Necropsy, also known as an autopsy, is a systematic examination of a horse's body after death to determine the cause of death and evaluate any disease or injury. This procedure involves a thorough assessment of the horse's organs and tissues, often including histopathological analysis to identify abnormalities at the microscopic level. Necropsy can provide valuable insights into equine health issues, contributing to a better understanding of disease processes, management practices, and potential preventive measures. This page compiles peer-reviewed research studies and scholarly articles that explore the methodologies, findings, and implications of necropsy in equine veterinary science.
Palmer AC, Rossdale PD.A neuropathological investigation was carried out on the brains of 18 foals suffering from the neonatal maladjustment syndrome and results were compared with those obtained from the brains of nine foals dying from other causes. Necrosis of the cerebral cortex of an ischaemic nature was found in nine of the neonatal maladjustment foals, frequently accompanied by local haemorrhage. In three of this group of foals there was also necrosis in the diencephalon and brain stem. In the brains of the nine other affected foals there was haemorrhage in the cerebrum and sometimes in the brain stem and cere...
Bolton JR, Merritt AM, Cimprich RE, Ramberg CF, Streett W.The D-xylose absorption test was applied to clinically normal horses and to horses with signs of gastrointestinal disease. A dosage of 0.5 grams of xylose per kilogram of bodyweight was useful in detecting horses that absorbed the pentose abnormally. The clinical findings were correlated with gross and microscopic findings by biopsy and at necropsy. Gastrointestinal lesions associated with abnormal xylose absorption were classified as: 1) villous atrophy; 2) edema of the lamina propria or 3) necrosis of the lamina propria.
Damron GW.A survey of horses for gastrointestinal trichomonads was conducted to determine the organism's role in equine diarrhea and to establish its proper identity and morphology. Trichomonads were found by cultural examination of feces of 101 (35%) of 289 apparently healthy horses. At necropsy, trichomonads were cultured from 11 (37%) of another 30 horses which showed no signs of diarrhea at the time of death. In 4 of the 11 horses, colonies of trichomonads numbered 30,000 to 150,000/ml of cecal fluid. Diarrhea was induced in 1 of 6 horses, with the fecal fluid containing 10,000 to 110,000 trichomona...
Moffatt RE, Kramer LL, Lerner D, Jones R.Concentrations of dioctyl sodium sulfosuccinate (DSS) ranging from three to five times the recommended dosage produced severe diarrhea, rapid dehydration and death in seven horses and 66 guinea pigs when administered experimentally per os. Clinicopathological findings indicated hemoconcentration in both horses and guinea pigs. There was a leucocytosis in the guinea pigs given the highest dosages. In all cases the principal finding at necropsy was extreme fluid distention of the intestinal tract. There was histopathological evidence of epithelial denudation and vascular stasis. The LD50 in the ...
Slocombe JO, McCraw BM.Four pony foals were inoculated with Strongylus edentatus infective larvae and on days 3 and 4 postinfection two of the ponies were treated with thiabendazole, each at the rate of 440 mg/kg of body weight. Total circulating eosinophil counts in untreated ponies increased to over 1700 per cu mm after the second week postinfection. In the treated ponies as well as in an uninfected untreated pony eosinophil counts did not increase beyond 100 per cu mm. At necropsy on day 35 postinfection the cecum, colon and omentum of treated ponies were normal and few tracks were present on the surface of the l...
Whitlock RH, Dellers RW, Shively JN.A three-week-old Arabian filly was admitted to the Large Animal Hospital with a respiratory disorder and died despite symptomatic treatment. The necropsy lesions were suggestive of viral pneumonia. An equine adenovirus were isolated from nasal and pharyngeal swabs and from several tissues after death. Typical adenovirus virions were demonstrated by electron microscopy.
Azzie MA.Contrary to common belief, Gastrodiscus aegyptiacus can be pathogenic to horses. History of cases of a particular stud, necropsy findings, diagnosis, and successful treatment with hexachlorophene and with dichlorvos are recorded. The presence of eggs can be established by a special flotation technique.
