

The ventral and dorsal components of the ascending colon are adjoined by the ascending mesocolon, and few case reports have described congenital or acquired malformations of this structure. This case series reports the occurrence of large mesenteric rents of the ascending mesocolon ( Hernia mesocolica coli ascendentis) in 6 adult horses diagnosed during exploratory laparotomy. Based on the history of the patients, the rents were most likely acquired. The rents were mainly located directly adjacent to the left dorsal colon, and without affecting the intestinal blood supply. The size of the defect varied between 20 and 80 cm, and in 5/6 cases it was a subacute or chronic rupture with rounded edges. Two different types of intestinal displacements in relation to the rent were found, with either a localized torsion of the dorsal colon or herniation of the pelvic flexure through the rent. In all cases, the intestine could be repositioned, and the rent was sutured. Despite some minor postoperative complications, the short- and long-term outcome was excellent. It was hypothesised that recurrent colon displacements or trauma elicited by an intrauterine foal may have been the cause of the rent in some of the cases.

not-yet-known not-yet-known not-yet-known unknown There is a paucity of literature describing equine lipoid pneumonia (LP) caused by inadvertent intra-pulmonary administration of liquid paraffin (mineral oil). This case report improves our understanding of LP by describing; 1) the first reported return of a horse to racing after LP, 2) the likely benefits of prolonged dexamethasone administration, 3) the detailed short- and long-term pulmonary and systemic responses to intra-pulmonary liquid paraffin, and 4) the prolonged pulmonary retention of liquid paraffin.

This report describes the identification of C7-T1 discospondylitis on myelography and confirmed on postmortem computed tomography and necropsy in a 4-year-old Standardbred gelding as the consequence of jugular vein catheterization and secondary septic thrombophlebitis. Staphylococcus aureus was isolated from both sites. Diagnosis was complicated by non-specific signs of pain and the acute presentation of the gelding. Clinical signs included cervical pain, low head carriage, fever, and ataxia. Antimicrobial therapy and multimodal pain management were initiated but were unsuccessful. Spread of infection from septic thrombophlebitis has uncommonly been reported in horses, and this is the first reported case of secondary discospondylitis in this species.

Background : Anthelmintic resistance in equine parasites is increasing. Frequent anthelmintic use accelerates selection for resistance. Objectives : Investigate how horse owners currently use anthelmintics to control intestinal parasites. Study design : Online survey. Methods: Questionnaire distributed via practices, equestrian organisations, etc., December 2021 to October 2022. Combination of multiple choice, Likert scale and free text questions. Descriptive / inferential statistics performed (Microsoft Excel and IBM SPSS). Results : 4232 useable responses. Owners of horses on livery yards less likely to make worming decisions compared to those on private properties (p<0.001); managers made decisions in 39.6% of horses on livery yards; 60.7% of owners sought worming advice from their veterinarian; 52.0% administered anthelmintics based on routine faecal egg counts (FECs) / tapeworm serology result; 30.0% routinely tested, but wormed at least once a year regardless of the results; 16.1% did not test, but wormed at least once a year. Owners were more likely to administer anthelmintics based on test results if they sought veterinary advice or were on a health programme (both p<0.001). Of those who routinely wormed, 54.9% wormed once a year; 45.1% wormed twice or more a year. Frequency of routine worming was higher if they didn’t routinely test (p<0.001); 88.9% simultaneously wormed all horses on the pasture. Moxidectin was the first choice for 82.2% of owners who routinely wormed at least once yearly. Routine FECs were performed by 84.7%, higher for those who sought veterinary advice (89.3%, p<0.001). Tapeworm ELISAs were utilised by 40.8%, higher for those on a health programme (68.1%; p<0.001); 58.5% routinely treated for tapeworms regardless of test results. Main Limitations : Selection bias. Conclusions : Owners apply moderately good diagnostic-led parasite control practices, but still common to regularly treat with anthelmintics (30.0% worming at least once a year regardless of the FEC results).

