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Topic:Infection
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.
[The polymerase chain reaction (PCR) for the detection of DNA of equine herpesviruses 1 and 4]. Formalin-fixed and Paraplast-embedded tissue samples of 42 aborted equine fetuses were examined by polymerase chain reaction for the presence of equine herpesvirus DNA. The used set of primers was located in the glycoprotein 13 open reading frame and allowed the amplification of both EHV 1 und EHV 4. By cleaving pattern analysis after Hinf I digestion EHV 1 could be distinguished from EHV 4. In 9 of the cases investigated EHV 1-DNA was detected. This finding is in absolute context with the results of the virological investigations.
Factors that influence passive transfer of immunoglobulins in foals. Effects of farm management, breed, mare age, gestation duration, and climatologic factors on colostral specific gravity, colostral IgG concentration, and foal serum IgG concentration were evaluated. Climatologic variables measured were daily maximal, minimal, and mean air temperature, precipitation, average relative humidity, and total solar radiation. Presuckle, postpartum colostrum samples were collected from 140 Standardbred, 94 Thoroughbred, and 59 Arabian mares from January through June during 1985 and 1986. Thoroughbred (farm A, n = 61; farm B, n = 33) and Arabian (farm C, n = 45; farm D...
Fecalith impaction in four miniature foals. Four miniature foals admitted with signs of progressive nonresponsive abdominal pain and no fecal production had fecalith impaction of the small colon. Duration of clinical signs ranged from 10 hours to 5 days. Removal of the fecalith via small colon enterotomy was a successful treatment in all 4 cases. Miniature foals may be predisposed to fecalith impaction of the small colon. If a miniature foal has signs of progressive nonresponsive abdominal pain, fecalith impaction needs to be considered. Surgical correction may be required.
Volvulus of the cecum and large colon caused by multiple mesenteric defects in a horse. A 2-year-old Standardbred colt was examined because of signs of abdominal pain of 12 hours' duration. Clinical signs of disease, including tachycardia and abdominal distention, and rectal palpation findings of distention and thickening of the ventral colon, were consistent with displacement or early strangulation obstruction of the large colon. Surgical exploration revealed volvulus of the large colon around an axis formed by the dorsal mesenteric attachment of the transverse colon. The cecum could be completely exteriorized and lacked the cecocolic ligament and dorsal mesenteric attachments. ...
Influence of endophyte-infected tall fescue on serum prolactin and progesterone in gravid mares. Thirty mares in late gestation were used in a 3-yr study to assess effects of the tall fescue endophyte Acremonium coenophialum on serum prolactin (PRL) and progesterone. Two paddocks of each treatment, 0 or 100% infected 'Kentucky 31' tall fescue, were grazed by the mares for 21 d. Blood was collected three times per week until parturition. At 7-d intervals, mares were challenged with thyrotropin-releasing hormone (TRH) while grazing and blood was collected postinjection. Mares grazing 100% infected tall fescue (E+) had decreased serum PRL compared with mares grazing the 0% infected tall fesc...
The IR3 gene of equine herpesvirus type 1: a unique gene regulated by sequences within the intron of the immediate-early gene. The complete nucleotide sequence of the inverted repeat component (IR; 12,776 bp each) of the genome of equine herpesvirus type 1 (EHV-1) has been determined. Transcription analyses have revealed that the EHV-1 IR sequence encodes at least 6 genes. In this report, we present the DNA sequence and transcriptional characterization of a gene (IR3) that maps entirely within the IR sequences. The IR3 open reading frame (ORF) is located between nucleotides (nt) 6123-6411 of the IR sequence and possesses an ORF of 95 amino acids. Interestingly, this ORF does not show homology to any known herpesvirus ...
An immunoperoxidase method applied to the diagnosis of equine herpesvirus abortion, using conventional and rapid microwave techniques. An indirect immunoperoxidase (IMP) technique was applied to cryostat and paraffin sections of liver from ten aborted equine foetuses. Equid herpesvirus type 1 (EHV-1) had been isolated from seven of them and EHV-4 from one: the remaining two were virologically negative and were not used as controls. In the eight virus-infected cases the immunostaining revealed foci of cells exhibiting a distinct brown cytoplasmic and inclusion body pigmentation. No specific signal was present in the non-infected controls. The method also was adapted for incubation in a microwave oven, which allowed the total l...
