Pathogenesis in horses refers to the biological mechanisms that lead to the development and progression of diseases within equine species. This process involves a complex interaction between the horse's immune system, genetic predispositions, environmental factors, and infectious agents such as bacteria, viruses, or parasites. Understanding pathogenesis is essential for identifying how diseases manifest and progress in horses, which can inform diagnostic and therapeutic strategies. Research in this area often focuses on specific diseases, examining factors such as pathogen entry, immune response, tissue damage, and recovery processes. This page compiles peer-reviewed research studies and scholarly articles that explore the mechanisms, contributing factors, and implications of pathogenesis in equine health.
Hainisch EK, Jindra C, Reicher P, Miglinci L, Brodesser DM, Brandt S.Equine sarcoids are common, locally aggressive skin tumors induced by bovine papillomavirus types 1, 2, and possibly 13 (BPV1, BPV2, BPV13). Current in vitro models do not mimic de novo infection. We established primary fibroblasts from horse skin and succeeded in infecting these cells with native BPV1 and BPV2 virions. Subsequent cell characterization was carried out by cell culture, immunological, and molecular biological techniques. Infection of fibroblasts with serial 10-fold virion dilutions (2 × 10-20 virions) uniformly led to DNA loads settling at around 150 copies/cell after four pass...
Akula S, Riihimäki M, Waern I, Åbrink M, Raine A, Hellman L, Wernersson S.Asthma is a chronic inflammatory airway disease and a serious health problem in horses as well as in humans. In humans and mice, mast cells (MCs) are known to be directly involved in asthma pathology and subtypes of MCs accumulate in different lung and airway compartments. The role and phenotype of MCs in equine asthma has not been well documented, although an accumulation of MCs in bronchoalveolar lavage fluid (BALF) is frequently seen. To characterize the phenotype of airway MCs in equine asthma we here developed a protocol, based on MACS Tyto sorting, resulting in the isolation of 92.9% pur...
Sanclemente JL, Rivera-Velez SM, Horohov DW, Dasgupta N, Sanz MG.Foals that develop pulmonary ultrasonographic lesions on Rhodococcus equi (R. equi) endemic farms are treated with antibiotics because those at risk of developing clinical pneumonia (~20%) cannot be recognised early. Candidate biomarkers identified using metabolomics may aid targeted treatment strategies against R. equi. Objective: (1) To describe how foal ageing affects their plasma metabolome (birth to 8 weeks) and (2) to establish the effects that experimental infection with Rhodococcus equi (R. equi) has on foal metabolome. Methods: Experimental study. Methods: Nine healthy newborn foals...
Mainguy-Seers S, Beaudry F, Fernandez-Prada C, Martin JG, Lavoie JP.Extracellular vesicles (EVs) contribute to intercellular communication through the transfer of their rich cargo to recipient cells. The EVs produced by LPS-stimulated neutrophils from healthy humans and horses increase airway smooth muscle (ASM) proliferation, but the roles of neutrophil EVs in asthma are largely unexplored. The aim of this study was to determine whether neutrophil-derived EVs isolated during the remission or exacerbation of asthma influence ASM proliferation differentially. Peripheral blood neutrophils were collected during remission and exacerbation in eight horses affected ...
Mustonen AM, Lehmonen N, Oikari S, Capra J, Raekallio M, Mykkänen A, Paakkonen T, Rilla K, Niemelä T, Nieminen P.Osteoarthritis (OA) is a degenerative joint disease with inadequately understood pathogenesis leading to pain and functional limitations. Extracellular vesicles (EVs) released by synovial joint cells can induce both pro- and anti-OA effects. Hyaluronic acid (HA) lubricates the surfaces of articular cartilage and is one of the bioactive molecules transported by EVs. In humans, altered EV counts and composition can be observed in OA synovial fluid (SF), while EV research is in early stages in the horse-a well-recognized OA model. The aim was to characterize SF EVs and their HA cargo in 19 horses...
Schliewert EC, Hooijberg EH, Steyn JS, Potgieter C, Fosgate GT, Goddard A.African Horse Sickness (AHS) is a vector-borne disease endemic to sub-Saharan Africa caused by African Horse Sickness Virus (AHVS). Infections in naïve horses have high morbidity and mortality rates. AHS pathogenesis is not well understood; neither the hematologic changes nor acute phase response occurring during infection has been fully evaluated. The study's objective was to characterize the hematologic changes and acute phase response during experimental infection with AHSV. Methods: 4 horses negative for AHSV group-specific antibodies. Methods: In this prospective, longitudinal study cond...
