Infections in horses encompass a range of diseases caused by various pathogens, including bacteria, viruses, fungi, and parasites. These infections can affect different systems within the horse, such as the respiratory, gastrointestinal, and integumentary systems, leading to a variety of clinical signs depending on the pathogen and the severity of the infection. Common infectious diseases in horses include equine influenza, strangles, and equine herpesvirus. Diagnosis often involves clinical examination, laboratory testing, and sometimes imaging, to identify the causative agent and assess the extent of the disease. Treatment strategies may include antimicrobial therapy, supportive care, and preventive measures such as vaccination and biosecurity practices. This page aggregates peer-reviewed research studies and scholarly articles that explore the pathogenesis, diagnosis, treatment, and prevention of infectious diseases in equine populations.
Youngquist RS, Blanchard TL, Lapin D, Klein W.Four groups of five pony mares each were used to determine if the intrauterine infusion of EDTA-Tris solution caused adverse effects on the endometrium. The uteri of mares were infused with either saline or EDTA-Tris solution or biopsied or sham-biopsied without infusion. Acute endometritis developed in one (20%) to three (60%) mares in each group during the seven days following treatment, but there were no differences (P > 0.05) in the incidence of endometritis among the groups. Endometrial fibrosis was not evident in biopsies taken on days 14, 30 and 60 following infusion of saline or EDT...
Mackey VS, Pool RR.Fracture of the lateral wing of the third phalanx with secondary infection of the distal interphalangeal joint occurred in a neurectomized mare. Puncture of the sole may have been the inciting cause, emphasizing the need for careful daily foot care in neurectomized horses.
Eysker M, Jansen J, Mirck MH.Inhibited early third stage larvae of Cyathostominae were found in the digested mucosa of the large intestine of 12 yearling, female Shetland ponies, which were used in two grazing experiments. The ponies were killed in late autumn. In some ponies the inhibited larvae were very abundant and in most animals the majority of the Cyathostominae populations consisted of these early third stage larvae, suggesting that the phenomenon has an epidemiological significance.
Kelly AP, Jones RT, Gillick JC, Sims LD.An outbreak of nervous disease in Standardbred horses occurred near Bendigo, in south-eastern Australia, in October 1980. Over a two week period 11 horses in four training stables were affected with gait abnormalities, depression and recumbency. Eight of the 11 died. The results of an investigation implicated Clostridium botulinum toxin as the cause. The toxin was food-borne as a contaminant of oaten chaff.
Whitwell KE, Greet TR.A flexible endoscope was used to obtain 223 tracheal washes from 191 horses in three clinical categories. Total cell counts, cytological and bacteriological examinations are reported and the features of the main cell types encountered described. The presence and degree of inflammatory airway disease was determined by a semiquantitative assessment of the neutrophil response and was an important consideration in the interpretation of the bacteriological results. Potential pathogens were isolated from approximately 30 per cent of samples. Cytological changes suggestive of lungworm infestation, vi...
Smit H, Gaastra W, Kamerling JP, Vliegenthart JF, de Graaf FK.The erythrocyte receptor for Escherichia coli K99 fimbrial adhesin was isolated from equine erythrocytes and characterized as Neu5Gc-alpha(2----3)-Galp-beta(1----4)-GLcp-beta(1----1)-Ceramide. This glycolipid acted as the receptor for K99 by four different experimental approaches: inhibition of equine erythrocyte hemagglutination by preincubation of K99-positive bacteria or purified K99 fimbriae with the isolated glycolipid; inhibition of attachment of K99-positive bacteria to porcine intestinal epithelial cells in the presence of the isolated glycolipid; induction of binding of K99-positive b...
Studdert MJ, Fitzpatrick DR, Horner GW, Westbury HA, Gleeson LJ.Representative strains of EHV isolated from an aborted foetus and from a horse with rhinopneumonitis in New Zealand had restriction endonuclease DNA fingerprints typical of those usually associated with these syndromes elsewhere and now designated EHV1 and 4 respectively. EHV1 was isolated from the brain and spinal cord of a 4-year-old gelding that died of myeloencephalitis. A mare on the same farm, at about the same time as the gelding developed myeloencephalitis, aborted and EHV1 was isolated from the tissues of the aborted foetus. Restriction endonuclease DNA fingerprints of the viruses iso...
