Mycobacterium species are a group of bacteria that can infect horses, leading to various clinical manifestations. These bacteria are known for their slow growth and complex cell wall structure, which contribute to their persistence in the environment and within host organisms. In horses, Mycobacterium infections can result in conditions such as granulomatous enteritis and lymphadenitis. Diagnosis can be challenging due to the nonspecific nature of clinical signs and the need for specialized laboratory techniques. This page compiles peer-reviewed research studies and scholarly articles that explore the epidemiology, pathogenesis, diagnostic methods, and treatment options for Mycobacterium infections in equine populations.
Kramer AJ, Meziara Wilson T, Kimura S, Groover E, DeLeon-Carnes M, Neto RLALT.A 23-y-old gelding was presented to a veterinary teaching hospital with a history of chronic, refractory diarrhea. Clinically, the horse was in poor body condition, with a thickened and corrugated large intestine identified by transcutaneous abdominal ultrasonography. At postmortem examination following euthanasia, the large colon and cecum had segmental thickening of the intestinal wall with innumerable mucosal ulcers and prominent polypoid mucosal masses. Many mesenteric and hepatic lymph nodes were enlarged. Histology revealed granulomatous and ulcerative typhlocolitis and granulomatous lym...
Fedorka CE, Schnobrich MR, Muderspach ND, Scoggin KE, Dedman MT, Weigle KE, May MG, Twist H, Linse CR, Douglas RH, Troedsson MHT.Equine embryonic loss following the development of endometrial cups delays return to cyclicity due to the production of equine chorionic gonadotropin (eCG). Natural degradation of endometrial cups coincides with an influx of immune cells at 100-120 days of gestation, but therapeutic stimulation of reduced eCG production has been relatively unsuccessful. Recently, we observed an increase in pro-inflammatory cytokine production following the use of the immunostimulant mycobacterium cell wall fraction (MCWF). Objective: To evaluate the efficacy of hysteroscopic-guided injection of MCWF on the a...
Caston SS, Sponseller BA, Dembek KA, Hostetter JM.A reformulation of Mycobacterium cell wall fraction immunotherapeutic can be used to successfully treat sarcoids in horses. Sarcoids are reported to be the most common equine skin tumors with tumor type and location influencing the choice of treatment. Wide surgical excision is curative for many tumors, but may not always be feasible. Previous studies have reported sarcoid regression after injection with mycobacterial cell wall immunotherapeutics. A new formulation of the Mycobacterium phlei cell wall fraction immunostimulant (Immunocidin Equine) was used to treat cutaneous tumors in horses. E...
Fedorka CE, Murase H, Loux SC, Loynachan AT, Walker OF, Squires EL, Ball BA, Troedsson MHT.Maintaining yearly foal production is important for the economic success of the broodmare, and this requires breeding to occur as quickly postpartum as possible. The initial postpartum estrus occurs within 5-20 days postpartum, whereas the uterus is still undergoing repair from tissue alterations during pregnancy and parturition, a process known as involution. Attempts have been made to hasten this process, but with minimal success. Mycobacterium cell wall fraction (MCWF) is an immunomodulator that has been shown to reduce bacterial growth and alter aspects of the immune response to breeding,...
Vail KJ, Stranahan LW, Richardson LM, Yanchik AE, Arnold CE, Porter BF, Wiener DJ.Mycobacterial infections in horses are uncommon, but are caused most frequently by Mycobacterium bovis of the Mycobacterium tuberculosis complex or Mycobacterium avium of the M. avium complex. Disease caused by Mycobacterium intracellulare, the second most common species within the M. avium complex, has not been reported in horses to date. Mycobacteriosis in horses most often presents as enteric, pulmonary or, rarely, systemic disease. Here we report a case of M. intracellulare infection in a horse presenting as a granulomatous nasal mass.
