Clinical and epidemiologic features of an epizootic of equine leukoencephalomalacia

A herd of 15 mature riding horses with a history of anorexia, weight loss, and lethargy was examined. The animals had been fed a 50/50 mixture of commercial sweet feed and corn screenings contaminated with a heavy growth of Fusarium moniliforme. Thirteen of the horses had one or more neurologic signs. The most characteristic signs were profound depression and mild ataxia. Over the 19-day course of the epizootic, the horses had increasing severe neurologic deficits, including unilateral blindness and delirium. Despite the clinical appearance of dehydration, 12 horses had low PCV (16 to 27%), hematocrit (21.2 to 31.0%; determined by automated cell counter), and RBC counts (3.76 to 5.5 x 10(6) RBC/microliters). White blood cell counts were variable (4,900 to 17,000 WBC/microliters). Necropsy findings included diffuse malacia of the white matter of the frontal cortex and severe multifocal perivascular hemorrhage in the white matter of the temporal cortex, basal ganglia, anterior medulla, and pons. One horse had a hepatic lesion consisting of a mixed inflammatory cell infiltrate and bile duct proliferation. The attack rate of this epizootic was 100%. The course of disease was unusually long in some animals. In an experiment, the fusarium-infected corn screenings were fed to horses and did not cause clinical signs or alterations in blood or serum biochemical values.     

Clinical and biochemical features of grass sickness (equine dysautonomia)

An attempt has been made to assess the diagnostic value of clinical features seen at initial examination of horses with grass sickness, colic cases and cases submitted as possible grass sickness but diagnosed subsequently as some other condition. There appears to be no single pathognomonic sign for grass sickness. A range of signs has been associated with grass sickness but these are of value only when related to the length of illness and the history. Biochemical tests related to intestinal tissue damage, stress and dehydration were evaluated and most were found to be of value in diagnosing acute grass sickness. No evidence was found relating selected mineral or vitamin deficiencies to grass sickness, nor were protein changes specific. A marked fall in glutathione peroxidase values was associated with grazing rather than disease.     

Clinical and neuropathological features of West Nile virus equine encephalomyelitis in Italy

West Nile (WN) virus infection is a mosquito-borne flavivirosis endemic in Africa and Asia. Clinical disease is usually rare and mild and only in a few cases the infection causes encephalomyelitis in horses, fever and meningoencephalitis in man. We report here the clinical and pathological findings in an epidemic of the disease involving 14 horses from Tuscany, Italy. All cases were observed from August to October 1998. Affected horses showed ataxia, weakness paresis of the hindlimbs and, in 6 cases, there was paraparesis progressing to tetraplegia and recumbency within 2 to 9 days. Eight animals recovered without any important consequences. Serological investigations revealed positivity to WN virus in all the 14 horses and the agent was isolated from the cerebellum and spinal cord of an affected horse. Postmortem examination was carried out on 6 horses. The neuropathological pattern was that of a mild to moderate, nonsuppurative polioencephalomyelitis with constant involvement of the ventral horns of the thoracic and lumbar spinal cord, where focal gliosis and haemorrhage were also apparent in some cases. Differential diagnoses with other equine viral encephalomyelitides are discussed. Climatological and environmental characteristics of the geographic area in which the outbreaks occurred suggest the existence of suitable conditions for the development of the disease. This is the first report of WN virus equine encephalomyelitis in Italy.     

Short- and long-term effects of platelet-rich plasma upon healthy equine joints: Clinical and laboratory aspects

This study aimed to verify whether transient inflammatory reactions incited by the administration of intra-articular platelet-rich plasma (PRP) affected joint components through short- and long-term in vivo evaluation of inflammatory biomarkers and extracellular matrix degradation products in synovial fluid. The effects of PRP were analyzed in a short phase protocol (SPP) and in a prolonged phase protocol (PPP), using saline-injected joints as controls. In the SPP, higher white blood cell counts and prostaglandin E₂ and total protein concentrations were observed in the synovial fluid of PRP-treated joints (P < 0.05). There were no differences between the interleukin-1β, interleukin-1 receptor antagonist protein, tumor necrosis factor-α, chondroitin sulfate, or hyaluronic acid concentrations between PRP and saline injected joints. In the PPP, there were no differences in evaluated parameters between groups. PRP injection elicits a mild and self-limiting inflammatory response shortly after administration, without long-term deleterious effects on joint homeostasis.     