Ellenberger MA, Kaeberle ML, Roth JA.A lymphocyte blastogenic assay was developed to serve as an in vitro correlate of cell-mediated immunity to Rhodococcus (Corynebacterium) equi (R equi) in the equine species. Lymphocytes obtained from a group of experimental ponies showed no response in cell culture to R equi heat extract or lysozyme extract antigens. Ponies were assigned to groups for experimental inoculation. Three ponies were inoculated subcutaneously with live R equi, 3 were given live R equi by intranasal and intratracheal routes, and 4 ponies were left untreated. Lymphocytes from all inoculated ponies had a mitogenic res...
Magnuson NS, Perryman LE, Wyatt CR, Ishizaka T, Mason PH, Namen AE, Banks KL, Magnuson JA.Peripheral blood mononuclear cells (PBMC) from 14 foals with hereditary severe combined immunodeficiency (SCID) were studied to determine the extent of lymphocyte differentiation that occurs in this disorder. PBMC from all 14 horses had the morphologic characteristics of large granular lymphocytes (LGL). Cells from only one of 14 horses were responsive to phytolectin stimulation in a standard blastogenesis assay; however, PBMC from all 14 horses proliferated in continuous culture in the presence of partially purified interleukin 2. Furthermore, there were differences in the growth patterns of ...
Cordy DR.Bacterial meningoventriculitis was studied in 26 neonatal ungulates. Preceded by a substantial bacteremia, usually due to Escherichia coli, the fibrinopurulent inflammation involved leptomeninges, choroid plexuses, and ventricle walls, but largely spared the neuraxial parenchyma. It is proposed that this surface-relatedness results from the transport of bacteria by monocytes of low bactericidal power, migrating by normal pathways to maintain significant surface populations of macrophages. The neuraxial parenchyma is spared because of its normal lack of a macrophage population. A similar pathog...
Morris DD, Bloom JC, Roby KA, Woods K, Tablin F.An eosinophilic myeloproliferative disorder resulted in edema and hemorrhagic diathesis in a 10-month-old Standardbred colt. Laboratory abnormalities included severe thrombocytopenia, anemia, mild hypoproteinemia, and marked eosinophilia. Circulating eosinophils were immature or atypical with variation in granule size, disproportionate nuclear to cytoplasmic maturation, and abnormal nuclear size and shape. Bone marrow aspirate had mainly atypical eosinophil precursors, few erythroid precursors, and no megakaryocytes. A blood transfusion and dexamethasone therapy resulted in some improvement; h...
van der Velden MA, Verzijlenberg F.The surgical treatment of eighty-nine horses and ponies suffering from chronic empyema of the maxillary sinus is reported. Treatment consisted in trephination and drainage of the sinus involved in thirty-six animals; the affected teeth were removed at the same time in fifty-three animals in which sinusitis was caused by an alveolitis. The recovery rate was seventy-five per cent in group one and seventy per cent in group two. Postoperative treatment is also reported and attention is paid to complications which may occur during and after surgery.
O'Niell FD, Issel CJ, Henk WG.Organ cultures of equine fetal tracheal and nasal turbinate epithelium were inoculated with equine influenza virus-A1 (EIV-A1), equine herpesvirus-1 (EHV-1), or equine rhinovirus-1 (ERV-1). Infected organ cultures were processed for scanning and transmission electron microscopy at various intervals and were compared with noninfected controls. Organ cultures inoculated with ERV-1 appeared normal with the exception of rare island-like lesions in infected nasal turbinate. Virus particles were not seen in thin sections of organ cultures infected with ERV-1. The EHV-1 caused extensive loss of the e...
Coignoul FL, Bertram TA, Cheville NF.Three pony mares and 4 pony foals were inoculated with a subtype 2 strain of equine herpesvirus 1. Foals had periods of fever 12 h and 2.5 days after inoculation and leukopenia, involving both neutrophils and lymphocytes, followed by leukocytosis. Mares had transient fever and leukopenia 24 hours after inoculation that were less severe than in foals. An increase in circulating virus-neutralizing antibody was seen in 2 of 3 inoculated mares, but not in foals. Attempts to isolate virus from blood were unsuccessful. These studies show that equine herpesvirus 1 subtype 2 is a mild pathogen for pon...
Sweeney RW, Sweeney CR.Horner's syndrome developed in 2 horses after routine jugular venipuncture. Signs included unilateral sweating of the face in both horses and ptosis in 1 horse. The signs resolved within 14 hours. Signs of a perivascular injection did not develop in either horse. Although Horner's syndrome has been reported after perivascular jugular injections these cases illustrate that the syndrome may develop following routine intravenous injections.