Silva FS, Lorenzett MP, Bianchi MV, Bastos HBA, Larentis GR, Paul LG, Snel GGM, Oliveira-Filho JP, Mattos RC, Sonne L.Although relatively uncommon in horses, infections caused by Mycobacterium spp. may affect the gastrointestinal tract. Mycobacterium branderi is a non-tuberculous Mycobacterium (NTM) that causes respiratory infections in man. Non-tuberculous mycobacteria may also affect horses; however, infection by M. branderi has not yet been reported in this species. This report describes the clinical, pathological, microbiological and molecular findings of M. branderi infection in a horse, causing granulomatous mesenteric lymphadenitis. A 17-year-old Thoroughbred stallion had a 3-month history of chronic d...
Hlokwe TM, Sutton D, Page P, Michel AL.Tuberculosis caused by Mycobacterium bovis (M. bovis) is very uncommon in horses worldwide. Methods: In the current study, an eight-year-old male Thoroughbred in good body condition was admitted to the Equine Clinic at the Onderstepoort Veterinary Academic Hospital in 2005 due to bilateral epistaxis accompanied by coughing. Routine examinations were conducted to determine the cause of the condition. Endoscopic examination revealed the major source of the epistaxis as the trachea, whereas thoracic radiography indicated the presence of a primary pulmonary mass. M. bovis was isolated from a bronc...
Sarradell JE, Alvarez J, Biscia M, Zumarraga M, Wunschmann A, Armien AG, Perez AM.A 2-year-old dappled Percheron horse had a wasting condition that did not respond to antibiotic treatments and ultimately resulted in death. Thickening of the wall of the large colon and enlargement of the mesenteric lymph nodes were observed at postmortem examination, along with the presence of pinpoint whitish foci in the liver. Microscopic examination of affected tissues revealed diffuse chronic granulomatous enterocolitis, granulomatous mesenteric lymphadenitis, and multifocal granulomatous hepatitis. The DNA extracted from paraffin-embedded intestinal and lymph node samples was analyzed u...
Oliveira-Filho JP, Monteiro LN, Delfiol DJ, Sequeira JL, Amorim RM, Fabris VE, Del Piero F, Borges AS.Sarcoidosis is a rare equine skin disease characterized primarily by an exfoliative and granulomatous dermatitis but also presenting granulomatous inflammation of multiple systems. The current report presents the clinical and histopathological findings of sarcoidosis in a 16-year-old American Quarter Horse gelding with nested polymerase chain reaction Mycobacterium spp. DNA detection within hepatic and skin samples. Mycobacterium spp. may play a role in the pathogenesis of equine sarcoidosis as has been proposed for human sarcoidosis.
Lyashchenko KP, Greenwald R, Esfandiari J, Lecu A, Waters WR, Posthaus H, Bodmer T, Janssens JP, Aloisio F, Graubner C, Grosclaude E, Piersigilli A....A case of pulmonary tuberculosis caused by Mycobacterium tuberculosis was diagnosed in a horse. Clinical evaluation performed prior to euthanasia did not suggest tuberculosis, but postmortem examination provided pathological and bacteriological evidence of mycobacteriosis. In the lungs, multiple tuberculoid granulomas communicating with the bronchiolar lumen, pleural effusion, and a granulomatous lymphadenitis involving mediastinal and tracheobronchial lymph nodes were found. Serologic response to M. tuberculosis antigens was detected in the infected horse, but not in the group of 42 potential...
Chiers K, Deschaght P, De Baere T, Dabrowski S, Kotlowski R, De Clercq D, Ducatelle R, Vaneechoutte M.Routine cultivation methods are able to distinguish between isolates of the Mycobacterium avium and the Mycobacterium tuberculosis complex. However, molecular tools are needed to further identify the several subspecies in the M. avium complex, especially for the subspecies avium and silvaticum. A rapid technique using HhaI restriction digestion of a 349 bp amplification product of the 85B antigen (α-antigen) gene was used for the identification of M. avium subsp. silvaticum in a three-year-old gelding presenting with caseous, necrotizing, granulomatous lesions. The result was confirmed by seq...
van Zyl A, Daniel J, Wayne J, McCowan C, Malik R, Jelfs P, Lavender CJ, Fyfe JA.Two horses were diagnosed as having Mycobacterium ulcerans infections. The first was a 21-year-old Quarterhorse-cross mare living in Mallacoota (a coastal town near the border of New South Wales and Victoria, Australia) that presented with lichenification, hair-loss and oedema on a fetlock, which subsequently ulcerated, as well as a non-healing ulcer on the wither. The second horse was a 32 year-old Standardbred gelding from Nicholson, near Bairnsdale, Victoria, that had an ulcerated lesion on its caudal thigh. Histologically, there were characteristic changes seen with M. ulcerans infections ...
