The study of diseases in horses encompasses a wide range of conditions affecting equine health, including infectious diseases, metabolic disorders, and genetic abnormalities. These diseases can impact various systems within the horse, such as respiratory, gastrointestinal, and musculoskeletal systems, and can lead to significant health challenges. Research in this area focuses on understanding the pathophysiology, diagnosis, prevention, and treatment of equine diseases. Common diseases studied include equine influenza, equine herpesvirus, and laminitis. This page provides access to peer-reviewed research studies and scholarly articles that explore the etiology, clinical presentation, and management strategies of diseases in horses, contributing to the advancement of equine veterinary medicine.
Orsini JA, Nunamaker DM, Jones CJ, Acland HM.A large oral squamous cell carcinoma in a 27-year-old Arabian stallion was removed by partial excision of the incisive bone. There was no gross evidence of recurrence or metastasis 5 months later.
Posnett ES, Fehrsen J, De Waal DT, Ambrosio RE.The ability of the Babesia equi repetitive probes, pSE2 and pSB20, to detect parasites in blood from experimentally infected, naturally infected and carrier animals was tested using a spot hybridization assay. The clinical course of the experimentally infected horses was monitored using microscopy, indirect fluorescent antibody tests, packed cell volume, temperature and the probe assay. The probes sensitively monitored the parasite level during the development of the disease and correlated well with the other parameters tested. The sensitivity of the probe assay was superior to that of light m...
Madelin TM, Clarke AF, Mair TS.Sera from 54 two- to three-year-old Thoroughbred horses from an English racing stable were examined for precipitins to antigen extracts prepared from 18 species of moulds (fungi and thermophilic actinomycetes) isolated from the same stable. Twenty-seven horses exhibited serum precipitins to one or more antigens; sixteen of the mould antigens elicited positive reactions in sera from one or more horses. Significantly more precipitins occurred in sera of those horses stabled in a barn than among those stabled in individual boxes. This indicated a possible association between type of housing, leve...
Ogunnariwo JA, Alcantara J, Schryvers AB.Two clinical isolates of Pasteurella multocida associated with bovine pneumonia were examined for iron acquisition. Both isolates were capable of obtaining iron for growth from bovine but not from human, avian, equine or porcine transferrin. This correlated with specific binding of bovine transferrin by iron-limited cells or isolated membranes. No siderophore was detected in the strains by a general screening assay. In response to iron-limited conditions, a number of high molecular mass iron-regulated outer membrane proteins were produced including an 82 kDa receptor protein which was affinity...
Zicker SC, Spensley MS, Rogers QR, Willits NH.Concentrations of amino acids in the plasma of 13 neonatal foals with septicemia were compared with the concentrations of amino acids in the plasma of 13 age-matched neonatal foals without septicemia. Analysis of the results revealed significantly lower concentrations of arginine, citrulline, isoleucine, proline, threonine, and valine in the plasma of foals with septicemia. The ratio of the plasma concentrations of the branched chain amino acids (isoleucine, leucine, and valine) to the aromatic amino acids (phenylalanine and tyrosine), was also significantly lower in the foals with septicemia....
van der Kolk JH, Klein WR, van der Putten SW, Mol JA.A thirteen-year-old Dutch warmblooded mare was referred to the Faculty of Veterinary Medicine because of a sinusitis. She was thin with a potbellied appearance. Her coat was dull with long wavy hair. Unilateral (left) purulent nasal discharge was evident. A cbc revealed leucopenia (3.9 G.L.-1) and plasma biochemical analysis revealed a plasma glucose concentration of 10.1 mmol.L-1. Thermostable alkaline phosphatase (at 65 degrees C during 2 minutes) could not be demonstrated. Basal plasma cortisol concentration was lowered (114 nmol.L-1) and basal plasma ACTH concentration was highly elevated ...
Berry CR, O'Brien TR, Madigan JE, Hager DA.Clinical records and thoracic radiographs of 19 horses with a confirmed pathologic diagnosis of silicosis were reviewed. These horses had histories of varying degrees of chronic weight loss, exercise intolerance, and respiratory distress. At the time of presentation, two horses were asymptomatic. Ten horses were geldings and nine were female. The mean age of the 19 horses was 10.7 +/- 5.5 years. Fourteen horses were identified as being from the Monterey-Carmel Peninsula of midcoastal California. An abnormal, structured interstitial pulmonary pattern was identified on thoracic radiographs in ea...