Ahearne MM, Pentzke-Lemus LL, Romano AM, Larsen ED, Watson AM, O'Fallon EA, Landolt GA.Equine influenza virus is a common cause of respiratory disease in equids. Few reports describe clinical presentation and disease progression in donkeys. Objective: Describe the clinical and diagnostic findings, outcome, and pathologic lesions associated with influenza pneumonia in donkeys. Methods: Thirteen unvaccinated donkeys ranging from 1 week to 12 years of age and sharing clinical signs and exposure history. Methods: Retrospective case series. Medical records from June to July 2020 at the Colorado State Veterinary Teaching Hospital and collaborating referring veterinary practices wer...
Thampi P, Samulski RJ, Grieger JC, Phillips JN, McIlwraith CW, Goodrich LR.With an intrinsically low ability for self-repair, articular cartilage injuries often progress to cartilage loss and joint degeneration resulting in osteoarthritis (OA). Osteoarthritis and the associated articular cartilage changes can be debilitating, resulting in lameness and functional disability both in human and equine patients. While articular cartilage damage plays a central role in the pathogenesis of OA, the contribution of other joint tissues to the pathogenesis of OA has increasingly been recognized thus prompting a whole organ approach for therapeutic strategies. Gene therapy metho...
Kornicka-Garbowska K, Groborz S, Lynda B, Galuppo L, Marycz K.Synovitis (SI) is one of the most common and serious orthopedic diseases in horses of different age, breed and sex, which contributes to the development of osteoarthritis. The burden of SI includes economic loss and represents a real challenge for current veterinary health care. At the molecular level, fibroblasts-like synoviocytes (FLS) are recognized as major cell populations involved in SI pathogenesis. In the course of SI, FLSs are losing their protective and pro-regenerative cytological features, become highly proliferative and initiate various stress signaling pathways. Fibroblast-like s...
Rocchigiani G, Verin R, Uzal FA, Singer ER, Pregel P, Ressel L, Ricci E.Exercise-induced pulmonary hemorrhage (EIPH) is a common condition of Thoroughbred racehorses that is usually responsible for reduced performance, while exercise-associated fatal pulmonary hemorrhage (EAFPH) is characterized by severe pulmonary bleeding of unknown pathogenesis resulting in sudden death during strenuous exercise. The aim of the study was to characterize and compare anamnestic data together with pulmonary gross, histologic, and ultrastructural findings in racehorses with EIPH (n = 10), EAFPH (n = 10), and control horses (n = 5). No differences in anamnesis were identified betwee...
Chodkowski M, Słońska A, Gregorczyk-Zboroch K, Nowak-Zyczynska Z, Golke A, Krzyżowska M, Bańbura MW, Cymerys J.Mitochondria are key cellular organelles responsible for many essential functions, including ATP production, ion homeostasis and apoptosis induction. Recent studies indicate their significant role during viral infection. In the present study, we examined the effects of equine herpesvirus type 1 (EHV-1) infection on the morphology and mitochondrial function in primary murine neurons in vitro. We used three EHV-1 strains: two non-neuropathogenic (Jan-E and Rac-H) and one neuropathogenic (EHV-1 26). The organization of the mitochondrial network during EHV-1 infection was assessed by immunofluores...
Li J, Zhu Y, Mi J, Zhao Y, Holyoak GR, Yi Z, Wu R, Wang Z, Zeng S.Endometrial and vaginal microbiomes are critical in the study of endometritis, which is an important cause of infertility in donkeys. Our objective was to investigate the difference of the endometrial and vaginal microbiomes between healthy donkey jennies (group C) and jennies with endometritis (group E). Endometrial and vaginal swab samples were collected, and the 16 s rRNA gene amplicon high-throughput sequencing technique was applied to identify the microbial composition in the samples. A similar microbial composition pattern was found between endometrial and vaginal samples, which indica...
Cvitas I, Oberhaensli S, Leeb T, Marti E.Equine insect bite hypersensitivity (IBH) is the most common skin disease affecting horses. It is described as an IgE-mediated, Type I hypersensitivity reaction to salivary gland proteins of Culicoides insects. Together with Th2 cells, epithelial barrier cells play an important role in development of Type I hypersensitivities. In order to elucidate the role of equine keratinocytes in development of IBH, we stimulated keratinocytes derived from IBH-affected (IBH-KER) (n = 9) and healthy horses (H-KER) (n = 9) with Culicoides recombinant allergens and extract, allergic cytokine milieu (ACM) and ...