Ryhner T, Wittenbrink M, Nitzl D, Zeller S, Gygax D, Wehrli Eser M.In this case report a 10 year old Freiberger mare with a Mycobacterium avium subsp. avium infection is presented. This infection leads to a tuberculosis like disease with granulomatous alterations particularly of the intestines and lungs and is only sporadically reported in horses of Central Europe. Diarrhoea, mastitis and neck stiffness as well as dyspnoea and chronic cough are more specific symptoms of the infection, while weight loss, weakness and lethargy are nonspecific signs. As these clinical signs can occur in many other diseases, the diagnosis of mycobacterial infection is difficult a...
Keller KM, Queiroz BD, Keller LA, Ribeiro JM, Cavaglieri LR, Pereyra ML, Dalcero AM, Rosa CA.Feed contamination can lead to nutrient losses and detrimental effects on animal health and production. The purposes of this study were to investigate the mycobiota in equine mixed feeds and to determine natural contamination with aflatoxin B1 (AFB1) and fumonisin B1 (FB1). Fungal enumeration of equine feed samples was done. A commercially available enzyme-linked immunosorbent assay kit was applied to quantify AFB1 and FB1. A comparison between ELISA and HPLC was carried out. Feed mould counts ranged from <1 x 10(2) to 1 x 10(5) cfu/g. The most frequent genus isolated was Aspergillus (40.54...
Hewes CA, Schneider RK, Baszler TV, Oaks JL.A 12-year-old American Saddlebred gelding was referred to a veterinary teaching hospital for evaluation of a chronic lameness problem in the right radiocarpal joint. The horse had been treated for osteoarthritis of the right radiocarpal joint with multiple injections of cortisone during the past 3 years. The horse was severely lame on the right forelimb at a trot. Radiography and computed tomography revealed a 3 x 2-cm lytic defect in the distal portion of the radius and periarticular bone proliferation around the right radiocarpal joint. Ultrasonography of the distal portion of the radius rev...
Leifsson PS, Olsen SN, Larsen S.This paper is the first report of systemic tuberculosis involving the eyes in a horse. The animal lost condition and gradually became increasingly blind in both eyes; it was eventually euthanased. The pathological findings included bilateral, mycobacterial granulomatous uveitis with unilateral retinal detachment and necrosis, and disseminated, mycobacterial granulomatous foci in the myocardium, lungs, bronchial lymph nodes, kidneys, liver, pancreas, colon and visceral serosal surfaces, with the most extensive lesions in the myocardium. The mycobacteria were identified as Mycobacterium avium.
Buergelt CD, Green SL, Mayhew IG, Wilson JH, Merritt AM.The clinical, bacteriologic and pathologic findings of three adult horses suffering from avian tuberculosis are presented. Chronic weight loss and hypoproteinemia were pertinent clinical abnormalities in all three horses. Gross pathologic lesions were characterized by chronic enterocolitis with mesenteric lymphadenopathy in two horses and hepatic granulomas in the third horse. The microscopic diagnoses were chronic, non-caseating granulomatous enterocolitis, and necrotizing, non-mineralizing granulomatous hepatitis, respectively. All three horses had granulomatous lymphadenitis of mesenteric l...