Van Oirschot JT, Bruin G, de Boer-Luytze E, Smolders G.Foals that were born to mares vaccinated twice a year against influenza had moderate to high haemagglutination-inhibition antibody titers at 24 hours after birth. The foals were vaccinated at six and ten weeks of age, and again at three to five months after birth. Four months after the third vaccination no antibodies against A/H7N7 and A/H3N8 influenza viruses were detected in these foals. Thus, maternal antibodies probably prevented the development of antibodies against equine influenza virus after vaccination. Foals born to the same mares one year later were monitored to determine the rate o...
Davis DM, Honnas CM, Hedlund CS, Schneiter HL.A 3-day-old Thoroughbred foal developed a large, air-distended, midcervical swelling that was diagnosed as a congenital tracheal bronchus with associated ectopic lung tissue. Clinical signs consisted of a compressible air-filled sac that enveloped the trachea. The nature and extent of the defect were evaluated endoscopically and radiographically. Surgical resection of the bronchus and associated air-filled sac resulted in a functionally and cosmetically acceptable outcome.
Teifke JP, Weiss E.Unfixed and formalin-fixed frozen sections and paraffin-sections of histopathologically confirmed sarcoids of 20 horses were studied in the PCR. The used set of primers was located in the E5 open reading frame fitting both to bovine papillomavirus 1 (BPV-1) and BPV-2. Independent of the quality of the used tissues BPV-DNA was detected in all 20 sarcoids. By cleaving with restriction endonuclease Bst XI it was shown that the DNA-sequences amplified by PCR were identical with that of BPV-1. The results support the general view that BPV play an important role in equine sarcoids.
Stitz L, Richt JA, Rott R.An overview of the pathogenesis of Borna disease (BD) in rats as a model for the naturally occurring infection in horses and sheep is presented. Our findings revealed a virus infection in which a virus-specific T cell-mediated immune response leads to disease. The immune cells capable of mediating this immunopathological reaction were defined as helper/inducer T cells. In all, the described observations indicate that CD4+ T cells and macrophages trigger a delayed-type hypersensitivity reaction and cause BD together with other cells of the immune system.
Van Rensburg IB, Collett MG, Ronen N, Gerdes T.An adult stallion presented with a severe papular dermatitis of especially the neck, chest and genitalia. A marked scrotal oedema was present. Histopathological examination of skin biopsies, revealed the presence of numerous intracytoplasmic molluscum bodies in areas of focal epidermal hyperplasia. Electron microscopical examination showed the presence of typical pox virions in affected epidermal cells. Attempts at viral isolation were unsuccessful. This is believed to be the first reported case of molluscum contagiosum in a horse in the Republic of South Africa.
Posnett ES, Ambrosio RE.A genomic library of Babesia caballi DNA was constructed in the plasmid vector pUC13. The specificity of the clones for B. caballi was established by the lack of hybridization to Babesia equi, Babesia bovis, Babesia bigemina and equine DNA. Two probes, pBC11 and pBC191, were isolated that could detect 0.25 ng and 0.125 ng of B. caballi DNA, corresponding to a parasitaemia of 0.12% and 0.06% respectively. pBC191 could detect B. caballi parasites in the blood of an experimentally infected horse as well as in naturally infected horses.
Ross PF, Rice LG, Plattner RD, Osweiler GD, Wilson TM, Owens DL, Nelson HA, Richard JL.Ninety-eight samples of feeds associated with 44 cases of equine leukoencephalomalacia (ELEM) and 83 samples of feed associated with 42 cases of a porcine pulmonary edema syndrome (PPE) were analyzed for fumonisin B1 (FB1). For comparison purposes, 51 feed samples not associated with PPE or ELEM were also analyzed. Feed associated with ELEM contained FB1 ranging from less than 1 microgram/g to 126 micrograms/g with 75% of the cases having at least 1 sample above 10 micrograms/g. Feeds associated with PPE ranged from less than 1 microgram/g to 330 micrograms/g with 71% of the cases having at le...
Maede Y, Inaba M, Amano Y, Murase T, Goto I, Itakura C.Cryoglobulin was isolated from a horse which had glomerulo-nephritis and a history of swelling and skin ulcers of the limbs in the winter. The isolated cryoglobulin showed a single peak on a gel permeation chromatography column with an apparent molecular mass (Mr) of 180,000 which could be divided into two gamma bands by cellulose acetate electrophoresis. Immunoelectrophoretic analysis revealed that the cryoglobulin formed two precipitation lines with anti-horse IgG. Spur formation was observed when the cryoglobulin and the IgG purified from a normal healthy horse were cross-reacted with anti-...
den Boon JA, Snijder EJ, Chirnside ED, de Vries AA, Horzinek MC, Spaan WJ.The nucleotide sequence of the genome of equine arteritis virus (EAV) was determined from a set of overlapping cDNA clones and was found to contain eight open reading frames (ORFs). ORFs 2 through 7 are expressed from six 3'-coterminal subgenomic mRNAs, which are transcribed from the 3'-terminal quarter of the viral genome. A number of these ORFs are predicted to encode structural EAV proteins. The organization and expression of the 3' part of the EAV genome are remarkably similar to those of coronaviruses and toroviruses. The 5'-terminal three-quarters of the genome contain the putative EAV p...