Adepu S, Ekman S, Leth J, Johansson U, Lindahl A, Skiöldebrand E.Native biglycan (BGN), which can undergo proteolytic cleavage in pathological conditions, is well known to be involved in bone formation and mineralization. This study aimed to delineate the specific cleavage fragment, a neo-epitope for BGN (BGN), in synovial fluid (SF) from young racehorses in training, osteoarthritic (OA) joints with subchondral bone sclerosis (SCBS), and chip fracture joints. A custom-made inhibition ELISA was developed to quantify BGN in SF. Cohort 1: A longitudinal study comprising 10 racehorses undergoing long-term training. Cohort 2: A cross-sectional study comprising j...
Janssen P, Tosi I, Hego A, Maréchal P, Marichal T, Radermecker C.Asthma encompasses a spectrum of heterogenous immune-mediated respiratory disorders sharing a similar clinical pattern characterized by cough, wheeze and exercise intolerance. In horses, equine asthma can be subdivided into severe or moderate asthma according to clinical symptoms and the extent of airway neutrophilic inflammation. While severe asthmatic horses are characterized by an elevated neutrophilic inflammation of the lower airways, cough, dyspnea at rest and high mucus secretion, horses with moderate asthma show a milder neutrophilic inflammation, exhibit intolerance to exercise but no...
Jasiński T, Zdrojkowski Ł, Ferreira-Dias G, Kautz E, Juszczuk-Kubiak E, Domino M.Endometrosis is a frequently occurring disease decreasing mares' fertility. Thus, it is an important disease of the endometrium associated with epithelial and stromal cell alterations, endometrium gland degeneration and periglandular fibrosis. Multiple degenerative changes are found in uterine mucosa, the endometrium. However, their pathogenesis is not well known. It is thought that nuclear factor-κB (NF-κB), a cell metabolism regulator, and its activation pathways take part in it. The transcription of the profibrotic pathway genes of the NF-κB in fibrotic endometria differed between the fo...
Andersen C, Jacobsen S, Walters M, Lindegaard C.Osteoarthritis (OA) is a significant health issue in humans as well as horses. Experimental models of equine carpal OA have been used to investigate OA pathogenesis and potential therapeutic candidates. A 5-scale scoring system (OARSI) for macroscopic pathological cartilage changes already exists, but there is a need for a scoring system with better differentiation of severity. The aim of this study was therefore to develop and validate such a scoring system. Results: New scoring system were developed for cartilage erosions (Copenhagen Equine Total Cartilage Score, CEqTCS) along with synovial ...
Marchant EA, Semevolos SA.The marginal transitional zone is peripherally located within the diarthrodial joint, and represents the interface of articular cartilage, periosteum, and the fibrous joint capsule. The purpose of this study is to characterize the protein expression of matrix and molecular regulators in the marginal transitional zone of foals having osteochondrosis (OC) compared to normal foals. Several families of proteins with known roles in cartilage and bone development are investigated, including matrix molecules, Wnt signaling, apoptotic factors and paracrine cell signaling molecules. Our results demonst...
Lo Feudo CM, Stancari G, Collavo F, Stucchi L, Conturba B, Zucca E, Ferrucci F.Dynamic upper airway obstructions (DUAO) are common in racehorses, but their pathogenetic mechanisms have not been completely clarified yet. Multiple studies suggest that alterations of the pharyngo-laryngeal region visible at resting endoscopy may be predictive of the onset of DUAO, and the development of DUAO may be associated with pharyngeal lymphoid hyperplasia (PLH), lower airway inflammation (LAI) and exercise-induced pulmonary hemorrhage (EIPH). The present study aims to investigate the possible relationship between the findings of a complete resting evaluation of the upper and lower ai...
Murase H, El-Sheikh Ali H, Ruby RE, Scoggin KE, Ball BA.Equine premature placental separation (PPS) is poorly understood and represents an important risk factor for fetal/neonatal hypoxia. Objective: To examine transcriptomic changes in the chorioallantois (CA) from mares with clinical PPS compared with the CA from normal foaling mares. Differential gene expression was determined and gene ontology as well as molecular pathways related to PPS were characterised. Methods: Retrospective case: control study. Methods: CA were collected from Thoroughbred mares with a clinical history of PPS (n = 33) and from control Thoroughbred mares (n = 4) with no...
Podstawski P, Ropka-Molik K, Semik-Gurgul E, Samiec M, Skrzyszowska M, Podstawski Z, Szmatoła T, Witkowski M, Pawlina-Tyszko K.An important component of tissues is the extracellular matrix (ECM), which not only forms a tissue scaffold, but also provides the environment for numerous biochemical reactions. Its composition is strictly regulated, and any irregularities can result in the development of many diseases, including cancer. Sarcoid is the most common skin cancer in equids. Its formation results from the presence of the genetic material of the bovine papillomavirus (BPV). In addition, it is assumed that sarcoid-dependent oncogenic transformation arises from a disturbed wound healing process, which may be due to t...