Merritt AM, Kohn CW, Ramberg CF, Cimprich RE, Reid CF, Bolton JR.Five clinically normal, mature horses and 11 with chronic diarrhea were given 51Cr-tagged Cohn fraction V equine albumin intravenously. All urine and feces were collected separately, and blood for plasma analysis was taken periodically for 5 to 8 days after injection of the isotope. Plasma clearance of albumin into the intestinal tract of normal horses was calculated as 0.67 +/- 0.23 (SD) ml/kg of body weight/day, with 1.33 +/- 0.69% of the 51Cr dose appearing in the feces in 5 days. Of the 11 diarrheal horses, 8 had a plasma clearance of 0.49 +/- 0.21 ml/kg/day with 1.12 +/- 0.68% of the dose...
van Zyl A, Daniel J, Wayne J, McCowan C, Malik R, Jelfs P, Lavender CJ, Fyfe JA.Two horses were diagnosed as having Mycobacterium ulcerans infections. The first was a 21-year-old Quarterhorse-cross mare living in Mallacoota (a coastal town near the border of New South Wales and Victoria, Australia) that presented with lichenification, hair-loss and oedema on a fetlock, which subsequently ulcerated, as well as a non-healing ulcer on the wither. The second horse was a 32 year-old Standardbred gelding from Nicholson, near Bairnsdale, Victoria, that had an ulcerated lesion on its caudal thigh. Histologically, there were characteristic changes seen with M. ulcerans infections ...
Chiers K, Deschaght P, De Baere T, Dabrowski S, Kotlowski R, De Clercq D, Ducatelle R, Vaneechoutte M.Routine cultivation methods are able to distinguish between isolates of the Mycobacterium avium and the Mycobacterium tuberculosis complex. However, molecular tools are needed to further identify the several subspecies in the M. avium complex, especially for the subspecies avium and silvaticum. A rapid technique using HhaI restriction digestion of a 349 bp amplification product of the 85B antigen (α-antigen) gene was used for the identification of M. avium subsp. silvaticum in a three-year-old gelding presenting with caseous, necrotizing, granulomatous lesions. The result was confirmed by seq...
Keller KM, Queiroz BD, Keller LA, Ribeiro JM, Cavaglieri LR, Pereyra ML, Dalcero AM, Rosa CA.Feed contamination can lead to nutrient losses and detrimental effects on animal health and production. The purposes of this study were to investigate the mycobiota in equine mixed feeds and to determine natural contamination with aflatoxin B1 (AFB1) and fumonisin B1 (FB1). Fungal enumeration of equine feed samples was done. A commercially available enzyme-linked immunosorbent assay kit was applied to quantify AFB1 and FB1. A comparison between ELISA and HPLC was carried out. Feed mould counts ranged from <1 x 10(2) to 1 x 10(5) cfu/g. The most frequent genus isolated was Aspergillus (40.54...
Buergelt CD, Green SL, Mayhew IG, Wilson JH, Merritt AM.The clinical, bacteriologic and pathologic findings of three adult horses suffering from avian tuberculosis are presented. Chronic weight loss and hypoproteinemia were pertinent clinical abnormalities in all three horses. Gross pathologic lesions were characterized by chronic enterocolitis with mesenteric lymphadenopathy in two horses and hepatic granulomas in the third horse. The microscopic diagnoses were chronic, non-caseating granulomatous enterocolitis, and necrotizing, non-mineralizing granulomatous hepatitis, respectively. All three horses had granulomatous lymphadenitis of mesenteric l...
Lyashchenko KP, Greenwald R, Esfandiari J, Lecu A, Waters WR, Posthaus H, Bodmer T, Janssens JP, Aloisio F, Graubner C, Grosclaude E, Piersigilli A....A case of pulmonary tuberculosis caused by Mycobacterium tuberculosis was diagnosed in a horse. Clinical evaluation performed prior to euthanasia did not suggest tuberculosis, but postmortem examination provided pathological and bacteriological evidence of mycobacteriosis. In the lungs, multiple tuberculoid granulomas communicating with the bronchiolar lumen, pleural effusion, and a granulomatous lymphadenitis involving mediastinal and tracheobronchial lymph nodes were found. Serologic response to M. tuberculosis antigens was detected in the infected horse, but not in the group of 42 potential...