Clinical, cytologic and histopathologic manifestations of protothecosis in two dogs

Two cases of sudden onset of blindness associated with ocular protothecosis in dogs are reported. Both were adult, spayed female, mixed-breed dogs that lacked the usual clinical signs of systemic infection with Prototheca species. Physical abnormalities at the time of presentation were limited to the affected eyes which had serous discharge, hyperemic conjunctiva, and aqueous flare. The pupillary light reflexes were slow, and the menace reflexes were absent. Both dogs had glaucoma. Results of complete blood counts and serologic titres for antibodies to Blastomyces dermatitidis and Histoplasma capsulatum were within reference intervals. Protothecosis was diagnosed by cytologic analysis of vitreous humor and was confirmed at necropsy. These two cases were unusual because of their presenting signs and prolonged course of disease progression.     

Canine intraspinal meningiomas: imaging features, histopathologic classification, and long-term outcome in 34 dogs

BACKGROUND: Meningioma is the most common primary intraspinal nervous system tumor in dogs. Clinical findings, clinicopathologic data, and treatment of these tumors have been reported sporadically, but little information is available regarding cerebrospinal fluid (CSF) analysis, histologic tumor grade, or efficacy of radiation therapy as an adjunct to cytoreductive surgery. ANIMALS: Dogs with histologically confirmed intraspinal meningiomas (n = 34). METHODS: A retrospective study of dogs with intraspinal meningiomas between 1984 and 2006 was carried out. Signalment, historical information, physical examination, clinicopathologic data, radiation therapy protocols, surgery reports, and all available images were reviewed. All tumors were histologically classified and graded as defined by the international World Health Organization classification scheme for central nervous system tumors. RESULTS: Intraspinal mengiomas in dogs are most common in the cervical spinal cord but can be found throughout the neuraxis. Location is correlated with histologic grade, with grade I tumors more likely to be in the cervical region than grade II tumors. Myelography generally shows an intradural extramedullary compressive lesion. On magnetic resonance imaging, the masses are strongly and uniformly contrast enhancing and a dural tail often is present. CSF analysis usually shows increased protein concentration with mild to moderate mixed pleocytosis. Surgical resection is an effective means of improving neurologic status, and adjunctive radiation therapy may lead to an improved outcome. CONCLUSIONS AND CLINICAL IMPORTANCE: Biopsy is necessary for definitive diagnosis, but imaging and CSF analysis can suggest a diagnosis of meningioma. Treatment of meningiomas with surgery and radiation therapy can result in a fair to excellent prognosis.     

Clinical, virologic, and histopathologic observations of induced porcine parvovirus infection in boars

Twelve 8- to 12-month-old crossbred boars were inoculated with a virulent strain (NADL-8) of porcine parvovirus (PPV). Hemicastrations were performed on 6 boars 3, 7, 10, 14, 21, and 28 days after an IM injection of 10(8) median cell culture infectious dose (CCID50) of PPV (n = 3) or injection of 10(7.4) CCID50 given intratesticularly (IT, n = 3). Noninfected cell culture medium (0.25 ml) was injected into each testicle of a 7th boar (IT inoculated control). Virus or viral antigen was detected in testicular and epididymal tissues up to 14 days after inoculation. Direct immunofluorescence indicated that viral antigen was mainly associated with the vasculature of the interstitium. Microscopic lesions were not evident in the testicles and epididymides of IM inoculated boars. Acute-to-chronic testicular degeneration was evident in the IT inoculated boars, as well as in the IT inoculated control boar. Six boars were inoculated IM or orally/nasally with 10(7.9) CCID50 of PPV. Semen was collected twice weekly for 8 weeks after inoculation. Virus was not detected in any ejaculates. Semen also was collected from 4 boars for 5 weeks before inoculation, and preinoculation and post-inoculation semen quality was compared. Pronounced changes in sperm output, ejaculate volume, motility, or morphologic defects were not observed. The reproductive consequences of experimental PPV infection in boars were minimal because reproductive function was unaffected and venereal transmission of PPV was not detected.     

Historical, clinical and laboratory features of 126 hyperthyroid cats.

