Pathology in horses involves the study of diseases and abnormalities affecting equine health, encompassing a range of conditions that can impact various systems within the horse's body. This field examines the causes, mechanisms, and effects of diseases, as well as the structural and functional changes they induce in equine tissues and organs. Common pathological conditions in horses include laminitis, colic, equine infectious anemia, and respiratory disorders. Understanding these diseases involves evaluating clinical signs, diagnostic methods, and treatment options. This page compiles peer-reviewed research studies and scholarly articles that explore the etiology, pathogenesis, and clinical implications of pathological conditions in horses.
Platt H, Whitwell KE.A form of generalized fat necrosis and steatitis occurs in pony and donkey foals. The clinical and pathological features of this disorder are described and its possible relationship to a similar condition in the Thoroughbred foal, and to yellow Fat Disease in other species, is discussed.
Barnett AL, Steel JD, Stewart GA.Free erythrocyte protoporphyrin was estimated in 166 Thoroughbred horses and the mean value was found to be 4o vg.Poo ml. packed cells. Signifi-cantly lower haemoglobin concentrations were found in 21 horses whose erythrocyte protoporphyrin concentration was 7o p.g.lioo ml. packed cells or greater.
Henderson BE, Chappell WA, Johnston JG, Sudia WD.Henderson, B. E., W. A. Chappell, J. G. Johnston, Jr. and W. D. Sudia (CDC, Atlanta, Ga. 30333). Experimental Infection of horses with three strains of Venezuelan equine encephalomyelitis virus. I. Clinical and virological studies. Amer J Epidem 93: 194–205, 1971.—Clinical effect, viremias and antibody responses were compared in horses inoculated with the following strains of Venezuelan equine encephalomyelitis (VEE) virus: Fe3-7C, isolated from Culex (Melano-conion) spp. mosquitoes collected In 1963 in the Florida Everglades; TC-83, the Fort Detrick live, attenuated vaccine strain; and GJ...
Palmisano M, Bender S, Johnson AL.We describe the unique clinical presentation of a central nervous system neoplasm in a 6-month-old draft horse cross gelding. Based on the neurologic examination at admission, neurolocalization was most consistent with a mildly asymmetric cervical, multifocal, or diffuse myelopathy. Mild vestibular involvement also was considered, but no cranial nerve deficits were observed. The gelding was negative for Sarcocystis neurona or Neospora hughesi based on paired serum and cerebrospinal fluid (CSF) samples analyzed, with no evidence of cervical compression based on contrast myelography. The horse w...
Charman RE, Vasey JR.Chronic facial defects extending into the sinuses of two mares were repaired using periosteal flaps. Partial osseous bridging was established over the defects following repair. Previous attempts to close the defects with skin alone had failed. A periosteal flap is a simple surgical technique that provides the foundations for successful repair, despite the chronicity of some fistulae.
Kraft W.Neurological examination in equine practice, physiological findings and pathological disturbances are described. Because of the sizes of the horse the neurological examination is more difficult than in small animals. The examination of cerebrospinal fluid is a worthful completion and is able to refer to the etiology of a certain disease. The technique of the puncture of cerebrospinal fluid is described.
Gysens L, Depuydt E, Patruno M, Haspeslagh M, Spaas JH, Martens A.Sarcoids are the most common equine skin tumours Although they do not metastasize, they can be locally aggressive and cause significant clinical symptoms in affected horses. Despite being common, very little is known about the host immune response and the biological mechanisms underlying persistence and recurrence of equine sarcoids. The latter reflects the need for further research in this field. This in-vitro study used sarcoid explants from horses with naturally occurring sarcoids (n = 12) to evaluate the induction of a humoral immune response directed against equine sarcoid-derived bovin...
