Pathology in horses involves the study of diseases and abnormalities affecting equine health, encompassing a range of conditions that can impact various systems within the horse's body. This field examines the causes, mechanisms, and effects of diseases, as well as the structural and functional changes they induce in equine tissues and organs. Common pathological conditions in horses include laminitis, colic, equine infectious anemia, and respiratory disorders. Understanding these diseases involves evaluating clinical signs, diagnostic methods, and treatment options. This page compiles peer-reviewed research studies and scholarly articles that explore the etiology, pathogenesis, and clinical implications of pathological conditions in horses.
RANDALL CC, ORR MF, SCHELL FG.Intracellular organisms resembling Histoplasma capsulatum have been observed in apparently normal amnio-allantoic membrane and adult horse spleen maintained in tissue culture.
The significance of this finding and comparison with another fungus Cryptococcus jarciminosus is discussed.
ALEXANDER F, BENZIE D.1. The disposition and surface relations of the alimentary tract of the foal have been studied radiographically.
2. The rate of progress of a barium meal through the digestive tract was determined. The barium traversed the stomach and ileum of the weaned foal faster than that of the suckling foal, but was longer retained in the cæcum and ventral colon of the weaned foal.
TOMCSIK J, SCHWARZWEISS H.1. From beef stroma pretreated at room temperature with acetone and alcohol, a fraction was isolated with boiling 100% alcohol which, in a dilution of 1:500,000, combines with the sheep blood agglutinin of human serum produced during serum sickness. Using the terminology of Schiff, this fraction corresponds to the heterogenetic serum sickness antigen; it could be separated to a large extent from the heterogenetic mononucleosis antigen which also occurs in beef stroma.
2. The so-called serum sickness antigen also occurs heterogenetically in guinea pig kidney and it could also be isolated from ...
Teague P, Dark M, Verdugo D, Freeman D, McFarlane D.The equine pancreas remains understudied, particularly in the context of endocrine disease. This study aimed to characterize regional islet distribution and composition in the normal equine pancreas and investigate how hyperinsulinemia (HI) and pituitary pars intermedia dysfunction (PPID) influence pancreatic islet morphology and hormone expression. In the first experiment, pancreas samples from eight healthy horses were collected and analyzed across three anatomical locations: left lobe, body, and right lobe. The left lobe exhibited a greater relative islet area and perimeter compared to the ...
Boeger L, Volkmann N, Probst J, Kemper N, Venner M.The emergence of antimicrobial resistance raises concerns about using antibiotics in veterinary medicine, particularly in cases of bronchopneumonia in foals diagnosed early based on a screening programme. Many subclinical foals recover spontaneously, thus, interest in more restrictive antibiotic usage is increasing. Objective: To determine whether initiating antimicrobial therapy at a later stage of bronchopneumonia decreases antimicrobial usage without compromising successful resolution of pathology in affected foals. Methods: A total of 1200 warmblood foals born in 2020, 2022, 2023 and 2024 ...
Mendes RP, Gonzaga MS, Matheus MM, Bittar MJ, Doria RGS, Corrêa RR.Developmental and eruption abnormalities are common and can result in progressive dental diseases. Ectopic eruption of the affected tooth may be the result of these processes. This study aims to report the occurrence of a permanent mandibular tooth in a horizontal position, with retention of the corresponding deciduous tooth, in a miniature horse. A 2-year-old female miniature horse was admitted to the veterinary hospital with a hard swelling on the left mandibular ramus, which had been growing continuously for three months. After a complete evaluation, it was concluded that the swelling was t...
Andrade AC, Fonseca SMC, Silva Filho GB, Melo ET, Santos JRP, Frota MLSL, Duarte JMBS, Evêncio-Neto J, Brito LB, Lima TS, Wicpolt NS, Riet-Correa F....We report an outbreak of Crotalaria juncea intoxication in horses exhibiting progressive weight loss and respiratory distress in northeastern Brazil. Necropsy revealed firm, non-collapsed lungs with extensive interstitial fibrosis, bronchiolar epithelial hyperplasia with club cells proliferation, and marked pulmonary arterial remodeling. Hepatic lesions consisted primarily of centrilobular necrosis, probably resulting from hypoxic injury related to anemia and prolonged agonic death. Pasture inspection identified significant invasion by shrubs of C. juncea in various phenological stages.