Harrington DD.Spontaneous Tyzzer's disease is described in quarter horse foals which died suddenly with no clinical history of apparent illness. Significant gross findings included icterus, focal paletan areas in the liver and catarrhal entercolitis. Focal dark red lesions were present in the small intestine of one foal, and the mesenteric lymph nodes of another were enlarged and hyperemic. Histopathologically, the liver showed multiple discrete and confluent foci of necrosis, fatty change, sinusoid congestion and haemorrhage. Bundles of intracytoplasmic bacilli were demonstrated in hepatocytes at the margi...
Amend JF, Ross JN, Garner HE, Rosborough JP, Hoff HE.This report describes the measurement of systolic time intervals in a nine year old female domestic pony which was found at necropsy to show coarctation of the aorta and bilateral ventricular hypertrophy. Electrocardiogram, phonocardiogram and direct arterial blood pressure were recorded from the pony in a standing unmedicated state and systolic time intervals were measured from the resulting tracings. A prolongation of left ventricular ejection time and shortening of the pre-ejection period were observed in comparison to a group of normal ponies similarly examined. Such changes are consistent...
McCraw BM, Slocombe JO.Pony foals inoculated with infective Strongylus edentatus larvae were monitored for clinical signs and selected blood changes and were examined at necropsy from two to 56 days postinfection. Larvae penetrated the intestine and reached the liver intravenously before 40 hours postinfection. Occasional thrombi and larval tracks associated with the intima of cecal and colic veins suggested aberrant paths. Larvae in the liver doubled in width between seven and 15 days postinfection and a sudden increment in circulating eosinophils occurred between 11 and 15 days. These changes were probably associa...
Ardans AA, Pritchett RF, Zee YC.A viral agent was isolated from lung tissue obtained upon necropsy of an Arabian foal which had exhibited clinical signs of pneumonia. The virus is 75 nm in diameter, cubic in symmetry, and resistant to chloroform and low pH (3.0). It contains deoxyribonucleic acid and has a buoyant density of 1.31 g/cm(3) in cesium chloride. These findings indicate that the virus is a member of the adenovirus group.
Else RW, Holmes JR.The normal histology of cardiac tissues has been described by many authors, for example Gross and Kugel (1931), Trautmann and Fiebiger (1952), Gould (1968), Bloom and Fawcett (1969) and Ham (1969). In the horse, a few reports have described microscopic valvular pathology in detail (Ackerknecht 1923, Imre 1933, Ubach and Cler 1944). Experimentally induced lesions have been reported by Wadsworth (1919), Wadsworth and Sickles (1927) and Miller (1944), and endocarditis was described by Winqvist (1945) and Dobin (1959, 1968).
In 1966, Smetzer, Bishop and Smith outlined the valvular pathology ass...
Kimble KM, Gomez G, Szule JA, Dubey JP, Buchanan B, Porter BF.An adult American Quarter Horse gelding with a history of weight loss presented with an acute onset of colic, fever, soft faeces and elevated liver enzymes. At necropsy, there were gastric mucosal masses and evidence of caecal necrosis. Histologically, the masses were lymph nodes with granulomatous inflammation and areas of liquefactive necrosis. Within and surrounding necrotic areas were free and intrahistiocytic clusters of protozoal tachyzoites. Similar but milder inflammation was evident in the spleen, lungs and liver. Necrotizing typhlitis was also evident. Immunolabelling for Toxoplasma ...
French DD, Klei TR, Taylor HW, Chapman MR, Wright FR.The efficacy of ivermectin in oral paste formulation at a dosage of 200 micrograms/kg of body weight was tested against naturally acquired larval and adult stages of Parascaris equorum, in a controlled study. Twenty infected pony foals 18 to 27 weeks of age were randomly allocated to 2 groups of 10 each and were placed in dry lots. Foals in 1 group were given ivermectin on day 0. Necropsies and parasite recoveries from small intestines and lung tissues were performed on 5 foals in each group at 2 weeks after treatment (WAT) and on the remaining foals at 5 WAT. Ivermectin was 100% effective aga...