The historical and clinical features and the haematological and biochemical changes in 126 cats with hyperthyroidism are described; 125 of the cats were domestic short- or longhaired, and one was a chinchilla. There were 62 males and 64 females with a mean age of 13.0 years. The duration of signs ranged from two days to two years with a mean of 5.4 months. The historical and clinical features were weight loss, polyphagia, polyuria/polydipsia, tachycardia, hyperactivity, diarrhoea, respiratory abnormalities, other cardiac abnormalities, skin lesions, vomiting, moderately raised temperature, decreased activity, decreased appetite, congestive cardiac failure, haematuria and intermittently decreased appetite. Goitre was palpable in 123 cats. The serum total thyroxine concentrations of the cats were more than three standard deviations above the mean of the reference range. Serum total tri-iodothyronine concentrations ranged from 0.78 to 14.96 nmol/litre and were within the reference range in 11 of the cats. Mild hyperthyroidism was a much commoner cause of high normal or marginally above normal thyroid hormone concentrations than severe, concurrent, non-thyroidal illness. Other common biochemical changes were increased of serum alanine aminotransferase, urea, aspartate aminotransferase, alkaline phosphatase and lactate dehydrogenase. There were minimal changes in the red cell parameters. Leucocyte changes showed two trends: a mature neutrophilia, either with or without an accompanying leucocytosis often in association with a lymphopenia, or an eosinophilia, either with or without a lymphocytosis.     

Significant features of the epidemiology of equine influenza in Queensland, Australia, 2007

An outbreak of equine influenza (EI) caused by influenza A H3N8 subtype virus occurred in the Australian states of Queensland and New South Wales in August 2007. Infection in the Australian horse population was associated with the introduction of infection by horses from overseas. The first case of EI in Queensland was detected on 25 August 2007 at an equestrian sporting event. Infection subsequently spread locally and to other clusters through horse movements prior to the implementation of an official standstill. There were five main clusters of infected properties during this outbreak and several outliers, which were investigated to find the potential mechanism of disease spread. To contain the outbreak, Queensland was divided into infection status zones, with different movement controls applied to each zone. Vaccination was implemented strategically in infected areas and within horse subpopulations. Control and eventual eradication of EI from Queensland was achieved through a combination of quarantine, biosecurity measures, movement control, rapid diagnostic testing and vaccination.     

Clinical and laboratory features of a severe form of von Willebrand disease in Shetland sheepdogs

Ten clinically affected Shetland Sheepdogs were evaluated to define their severe bleeding diathesis and were determined to have von Willebrand factor antigen (vWF:Ag) values less than 0.1% by ELISA assay. The virtual absence of vWF protein by ELISA assay and on multimeric analysis was diagnostic of either homozygosity or probable double heterozygosity for the canine von Willebrand disease (vWD) gene. Clinically affected dogs have type-III vWD and are the offspring of 2 heterozygous parents carrying type-I vWD. Twenty-three percent (1,428 dogs) of the more than 6,000 Shetland Sheepdogs screened for vWD at our facility since 1982 tested within the heterozygous carrier range for the common type-I form of this inherited disorder. Veterinarians and breeders should be aware of the potential for bleeding associated with elective and medical procedures in Shetland Sheepdogs and should use caution when breeding carriers of vWD because of the risk of producing clinically affected offspring with severe type-III vWD.     

Investigating equine ingestive, maternal, and sexual behavior in the field and in the laboratory.

Some of the techniques that may be used to study social, reproductive, and ingestive behavior in horses are described in this paper. One of the aspects of equine social behavior is the dominance hierarchy or patterns of agonistic behavior. Paired or group feeding from a single food source may be used to determine dominance hierarchies quickly. Focal animal studies of undisturbed groups of horses may also be used; this method takes longer, but may reveal affiliative as well as agonistic relationships among the horses. Reproductive behavior includes flehmen, the functional significance of which can be determined using combinations of field observations of harem groups and laboratory studies of stallions exposed to female urine or feces in the absence of the donor mare. Ingestive behavior may include food, salt, or water intake. Direct and indirect measurements of intake can be made and used to answer questions regarding the ability of horses to control their energy intake when the diet is diluted, the effect of feral equids on the ecology of an area, and the abilities of horses to compensate for dehydration and hypovolemia.     