Barrantes Murillo DF, Camillo G, Souza Serrano B, Almeida Luciano LP, Castilho Bichara GV, Chaves Vás CA, Furlan Gouvêa FH, Brandini Nespoli PE....Facial abnormalities and brain defects in aborted equine fetuses are rarely reported, and the causes that predispose the occurrence of this condition are difficult to identify. This work reports the morphological and tomographic findings of a case of cryptophthalmia, microphthalmia, oronasal malformation, and hydrocephalus in an aborted equine fetus with umbilical cord torsion in the state of Mato Grosso, Brazil, from a primiparous Quarter Horse female, with 7 months of gestational age. The occurrence of miscarriage was associated with compromised maternal-fetal blood flow due to umbilical cor...
Häussling MPP, Steinberg T, Büttner K, Hannig C, Hannig M, Lemke L, Zierau O, Staszyk C.Destructive lesions of the peripheral and infundibular cementum are increasingly recognized in equine dentistry. While similarities to human caries have been noted, current evidence does not conclusively support this classification. This study aims to assess the prevalence, distribution, and potential risk factors associated with these lesions in a defined horse population. Unassigned: A total of 114 horses from northern Germany underwent standardized oral examination between 2021 and 2023. Clinical data on peripheral and infundibular lesions, diastemata, and influencing factors such as age an...
Dillmann JB, Dos Santos TS, Dos Santos RC, Monteiro SG.Equine cutaneous pythiosis, caused by Pythium insidiosum, is a severe disease in tropical and subtropical regions, often leading to progressive granulomatous lesions with poor response to conventional therapies. Standard treatment includes surgical excision and immunotherapy, but recurrence is common, particularly in distal limb lesions. Maggot Debridement Therapy (MDT) with disinfected Lucilia cuprina larvae provides selective debridement, microbial control, and stimulation of granulation, representing a potential adjunctive option. This report describes the successful use of MDT combined wit...
González N, Varela A, de Blas N, Gil L.At present, oviductal pathologies and their influence on mare fertility have not been clearly determined. Checking changes throughout the year in the oviductal structure may be relevant to understand the influence on the appearance of problems in oviductal functionality and, thus, the impact on fertility, which is the objective of this work. The oviducts of 56 mares were examined. Their anatomy, permeability, oviductal cellularity and the presence of pathologies were assessed to establish the correlations between the time of the year and each of these parameters. We cannot conclude whether the...
Johnson JP, Cardenas FA, Asakawa MG, Oikawa MA.Myofibroblastic fibrosarcoma (MFS) is a malignant soft tissue tumour that is rare in domestic animals. Here we report a case of congenital MFS in an Arabian foal at birth. A large solitary subcutaneous mass arising in the left temporal region was found in the foal. On cut section, an unencapsulated hemispheric, white-yellowish, elastic fibrous mass was attached to the temporal bone. Histologically, the mass was composed of a neoplastic proliferation of spindle-shaped fibroblasts arranged in fasciculate or interwoven streams and bundles, with low nuclear atypia and mitotic rate, local invasion ...
Fischetti L, Perina F, Sarli G, Ellero N, Freccero F, Castagnetti C, Mariella J.A 286-day pregnant mare was referred for signs of impending abortion. The ultrasonographic evaluation revealed a high normal combined thickness of the utero-placental unit (CTUP), oligohydroallantois and a living fetus. No vulvar discharge was observed, and the cervical swab culture was negative. After a choke, the mare received NSAIDs and antibiotics and then developed systemic inflammatory response syndrome (SIRS) and aborted. The amniotic portion of the umbilical cord was excessively long and twisted and the chorionic side of the placenta showed a brown discoloration and rough surface area....