Background : Anthelmintic resistance in equine parasites is increasing. Pasture management is a vital component of parasite control, and is important to limit the development of resistance. Objectives : Investigate how horse owners use management procedures to control common intestinal parasites in horses. Study design : Online survey. Methods : Questionnaire distributed via practices, equestrian organisations, etc., December 2021 - October 2022. Combination of multiple choice, Likert scale and free text questions. Descriptive and inferential statistics performed in Microsoft Excel and IBM SPSS. Results : 4232 useable responses from the UK, predominantly England (85.4%). Premises included livery yards (45.7%) and private properties (51.1%). Most horses (70.4%) were aged 6-20 years. Over half (55.9%) were used for general riding/pleasure; 58.9% grazed with 1-3 other horses, while 20.7% grazed alone; 21.5% alternated or co-grazed with ruminants (significantly higher for horses grazing on private properties compared to horses grazing on livery yards; 73.3% of owners removed faeces from pastures (poo-picking), of which 86.4% removed faeces twice a week or more. Owners of horses pastured individually were significantly more likely to poo-pick (89.8%) than horses pastured in groups (68.9%); 77.1% of respondents rested pastures, but less than 5% for over 6 months. Only 5.1% of owners reported they had experienced illnesses related to worms in any horse (commonest clinical signs were colic and weight loss). Limitations : Selection bias. Conclusions : Results suggest a lack of understanding of the principles of non-chemical parasite control among many horse owners. Many owners (>25%) are not routinely poo-picking. Horses pastured alone or kept on a private property were significantly more likely to have their faeces regularly removed than thoses pastured in groups or kept on livery yards.

This paper describes the clinical and histopathological features of a 16-year-old Cob mare who sustained a hemorrhagic cerebrovascular accident or stroke. The mare presented with an acute onset of neurological signs, with a neuroanatomical localization to the midbrain and thalamus regions. The mare was reported to have suffered from ataxia on all 4 limbs which started 7 days prior to referral, she was also showing several signs of left-sided cranial nerves deficits. On initial examination, the mare presented with quadrilateral ataxia, left-sided facial paralysis, weak tongue tone and a left-sided nose tilt as well as a hemineglect syndrome characterized by an inability to eat food presented on the right side of her mouth. Complete blood count and biochemistry analyses did not reveal any abnormalities, and a standing head CT revealed the presence of a hyperdense lesion localized in the left ventral cortex and thalamus region, which could be consistent with a vascular lesion, cholesterol granuloma or a mass. The mare was monitored, and as her condition slightly improved, she was discharged from the Hospital. Four weeks later, the clinical signs recurred and as the ataxia presented a danger for the mare and anyone handling her, the decision was made to euthanize her. A post-mortem CT scan of the head revealed an enlargement of the previous lesion, and the histopathological examination confirmed the presence of a hemorrhage within the brain, associated with neoplastic emboli. Hemorrhagic stroke has not previously been well described in horses therefore presents a challenge in diagnosis. Treatment in small animals is mainly conservative.

Sialolithiasis is an uncommon condition of the salivary gland in the horse, primarily affecting the parotid salivary duct. Clinical signs may include salivary stasis within the gland and potential progression to sialadenitis, facial draining tract, or a permanent fistula. A 19-year-old Warmblood gelding was referred with severe septic sialadenitis of the right parotid gland. A 4 cm sialolith was detected radiographically and removed surgically. Although surgery was uneventful and patency of the salivary duct was assessed intra-operatively, mild accumulation of saliva within the gland was noted one day later. A stenosis caudal to where the sialolith was lodged was diagnosed through contrast radiography. Balloon dilatation of the stenosis was attempted unsatisfactorily and a polyethylene catheter was placed and sutured to the oral mucosa to maintain the parotid empty. A week later, the oral portion of the catheter was chewed by the horse, preventing catheter removal without surgery. Subsequently, ultrasonographic and radiographic re-evaluations were performed routinely to assess the patency of the catheter or complications associated with long-term placement. After 1 year, no salivary stasis in the gland or complications were observed. This is the first description of successful long-term indwelling catheter placement to resolve stenosis of the salivary duct. This procedure offers a simple, economical, and safe option compared to more complicated or invasive techniques previously described in horses, with excellent functional and cosmetic results.

