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.
Divers TJ, Byars TD, Murch O, Sigel CW.Proteus mirabilis cystitis was induced in 9 ponies by chemically eroding the bladder mucosa before the organism was inoculated. Comparisons were made in the treatment of P mirabilis cystitis between ponies treated daily for 13 days with a trimethoprim-sulfadiazine (TMP-SDZ) paste and both positive and negative controls. Urine cultures from ponies treated with TMP-SDZ became negative for P mirabilis between days 3 and 9 after the start of the treatment, whereas positive controls remained infected until day 13. Urine cultures from all ponies were negative for P mirabilis on day 28. Urine concent...
McCollum WH.Twenty horses that were seronegative for equine arteritis virus antibodies were inoculated IM with live equine arteritis virus vaccine. The inoculation did not cause clinical signs of disease. A mild, transient febrile reaction developed in 6 horses, 3 of which were in poor condition before inoculation. Six horses, 2 of which were in poor condition before inoculation, experienced mild lymphopenia. Necropsy revealed mild lesions in the lymph nodes of 6 horses (3 of which were in poor condition before inoculation). Maximum concentrations of virus were detected in the lymph nodes and were consist...
Clayton HM, Trawford AF.A field study was designed to investigate the re-establishment of patent lungworm infections in donkeys following an anthelmintic treatment regime which was effective against Dictyocaulus arnfieldi. In April 1979 faecal samples from 259 donkeys were examined and each animal classified as a negative, low positive or high positive excretor of lungworm larvae. During the summer the control group of 126 donkeys showed an increase in the number of excretors from 80 per cent in April to 91 per cent in October. At the same time there was a rise in the faecal larval output of individual animals so tha...
Smith BP.The practical implications of equine salmonellosis in the light of present knowledge are reviewed. Emphasis is placed on the various clinical forms which the disease may take. These include asymptomatic infections, signs of fever, anorexia and depression, severe acute diarrhoea and the septicaemic form. Diagnosis depends on recovery of the organism from the blood or faeces or, at necropsy, from tissues. In asymptomatic infections, it may be necessary to make serial faecal cultures over several days before a negative diagnosis may be made with any degree of certainty. Isolation of salmonellae i...
Scherer WF, Cupp EW, Lok JB, Brenner RJ, Ordonez JV.The minimal intestinal dose of an enzootic strain of Venezuelan encephalitis (VE) virus for Culex (Melanoconion) taeniopus mosquitoes caught at a marsh habitat of VE virus in Guatemala was less than five plaque forming units (pfu) of virus. Ingestion of this dose of virus in blood of viremic hamsters resulted in transmission of virus to other hamsters. This low intestinal threshold of an enzootic strain of VE virus indicates that the natural Guatemalan population of Cu. (Mel.) taeniopus can acquire VE virus from vertebrates that have viremia levels as low as 1,000-5,000 pfu/ml of blood, provid...
Wynne E, Slocombe JO, Wilkie BN.Rabbit antisera were prepared against veronal buffered saline extracts of L4 and L5 Strongylus vulgaris, adult S. vulgaris and adult Strongylus equinus retrieved from naturally infected horses. In agar gel diffusion with these antisera, adult S vulgaris and S. equinus each appeared to have at least one unique antigen; larval S. vulgaris appeared to have two species-specific and two stage-specific antigens. There were several common antigens. Excretory and secretory products were collected also from L4 and L5 an maintained over several days in tissue culture fluid. In agar gel diffusion against...
Lyons ET, Drudge JH, Tolliver SC.Activity of 15 compounds, given alone or in mixtures [butamisole, cambendazole, caviphos, febantel (alone or with trichlorfon), fenbendazole, ivermectin, levamisole-piperazine, oxfendazole, oxibendazole, pyrantel pamoate (alone or with piperazine-carbon disulfide complex), thiabendazole (alone or with piperazine or with trichlorfon), tioxidazole, and trichlorfon], against Thelazia lacrymalis was evaluated in 102 equids. Determination of activity was based on comparison of infection rate in treated animals examined at necropsy with infection rate of dead equids in our contemporary surveys. None...
Slocombe JO, McCraw BM.Twelve pony foals were reared worm-free and inoculated with Strongylus vulgaris. On day 7 after inoculation, 6 ponies were given ivermectin IM at a dose of 200 micrograms/kg of body weight and on day 28 were necropsied. Ivermectin was effective in eliminating early 4th-stage S vulgaris larvae and reducing clinical signs associated with acute arteritis. After administrative ivermectin was effective against early 4th-stage Strongylus vulgaris larvae in ponies when administered at 100, 300, or 800 micrograms/kg of body weight. The purpose of the present study was to report on a more extensive tri...
Kriek NP, Kellerman TS, Marasas WF.An isolate of Fusarium verticillioides (MRC826) that induced experimental leukoencephalomalacia, also caused acute toxicity when fed to pigs and administered per rumen fistula to sheep. Pigs developed severe pulmonary oedema while sheep manifested severe nephrosis and hepatosis. A less toxic isolate (F. verticillioides MRC602), fed to baboons, resulted in acute congestive heart failure or hepatic cirrhosis, depending on the dose. Both isolates were toxic to rats and caused similar lesions, namely, hepatic cirrhosis and intraventricular cardiac thrombosis.