Guillemette JG, Matsushima-Hibiya Y, Atkinson T, Smith M.A gene for expression of horse heart myoglobin in Escherichia coli has been constructed in one step from long synthetic oligonucleotides. The synthetic gene contains an efficient translation initiation signal and used codons that are commonly found in E. coli. Unique restriction sites are placed throughout the gene. It has been inserted in a phagemid vector and is expressed from the lac promoter in E. coli at high efficiency, the soluble heme protein representing approximately 10% of soluble protein. Two versions of horse heart myoglobin were produced with aspartic acid or asparagine at residu...
Traub-Dargatz JL, Salman MD, Voss JL.This paper reports the results of a survey conducted among members of the American Association of Equine Practitioners, concerning medical problems of adult horses. A one-page questionnaire listing 36 medical problems grouped by body system was completed by 1,149 veterinarians. The top-ranked disease was colic, followed by viral respiratory tract disease, endometritis, dermatitis, and parasitism. When responses were evaluated by type of practice, location of practice, and number of veterinarians in the practice, ranking of the top 2 diseases was the same for the total respondents. Ranking of d...
Tulleners EP.A submucosal abscess, located on the dorsal surface of the epiglottis, was diagnosed in 2 Thoroughbred racehorses by use of endoscopy. Both horses had exercise intolerance. One horse had intermittent dorsal displacement of the soft palate, coughed while eating and galloping, and made an abnormal respiratory noise. Both abscesses were drained transendoscopically by use of a contact neodymium:yttrium aluminum garnet laser. Eleven days after surgery, the surgical sites appeared to have healed. Clinical signs resolved permanently, and both horses returned to successful racing careers.
Meyers PJ, Varner DD.A mummified fetus was aborted at 284 days of gestation from a Quarter Horse mare with a history of consecutive abortions. The abortion occurred 12 days after administration of supplemental progestogen had been discontinued. Results of a breeding soundness evaluation revealed that this mare had a short uterine body. Other abnormalities were not discovered. This condition may have been responsible for repeated abortions in this mare, and may represent a cause of fetal mummification other than twin pregnancy in mares.
Stoneham SJ, Digby NJ, Ricketts SW.The importance of colostrum for the passive transfer of maternal immunity to foals is well recognised. This survey reports the incidence of the failure of passive transfer of colostral immunity in thoroughbred foals in the United Kingdom during 1988 to 1990, and the effect of plasma transfusions on IgG levels in a group of them. The incidence of disease in these foals first month of life is also recorded.
Young RL, Snyder JR, Pascoe JR, Olander HJ, Hinds DM.Six enterotomies 3 cm long, spaced at 3 cm intervals, were made in the antimesenteric border of the pelvic flexure of the ascending colon in five adult horses. Ten incisions each were sutured with a Utrecht pattern (single layer), a full-thickness simple continuous oversewn with a Cushing pattern (two layer), and a mucosal simple continuous with a seromuscular simple continuous oversewn with a Cushing pattern (three layer). In all horses, chromic gut and polyglactin 910 were each used once for each pattern. On day 6, the pelvic flexure was excised and the colonic vessels were injected with a r...
Dorman DC, Haschek WM.Toxicosis attributable to propylene glycol (1,2-propanediol) was suspected in an 8-year-old 450- to 500-kg male Quarter Horse. Clinical signs of toxicosis developed within 15 minutes of the accidental iatrogenic oral administration of 3.8 L of propylene glycol. Clinical signs of toxicosis included salivation, sweating, ataxia, and signs of pain. Additionally, at 24 hours after propylene glycol ingestion, the horse became increasingly atactic, had an abnormal breath odor, developed rapid shallow breathing, and was cyanotic. The horse died of apparent respiratory arrest 28 hours after the propyl...
Luethy D, Colmer S, Jodzio D, Bender S, Porter E, Hemmen Z, Fultz L, Craft W, Walker R, Johnson A, Holbrook T.Ultrasound-guided cervical centesis has gained popularity as a method for collecting cerebrospinal fluid (CSF) from standing horses. There are anecdotal reports of neck stiffness, regional swelling, sensitivity to palpation, and fever after the procedure. We report 2 horses with complications that occurred within days of C1-C2 centesis and ultimately resulted in euthanasia. Both C1-C2 centesis were performed routinely, with CSF cytologic analysis providing no evidence of blood contamination. Post-mortem examination revealed equine degenerative myeloencephalopathy as the primary disorder causin...