Bauquier J, Stent A, Gibney J, Jerrett I, White J, Tennent-Brown B, Pearce A, Pitt J.Investigation of toxicosis caused by Malva parviflora was required after 4 horses from the same farm developed severe muscle fasciculations, tachycardia, sweating and periods of recumbency leading to death or euthanasia after ingesting the plant. Objective: To describe historical, clinical, clinicopathological and pathological findings of 4 horses with suspected M. parviflora toxicosis. The role of cyclopropene fatty acids (found in M. parviflora) and mechanism for toxicosis are proposed. Methods: Case series. Methods: Historical, physical examination, clinicopathological and pathological find...
Lyons ET, Tolliver SC, Collins SS.Critical tests were carried out in 2008 in four yearling horses (H-2, H-4, H-10, and H-11) born and raised together on a farm (MC) in Central Kentucky. These horses were treated intraorally with ivermectin paste at the dose rate of 200 microg/kg. The main interest was to try and determine more precisely, from posttreatment (PT) worm count data, the current activity of ivermectin against small strongyles in a horse herd. These horses had been treated repeatedly with this compound and counts of small strongyle eggs per gram of feces (EPGs) of these parasites have been returning sooner than previ...
Reedy SE, Powell DM, Williams NM, Dodson MV, Fitzgerald BP.This paper describes attempts to initiate equine adipocyte cultures from necropsy cases with varying intervals from time of death to isolation and culture. Equine adipocytes were isolated from 21 necropsy cases, regardless of the interval from time after death to establishment in primary ceiling cultures. However, while all cultures produced adipocytes, only 2 attempts to produce long-term equine adipocyte cultures from the subcutaneous rump fat depots were successful and not contaminated. Findings from these experiments indicate that it is possible to collect and culture equine adipocytes fro...
Thomasy SM, Moeller BC, Stanley SD.To compare the density and binding characteristics of opioid receptor subtypes in horse, rat, and guinea pig cerebral cortex and cerebellum. Methods: Prospective receptor binding study. Methods: Whole brains were obtained from four neurologically normal adult horses during necropsy. Rat and guinea pig brains were obtained commercially. Methods: The cerebellum and cerebral cortex were dissected from each brain, and tissue homogenates prepared. A radioligand binding technique with the highly selective ligands [(3)H]-DAMGO, [(3)H]-U69593, and [(3)H]-DPDPE was used to identify the mu- (mu), kappa-...
Jenkins E, Backwell AL, Bellaw J, Colpitts J, Liboiron A, McRuer D, Medill S, Parker S, Shury T, Smith M, Tschritter C, Wagner B, Poissant J....Sable Island, Nova Scotia, Canada hosts one of few natural populations of feral horses (Equus caballus) never exposed to anthelmintics. Coproculture revealed cyathostomes, Strongylus equinus, S. edentatus, and S. vulgaris, with S. equinus (unusually) dominating in adult horses and cyathostomes dominating in young horses (<3 years of age). We examined 35 horses found dead in the springs of 2017 and 2018, as well as fecal samples from live horses in spring (n = 45) and summer 2018 (n = 236) using McMaster fecal flotation and Baermann larval sedimentation on fresh samples, and modified Wiscon...
Beech J, Boston R, Lindborg S, Russell GE.To compare the effect of thyrotropin-releasing hormone (TRH) administration on endogenous ACTH concentrations in healthy horses and those with pituitary pars inter-media hyperplasia and compare the test with the dexamethasone suppression test (DST). Methods: Prospective case series. Methods: 15 horses with clinical signs of pituitary pars intermedia dysfunction (PPID), 4 horses with equivocal signs of PPID, and 29 horses without signs of PPID. Methods: ACTH concentrations prior to and after administration of TRH were measured 61 times in 48 horses. Results of the DST (cortisol response) were c...
Williamson RM, Beveridge I, Gasser RB.To compare the sensitivities of three coprological techniques for the diagnosis of Anoplocephala perfoliata infection in horses and to assess the value of the methods for diagnosis of horses at risk of clinical cestodiasis. Methods: Faecal samples were collected from necropsied horses with or without A perfoliata infection and examined using one sedimentation and two different flotation methods. The coprological results were compared with worm counts performed at necropsy of the horses and the degree of mucosal damage. In addition, the efficiency of recovery of A perfoliata eggs from faeces wa...