Lyons ET, Drudge JH, Tolliver SC.Critical tests were conducted in 14 naturally infected equids (13 horses and 1 pony) to evaluate the antiparasitic activity of haloxon. Single doses were administered by stomach tube to 3 horses and 1 pony (60 mg/kg of body weight), by addition to the feed of 3 horses (60 mg/kg), and intraorally by powder gun to 7 horses (65 mg/kg). Haloxon was efficacious (99% to 100%) against infections of Parascaris equorum, Oxyuris equi (mature and immature), and Strongylus vulgaris at both dosage levels. Probstmayria vivipara parasites were removed in 1 horse treated at 60 mg/kg by stomach tube and S equi...
Malan FS, Reinecke RK, Scialdo RC.A single oral dose of fenbendazole (FBZ) paste at 7,5 mg/kg body mass was given to 5 horses. It was highly effective against adults of the following genera: Cyathostomum, Cylicostephanus, Cylicondontophorus, Poteriostomum, Cylicocyclus, Triodontophorus, Oesophagodontus (and other genera belonging to the subfamily Cyathostominae). Similarly, high efficacy was obtained against the adults of the following species: Oxyuris equi, Strongylus vulgaris, Strongylus equinus and Probstmayria vivipara. These results were confirmed in 12 horses and in addition FBZ at 7,5 mg/kg was highly effective against ...
Roberts MC, Sutton RH, Lovell DK.A 13-year-old Standardbred stallion presented with a unilateral mucopurulent nasal discharge and airway obstruction was found to have an extensive cryptococcal nasal granuloma. Treatment was not attempted. The stallion was destroyed 26 months later having completed 2 successful breeding seasons. The granuloma had gradually increased in size and almost completely occupied the left nasal cavity and paranasal sinuses. It was characterised histologically by fibrous and myxomatous tissue and masses of yeasts. A cryptococcal granuloma found within the wall of the jejunum could represent evidence of ...
Rommel FA, Sahu SP.Intrauterine inoculation of pony mares with the bacterium that is the causative agent of contagious equine metritis (CEM) resulted in clinical disease. A humoral immune response could be detected by agglutination and complement fixation (CF), and in some cases precipitating antibody was found by immunodiffusion tests. Agglutinating antibody was the most reliable serological indicator of overt infection and was detected in 8 ot 28 mares after initial intrauterine inoculation of 3-4 x 10(5) bacteria. Seventy percent of mares given a second inoculation and all mares given a third inoculation of 3...
Pointelli E, Santa-maria MA, Caretta G.A total of 1267 microfungi, including 35 Myxomycetes, were recorded from the fecal samples of the 60 horses; of these 395 were found on 20 saddle-horse feces, 363 on 20 race-horses and 509 on 20 working horses. Eighty two species representing 53 genera were recorded; of these 7 were Zygomycetes, 18 Ascomycetes, 1 Basidiomycetes and 25 Fungi Imperfecti: 2 Myxomycetes. Common coprophilous fungi are in decreasing order Pilobolus kleinii, Saccobolus depauperatus, Mucor hiemalis, Lasiobolus ciliatus, Podospora curvula, Petriella guttulata, M. circinelloides, Coprinus radiatus, Dictyostelium mucoroi...
Schiefer HB.Colitis "X" is a sporadic diarrheal disease of horses with clinical signs of dehydration, electrolyte imbalances and "shock"-like features. Macroscopic and microscopic findings include signs of disseminated intravascular coagulation, necrosis of colonic mucosa and presence of large numbers of bacteria in the devitalized parts of the intestine. Recently published work suggests that the causative agent may be Clostridium perfringens, Type A, but the bacteria are recoverable only in the preliminary stages of the disease. Excess protein and lack of cellulose content in the diet is thought to be th...
Pandey VS.Between August 1978 and July 1979 the anterior mesenteric artery and its branches were collected regularly from adult horses and examined for Strongylus vulgaris larvae. The incidence of infection varied from 55 to 100% (annual mean 80%). The mean monthly number of larvae ranged form 3 to 22 with an annual overall mean of 13. The arterial infection was at its minimum in December to January, rose gradually to attain the peak in June and declined thereafter. These observations indicated that S. vulgaris is an annual species in Morocco, infection occurring during the rainy season (November-April)...
McColl HP, Orchard VA.Sir,—A series of happy coincidences (serendipity?) has led us to a simple treatment which seems to have successfully alleviated symptoms of “rye-grass staggers” in a horse, a calf and two badly affected sheep. Although primarily engaged in a search for the causative agent(s) of rye-grass staggers, casual conversations with people having long experience of this disorder revealed many interesting observations. One of these was a racing-stable remedy for rye-grass staggers, which was the administration of “a couple of handfulls” of Epsom salts in a bran mash, with as much puha (Sonchus ...