Ryhner T, Wittenbrink M, Nitzl D, Zeller S, Gygax D, Wehrli Eser M.In this case report a 10 year old Freiberger mare with a Mycobacterium avium subsp. avium infection is presented. This infection leads to a tuberculosis like disease with granulomatous alterations particularly of the intestines and lungs and is only sporadically reported in horses of Central Europe. Diarrhoea, mastitis and neck stiffness as well as dyspnoea and chronic cough are more specific symptoms of the infection, while weight loss, weakness and lethargy are nonspecific signs. As these clinical signs can occur in many other diseases, the diagnosis of mycobacterial infection is difficult a...
Oliveira-Filho JP, Monteiro LN, Delfiol DJ, Sequeira JL, Amorim RM, Fabris VE, Del Piero F, Borges AS.Sarcoidosis is a rare equine skin disease characterized primarily by an exfoliative and granulomatous dermatitis but also presenting granulomatous inflammation of multiple systems. The current report presents the clinical and histopathological findings of sarcoidosis in a 16-year-old American Quarter Horse gelding with nested polymerase chain reaction Mycobacterium spp. DNA detection within hepatic and skin samples. Mycobacterium spp. may play a role in the pathogenesis of equine sarcoidosis as has been proposed for human sarcoidosis.
Vail KJ, Stranahan LW, Richardson LM, Yanchik AE, Arnold CE, Porter BF, Wiener DJ.Mycobacterial infections in horses are uncommon, but are caused most frequently by Mycobacterium bovis of the Mycobacterium tuberculosis complex or Mycobacterium avium of the M. avium complex. Disease caused by Mycobacterium intracellulare, the second most common species within the M. avium complex, has not been reported in horses to date. Mycobacteriosis in horses most often presents as enteric, pulmonary or, rarely, systemic disease. Here we report a case of M. intracellulare infection in a horse presenting as a granulomatous nasal mass.
Hlokwe TM, Sutton D, Page P, Michel AL.Tuberculosis caused by Mycobacterium bovis (M. bovis) is very uncommon in horses worldwide. Methods: In the current study, an eight-year-old male Thoroughbred in good body condition was admitted to the Equine Clinic at the Onderstepoort Veterinary Academic Hospital in 2005 due to bilateral epistaxis accompanied by coughing. Routine examinations were conducted to determine the cause of the condition. Endoscopic examination revealed the major source of the epistaxis as the trachea, whereas thoracic radiography indicated the presence of a primary pulmonary mass. M. bovis was isolated from a bronc...
Silva FS, Lorenzett MP, Bianchi MV, Bastos HBA, Larentis GR, Paul LG, Snel GGM, Oliveira-Filho JP, Mattos RC, Sonne L.Although relatively uncommon in horses, infections caused by Mycobacterium spp. may affect the gastrointestinal tract. Mycobacterium branderi is a non-tuberculous Mycobacterium (NTM) that causes respiratory infections in man. Non-tuberculous mycobacteria may also affect horses; however, infection by M. branderi has not yet been reported in this species. This report describes the clinical, pathological, microbiological and molecular findings of M. branderi infection in a horse, causing granulomatous mesenteric lymphadenitis. A 17-year-old Thoroughbred stallion had a 3-month history of chronic d...
Fedorka CE, Murase H, Loux SC, Loynachan AT, Walker OF, Squires EL, Ball BA, Troedsson MHT.Maintaining yearly foal production is important for the economic success of the broodmare, and this requires breeding to occur as quickly postpartum as possible. The initial postpartum estrus occurs within 5-20 days postpartum, whereas the uterus is still undergoing repair from tissue alterations during pregnancy and parturition, a process known as involution. Attempts have been made to hasten this process, but with minimal success. Mycobacterium cell wall fraction (MCWF) is an immunomodulator that has been shown to reduce bacterial growth and alter aspects of the immune response to breeding,...
Hewes CA, Schneider RK, Baszler TV, Oaks JL.A 12-year-old American Saddlebred gelding was referred to a veterinary teaching hospital for evaluation of a chronic lameness problem in the right radiocarpal joint. The horse had been treated for osteoarthritis of the right radiocarpal joint with multiple injections of cortisone during the past 3 years. The horse was severely lame on the right forelimb at a trot. Radiography and computed tomography revealed a 3 x 2-cm lytic defect in the distal portion of the radius and periarticular bone proliferation around the right radiocarpal joint. Ultrasonography of the distal portion of the radius rev...