Madison JB, Scarratt WK.The deposition of immune complexes in the synovial membrane resulted in polysynovitis in 4 foals. All 4 foals had an infection at a site other than the joints. The polysynovitis was characterized by marked effusions of affected joints and joint stiffness. Bacterial and mycoplasmal cultures of the joints did not yield growth. Staining of synovial membrane biopsy specimens with fluorescein-labeled anti-equine IgG revealed immune complexes in the synovial membrane. Immune-mediated polysynovitis might develop in foals with bacterial infections. We propose that deposition of immunoglobulin in the s...
Kelly DF, Watson WJ.An aged Connemara mare had a neurological illness lasting 3 weeks and characterised by episodes of dullness, head-pressing, staggering gait and hyperexcitability. The signs recurred at intervals of 3 to 4 days, with intervening periods of apparent normality. Post-mortem examination revealed an epidermoid cyst on the dorsal surface of the occipital lobe of the left cerebral hemisphere. The cyst was lined by stratified squamous epithelium and contained desquamated keratinised material and blood. The lesion is considered to be a congenital malformation which enlarges and produces space-occupying ...
Hardy J, Marcoux M, Eisenberg H.A suspected lesion of osteochondrosis dissecans involving the anconeal process of the humeroradial joint (elbow) was found in 2 horses. In horse 1, the lesion was found during routine lameness examination, during which alleviation of the lameness was achieved after intra-articular anesthesia of the elbow. In horse 2, the lesion was found at necropsy. Horse 1 responded satisfactorily to intra-articular treatment with hyaluronic acid. Both horses also had other joints affected with osteochondrosis dissecans.
McEntee M.A cutaneous mass (1.5 cm in diameter) was removed from the head of a horse and was diagnosed histologically as eumycotic mycetoma. Immunofluorescence, performed on formalin-fixed, paraffin-embedded tissue, identified Pseudallescheria boydii as the etiologic agent. Findings from earlier reports of eumycotic mycetoma were compared with those of this horse.
Kirisawa R, Hosoi Y, Yamaya R, Taniyama H, Okamoto M, Tsunoda N, Hagiwara K, Iwai H.We isolated a variant equine herpesvirus-1 (EHV-1), strain 5089, from the lung of a dead neonatal foal in Japan and characterized the biological nature of the virus. The virus spread in cultured cells mainly by cell-to-cell infection, unlike wild-type EHV-1, which spreads efficiently as a cell-free virus. The virus titer in cultured supernatant and the intracellular virus titer were low compared to those of wild-type EHV-1. Heparin treatment of the virus had no effect on viral infectivity in cell culture. Glycoprotein C (gC) was not detected by Western blotting and fluorescent antibody tests i...
Hovda LR, Shaftoe S, Rose ML, Clemmons LH.A mediastinal squamous cell carcinoma and thyroid carcinoma were found in an aged horse. Clinical signs consisted of bilateral thyroid gland enlargement, chronic cough, and mild respiratory distress. The neoplasms were not treated. Squamous cell carcinoma is a common neoplasm in horses, but not in the cranial portion of the mediastinum. Thyroid carcinomas in horses are uncommon. This combination of neoplasms is rare and may have been associated with a defect in the immune system.
Sokół R, Raś-Noryńska M, Michalczyk M, Raś A, Rapacz-Leonard A, Koziatek S.Studies were carried out in year 2014 during the pasture period (from April to October) in Warmia and Mazury Region. Fecal samples were taken from cold- and warmblood horses from individual and agrotouristic farms with the different housing, feeding and pasture- care practices. Total of 512 horses were examined (320 mares, 170 geldings and 22 stallions). In the group of 185 horses from individual farms, 119 animals (64.3%) were infected with gastro-intestinal parasites. Among the 372 horses from agrotouristic farms 169 (51.7%) were infected with parasites. Most of the animals expelled the eggs...
Zamora CS, Vitums A, Nyrop KA, Sande RD.The heart of a 6-week old Arabian filly with a history of poor health and exercise intolerance revealed at postmortem examination, multiple cardiac malformations which included atresia of the right atrioventricular orifice (tricuspid atresia, with associated atrial and ventricular septal defects), complete transposition of the great arteries, anomalous drainage of the venae cavae and coronary sinus into the left atrium, coarctation of the aorta, and a small but patent ductus arteriosus. The course of blood through the heart was suggested and discussed.