Characterization of Sarcocystis neurona from a thoroughbred with equine protozoal myeloencephalitis. Morphological information is presented for syntype material of the etiologic agent of equine protozoal myeloencephalitis, Sarcocystis neurona. A clinical description of the horse from which the organism was isolated and the methodology used to immunosuppress the horse in an attempt to increase parasite numbers are also given. The description includes microscopic details observed both with light and transmission electron microscopy. Mainly stages from tissue are illustrated, but information is also presented on the development of the organism after inoculation onto monolayers of bovine monocyte...
Pathways of lymph flow through intestinal lymph nodes in the horse. In the horse, several thousand lymph nodes receive lymph from the intestine, part of which is very large and contains microorganisms that enable the animal to utilize refractory dietary constituents such as cellulose. The aim of this study was to describe the pathways by which lymph is delivered into, traverses, and is drained from these lymph nodes. These pathways were studied with either Microfil or methacrylate casting materials and with light and electron microscopy. The afferent lymphatic vessel delivering lymph into one of the nodes divides over the capsular surface and within trabeculae...
Pinealitis coincident with recurrent uveitis: immunohistochemical studies. Although experimental models of autoimmune uveitis predict pinealitis coincident with uveitis, there is no direct evidence of pineal pathology accompanying a human uveitis. Horses with naturally occurring uveitis are a potential source of eye and pineal tissues that are not available from human patients with active uveitis. We have observed pinealitis in a mare with equine recurrent uveitis. By immunohistochemistry we demonstrated immunoglobulin and MHC Class II antigen on infiltrating and resident cells of eye and pineal gland. These results support the relevance of the animal models and sugg...
[Causes of prenatal foal loss in Switzerland]. In Switzerland during the foaling season 1988 and 1989 the cause of abortion in 60 foals was investigated. Special attention was paid to infections with equine herpesvirus 1 (EHV 1). Diagnosis were based on post-mortem, histopathological, bacteriological and immunofluorescence investigation. The results confirm data from other countries, that EHV 1 is the most prevalent viral (20%) cause of abortion, followed by various bacterial agents (12%). Other causes were umbilical torsion, twin pregnancy and malformations. In 18% of the cases the investigation of fetuses did not give any results as to t...
Domestic animal models of severe combined immunodeficiency: canine X-linked severe combined immunodeficiency and severe combined immunodeficiency in horses. This review describes the clinical, immunologic and pathologic features of two naturally-occurring models of severe combined immunodeficiency (SCID) in domestic animals that represent different forms of human SCID. Canine X-linked SCID (XSCID) has an X-linked recessive mode of inheritance and, as such, represents a model for the most common form of human SCID in the United States. Affected dogs have normal percentages of circulating B cells and low to normal percentages of phenotypically mature, but nonfunctional T cells. Severe combined immunodeficiency in the horse is an autosomal recessive ...
Rotavirus serotype G3 predominates in horses. Foal fecal group A rotavirus strains were characterized by electropherotype, serotype, and subgroup and shown to be distinctly different from rotaviruses of other mammals. Of 86 strains that were electropherotyped, 98% had similar profiles, with gene segments 3 and 4 close together and segments 7, 8, and 9 widely spaced. Of 70 strains that had sufficient detectable VP7 antigen to be serotyped by enzyme-linked immunosorbent assays (ELISAs), 63% were serotype G3 (39% were subtype G3A and 24% were subtype G3B), 4% were serotype G13, and 33% were untypeable. Serotypes G1, G2, G4, G5, G6, G9, G10, ...
Early foetal death in the mare. Histological, bacteriological and cytological findings in the endometrium. Fifteen mares which had each lost their pregnancies 2 to 8 times during the preceding 6 years were used in a study comprising 1 or 2 breeding seasons for each mare. During the research period all 15 mares conceived and 10 of the mares had normal pregnancies in the 1st experimental year. Five mares resorbed/aborted once or twice during the 1st year. This was followed by a pregnancy that terminated in a live foal. Histopathological examinations of uterine biopsies showed a wide range of histopathological conditions, from absence of changes excessive for the mare's age and parity to the most seve...
Pathogenesis of equine herpesvirus-1 in specific pathogen-free foals: primary and secondary infections and reactivation. Six specific pathogen-free foals shown to be free of equine herpesvirus-1 and 4 (EHV-1 and -4) and lacking in maternally-derived antibodies were used to investigate the pathogenesis of EHV-1 in horses. Following primary intranasal inoculation with EHV-1 all foals showed signs of a mild, self-limiting upper respiratory tract infection. A leucopenia was observed, comprising both a lymphopenia and neutropenia. Virus was isolated from nasal mucus and buffy coat cells over several days during the clinical episode and after the animals became clinically normal. Notwithstanding the mildness of the cl...