Mann S, Abuelo A, Stokol T, Wakshlag JJ, Bayly W, Reed S, Gandy J, Ramsay JD, Divers TJ.High serum γ-glutamyl-transferase (GGT) activity syndrome in racehorses has been associated with maladaption to exercise. Investigation of affected horses before and immediately after standard exercise may provide critical insight into the syndrome's pathophysiology. Objective: To investigate blood biomarker changes in actively competing racehorses with high GGT activity associated with an exercise challenge. Methods: Case-control study. Methods: High GGT case (age: 2-3 years) and normal GGT control (age: 2-7 years) pairs (3 Thoroughbred, 4 Standardbred pairs) at least 3 months into thei...
Di Pietro R, Dubuc V, Manguin E, Giroux-Lafond R, Bédard C, Boivin R, Lavoie JP, Vesper SJ, Leclere M.To quantify dectin-1 expression in bronchoalveolar lavage fluid (BALF), create polyclonal antibodies against equine dectin-1 and localize it in tissues, and quantify fungal exposure in pastured and stabled asthmatic and nonasthmatic horses. Methods: BALF samples from 6 controls and 6 horses with severe asthma. Stored lung and nasal wash samples. Methods: Dectin-1 expression was quantified by quantitative PCR (qPCR). Purified peptide from equine dectin-1 was used to generate polyclonal antibodies and was confirmed with immunological testing. Fungal exposure was quantified in BALF samples by cou...
Burns SJ, Westerman AG, Harrison LR.Mare Reproductive Loss Syndrome (MRLS) is the term given to abortions in mares associated with Eastern Tent caterpillars (ETC; Malacosoma americanum). This paper aims to examine if the hypothesis for a toxin as the cause of MRLS holds up to testing using Westerman's Correlates of Causal Strength of Evidence (WCCSE) and fits with known environmental factors that influence the occurrence of MRLS. Using WCCSE all correlates fit with a toxin as a potential causative agent. Environmental factors also fitted with this hypothesis. MRLS events were associated with higher than normal ambient temperatur...
Hamza E, Cosandey J, Gerber V, Koch C, Unger L.MicroRNAs (miRNAs) have been proposed as biomarkers for equine sarcoid (ES) disease. In this study, the suitability of three whole blood miRNAs to diagnose ES and to predict and monitor the outcome of therapy was explored. Using reverse transcription-quantitative polymerase chain reaction (RT-qPCR), expression levels of eca-miR-127, eca-miR-379, and eca-miR-432 in whole blood of ES-affected equids before and at least one year after therapy were compared to those of unaffected control equids. Associations of age, sex, species, diagnosis, and therapy outcome with miRNA expression levels were exa...
Valberg SJ, Schultz AE, Finno CJ, Bellone RR, Hughes SS.The prevalence of clinical signs and factors triggering muscle atrophy and rhabdomyolysis associated with an MYH1 mutation in Quarter Horses and related breeds (QH) remain poorly understood. Objective: Determine the prevalence and potential triggers of atrophy and stiffness in horses homozygous reference (N/N), heterozygous (My/N), and homozygous (My/My) for the MYH1 mutation. Methods: Two-hundred seventy-five N/N, 100 My/N, and 10 My/My QH. Methods: A retrospective case-control study using a closed-ended questionnaire completed by clients of the Veterinary Genetics Laboratory at the Universit...
Hussey GS, Giessler KS.Equine herpesvirus-1 (EHV-1) myeloencephalopathy (EHM) is a devastating consequence of EHV-1 infection that has significant economic consequences. However, clinical EHM is relatively rare and occurs in only approximately 10% of infected horses. While there is a positive correlation between the duration and magnitude of viremia and incidence of EHM, it is likely that a combination of host and viral factors determine whether EHM occurs. The identification of these factors is of high interest for the equine community and has been the topic of much research for vaccine development and to predict w...
Raizner NT, Gedon NKY, Zablotski Y, Kania SA, Kühnle HF, Kühnle C, Mueller RS.Equine pastern dermatitis (EPD) is a common multifactorial clinical syndrome in horses. Treatment can be difficult; pathogenesis and triggering factors cannot always be determined. Objective: To assess risk factors for developing EPD in a large group of horses kept under the same conditions and to analyse whether or not a spot-on containing essential fatty acids and antimicrobial agents is able to prevent the development of EPD or accelerate the healing process. Methods: Each year 50 young, privately owned, warmblood horses were prospectively included. Methods: All horses were examined weekly ...
