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Topic:Pathology
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.
Experimental cantharidiasis in the horse. Crystalline cantharidin in an alfalfa cake or in aqueous suspension was given to 8 horses at a dosage level of 450 to 489 micrograms/kg of body weight (group 1) and 2 horses at a dosage level of 720 micrograms/kg (group 2) via nasogastric tube. Both group 2 horses and 1 group 1 horse died. Horses were evaluated at 6-hour intervals for 36 hours and then again at postcantharidin hours 48. Data evaluation consisted of a comparison of the nonsurvival and survival data to one another and their respective base-line values at each sampling period, irrespective of the route of administration and dosag...
Inhibited development of cyathostominae in the horse in the early third stage. Inhibited early third stage larvae of Cyathostominae were found in the digested mucosa of the large intestine of 12 yearling, female Shetland ponies, which were used in two grazing experiments. The ponies were killed in late autumn. In some ponies the inhibited larvae were very abundant and in most animals the majority of the Cyathostominae populations consisted of these early third stage larvae, suggesting that the phenomenon has an epidemiological significance.
Vestibular syndrome associated with temporohyoid joint fusion and temporal bone fracture in three horses. Acute onset of vestibulocochlear and facial nerve dysfunction due to a stress fracture of the petrous part of the temporal bone was diagnosed in 3 horses. The fracture was secondary to chronic inflammatory changes in the petrous part of the temporal bone and the proximal stylohyoid bone, with fusion of the temporohyoid joint. Bacterial meningoencephalitis was a complicating factor. Treatment resulted in reduction of severity of clinical signs in 2 of the 3 cases, but residual compensated vestibular deficits persisted.
Pitfalls in immunofluorescence testing in dermatology. III. Pemphigus-like antibodies in the horse and direct immunofluorescence testing in equine dermatophilosis. Indirect immunofluorescence testing for pemphigus-like antibodies was performed on 79 horses: 28 horses with various nonpemphigus dermatologic diseases, 21 horses with various nondermatologic diseases, and 30 normal horses. Pemphigus-like antibodies were detected in 6 horses: 3 normal horses with titers of 1:40, 2 horses with dermatophilosis at titers of 1:10 and 1:80, and 1 horse with lymphosarcoma at a titer of 1:320. It was concluded that equine pemphigus-like antibodies are a potential source of misinterpretation and misdiagnosis in indirect immunofluorescence testing. Direct immunofluores...
Prevalence of equine sarcocystis in British horses and a comparison of two detection methods. Sarcocystis was detected in oesophageal samples from 245 (62 per cent) of 394 horses and ponies killed at a Cheshire abattoir between February and August 1981. Prevalence of infection was closely related to age, increasing from 28.6 per cent of animals up to two years old to 88.9 per cent of those over eight years old. There were no significant regional differences in prevalence between horses from north west England, Yorkshire or South Wales. Significantly more female horses were infected (69.7 per cent) compared with males (56.2 per cent). Gross examination methods detected fewer than 55 per...
Chondrosarcoma in the radius of a horse. An aged Thoroughbred stallion was examined because of progressive lameness, carpal swelling, and weight loss. Radiography revealed a destructive lesion in the caudomedial, distal portion of the radius. Chondrosarcoma was diagnosed by tumor-core biopsy. Gross and histologic evaluation of the neoplasm after necropsy revealed a locally invasive chondrosarcoma at the distal end of the radius that infiltrated the radiocarpal joint capsule and invaded the carpal bones. The malignant nature of this tumor was evident by its invasiveness and histologic features of cell pleomorphism and presence of mito...
Dirofilariasis with arteriosclerosis in a horse. Arteriosclerosis caused by Dirofilaria immitis adult parasites was diagnosed in a 20-month-old Quarter horse stallion that died from cantharidin toxicosis. Microscopically, the pulmonary vascular changes were typical of those described as "proliferative endarteritis" in D immitis-infected dogs.
Equine hydatidosis: a new record for New Zealand. Cysts found in the liver of a horse which had never been out of New Zealand were used to infect two dogs which were slaughtered 35 days after infection. Large numbers of Echinococcus granulosus were recovered. These cestodes were compared with mature dog-sheep cestodes, using light and scanning electron microscopy and identified as the dog-horse strain of E.granulosus.
Immunoglobulin levels in tears and aqueous humor of horses before and after diethylcarbamazine (DEC) therapy. A quantitative investigation of equine tear and aqueous humor immunoglobulins was done using normal horses and ponies as well as horses and ponies infected with Onchocerca cervicalis. The equine immunoglobulin isotypes IgGa, IgM, IgA and IgG(T) were quantitated by either single radial immunodiffusion (SRID) or radioimmunoassay (RIA). Tear immunoglobulin levels for IgGa (128 +/- 151 micrograms/ml), IgA (1,664 +/- 1,038 micrograms/ml) and IgM (106 +/- 74 micrograms/ml) were measured, while IgG(T) was not detectable. In horses with ocular inflammation the IgGa was 18-fold higher in the tears, 2,2...
Vascular pathology in phenylbutazone intoxicated horses. Three mature Thoroughbred geldings were given 13.63 mg phenylbutazone/Kg bodyweight intravenously for 3 days and repeated in one horse 4 days later. After 4, 7 and 10 days (double treatment), degeneration of the wall of small veins occurred in all horses. The veins were dilated and/or showed hyalin degeneration. The phlebopathy was interpreted to be paramount in phenylbutazone intoxication. All other manifestations, including erythro- and leukodiapedesis, submucosal edema and ulceration of the gastrointestinal mucosa, phlebothrombosis and significant changes in the hemogram and serum chemistry...