Kuwano A, Yoshihara T, Takatori K, Kosuge J.This paper describes onychomycosis in horses and reports the pathological findings, associated fungi and incidence of concurrent white line disease. In addition to these observations, relevance between post mortem and clinical findings of onychomycosis are discussed in 3 necropsied horses. Samples were collected from 100 hooves from a total of 51 Thoroughbreds suffering from white line disease. Of these, 15 hooves from 13 horses were also complicated with severe hoof wall fissure formation. Preparations from the same samples were used both for histopathology and for culture to identify the ass...
Kuebelbeck KL, Slone DE, May KA.To determine if omentectomy would decrease the frequency of postoperative intraabdominal adhesions. Methods: Retrospective study. Methods: 44 horses that had either two ventral median celiotomies or a ventral median celiotomy and a necropsy more than 4 days later; 19 of these horses had their omentum removed at the initial surgery. Methods: Data retrieved from the records included location and type of intraabdominal adhesions; location of the surgical lesion; relationship of adhesions to the surgical lesion; surgical procedures; duration of initial surgery; time interval between procedures; ag...
Levine JM, Scrivani PV, Divers TJ, Furr M, Mayhew IJ, Reed S, Levine GJ, Foreman JH, Boudreau C, Credille BC, Tennent-Brown B, Cohen ND.To compare signalment of horses with cervical vertebral malformation-malarticulation (CVM) with that of control horses and to describe results of clinical examination, diagnostic imaging and necropsy findings, and reported outcome in horses with CVM. Methods: Retrospective case-control study. Methods: 270 horses with CVM and 608 control horses admitted to 6 veterinary hospitals from 1992 through 2007. Methods: Medical records of participating hospitals were reviewed to identify horses with CVM (ie, case horses) and contemporaneous control (non-CVM-affected) horses that were admitted for treatm...
Bertone AL, Stashak TS, Sullins KE, Ralston SL.Ten normal horses had approximately 95% of the length of the large colon resected with a side-to-side anastomosis between right ventral and right dorsal colon performed with surgical stapling equipment. Four horses died shortly after surgery of colitis (1 horse) or failure of the TA 90 transection staple line (3 horses). Another horse died 4 months after surgery from disseminated streptococcal infection but had recovered well from the colon resection. Five horses survived long term (18 months) with no clinical evidence of adverse effects of the resection. Surviving horses had weight loss and s...
Machida N, Nakamura T, Kiryu K, Haramaki S, Too K.A 20-year-old pony mare with persistent ventricular tachycardia (VT) was examined cardiopathologically. At necropsy, the heart was enlarged and rounded with both ventricular dilatation. In a longitudinal section of the ventricular septum, a large grayish white patchy lesion (5 x 25 mm) was detected in the relatively higher portion. Microscopically, the lesion was extensive myocardial fibrosis located in the vicinity of the proximal part of the left bundle branch. Partially the fibrotic lesion was in contact with the branch. Such a lesion might play an important role in creating a suitable back...
Yang C, Weisbrode S, Yardley J, Schroeder E, Premanandan C.Ischaemia-induced physeal injury has not been described previously in the horse. A 1-month-old Quarter horse foal was submitted for necropsy examination due to an acute onset of ataxia followed by a 4-week history of progressive decline. Focal narrowing of the spinal canal due to ventral compression by the rotation of the cranial aspect of the third cervical vertebra (C3) was observed. The metaphysis and diaphysis of C3 were markedly shortened and white-tan in colour. Microscopically, there was complete loss of the dorsal compact bone of C3 and replacement of 80% of the physis that runs parall...
Lyons ET, Drudge JH, Swerczek TW, Crowe MW, Tolliver SC.At necropsy of 49 Thoroughbreds from farms with generally good parasite control programs in central Kentucky, examination was specifically made for presence of Strongylus vulgaris in all of the horses and of Parascaris equorum in 21 of them. None of the deaths of the horses was caused by infections of internal parasites. Visceral arteries were examined for specimens of S vulgaris and lesions related to migrating stages of this parasite. Contents of the small intestines were examined for P equorum. Specimens of S vulgaris were recovered from 19 (39%) horses, and arterial lesions were observed i...