Van Hoogmoed LM, Snyder JR, Nieto J, Harmon FA.To determine whether a customized solution could attenuate the effects of low-flow ischemia and reperfusion injury of the equine jejunum. Methods: A segment of jejunum obtained from 21 healthy adult horses. Methods: A segment of jejunum was maintained in an isolated extracorporeal circuit, and arterial flow was reduced to 20% of baseline for 40 minutes (ischemia) followed by 60 minutes of reperfusion. In 1 group, a customized solution was infused at a rate of 1 ml/min during low-flow ischemia and 3 ml/min during reperfusion. In a second group, the solution was infused at the same rate during l...
Guarda F, Rattazzi C.The authors describe pathologic and histopathologic findings of three cardiac aneurysms in horses, two of which in the left ventricle and one in the right ventricle. The aneurysms were always associated with multiple foci of myocardiac fibrosis. A hypothesis concerning histogenesis of the lesion is formulated.
Erkert RS, MacAllister CG, Higbee R, Moll HD, Reiners S, Crowson C, Bahr R, Bartels KE.Use of a neodymium:yttrium-aluminum-garnet laser to remove exuberant granulation tissue from the esophagus of a horse A 4-year-old Quarter Horse mare was evaluated because of recurrent esophageal obstruction. Endoscopic examination revealed a proliferative mass in the esophagus approximately 55 cm aborad to the nares. Histologic examination of biopsy specimens revealed diffuse suppurative esophagitis and granulation tissue with no evidence of neoplasia. The mass was excisedand ablated transendoscopically with a neodymium:yttrium-aluminum-garnet laser. During a follow-up examination 2 weeks aft...
Fatemi-Nainie S, Anderson LW, Cheevers WP.MC-1 is an equine sarcoid-derived cell line which spontaneously releases a retrovirus possessing genomic sequence homology with an inducible endogenous retrovirus of normal equine cells. A complete characterization of MC-1 tumor cells was undertaken, including morphology, growth kinetics, and saturation density, selective growth in semisolid media, uptake of 2-deoxyglucose, and tumorigenicity in athymic nude mice. MC-1 cells, in contrast to normal equine dermal fibroblasts, exhibit all of the characteristics of malignantly transformed cells.
Lepage OM, Laverty S, Drolet R, Lavoie JP.A case of infiltrative lipoma in the left flank of a yearling Quarter Horse is described. Rectal palpation, percutaneous ultrasonographic examination, the marbled appearance and poor delineation from surrounding tissues strongly suggested an infiltrative lipoma. This was confirmed by histological examination. Infiltrative lipomas should be included in the differential diagnosis of soft masses located in equine muscle.
Beard WL, Byrne BA, Henninger RW.Irreducible ileocecal intussusceptions pose a difficult surgical problem. Strangulating ileocecal intussusceptions involving the ileum and jejunum were identified in 2 horses undergoing exploratory laparotomy because of colic. Surgical correction in both horses was achieved by amputation of the ileocecal intussusception from within the cecal lumen, via typhlotomy. The inverted ileal stump was blindly stapled near the ileocecal orifice after pulling the intussusceptum into the cecum. A jejunocecostomy was performed to reestablish intestinal continuity.
Patterson-Kane JC, Tramontin RR, Giles RC, Harrison LR.A 14-year-old Thoroughbred gelding with a history of acute onset of hematuria was presented for necropsy. Transitional cell carcinoma of the urinary bladder with intra-abdominal dissemination was diagnosed. Tumor masses were observed on the splenic capsule and surrounding the distal abdominal aorta. Tumor cells showed diffuse cytoplasmic reactivity for cytokeratin but were negative for epithelial membrane antigen, carcinoembryonic antigen, tumor-associated glycoprotein 72, and vimentin.
Sweeney CR, Weiher J, Baez JL, Lindborg SR.The endobronchial anatomy of 12 lung specimens from horses and 12 healthy, standing, sedated horses was evaluated, using a 200-cm-long, 9.5-mm-diameter videoendoscope. On the basis of these findings, the nomenclature system of Amis and McKiernan was modified for identification of airways of horses during bronchoscopy. Lobar bronchi are identified on the basis of the side of the bronchial tree on which they were found and the order in which they originated from the primary bronchus. Thus, RB1, RB2, and RB3 referred to right cranial lobar bronchus, respectively. On the left side, the designation...