Austin RJ, Dies KH.The protozoan, Klossiella equi was found in the kidneys of an aged Shetland mare raised in the Fredericton area of New Brunswick. This is the first published report of K. equi in a horse in Canada. The microscopic appearance of the parasite in the kidney is described. A brief discussion of other conditions seen in the horse is also presented.
Searcy GP, Orr JP.A nine year old quarter horse exhibited progressive weight loss and inappetance over a 47 day period. There was clinical evidence of pleuritis and pneumonia substantiated by leukocytosis and elevated protein in pleural fluid. Over the entire period the horse was neutropenic and had circulating abnormal immature granulocytes and low numbers of blast cells. Anemia and thrombocytopenia progressively worsened. Bone marrow examination revealed very few mature granulocytes but large numbers of immature cells of the granulocytic series and marked megaloblastic transformation of erythroid cells. These...
Stick JA, Derksen FJ, Scott EA.Cervical esophagostomy for tube feeding was evaluated in 11 ponies. Minor complications responded to supportive therapy in 8 ponies. Two died of complications, and 1 pony had a permanent fistula because of persistent infection. There was a positive correlation between the duration of tube feeding and the event of closure of the esophageal stoma after the tube was removed. There was no difference in the frequency of complications related to duration of tube feeding. When the distal end of the feeding tube was located in the thoracic portion of the esophagus, instead of in the stomach, tubes wer...
van Oirschot JT, Masurel N, Huffels AD, Anker WJ.Influenza virus A-equi 2(Heq2Neq2) caused an epizootic in the Netherlands in the winter of 1978-1979. Horses vaccinated with A/Equi/Praha/56 (HEq1Neq1) and A/Equi/Miami/63 (Heq2Neq2) were also infected and showed clinical signs. The virus involved showed a marked antigenic drift from the prototype and vaccine strain A/Equi/Miami/63 (Heq2Neq2). Infection of ferrets with the Dutch/79 isolates gave rise to high haemagglutination-inhibition antibody titres to a number of A-Equi 2-1963, 1968 and 1979 viruses. The incorporation of this virus into future influenza vaccines should be considered.
Schulz KS, Simmons TR, Johnson R.An 8-year-old mare was presented to the New York State College of Veterinary Medicine Large Animal Clinic for evaluation of anorexia, fever and icterus. The mare had a 5-day history of anorexia, depression and tongue protrusion. Diagnostic procedures included serum hepatic enzyme activities, serum bile acid concentrations, blood ammonia evaluations and hepatic ultrasound and ultrasound guided biopsy. The history, clinical pathology and histopathology in this case supported a probable diagnosis of primary septic cholangiohepatitis.
Fröhlich W, Wlaschitz S, Riedelberger K, Reifinger M.A case of endocarditis of the aortic valve in a 11 year old thoroughbred is presented. Diagnostic approach, the value of echocardiography, and the various symptoms, complications and prognosis are discussed. The horse with ruptured aortic valves due to endocarditis with severe aortic and mitral regurgitation causing congestive heart failure, was euthanised due to bad prognosis.
Klei TR.Diagnosis of internal parasitism is based on many factors, including clinical signs, case histories of individual animals and the herds of which they are a part, and, finally, specific laboratory findings. Laboratory methods used can be divided into those associated with the qualitative and quantitative examination of feces for parasite eggs, larvae, and oocysts, and laboratory findings on changes in physiologic status of individuals that may be produced by specific parasites.
Townsend M, Fowler B, Aulakh GK, Singh B.Endotoxin-induced diseases cause significant mortality and morbidity in the horse, leading to enormous economic damage to the equine industry. Neutrophils play a critical role in initiating the immune response in the lung. Pattern recognition receptors (PRRs) are programmed to recognize microbial structures unique to pathogens and mount an immune response. Pentraxin 3 (PTX3) is a PRR that is produced at sites of inflammation by many cell types upon stimulation by pro-inflammatory cytokines and agonists, such as endotoxins [also known as lipopolysaccharides (LPS)]. Pentraxin 3 recognizes and bi...
Rastegaev IuM.Alongside with a high intensity of infection of horses with botfly larvae there was observed mass aberrant parasitism of horse botflies in farms of Astrakhan, Guryev and Uralsk Provinces, and in the Kalmyk ASSR in 1980-1981 and 1987. As a result of extremely high aggregation of horse botfly larvae in their usual localization places, Gasterophilus pecorum larvae remained, due to interspecific competition, in nonspecific places (oral cavity, pharynx), adapted to new habitats and normally developed. Their number varied from 260 to 750 specimens. Localization of G. pecorum larvae in the mentioned ...
Held JP, Blackford JT.Three cases of vaginal perforation after coitus are discussed. The most consistent clinical sign is a small amount of blood escaping from the vulvar lips immediately after breeding. Secondary infection and posttraumatic swelling may cause abdominal pain due to rectal impaction. Treatment with high levels of an appropriate antibiotic is important to reduce the risk of a severe infectious peritonitis. The use of artificial insemination or a breeding roll to prevent full intromission is recommended.