Rottman JB, Roberts MC, Cullen JM.Rectal palpation of a 30-year-old mixed-breed mare with chronic weight loss and intermittent, refractory abdominal pain revealed a mass in the right caudoventral portion of the abdomen. Hematologic and serum biochemical findings were normal except for slight mature neutrophilia and mildly high alkaline phosphatase activity and total bilirubin concentration. Cytologic examination of a specimen obtained by abdominocentesis revealed equal numbers of nondegenerative neutrophils and macrophages, but no evidence of neoplastic cells. The mare continued to have signs of abdominal discomfort and was eu...
Major MD, Grant BD, White KK, Ratzlaff MH, Gallina AM, Donati RM.The suspensory apparatus of one forelimb was surgically disrupted in six adult horses by transecting the distal sesamoidean ligaments. A double-braided prosthetic ligament made of aramid yarn was installed to support the flexor surface of the metacarpophalangeal joint. The prosthesis was routed through tunnels in the third metacarpal bone and proximal phalanx, and secured to bone with screws. Evaluation by radiography, synovial fluid analysis, cinematography, and dynamography was performed before surgery and at weeks 16 and 30. Supracondylar cortical lysis and periosteal proliferation were obs...
Uzal FA, Navarro MA, Asin J, Henderson EE.The clostridial diseases of horses can be divided into three major groups: enteric/enterotoxic, histotoxic, and neurotoxic. The main enteric/enterotoxic diseases include those produced by Clostridium perfringens type C and Clostridioides difficile, both of which are characterized by enterocolitis. The main histotoxic diseases are gas gangrene, Tyzzer disease, and infectious necrotic hepatitis. Gas gangrene is produced by one or more of the following microorganisms: C. perfringens type A, Clostridium septicum, Paeniclostridium sordellii, and Clostridium novyi type A, and it is characterized by ...
Lawhon SD, Taylor A, Fajt VR.Clinical specimens from dogs, cats, and horses were examined for the presence of obligate anaerobic bacteria. Of 4,018 specimens cultured, 368 yielded 606 isolates of obligate anaerobic bacteria (248 from dogs, 50 from cats, and 308 from horses). There were 100 specimens from 94 animals from which only anaerobes were isolated (25 dogs, 8 cats, and 61 horses). The most common sites tested were abdominal fluid (dogs and cats) and intestinal contents (horses). The most common microorganism isolated from dogs, cats, and horses was Clostridium perfringens (75, 13, and101 isolates, respectively). Th...
McElroy A, Rashmir A, Manfredi J, Sledge D, Carr E, Stopa E, Klinge P.Myodural bridges have been described in various species as connective tissue structures "bridging" small cranio-cervical muscles to the dura. Myodural bridges are thought to stabilize the dural sac during head and neck movements and promote cerebrospinal fluid motion; however, their role in neurological diseases has not yet been established. We report ultrasonographic visualization, necropsy, histopathologic and ultrastructural findings of myodural bridges in horses with hereditary equine regional dermal asthenia (HERDA), an equine model of Ehlers-Danlos syndromes. Five HERDA and 5 control hor...
Hinrichs K, Riera FL, Klunder LR.Embryo transfer was performed in three mares with gonadal dysgenesis. Karyotypes of the mares were as follows: Mare 1, 63,XX, 64,XX, 65,XX; Mare 2, 63,X; and Mare 3, 65,XXX. The mares were administered progesterone in oil, 300 mg intramuscularly daily, starting 1 or 2 days after donor mare ovulation. Embryos were transferred on day 7 after donor ovulation. Mare 1 became pregnant after the first embryo transfer and had a normally developing fetus on necropsy on day 45 of gestation. Mare 3 became pregnant after the third embryo transfer, but the embryo was lost between day 14 and day 18 of gesta...