Merritt AM, Kohn CW, Ramberg CF, Cimprich RE, Reid CF, Bolton JR.Five clinically normal, mature horses and 11 with chronic diarrhea were given 51Cr-tagged Cohn fraction V equine albumin intravenously. All urine and feces were collected separately, and blood for plasma analysis was taken periodically for 5 to 8 days after injection of the isotope. Plasma clearance of albumin into the intestinal tract of normal horses was calculated as 0.67 +/- 0.23 (SD) ml/kg of body weight/day, with 1.33 +/- 0.69% of the 51Cr dose appearing in the feces in 5 days. Of the 11 diarrheal horses, 8 had a plasma clearance of 0.49 +/- 0.21 ml/kg/day with 1.12 +/- 0.68% of the dose...
Caston SS, Sponseller BA, Dembek KA, Hostetter JM.A reformulation of Mycobacterium cell wall fraction immunotherapeutic can be used to successfully treat sarcoids in horses. Sarcoids are reported to be the most common equine skin tumors with tumor type and location influencing the choice of treatment. Wide surgical excision is curative for many tumors, but may not always be feasible. Previous studies have reported sarcoid regression after injection with mycobacterial cell wall immunotherapeutics. A new formulation of the Mycobacterium phlei cell wall fraction immunostimulant (Immunocidin Equine) was used to treat cutaneous tumors in horses. E...
Leifsson PS, Olsen SN, Larsen S.This paper is the first report of systemic tuberculosis involving the eyes in a horse. The animal lost condition and gradually became increasingly blind in both eyes; it was eventually euthanased. The pathological findings included bilateral, mycobacterial granulomatous uveitis with unilateral retinal detachment and necrosis, and disseminated, mycobacterial granulomatous foci in the myocardium, lungs, bronchial lymph nodes, kidneys, liver, pancreas, colon and visceral serosal surfaces, with the most extensive lesions in the myocardium. The mycobacteria were identified as Mycobacterium avium.
Sarradell JE, Alvarez J, Biscia M, Zumarraga M, Wunschmann A, Armien AG, Perez AM.A 2-year-old dappled Percheron horse had a wasting condition that did not respond to antibiotic treatments and ultimately resulted in death. Thickening of the wall of the large colon and enlargement of the mesenteric lymph nodes were observed at postmortem examination, along with the presence of pinpoint whitish foci in the liver. Microscopic examination of affected tissues revealed diffuse chronic granulomatous enterocolitis, granulomatous mesenteric lymphadenitis, and multifocal granulomatous hepatitis. The DNA extracted from paraffin-embedded intestinal and lymph node samples was analyzed u...
Fedorka CE, Schnobrich MR, Muderspach ND, Scoggin KE, Dedman MT, Weigle KE, May MG, Twist H, Linse CR, Douglas RH, Troedsson MHT.Equine embryonic loss following the development of endometrial cups delays return to cyclicity due to the production of equine chorionic gonadotropin (eCG). Natural degradation of endometrial cups coincides with an influx of immune cells at 100-120 days of gestation, but therapeutic stimulation of reduced eCG production has been relatively unsuccessful. Recently, we observed an increase in pro-inflammatory cytokine production following the use of the immunostimulant mycobacterium cell wall fraction (MCWF). Objective: To evaluate the efficacy of hysteroscopic-guided injection of MCWF on the a...
Kramer AJ, Meziara Wilson T, Kimura S, Groover E, DeLeon-Carnes M, Neto RLALT.A 23-y-old gelding was presented to a veterinary teaching hospital with a history of chronic, refractory diarrhea. Clinically, the horse was in poor body condition, with a thickened and corrugated large intestine identified by transcutaneous abdominal ultrasonography. At postmortem examination following euthanasia, the large colon and cecum had segmental thickening of the intestinal wall with innumerable mucosal ulcers and prominent polypoid mucosal masses. Many mesenteric and hepatic lymph nodes were enlarged. Histology revealed granulomatous and ulcerative typhlocolitis and granulomatous lym...