Maduromycosis (Madurella mycetomatis) in a horse. A case of maduromycosis mycetoma caused by Madurella mycetomatis is reported. The horse presented with multiple subcutaneous swelling over the right scapula. There were no discharging fistulae present. Macroscopically the lesion contained a black granular material embedded in a granulomatous mass. Microscopically large numbers of microcolonies were present containing segmented hyphae. No typical chlamydospores were observed. Cultures yielded a fungus identified as Madurella mycetomatis. Treatment consisted of surgical excision and local treatment with thiabendazole powder.
Seasonal variation of histomorphologic features of equine endometrium. The effect of seasonal morphologic variation of equine endometrium on histologic interpretation of periglandular fibrosis was investigated in 5 mares. Endometrial tissue was procured monthly and examined microscopically for the degree of periglandular fibrosis. A prognostic category for each mare was based on the mean number of fibrotic foci per linear field of 5.5 mm. It was found that seasonal changes reflected in endometrial glands and stroma influenced quantitative assessment of fibrosis. This occasionally resulted in a change in the assigned prognostic category. Marked nonseasonal variati...
Culture characteristics and tumorigenicity of the equine sarcoid-derived MC-1 cell line. 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.
Pyloric stenosis in a yearling with an incidental finding of Capillaria hepatica in the liver. PYLORIC stenosis occurs commonly in man and the dog but only rarely in the horse and cat. Two reports of pyloric stenosis in the horse have been published, both of these occurring in foals of less than two months of age (Barth, Barber and Mackenzie 1980; Crowhurst, Simpson, McEnery and Greenwood 1975). Surgery on the pylorus performed under general anaesthesia was successful in both cases. This report describes a case of pyloric stenosis in a Thoroughbred yearling.
Perilla ketone toxicity: a chemical model for the study of equine restrictive lung disease. Perilla ketone was assessed for its usefulness as a model of equine restrictive pulmonary disease. Three ponies were given 18 mg/kg bodyweight synthetic perilla ketone in dimethyl-sulphoxide. Within 24 h of administration, respiratory rate, peak inspiratory and expiratory flow rates and minute volume were increased. By 48 h there was a significant decrease in tidal volume, and blood pH and base excess were also decreased but not outside normal limits. At necropsy there was congestion and oedema of the lungs. Histologically there was diffuse alveolar injury but no evidence of significant obstru...
Cauda equina neuritis: a chronic idiopathic polyneuritis in two horses. Two cases of cauda equina neuritis are compared and contrasted. Neurological deficits of the tail and perineum were noted and functional deficits were seen in gait, urination, defecation and cranial nerve function. Lesions consisted of nonsuppurative inflammation of the nerve trunks and proliferation of the perineurium of the cauda equina. Cranial nerve involvement in one case supported a diagnosis of polyneuritis equi rather than cauda equina neuritis. The possible etiologies and pathogenesis of this disease are discussed.
The comparative pathology of equine cutaneous phycomycosis. Pythiosis (204 cases, 77%), basidiobolomycosis (48 cases, 18%), and conidiobolomycosis (14 cases, 5%) were diagnosed morphologically from 266 horses with phycomycosis. All lesions were cutaneous ulcerative granulomas and three horses with pythiosis had metastatic lesions in regional lymph nodes. Lesions of pythiosis contained characteristic yellow, coral-like coagula and had a fibrotic surface containing sinus tract openings. Basidiobolomycosis was characterized by infrequent small yellow coagula and a yellow line of fungal invasion beneath an edematous surface. Lesions of conidiobolomycosis h...
Plaque assay of equine influenza virus. ESK cells, a stable cell line derived from a swine embryo kidney, were found to be a good medium for plaque formation of the Prague and Miami strains of equine influenza virus. Factors influencing the plaque formation were investigated and a plaque assay for these viruses was worked out. The method is not only simple enough for routine use, but also is as sensitive as the egg inoculation method. The method was readily adapted for a neutralization test.
Choledocholithiasis in a horse. Choledocholithiasis was diagnosed in a five-year-old gelding on the basis of laboratory results and histopathology. Surgery was performed to relieve the obstruction. The horse responded favorably and at 39 days postoperatively was clinically and clinicopathologically normal.
Pathology of equine granulomatous enteritis. A morphological study on equine granulomatous enteritis (EGE) in 13 horses is presented. All horses were young (1 to 5 years old) standardbreds. Based on gross pathology, cases were classified into those with diffuse (11 cases) and those with localized (2 cases) small bowel lesions. The granulomatous reaction in the gut was marked by diffuse and patchy infiltrates and distinct granulomas, composed of epithelioid cells, macrophages and lymphoid cells, and was devoid of necrosis. Salient accompanying features of the small bowel included lymphoid hyperplasia, peri-lymphatic and transmural inflamm...
Laser therapy in the horse: histopathologic response. Surgical incisions were made in the skin and superficial digital flexor tendons in horses. A low intensity laser therapy device was used to treat the limbs. After laser therapy was completed, skin and superficial digital flexor tendons from incised laser-irradiated, incised-control, and nonincised-control limbs were compared microscopically. Qualitative differences between laser irradiated and nonirradiated tissues were not found. The laser therapy device used in this study may be of insufficient power to affect wound healing.
Management of thermal injuries in large animals. The pathophysiology and histopathology of thermal burns in large animals is very similar to that in humans. Burns are classified as first degree, superficial and deep second degree, third degree, and fourth degree, depending upon the depth of thermal injury. Most severe burns will produce a local and a systemic response--both of which must be properly treated to increase the patient's chances for survival. The systemic response is mainly characterized by hypovolemia, fluid and electrolyte loss, protein loss, pulmonary edema, increased caloric requirements, and depressed immune responses. The l...