Grauerholz H.Interrelations between respiration and changes in amplitudes of the QRS-complex of the ECG of horses were investigated. The value of the R-vector and both its components Rx and Ry decrease during inspiration and increase in the expiration phase. It means, that the R-waves in leads from cranial to caudal (y, II, aVF) and from right to left (I) become smaller with inspiration and larger with expiration. The difference of the amplitudes may be important, especially in horses with respiratory problems, so that it has to be noted when evaluating electrocardiograms. For that purpose it is not necess...
Moore PF, Hacker DV, Buyukmihci NC.Angiosarcomas arising in ocular tissues of four aging horses are described. Tumors were locally invasive and eventually metastasized via the mandibular and cervical lymph nodes. Pathologically, the tumors contained well-differentiated regions, in which vascular channels were lined by pleomorphic endothelial cells, as well as poorly-differentiated regions, in which vascular channels were either rudimentary or absent. Red blood cells were scare in vascular structures formed by the tumors. Factor VIII related antigen (VIII:RAg), a blood vascular endothelial marker, was demonstrated by immunohisto...
Lindsell CE, Hilbert BJ, McGill CA.Osteochondrosis dissecans was diagnosed clinically and radiographically in 31 joints of 21 horses. The horses ranged in age from 8 months to 5 years at the time of presentation. The usual age of onset of clinical signs was 18 to 24 months. Presenting complaints included joint effusion and lameness of either gradual or sudden onset. In Thoroughbred horses, the stifle joint was the most common site of lesions and in Standardbred horses lesions occurred more commonly in the hock. In 16 of the 21 horses, the contralateral joint was radiographed and 9 of these horses had bilateral lesions. Thorough...
Wilson DA, Foreman JH, Boero MJ, Didier PJ, Lerner DJ.A large granulosa cell tumor was believed to be responsible for causing obstruction and subsequent rupture of the small colon in a 10-year-old Quarter Horse mare. Two months earlier, a mass, tentatively diagnosed as granulosa cell tumor of the left ovary, had been identified by means of rectal palpation and ultrasonography. The mare was evaluated for clinical signs of acute, severe, abdominal pain, increased heart rate, cyanotic mucous membranes, clinical dehydration, with high PCV, leukopenia, and extreme abdominal distension. A large soft tissue mass and taut band that constricted the lumen ...
Gunson DE, Rooney JR.An 8-year-old gelding with a long-standing, streptococcal respiratory infection developed dyspnoea and colic. Laparotomy disclosed numerous, discrete, hemorrhagic, thick areas of necrosis throughout the intestinal tract. At postmortem examination similar lesions were seen in the laryngeal mucosa and in many skeletal muscles. Microscopically these lesions had massive necrosis and hemorrhage with a leucocytoclastic vasculitis in adjacent tissue. This condition resembled anaphylactoid purpura (Henoch-Schönlein disease) in man. Fungal infection was ruled out by special stains which failed to show...
Menzies-Gow NJ, Young NJ.Enterococcus faecium, a major cause of potentially life-threatening hospital-acquired human infections, can be resistant to several antimicrobials, such that streptogramin quinupristin-dalfopristin (Q/D) is one of the few antibiotics still effective. Consequently use of the streptogramin virginiamycin as an animal growth promoter was banned in the EU in 1999 as some believed this contributed to the emergence of Q/D resistant E. faecium. Virginiamycin is advocated for preventing equine pasture-associated laminitis, but its effect on equine faecal bacterial Q/D resistance has not been determined...
Green P, Tong JM.Although wood chewing by horses is recognised as a common vice, there are few reports of specific disease associated with the habit. Two cases of acute obstruction of the small intestine by solid aggregations of wood splinters are described in horses which were both habitual wood chewers. Details are presented of the clinical findings in these cases, including the surgical treatment of acute colic. Both horses returned to full working fitness. The authors review the syndrome of enterolithiasis in horses, and discuss the causes and significance of wood chewing as a stable vice.
Spyrou V, Papanastassopoulou M, Psychas V, Billinis Ch, Koumbati M, Vlemmas J, Koptopoulos G.There appears to be a lack of information concerning responses of mules to natural infection or experimental inoculation with equine infectious anemia virus (EIAV). In the present study EIAV was isolated from mules, for the first time, and its pathogenicity in naturally infected and experimentally inoculated animals was investigated. Two naturally infected (A and B) and three EIAV free mules (C, D and E) were used for this purpose. Mule A developed clinical signs, whereas mule B remained asymptomatic until the end of the study. Mules C and D were each inoculated with 10ml of blood from mule A ...