McGorum BC, Dixon PM, Halliwell RE.Eight control and 8 asymptomatic COPD-affected horses were given, on separate occasions, inhalation challenges with extracts of Micropolyspora faeni, Aspergillus fumigatus and Thermoactinomyces vulgaris. All horses were also given nebulised phosphate-buffered saline (PBS) challenges and 'natural challenges' (NCs), i.e. exposure to hay and straw, as control challenges. Responses were assessed by clinical, pulmonary mechanics, arterial blood gas tensions, arterial blood pH and bronchoalveolar lavage fluid cytological examinations. PBS challenges had no effect on control or COPD-affected horses, ...
Brandt S, Haralambus R, Shafti-Keramat S, Steinborn R, Stanek C, Kirnbauer R.Bovine papillomavirus type 1 or 2 (BPV-1, BPV-2) are accepted causal factors in equine sarcoid pathogenesis. Whereas viral genomes are consistently found and expressed within lesions, intact virions have never been detected, thus permissiveness of sarcoids for BPV-1 replication remains unclear. To reassess this issue, an immunocapture PCR (IC/PCR) was established using L1-specific antibodies to capture L1-DNA complexes followed by amplification of the viral genome. Following validation of the assay, 13 sarcoid-bearing horses were evaluated by IC/PCR. Samples were derived from 21 tumours, 4 per...
Chiaradia E, Pepe M, Tartaglia M, Scoppetta F, D'Ambrosio C, Renzone G, Avellini L, Moriconi F, Gaiti A, Bertuglia A, Beccati F, Scaloni A.Osteoarthritis (OA) and osteochondrosis (OC) are two of the main challenges in orthopedics, whose definitive diagnosis is usually based on radiographic/arthroscopic evidences. Their early diagnosis should allow preventive or timely therapeutic actions, which are generally precluded from the poor relationships occurring between symptomatologic and radiographic evidences. These limitations should be overcome by improving the knowledge on articular tissue metabolism and on molecular factors regulating its normal homeostasis, also identifying novel OA and OC biomarkers suitable for their earlier d...
Poelaert KCK, Van Cleemput J, Laval K, Favoreel HW, Couck L, Van den Broeck W, Azab W, Nauwynck HJ.Equine herpesvirus 1 (EHV1) replicates in the respiratory epithelium and disseminates through the body via a cell-associated viremia in leukocytes, despite the presence of neutralizing antibodies. "Hijacked" leukocytes, previously identified as monocytic cells and T lymphocytes, transmit EHV1 to endothelial cells of the endometrium or central nervous system, causing reproductive (abortigenic variants) or neurological (neurological variants) disorders. In the present study, we questioned the potential route of EHV1 infection of T lymphocytes and how EHV1 misuses T lymphocytes as a vehicle to re...
Woodward A, Rash AS, Medcalf E, Bryant NA, Elton DM.Equine influenza is a major cause of respiratory infections in horses and causes widespread epidemics, despite the availability of commercial vaccines. Antigenic drift within the haemagglutinin (HA) glycoprotein is thought to play a part in vaccination breakdown. Here, we carried out a detailed investigation of the 1989 UK outbreak, using reverse genetics and site-directed mutagenesis, to determine the individual contribution of amino acid substitutions within HA. Mutations at positions 159, 189 and 227 all altered antigenicity, as measured by haemagglutination-inhibition assays. We also compa...
Smith DR, Schmaljohn CS, Badger C, Ostrowski K, Zeng X, Grimes SD, Rayner JO.Venezuelan, eastern, and western equine encephalitis viruses (VEEV, EEEV, and WEEV) are mosquito-borne viruses in the Americas that cause central nervous system (CNS) disease in humans and equids. In this study, we directly characterized the pathogenesis of VEEV, EEEV, and WEEV in cynomolgus macaques following subcutaneous exposure because this route more closely mimics natural infection via mosquito transmission or by an accidental needle stick. Our results highlight how EEEV is significantly more pathogenic compared to VEEV similarly to what is observed in humans. Interestingly, EEEV appears...