Nation PN.Over sixteen years, 49 horses were diagnosed by Alberta Agriculture Animal Health laboratories as having "alsike clover poisoning". There was a distinct northwestern distribution of cases, the majority coming from the Peace River district. This distribution is opposite to that of the Alberta horse population, but coincides with areas of alsike clover cultivation. Cases could be divided into chronic or nervous clinical presentations, as described by Schofield. Tissues from 45 animals were retrieved and examined microscopically. Significant histological lesions were confined to the liver and con...
Milde AK.The objective of this study was to establish whether the carpal joints in horses are subject to development of arthrosis to a larger extent than previously assumed. Furthermore, an attempt has been made to clarify whether clinical diagnostical resources presently available are sufficient for accurate evaluation of the status in carpus. The present results show that an analysis of the synovia fluid is of little value in case of chronica arthrosis in carpus. Histilogical examination of the synovia membrane has been of limited value in this cases as it has not been possible to arrive at a definit...
Röcken H, Wenz C.A unilateral malformation of the eye of a thoroughbred foal is described. The specific form of the tiny lens we named, "lenticulus". It is correlated with a maximal unchangeable mydriasis. The bulb shows physiological size. A brown-black pigmented mass inhibited (internal) inspection and examination of the middle and rear part of the eye. Special emphasis is laid on the insecure behaviour of the foal. A connection with an iridocyclochoroiditis, which was treated in the mare about a year ago, and the pathological changes in the eye of the foal is not evident.
Kelly LH, Uzal FA, Poppenga RH, Kinde H, Hill AE, Wilson WD, Webb BT.Two horses that consumed well water with high fluoride content exhibited clinical signs of chronic dental and skeletal fluoride toxicosis and were later euthanized and autopsied. Both horses had degenerative disease of multiple joints and multiple dental defects. Elevated fluoride concentrations were found in bone and tooth samples of both horses, well water, and feed. Microscopically, abnormalities were noted in bone and tooth samples, and consisted mostly of foci of cement necrosis and hypercementosis. Horses exhibiting bilateral, highly symmetrical dental and/or skeletal lesions, with chron...
Kumbhani TR, Raval SH, Parmar RS, Patel JG, Bechara VJ, Sindhi PI, Modh SP.A 6-year-old Marwari mare presented with recurrent vulvar growth. The growth was surgically excised, fixed and processed routinely. Microscopically, neoplasm showed proliferation of epithelial and myoepithelial cells with tubulopapillary pattern. On immunohistochemistry, myoepithelial cells showed strong immunoreactivity with smooth muscle actin alpha and p63. On basis of histopathology and immunohistochemistry, tumour was diagnosed as complex apocrine carcinoma. This case report describes first confirm vulvar complex apocrine carcinoma in equines.
Evers P, Hoffmann B.This paper describes the use of hormone analysis in the diagnosis of adrenal cortex dysfunction in the dog, cat and horse. Analytical problems concerning the determination of corticosteroid levels are discussed and the pathology of adrenal dysfunction is briefly presented. The paper focuses on the problems in establishing physiological norms for adrenal function based on the established assays. Own experiences and other reported data are referred to.
Sano Y, Kuwajima H, Kanai H, Baba C, Azami K, Matsuda K.A 24-year-old, Thoroughbred gelding presented with difficulty breathing for a few days and intermittent nose bleeding before dying. At necropsy, the bronchoesophageal artery and the bronchial artery that flowed into the left anterior lobe were tortuous and dilated, and it was found that dilated tortuous branches of the bronchial artery ran over the dorsal and ventral surfaces of the left anterior lobe. Histopathologically, an anastomosis between a muscular artery and an elastic artery were demonstrated, which were identified as bronchial and pulmonary arteries, respectively. Based on the gross...