Carvalho KS, de Barros CSL, Mendonça FS, Machado M, Riet-Correa F.In Brazil, CNS diseases in equids were little known until the 1980s. Since then, several diagnostic laboratories have been operating in different universities, initially in the South and Southeast regions and, later, in the Central-West, Northeast and North regions. However, the knowledge accumulated from the diagnoses of nervous system diseases of equids made at these institutions over the years has not been reviewed comprehensively, and many papers are published in Portuguese. Here, we review 18 diseases that occur in the nervous system of equids in Brazil, including some critical infectious...
Martano M, Montagnaro S, Power K, Cuccaro B, Cutarelli A, Maiolino P, Restucci B.This study investigated the presence of δ bovine papillomaviruses (BPV-1, BPV-2, BPV-13, BPV-14) in equine skin lesions from Southern Italy, focusing on equine sarcoids and their histopathological correlations. 63 equine skin samples were analysed using PCR and sequencing for BPV detection, and their histopathological features were assessed. BPV DNA was detected in 69.84% of the samples, with BPV-1 and BPV-2 being the most prevalent genotype, followed by BPV-13, while BPV-14 was not detected. BPV DNA was also found in non-sarcoid tumours and non-neoplastic conditions. Histopathological analys...
Maeda Y, Kanno C, Sugiyama M, Yamamoto R, Sato S, Ando R, Noda R, Kawaguchi H, Takahashi F.A 17-year-old Thoroughbred stallion died suddenly after grazing. Necropsy revealed massive hemorrhage in the pericardial sac, suggesting cardiac tamponade. Aortic perforation was observed at the aortic origin, and hemorrhage was observed in and around the epicardium. Superficial observation of the aortic lumen revealed a transverse tear of the aortic wall at the bases of the right semilunar valve and septal semilunar valve. Fibro-osseous changes with calcification were histopathologically observed at the site of the rupture. A nodular goiter was observed in the left thyroid gland. The horse di...
Hisaeda K, LE NAT, Kadekaru S, Ono T, Hiasa Y, Ohzawa E, Hata A, Kutara K, Sugimoto K, Une Y, Iwata E, Kunieda T, Zhang C, Kitagawa H.We evaluated metabolic abnormalities in six neonatal Noma foals (Nos. 54-57, 62, and 66) that died shortly after birth, using laboratory tests, pathological examinations, serum amino acid (AA) analyses, gas chromatography/mass spectrometry (GC/MS), and genetic analyses. Nonspecific clinical symptoms, such as poor suckling and weakness, were commonly observed at birth. Sepsis caused by various bacterial infections was detected in foal Nos. 54, 62, and 66, while a heart malformation was identified in foal No. 57. Laboratory tests showed high aspartate transaminase, lactate dehydrogenase, and cre...
Neira-Egea P, Alamar Malvoisin C, de la Cuesta-Torrado M, Bautista-Erler C, Vitale V, Jolly S, Cesarini C. spp. are ubiquitous yeasts that are part of most mammals' microbiota and can become opportunistic pathogens under predisposing conditions. Interestingly, recent studies in human medicine report an increased abundance of spp. in association with inflammatory bowel disease (IBD). Gastrointestinal candidiasis has been primarily reported in neonatal foals, but not in adult horses. The aim of this study is to describe the morphological, histopathological, and microbiological features of gastric lesions associated with infiltration in five horses referred to two tertiary hospitals for different r...
Ceriotti S, Clark-Price S, Cole R, Kramer A, Sandey M, Mora M.This case describes a 15-year-old Thoroughbred mare with fistulous withers that progressed to vertebral osteomyelitis and spinal epidural abscess (SEA), a severe complication that has yet to be reported. Initially treated with antibiotics and anti-inflammatory medication, the mare developed acute hindlimb ataxia and spastic paresis, suggesting spinal cord compression at T3-L3. Diagnostic imaging revealed vertebral fractures and abscessation, but vertebral canal involvement could not be confirmed. Despite aggressive medical therapy, including antimicrobials, corticosteroids, and neuroprotective...