Background: The paracondylar process is of clinical interest due to its proximity to anatomical structures involved in vital functions. There are limited reports describing abnormalities affecting the paracondylar process (PCP), with traumatic fractures being the most prevalent pathology. Affected horses can present with a variety of signs including headshaking, facial paralysis and/or poor performance. In almost all cases reported in the literature to date, computed tomography has been used to diagnose a PCP fracture. Objectives: The aim of this study was to develop a radiographic technique for imaging the PCP, to determine the optimum radiographic projection angle and trial its use in standing sedated horses. Study design: Pilot study conducted in 10 standing sedated horses. Methods: Three tangential radiographs of the left and right paracondylar processes at 5º, 15º and 20º to the transverse plane were obtained in 10 standing sedated horses. Three blinded observers independently ranked each of the three images for clarity of viewing the PCP. The radiographic projection allowed imaging of the ventral portion of the PCP while avoiding superimposition of other osseous structures. Results: The highest grades were obtained for radiographs with a 5º angle from the transverse plane, and the lowest grades were obtained for a 20º angle. Main limitations: Complex anatomy of the PCP with superimposition of osseous and soft tissue structures. Conclusions: The radiographic technique for the PCP can be safely performed in standing, sedated horses. It is suitable for implementation in general veterinary practice before considering referral for advanced imaging techniques in horses presenting with headshaking or facial paralysis.

Lameness in the horse is one of the most common reasons a horse is seen by a veterinarian. As the foot is frequently the source of lameness, research utilizing reversible methods of foot lameness induction are vital to improvements of the knowledge in this area. This literature review aims to describe published methods of reversible foot lameness induction, identify any limitations of these methods, and summarize findings of research where these methods have been utilized.

Summary: A rare case of bilateral perineal hernia was reported in a 24-year-old Italian Trotter mare. This condition is described as a protrusion of retroperitoneal fat, and/or the abdominal or pelvic viscera through the pelvic diaphragm which supports the rectal wall. It is commonly observed in olduncastrated old male dogs, but occurs very rarely in large ruminants; to the Authors’ knowledge, it has never been described in horses. Chronic weight loss is the main clinical sign, even if the main concern regards the entrapment and the strangulation of the bowel content. Reaching a diagnosis involves clinical signs, palpation, ultrasound evaluation and rectal examination. The approach chosen in all the cases of perineal hernia described in large ruminants is appositional herniorrhaphy; for this reason, it was utilised as the first surgical choice in the present case. Due to its failure, a new surgical approach was used The second procedure involved the transposition of the semimembranosus muscle. The short-term outcome after the second surgery presented no recurrence or complications. It is therefore necessary to consider perineal hernia among the various differential diagnosis of perineal swellings in horses. Additional cases are required to determine its benefits.

A fifteen-year-old warmblood gelding was presented with recurrence of a histologically confirmed osteosarcoma of the left second and third metacarpal bones three years after initial diagnosis and treatment. Initially, surgical excision was performed, followed by local injection of carboplatin 11 weeks later. The horse was sound after surgery and was used for low level dressage and jumping. Three years later, the horse developed acute onset of lameness in the left forelimb and a painful soft tissue swelling at the proximomedial metacarpal region. Radiographs showed a spiculated periosteal reaction on the medial aspect of the third metacarpal bone, indicating re-activation of the lesion. Stereotactic radiation therapy was performed with a protocol consisting of three fractions under general anaesthesia (Mo-We-Fr schedule), and a total dose of 30 Gy. The technique used was volumetric modulated arc therapy guided by cone beam computed tomography for daily positioning. Following the radiation therapy, the horse became sound at walk and one month later, it became sound at trot. Follow-up by veterinary examination eighteen months after final treatment revealed no lameness at walk and trot, and a stable radiographic appearance.

** Other clinical commentaries don’t have an abstract, so I have assumed one is not expected?