Wieringa R, De Vries AA, Post SM, Rottier PJ.Equine arteritis virus (EAV) is an enveloped, positive-strand RNA virus belonging to the family Arteriviridae of the order NIDOVIRALES: EAV virions contain six different envelope proteins. The glycoprotein GP(5) (previously named G(L)) and the unglycosylated membrane protein M are the major envelope proteins, while the glycoproteins GP(2b) (previously named G(S)), GP(3), and GP(4) are minor structural proteins. The unglycosylated small hydrophobic envelope protein E is present in virus particles in intermediate molar amounts compared to the other transmembrane proteins. The GP(5) and M protein...
Sullivan S, Hinchcliff K.Exercise-induced pulmonary hemorrhage (EIPH) is an important disease of horses that perform high-intensity athletic activity. EIPH is an ongoing concern for the racing industry because of its high prevalence; potential impact on performance; welfare concerns; and use of prophylactic medications, such as furosemide, on race day. During the last 10 years, significant progress has been made in understanding the pathogenesis and risk factors for EIPH and the impact of the disease on performance and career. This article summarizes the most recent advances in EIPH.
Marois P, Boudreault A, DiFranco E, Pavilanis V.Rhesus monkeys and ferrets were exposed to intranasal inoculation of several strains of egg-adapted avian, equine and human influenza viruses and to strains of mouse-adapted equine influenza viruses. Local replication of virus and seroconversion were observed in the majority of these animals. However, clinical infection was observed only in ferrets.
Nash DM, Sheldon IM, Herath S, Lane EA.Reproductive efficiency in mares is low and persistent mating-induced endometritis (PMIE) is an important cause of subfertility. Mating-induced endometritis (MIE) an obligate precursor to PMIE, is a ubiquitous, transient inflammatory response to the presence of sperm, seminal components and pathogens. However, the specific inflammatory pathways that derive from MIE and that may also be precursors to PMIE are not clear. The ability to identify and measure robust, repeatable markers of inflammation integral to MIE may be key to understanding the progression to PMIE. The aim of the study was to (...
Del Piero F.Equine viral arteritis (EVA) can cause prominent economic losses for the equine industry. The purpose of this review is to provide the pathologist some familiarity with the clinical history, lesions, pathogenesis, and diagnosis of EVA. EVA is caused by an arterivirus (equine arteritis virus, EAV), and the vascular system is the principal but not unique viral target. EVA has variable presentations, including interstitial pneumonia, panvasculitis with edema, thrombosis and hemorrhage, lymphoid necrosis, renal tubular necrosis, abortion, and inflammation of male accessory genital glands. EAV anti...
Goodyear A, Troyer R, Bielefeldt-Ohmann H, Dow S.The Gram-negative bacterium Burkholderia mallei causes rapidly fatal illness in equines and humans when contracted by inhalation and also has the potential to be used as a bioweapon. However, little is known regarding the early innate immune responses and signaling mechanisms required to generate protection from pneumonic B. mallei infection. We showed previously that monocyte chemoattractant protein 1 (MCP-1) was a critical chemokine required for protection from pneumonic B. mallei infection. We have now extended those studies to identify key Toll-like receptor (TLR) signaling pathways, effec...
Axon JE, Palmer JE.The neonatal foal is in a period of transition between fetal and extrauterine life. The clinicopathologic findings in this period often reflect the in utero environment; thus, results need to be interpreted with the knowledge of changes that intrauterine life may produce. These changes can also assist the veterinarian in identifying a foal at high risk for developing clinical problems. The veterinarian should also be aware of the normal variations in clinicopathologic findings that occur as the foal matures. As with results from all diagnostic testing, the clinicopathologic results need to be ...
Del Piero F.Equine viral arteritis (EVA) can cause prominent economic losses for the equine industry. The purpose of this review is to provide the pathologist some familiarity with the clinical history, lesions, pathogenesis, and diagnosis of EVA. EVA is caused by an arterivirus (equine arteritis virus, EAV), and the vascular system is the principal but not unique viral target. EVA has variable presentations, including interstitial pneumonia, panvasculitis with edema, thrombosis and hemorrhage, lymphoid necrosis, renal tubular necrosis, abortion, and inflammation of male accessory genital glands. EAV anti...
Sponseller BT, Valberg SJ, Schultz NE, Bedford H, Wong DM, Kersh K, Shelton GD.Seasonal pasture myopathy (SPM) is a highly fatal form of nonexertional rhabdomyolysis that occurs in pastured horses in the United States during autumn or spring. In Europe, a similar condition, atypical myopathy (AM), is common. Recently, a defect of lipid metabolism, multiple acyl-CoA dehydrogenase deficiency (MADD), has been identified in horses with AM. Objective: To determine if SPM in the United States is caused by MADD. Methods: Six horses diagnosed with SPM based on history, clinical signs, and serum creatine kinase activity, or postmortem findings. Methods: Retrospective descriptive ...