Sweeney CR, Sweeney RW, Divers TJ.Case records of 48 foals with pneumonia due to Rhodococcus equi were reviewed. Twenty of the 48 foals survived and 28 died or were euthanized. There was no significant difference between the survivors and non-survivors in the age of onset of illness, duration of illness prior to admission, the mean white blood cell (WBC) count, or the mean plasma fibrinogen content. All foals had R. equi isolated from a tracheobronchial aspirate or lung specimens obtained at necropsy. All organisms were susceptible in vitro (Kirby-Bauer) to erythromycin and gentamicin. Susceptibilities to other drugs were: tri...
Trope GD, McCowan CI, Tyrrell D, Lording PM, Maggs DJ.A 22-year-old Australian stockhorse gelding was presented with anterior uveitis in the right eye which was nonresponsive to anti-inflammatory therapy. Clinical examination revealed corneal edema and vascularization, marked hypopyon, and thickening of the dorsal iris, which was confirmed by ultrasonography. Hematologic and biochemical analyses, abdominal and thoracic ultrasonography, and abdominocentesis with cytologic and biochemical analysis revealed no significant abnormalities. Cytological examination of an aqueous humor sample revealed a population of predominantly large lymphoblasts with ...
Brees DJ, Sondhoff AH, Kluge JP, Andreasen CB, Brown CM.A 7-month-old foal was admitted to the hospital with a history of lethargy, weight loss, mild diarrhea, and anorexia. A diagnosis of proliferative enteritis caused by Lawsonia intracellularis-like organisms was made after necropsy and histologic examination of the small intestine. Although infection with L intracellularis-like organisms is a rare cause of enteritis in foals, it should be considered in the differential diagnosis, especially if the foal was housed in the proximity of pigs or pig feces. Antemortem diagnosis remains challenging because isolation of the organism in fecal material r...
Nakayama H, Shiga T, Uchida K, Chambers JK, Morino T, Sasaki N.There is no nationwide necropsy database of animals in Japan, and most of the records are available from the postwar period. To clarify the chronological transition of animal necropsy cases in Tokyo, Japan, the records accumulated in The University of Tokyo from 1902 were investigated. Of necropsy records on paper or electronic from 1902 to 2021 kept at the Laboratory of Veterinary Pathology, The University of Tokyo, totally 3,137 cases including 572 in 1903-1914 (the Meiji-Taisho period), 1,258 in 1956-1969 (the Showa period) and 1,307 in 2006-2020 (the Heisei-Reiwa period), respectively, wer...
Corapi WV, Birch SM, Carlson KL, Chaffin MK, Snowden KF.CASE DESCRIPTION-A 22-year-old American Paint Horse gelding from the Gulf Coast region of Texas was evaluated for regrowth of a perirectal squamous cell carcinoma that had been surgically removed 11 months previously. CLINICAL FINDINGS-A necrotic and ulcerated mass was present below the anus. The horse had paraphimosis and was having difficulty with urination. Histologic examination of the mass revealed that it was squamous cell carcinoma, and the horse was euthanized because of the unlikelihood that the mass could be adequately resected and its close proximity to the urethra. OUTCOME-At necro...
Uzal FA, Diab SS, Blanchard P, Moore J, Anthenill L, Shahriar F, Garcia JP, Songer JG.Clostridium perfringens type C is one of the most important agents of enteric disease in newborn foals. Clostridium difficile is now recognized as an important cause of enterocolitis in horses of all ages. While infections by C. perfringens type C or C. difficile are frequently seen, we are not aware of any report describing combined infection by these two microorganisms in foals. We present here five cases of foal enterocolitis associated with C. difficile and C. perfringens type C infection. Five foals between one and seven days of age were submitted for necropsy examination to the Californi...
Ricard RM, St-Jean G, Atwal HK, Wobeser BK.This study aims to identify the most common causes of equine perinatal loss up to 7 d of age in Canada. Equine. Necropsy reports from 360 equine perinatal loss cases were acquired from provincial veterinary diagnostic labs across Canada. Each case was classified into a basic cause (noninfectious, infectious, or unidentified) of perinatal loss, then further classified into primary and secondary categories for analysis. Of the basic causes of perinatal loss, noninfectious causes were the most common. Bacterial causes, such as septicemia, were the most common primary diagnosis overall. was the m...