Poci Palumbo MI, Maciel Cavalcante R, Martins Amorim R, De Vasconcelos Machado VM, Sousa Rocha N, Garcia Ribeiro M, Cagnini DQ, Secorun Borges A.Bacterial infection of the equine central nervous system is rare. This report describes the clinical features, computed tomography (CT) findings, and postmortem results of a 3-month-old female Quarter Horse with an intracranial abscess. Clinical signs included seizures, depression, and bilateral blindness. CT imaging demonstrated a large space-occupying lesion in the left cerebral hemisphere, associated with a frontal bone fracture. Necropsy and histopathology confirmed the presence of an abscess secondary to head trauma. Bacterial culture identified Streptococcus equi subsp. zooepidemicus as...
Robel M, Grest P, Riond B, Zablotski Y, Schoster A.Limited data are available on immune cells in the intestinal wall of healthy horses, hampering interpretation of results in case of disease. Objective: Characterize and quantify the immune cell populations and their distribution in duodenal and rectal biopsies of horses without gastrointestinal disease; compare immune cell counts (ICCTs) between full thickness- and mucosal biopsies. Methods: Twenty horses fit for slaughter, slaughtered for meat production. Methods: Full-thickness and endoscopic forceps obtained mucosal biopsies were taken within 30 min after slaughter from the duodenum and rec...
Kelley JL, Rawlinson JE, Bell CM.Cystic and pseudocystic masses of the equine maxilla and mandible are rare lesions that result in clinically significant morbidity and/or mortality for the patient. Previous literature consists of case reports or case series. Few studies have addressed the variety of cystic lesions and comparative features. The aim of this study was to retrospectively describe the clinical signs, imaging findings, histopathologic diagnoses, treatments, and clinical outcomes for cystic masses in the equine maxilla and mandible. Unassigned: Cases were recruited from six sources including a pathology laboratory, ...
Mazur SE, Toribio RE.Complications in critically ill equine patients are often related to the underlying disease process but can also be a consequence of diagnostic and therapeutic interventions. Complications can be specific to the affected organ or body system; however, in critically ill patients, they frequently affect the vasculature, acid-base, electrolyte, and fluid balance, energy homeostasis, and coagulation, with systemic consequences. Infrequent monitoring, late detection, failure to adapt therapies, hematologic and biochemical abnormalities, coagulopathies, and systemic inflammation can all contribute t...
Ralletti MV, Meistro F, Tarasconi MA, Mandrioli L, Renzi A, Rinnovati R, Spadari A.Extraskeletal chondromas (ESCs) are rare benign tumours composed of mature cartilage that typically develop in soft tissues. Their occurrence in horses is extremely uncommon and, to the authors' knowledge, no previous cases of lingual ESCs in equines have been reported. This report describes a two-year-old Quarter Horse colt presented with progressive dysphagia. Clinical examination revealed a solitary, multilobulated, firm-elastic mass located at the dorsal aboral portion (base) of the tongue. Diagnostic imaging ruled out bone involvement. The mass was surgically excised under general anaesth...
Esdaile E, Houston K, Till BJ, Sutton RB, Scurrell E, Ling M, Hartley C, Bellone RR.Although several inherited ocular disorders have been extensively studied in horses, few reports of equine ectopia lentis exist and no genetic investigations have been reported. Ectopia lentis in humans and other species is reported to be caused by trauma, genetic variants, and systemic diseases. The most commonly reported genetic causes are dominant alleles in FBN1. Here we examined a 3-day old Oldenburg x Thoroughbred colt due to concerns over bilateral ocular anomalies and hypothesized that either a recessively inherited allele or a dominant de novo allele was the genetic cause. Examination...
Muresu Ibba GM, Poeta A, De Lorenzi G, Pupillo G, D'Annunzio G, Pezzarossi A, Bisceglia I, Mangone L.Melanomas are dermal-epidermal and subcutaneous tumors commonly found in horses, especially those with grey coats. This study aimed to characterize melanomas in slaughtered horses by analyzing their distribution according to sex, age, and nationality, and to describe the veterinary inspection interventions required at slaughterhouses based on lymph node involvement and distant metastases in a province of northern Italy. Between January and December 2024, 182 grey horses were examined, and 28 cases of melanoma were identified (15% of grey horses) with an average age of 14 years: 8 males (mean a...