Teymournejad O, Lin M, Bekebrede H, Kamr A, Toribio RE, Arroyo LG, Baird JD, Rikihisa Y.Potomac horse fever (PHF), a severe and frequently fatal febrile diarrheal disease, has been known to be caused only by , an endosymbiont of digenean trematodes. Here, we report the cell culture isolation of a new species found in two locations in eastern Ontario, Canada, in 2016 and 2017 (in addition to 10 variable strains of ) from PCR-negative horses with clinical signs of PHF. Gene sequences of 16S rRNA and the major surface antigen P51 of this new species were distinct from those of all previously characterized strains and species, except for those from an uncharacterized species cu...
Leegwater PA, Vos-Loohuis M, Ducro BJ, Boegheim IJ, van Steenbeek FG, Nijman IJ, Monroe GR, Bastiaansen JW, Dibbits BW, van de Goor LH, Hellinga I....Inbreeding and population bottlenecks in the ancestry of Friesian horses has led to health issues such as dwarfism. The limbs of dwarfs are short and the ribs are protruding inwards at the costochondral junction, while the head and back appear normal. A striking feature of the condition is the flexor tendon laxity that leads to hyperextension of the fetlock joints. The growth plates of dwarfs display disorganized and thickened chondrocyte columns. The aim of this study was to identify the gene defect that causes the recessively inherited trait in Friesian horses to understand the disease proce...
Timoney JF, Kumar P.Little is known about entry and subsequent multiplication of Streptococcus equi following exposure of a susceptible horse. This information would have value in design of intranasal vaccines and understanding of shedding and protective immune responses. Objective: To determine entry points and sites of subsequent replication and dispersion of S. equi at different times after intranasal infection or commingling exposure. Methods: Previously unexposed horses and ponies were subjected to euthanasia 1, 3, 20 or 48 h following intranasal inoculation with biotin labelled or unlabelled S. equi CF32. S...
Wagner B.Since the initial characterization of IgE by Ishizaka et al. (1966), IgE was described in several mammalian species. In horses, a single gene encoding the IgE heavy chain constant region (IGHE gene) exists per haploid genome and several allelic variants of the equine IGHE gene were found. IgE occurs in its soluble form in equine serum and physiological concentrations of total IgE are around 1000-fold higher in normal horse than in normal human serum. Maternal IgE is enriched in the colostrum and transferred to the neonatal foal after birth. Foals do not produce detectable concentrations of end...
Li F, Drummer HE, Ficorilli N, Studdert MJ, Crabb BS.Equine rhinovirus 1 (ERhV1) is a recognized cause of acute febrile respiratory disease in horse, although the virus is rarely isolated from such animals, despite seroprevalence rates as high as 50% in some horse populations. Recently, ERhV1 has been shown to be most closely related to foot-and-mouth disease virus, raising questions as to its disease associations in horses. We report that ERhV1 infection was the likely cause of two separate outbreaks of severe febrile respiratory disease which involved more than 20 horses. Attempts to isolate ErhV1 from nasopharyngeal swabs by conventional cell...
McGuire TC, Crawford TB, Hallowell AL, Macomber LE.Failure in colostral immunoglobulin G (IgG) transfer was found in 9 of 87 Thoroughbred foals. Seven (78%) of these 9 foals acquired infections requiring therapy. Twelve of the foals had partial failure in colostral IgG transfer, and 3 of these had infections requiring therapy. The remaining 66 foals had normal transfer of colostral IgG, and only 2 had detectable infections. The failure of colostral IgG transfer was attributable to nursing problems in only one case. When presuckle postpartum colostrum was collected, 2 of 4 failures of colostral IgG transfer and 4 of 6 partial failures of colost...
Whitwell KE, Blunden AS.In 1988 an outbreak of the paralytic form of Equid herpesvirus type 1 (EHV-1) infection occurred on a stud farm and several animals died. This provided an opportunity to perform detailed pathological investigations to gain insights into the pathogenesis of this spontaneous disease. Two paretic mares, three foals, an aborted foetus and its non-paretic dam were examined. The endotheliotropism of the virus was clearly demonstrated by the use of an indirect immunoperoxidase (IP) stain. At autopsy, evidence of viral infection was widespread in the foetus and foals, but limited or absent in the mare...
de Grauw JC, van de Lest CH, van Weeren R, Brommer H, Brama PA.Joint pain is one of the most common causes of lameness in the horse but its pathogenesis is poorly understood. Objective: To investigate which synovial fluid markers may be related to the presence of clinically detectable joint pain in the horse. Methods: Concentrations of structural (CPII, C2C, GAG) and inflammatory markers (PGE2, LTB4, CysLTs, bradykinin and substance P) were measured in fetlock joint fluid from 22 horses in which lameness was localised to the fetlock region by perineural anaesthesia. Levels of these markers were then compared in horses that responded (n = 15) to those that...