Doige CE.A midsagittal centrum cleft of T5-6, malformation and fusion of T3-7, intra- and extraspinal cyst, and myelodysplasia were found in a 3-month-old female Arabian foal that had experienced posterior ataxia since birth. Based on studies in other species, ecto-endodermal adhesions early in embryogenesis leading to formation of an enterogenous cyst is the most probable pathogenesis.
Vreman S, Wiemer P, Keesler RI.A 10-year-old KWPN (Royal Warmblood Studbook of the Netherlands) gelding was euthanized after developing severe neurological symptoms preceded by severe epistaxis during laser treatment for progressive ethmoid haematoma (PEH) in the right nasal cavity. Postmortem examination of the head revealed a large amount of clotted blood between the right ventral and dorsal conchae in the nasal cavity and acute haemorrhage in the right subarachnoid space. Histologically, there was moderate, acute polioencephalomalacia in the neuropil adjacent to the haemorrhage. The haemorrhages were most likely caused b...
Smiet E.Lately there has been a tendency to discuss Equine Cushing's disease and its related phenomena, due to the amount of recently acquired research data. The author has composed a brief overview of the present situation emphasizing relevance for practitioners.
Rinnovati R, Xenos S, Beltrame A, Marigo A, Forni G, Morini M.A neurofibroma was excised from the subcutis on the medial side of the left thigh of a 15-year-old Warmblood gelding, which had shown lameness of the left hind limb. No other source of lameness was found. Two weeks after surgery, the horse was sound at a lameness examination.
Marsella R.Autoimmune dermatopathies are not common in horses. These autoimmune diseases can be idiopathic or triggered by an antigen such as drugs, vaccines, or neoplasia. The most common one is pemphigus foliaceus, which manifests as a pustular, crusting eruption. Other more common pustular diseases should be ruled out before considering pemphigus. Vasculitis is relatively common in horses and can be triggered by a variety of antigenic stimulations. Systemic lupus and true idiopathic autoimmune vasculitis are very rare in horses. Every effort should be made to reach a final diagnosis, as the prognosis ...
Prutton J, Tucker R.Neoplasia has been reported to involve the majority of the urinary system of the horse, with tumors affecting the kidneys and bladder most comprehensively described. Primary tumors of the external genitalia are relatively common in the horse and are easily identified on clinical examination while primary tumors of the upper urogenital tract are uncommon. This article will highlight the common tumors, their clinical presentations, and discuss potential medical and surgical treatment options available. The less common neoplasms will be mentioned but not discussed in depth.
Fintl C, Wilkins PA.There are a number of unusual tumors in the horse. Gross tumor characteristics, anatomical location, and signalment may assist with identification. Clinical pathology is often unrewarding with non-specific findings, while fine needle aspirates may not obtain sufficient tissue material to confirm a diagnosis. Although regular staining of biopsy material may be sufficient, immunohistochemistry markers may be required, especially in less differentiated tumors. The prognosis is dependent on the type, location, tumor size as well as on metastatic spread. A selection of unusual and rare tumors that ...
Lection J, Delvescovo B, Percival A, Wu T, Southard T, Diel de Amorim M, Cheong SH.In utero fracture and malunion of long bones is a rare condition in horses. Most foals with in utero fractures are aborted, and the identification of a fetal in utero fracture in a mare with dystocia has not been reported. A 7-year-old multiparous Standardbred mare presented to a referral center for correction of dystocia. Assisted vaginal delivery and controlled vaginal delivery attempts were unsuccessful mainly because of contracted tendons impeding mutation. As the foal was alive, a cesarean section was elected. The foal was delivered but ultimately euthanized because of the congenital abno...
Valberg SJ.Although horses most commonly develop exertional rhabdomyolysis, there are numerous causes for nonexertional rhabdomyolysis (nonER) that pose a serious health threat to horses. Their etiologies can be broadly categorized as toxic, genetic, inflammatory/infectious, nutritional, and traumatic and a variety of diagnostic tests are available to discern among them. This study discusses causes of nonER as well as diagnostics and treatments that are specific to each etiology. General treatment of acute rhabdomyolysis is covered in detail in the study in this issue on sporadic and recurrent exertional...