Rimayanti R, Khairullah AR, Mustofa I, Utomo B, Lestari TD, Utama S, Akintunde AO, Mulyati S, Hernawati T, Dawood AQ, Riady G, Khan IU, Rasad SD.... is a protozoan parasite that causes the sexually transmitted disease known as "dourine" in horses. This chronic illness is directly spread from one animal to another during mating. Doflein proposed the name in 1901. Despite being distributed worldwide, the broad use of artificial insemination technology over the past three decades has resulted in only a few cases being documented. The condition is typically fatal and is characterized by gradual emaciation, nervous system involvement, and edematous lesions of the genitals. The incubation period between exposure and the onset of clinical sympt...
McLachlan AD, Woolford L.Chlamydia psittaci was detected by real-time PCR in the lung, liver and kidney of an equine foetus that had aborted in South Australia in August 2023. The corresponding microscopic lesions included lymphocytic and histiocytic chorionitis, necrosis of placental villi associated with bacteria in the cytoplasm of trophoblastic epithelial cells, and multiple microgranulomas in the liver. Equine chlamydial abortion had not been diagnosed previously in South Australia. Eight days after examining the foetus and placenta, the veterinary pathologist developed fever and subsequently was admitted to hosp...
Haugaard SL, Nissen SD, Schneider MJ, Birk JB, Carstensen H, Hopster-Iversen C, Altıntaş A, Barrès R, Kjøbsted R, Wojtaszewski JFP, Herum KM....High recurrence rates after atrial fibrillation (AF) treatment may be driven by myocardial changes induced by the arrhythmia itself. Understanding the molecular mechanisms behind these changes is crucial for developing targeted therapies and improving outcomes. Objective: To characterise the cardiac transcriptome of healthy horses and explore transcriptional changes associated with persistent AF (naturally occurring and tachypacing-induced). Methods: Case-control study. Methods: RNA-sequencing was performed on atrial and ventricular tissue samples collected from six horses with naturally occur...
Kyle-LaBell E, Andersson A, Baughman B.Fibrocartilaginous embolic myelopathy (FCE) was diagnosed in a 15-year-old pony mare by histopathologic examination of the spinal cord. The horse was euthanized and submitted for necropsy following focal seizures and lateral recumbency for approximately 12 h. Histopathology of spinal cord segments C5-C7 revealed severe ischemic myelomalacia with intravascular amorphous material that stained positive with Alcian Blue, consistent with cartilaginous matrix. These features in addition to the acute onset of clinical signs are characteristic for FCE. This case report describes the clinical and histo...
Saberinia A, Ozmaei S, Anoushepour A.Conjunctivitis is an inflammation of the conjunctiva caused by infectious or non-infectious factors. Infectious conjunctivitis comes in two forms: viral and bacterial. Bacterial conjunctivitis is commonly caused by organisms such as Staphylococcus and Streptococcus, with the severity of the disease influenced by the specific bacterial species involved. Because both viral and bacterial conjunctivitis are highly contagious, preventive measures are essential to reduce transmission-especially to the unaffected eye. Objective: To evaluate the tear film osmolality in horses with bacterial conjunctiv...
Björnsdóttir S, Sigurðardóttir ÓG, Oddsdóttir C, Reynisdóttir I, Hanche-Olsen S, Gröndahl G.Acquired equine polyneuropathy is a neuromuscular syndrome characterized by digital extensor dysfunction, primarily affecting the pelvic limbs, with consistent, repeated knuckling. Despite being recognized as an emerging disease in Scandinavia since 1995, the aetiology remains unknown, and cases have been limited to Norway, Sweden, and Finland. Methods: On a combined breeding and training farm in Iceland, 30 out of 145 horses (21%) presented with acute pelvic weakness, pelvic limb digital extensor dysfunction, knuckling and/or recumbency, from May to August 2019. The affected horses, aged 2-9Â...