Dondi F, Lukacs RM, Gentilini F, Rinnovati R, Spadari A, Romagnoli N.Equine colic may be associated with an acute phase response (APR). Measurement of acute phase proteins (APPs) allows the detection of an APR and may help clinicians in monitoring the disease; however, the role of APPs in colic is unclear. This study aimed to evaluate the clinical usefulness of serum amyloid A (SAA), haptoglobin and ferritin in combination with an extended clinicopathological profile in equine colic. The medical records of 54 horses were retrospectively selected. Horses were grouped based on outcome (survivors vs. non-survivors), diagnosis (ischaemic/strangulating vs. non-ischa...
Schöniger S, Summers BA.In humans, neurofibroma and schwannoma are distinct entities within the group of benign peripheral nerve sheath tumors. In the veterinary literature, these tumors are often classified together simply as benign peripheral nerve sheath tumors, and diagnostic criteria for their subclassification are not well established. We describe peripheral nerve sheath tumors with microscopic, immunohistologic, and ultrastructural features similar to those in subtypes of human neurofibroma in 12 dogs, 2 horses, and 1 chicken. Dogs were of different breeds and were aged 2 months to 15 years. The canine tumors ...
Berlin D, Loeb E, Baneth G.Trypanosomiasis caused by Trypanosoma evansi ("Surra") is mainly a wasting disease affecting equids, camels and cattle as well as other domestic and wild animal species. In horses, infection may cause severe neurological abnormalities; however, the clinical progression, pathogenesis and molecular ante-mortem detection of this form of the disease have not been described in detail. A mare with progressive ataxia, head tilt, nystagmus and cranial nerve deficits submitted to treatment was diagnosed with central nervous system trypanosomiasis following the detection of a Trypanosoma tryposmastigote...
Vairo S, Van den Broeck W, Favoreel H, Scagliarini A, Nauwynck H.The upper respiratory tract mucosa represents the first line of defense, which has to be overcome by pathogens before invading the host. Considering the economic and ethical aspects involved in using experimental animals for pathogenesis studies, respiratory mucosal explants, in which the tissue's three-dimensional architecture is preserved, may be ideal alternatives. Different respiratory mucosal explant cultures have been developed. However, none of them could be inoculated with pathogens solely at the epithelium side. In the present study, equine nasal and nasopharyngeal explants were embed...
Vairo S, Vandekerckhove A, Steukers L, Glorieux S, Van den Broeck W, Nauwynck H.Equine viral arteritis (EVA) is an infectious disease with variable clinical outcome. Outbreaks, causing important economic losses, are becoming more frequent. Currently, there is a shortage of pathogenesis studies performed with European strains. In the present study, eight seronegative ponies were experimentally inoculated with the Belgian strain of equine arteritis virus (EAV) 08P178 (EU-1 clade) and monitored daily for clinical signs of EVA. Nasopharyngeal swabs, ocular swabs, bronchoalveolar cells and blood were collected for virological and serological testing. Two ponies were euthanized...
Cullor JS, Mannis MJ, Murphy CJ, Smith WL, Selsted ME, Reid TW.New approaches to antimicrobial therapy for ocular pathogens must overcome organisms that are resistant to current therapeutic modalities. This investigation examined the antimicrobial activity of novel antimicrobial neutrophil peptides (defensins NP-1 and NP-5) against isolates from clinical ocular microbial infections in humans and horses. The test panel of human clinical isolates included Candida albicans, an alpha-hemolytic Streptococcus, Streptococcus pneumoniae, Pseudomonas aeruginosa, and Morganella morganii. The test panel of equine pathogens included three clinical isolates of P aerug...
Rappocciolo G, Birch J, Ellis SA.There is good evidence that cytotoxic T lymphocytes play an important role in the clearance of equine herpesvirus-1 (EHV1) in horses. We have demonstrated that, in common with other alphaherpesviruses, EHV1 infection can lead to dramatic down-regulation of MHC class I expression at the cell surface, a common strategy for pathogen evasion of the host immune response. This down-regulation is specific for MHC class I and does not reflect a general shut-off of host-cell protein synthesis. The use of monoclonal antibodies that recognize different MHC class I epitopes has demonstrated that the effec...