Pathological findings in horses dying during an outbreak of the paralytic form of Equid herpesvirus type 1 (EHV-1) infection. 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...
Inhibition of equine complement activity by polysulfated glycosaminoglycans. The ability of polysulfated glycosaminoglycans (PSGAG) to inhibit the complement cascade was evaluated. The role of complement in inflammation and infection has been well documented. Inhibition of the complement cascade by PSGAG could explain why intra-articularly administered PSGAG diminish diarthrodial joint inflammation and potentiate septic arthritis in horses. Hemolytic complement testing was performed to evaluate the effect of PSGAG on the equine classical and alternate pathways of complement, using rabbit erythrocytes as the target cells. Concentration of PSGAG between 0.2 mg/ml and 0.6...
Diagnosis of equid herpesviruses -1 and -4 by polymerase chain reaction. The polymerase chain reaction (PCR) is a sensitive technique used to detect DNA of viral pathogens. We have applied the technique to the detection of Equid herpesviruses-1 and -4 (EHV-1 and EHV-4) DNA within nasopharyngeal swab samples from horses. Ninety-eight samples from suspected field cases and in-contact horses were analysed. The assays were conducted blind and later decoded and compared with virus isolation data. Our results indicate that PCR is a sensitive and rapid technique for the diagnosis of EHV-1 and EHV-4 infection.
[Teratogenic effect of the Venezuelan equine encephalitis virus: a review of the problem]. Clinical findings on Venezuelan Equine Encephalitis virus infection and the teratogenic effects of several Togaviruses are described. Similarities between the intrauterine alterations induced by Venezuelan Equine Encephalitis virus and rubella virus are pointed out. Findings described by Wenger in 1967 were those of massive cerebral necrosis in fetuses of women presumably suffering of encephalitis and they are commented along with the development of an animal experimental model at the end of 1970-1980. Pathogenesis of the intrauterine infection seemed to be related to changes in the placental ...
Alkaloids of Stipa robusta (sleepygrass) infected with an Acremonium endophyte. Stipa robusta (= Stipa vaseyi) is a perennial grass found in certain areas of the southwestern United States. It is commonly known as sleepygrass, as horses that ingest this grass may become profoundly somnolent or stuporous for periods of time lasting up to several days. In an attempt to determine the active principle(s), fractionation of a methanolic extract of sleepygrass infected with an Acremonium endophyte has yielded lysergic acid amide (20 micrograms/g dry wt), isolysergic amide (8), 8-hydroxylsergic acid amide (0.3), ergonovine (7), chanoclavine-I (15), and N-formylloline (18). Relate...
Determination of the early age of onset of equine recurrent laryngeal neuropathy. 2. Nerve pathology. The left and right recurrent laryngeal nerves and peroneal nerves from two groups of foals, one less than 1 month of age and the other 6 months of age, were examined by light and electron microscopy. While there was no evidence of fiber loss on light microscopy, occasional onion bulbs, regenerating clusters and swollen axons were seen in the recurrent laryngeal nerves. To quantitate these changes, total counts of the main pathological structures were performed using the electron microscope. In all the foals the most common abnormality seen in the laryngeal nerves were Bungner bands, which were...
The electron microscopic and immunohistochemical demonstration of a papillomavirus in equine aural plaques. This research study investigates the cause of aural plaques in horses and provides strong evidence that papillomaviruses are to blame. The study used various tools including electron microscopic examination, immunohistochemical [...]
Hepatoencephalopathy and hypocalcemia in a miniature horse mare. A pregnant, miniature horse mare had clinical signs of hepatoencephalopathy and concurrent hypocalcemia. The signs included dullness, inappetence, blindness, head pressing, weakness, muscle fasiculations, uveitis, and urinary incontinence. Hepatic dysfunction and hypocalcemia were confirmed by serum biochemical analysis. The mare was treated successfully with a continuous infusion of Ringer solution, calcium gluconate, dextrose, B-complex vitamins, sodium ampicillin, and flunixin meglumine; topical administration of ophthalmic ointments; and decompression of the urinary bladder. Histologic exa...
Medical and surgical management of small-colon impaction in horses: 28 cases (1984-1989). Medical records of 28 horses with impaction of the small colon were reviewed; 20 horses were admitted during the winter months. Diagnosis of small-colon impaction was made in 21 horses by rectal examination, and in 7 horses at exploratory celiotomy. Ten horses were treated medically, and 18 were treated surgically. Horses that were treated surgically were more likely to have abdominal distention than were those that responded to medical treatment (P less than 0.025). Signs of greater degree of abdominal pain and higher heart rate were seen in horses treated surgically, but these values were no...