Tzipori S, Hayes J, Sims L, Withers M.Streptococcus durans was isolated from a foal with profuse watery diarrhea and caused a similar syndrome when inoculated into foals via the orogastric route. The most consistent and striking histological feature was the extensive colonization of the mucosal surface of the small intestine by S. durans. Associated mucosal changes were mild to modeate, and brush border lactase and alkaline phosphatase production were depressed. S. durans also induced acute diarrhea in young gnotobiotic piglets. Mucosal changes were mild and, as with foals, the mucosal surface of the small intestine was colonized ...
Blythe LL, Watrous BJ, Schmitz JA, Kaneps AJ.Acute onset of vestibulocochlear and facial nerve dysfunction due to a stress fracture of the petrous part of the temporal bone was diagnosed in 3 horses. The fracture was secondary to chronic inflammatory changes in the petrous part of the temporal bone and the proximal stylohyoid bone, with fusion of the temporohyoid joint. Bacterial meningoencephalitis was a complicating factor. Treatment resulted in reduction of severity of clinical signs in 2 of the 3 cases, but residual compensated vestibular deficits persisted.
Blue MG, Hannwacker MA.Persistent purulent endometritis in a mare was attributed to an unclassified species of Corynebacterium. Following intrauterine infusions of 20% betadine for 5 days the purulent vulval discharge ceased and the mare appeared clinically normal. Based on histological examination of endometrial biopsy samples, the severe acute inflammatory reaction had largely resolved 2 days after therapy. Three maiden mares considered resistant to bacterial endometritis received single intrauterine inoculations of 1.8 X 10(9) colony-forming units of the Corynebacterium species. The uterine response was followed ...
Weiss M, Steck F, Kaderli R, Horzinek MC.After inoculation into 2 foals, Berne virus induced neutralizing antibody, but did not cause clinical symptoms. In a horizontal study of seropositive mares and their offspring, a decline of maternal antibodies and a sudden synchronous seroconversion in all foals were observed, again without clinical symptoms. The virus is widespread in the Swiss horse population and has been so during the last decade; rises in antibody titers were noted in 9% of paired sera sampled at random. Positive reactions were also obtained in serum neutralization tests and ELISA using small numbers of horse sera from Ge...
Dorr TE, Higgins RJ, Dangler CA, Madigan JE, Witham CL.Three cases of equine protozoal myeloencephalitis were diagnosed over a 12-month period in horses that had never left the state of California. These cases suggest that the disease is enzootic in California.
Coignoul FL, Bertram TA, Cheville NF.Neutrophils isolated from venous blood of adult and foal ponies inoculated with equine herpesvirus-1 were evaluated by in vitro function tests and by electron microscopy. Foals had fever and severe neutropenia 24 hours after inoculation; increased neutrophil random migration under agarose and decreased antibody-dependent cell-mediated cytotoxicity were significant at 24 hours, but values had returned to preinoculation levels by 72 hours. Mares had fever and leukopenia of less severity, increases in neutrophil migration, and longer persistence of primary granule release than were seen in foals....
Kornas S, Skalska M, Nowosad B, Gawor J.The objective of this study was to evaluate the strongyles species in 34 Pure Blood Arabian Horses: one-year-old mares (n = 12) and two-year old mares (n = 22) from the horse stud in 2005, kept under housed-pastured system and dewormed systematically, twice a year using the ivermectin compounds. Methods: The practical method of in vivo determination of strongyles species in horses is collection of these nematodes from the feaces after treatment. Nematodes were collected 24 hours after deworming from 1000 g sample of feaces, then were classified to appropriate species and relative abundance of ...
Breukink HJ, Németh F, van Dieten JS.The clinical examination, anaesthesia and surgery in a gelding with an incarcerated scrotal hernia are described. The results of examination of the blood at regular intervals are shown in a table. Surgery was performed without enterectomy. The postoperation course was uneventful. It is concluded that the possibility of scrotal hernia should be borne in mind, even in geldings with colic. The incarcerated portion of the small intestine is usually found to be the jejuno-ileal junction. The anaesthesiological and surgical features of equine scrotal hernia are discussed.
Strang C.Camilla Strang of the Animal Health Trust provides an overview of the diagnosis and control of conditions associated with infection by equine herpesvirus.