Epidemiological features of 5009 cases of equine cryptorchism

Data from 16 North American veterinary university teaching facilities, 5009 cryptorchid horses, were analysed using relative risk methodology. In five breeds (Thoroughbred, Standardbred, Morgan, Tennessee Walking horse and Arabian), cryptorchism was diagnosed significantly (P less than 0.05) less frequently than expected by their representation in the hospital population. Three breeds, (Percheron, American Saddle horse and American Quarterhorse), plus ponies (as a group) and crossbred horses were significantly over-represented within the series. The over-representation of Quarter-horses was evident at each veterinary teaching facility. Other developmental defects and testicular tumours diagnosed in cryptorchid horses were presented. Analysis of the frequency of diagnosis of second anomalies among cryptorchids showed testicular hypoplasia to occur significantly more often, and inguinal and umbilical hernias less often, than expected (P less than 0.05).     

Species-specificity of equine and porcine Lawsonia intracellularis isolates in laboratory animals

Lawsonia intracellularis infection causes proliferative enteropathy (PE) in many mammalian species, with porcine and equine proliferative enteropathy (PPE and EPE) known worldwide. Hamsters are a well-published animal model for PPE infection studies in pigs. There is no laboratory animal model for EPE infection studies and it is not known whether there is species-specificity for equine or porcine isolates of L. intracellularis in animal models. The objective of this study was to determine whether it is possible to generate typical EPE lesions in hamsters after inoculation with an equine strain of L. intracellularis (EPE strain) and whether it is comparatively possible to generate PPE lesions in rabbits after inoculation with a porcine strain of L. intracellularis (PPE strain). In 2 separate trials, 4-week-old and 3-week-old weanling golden Syrian hamsters were challenged with EPE strains and compared to uninfected (both trials) and PPE-infected controls (Trial 2 only). Concurrently, 6 female New Zealand white juvenile rabbits were infected with PPE strain and observed concomitantly to 8 similar rabbits infected with EPE strain for a different experiment. Hamsters and rabbits were observed for 21 to 24 days post-infection (DPI), depending on the experiment. Neither infected species developed clinical signs. The presence of disease was assessed with diagnostic techniques classically used for pigs and horses: immune-peroxidase monolayer assay on sera; quantitative polymerase chain reaction (qPCR) detection of molecular DNA in feces; and hematoxylin and eosin (H&E) stain and immunohistochemistry (IHC) on intestinal tissues. Our results showed that EPE-challenged hamsters do not develop infection when compared with PPE controls (IHC, P = 0.009; qPCR, P = 0.0003). Conversely, PPE-challenged rabbits do not develop typical intestinal lesions in comparison to EPE-challenged rabbits, with serological response at 14 DPI being significantly lower (P = 0.0023). In conclusion, PPE and EPE strains appear to have different host-specificities for hamsters and rabbits, respectively.     

Enzyme histochemical features of equine gluteus muscle fibers

Gluteal muscle specimens were taken from 4 horses. From 1 of the 4 gluteal muscles, serial sections were prepared. Individual muscle fibers were identified and studied, using photomicrographs of sections stained by different enzyme histochemical methods. In specimens in which cytoplasmic soluble enzymes were studied, use was made of the semi-permeable membrane technique to hamper enzyme diffusion into reaction fluids. Enzymes involved in glycogenolysis, glycolysis, the tricarboxylic acid cycle, synthesis of reduced nicotinamide adenine dinucleotide phosphate, the pentose phosphate cycle, the alpha-glycerolphosphate shuttle, the respiratory chain, catabolism, and muscular contraction were studied. Some key enzymes of different metabolic pathways were also included. Each of 3 fiber types identified had distinct features. Type I fibers were characterized by a relatively strong aerobic capacity, compared with type IIA fibers, which were more glycolytic and had strong aerobic and moderate-to-strong anaerobic capacity. Type IIB fibers were characterized by a relatively low aerobic and a relatively high anaerobic capacity, and were glycolytic. Activities of phosphofructokinase, glyceraldehyde-3-phosphate dehydrogenase, lactate dehydrogenase, and alpha-naphtylesterase (nonspecific esterase) were so markedly different in the 3 fiber types that fiber typing was possible, aided by the demonstration of the activities of these enzymes. In type IIB fibers, the pentose phosphate cycle was more important than in the other fiber types. Except for the unexplained high alpha-naphtylesterase activity in type IIB fibers, catabolic enzymes were not active in healthy equine muscle fibers.     

Immunohistochemical and histopathologic features of 14 malignant fibrous histiocytomas from Flat-Coated Retrievers

Flat-Coated Retrievers seem to be at increased risk of developing soft-tissue sarcomas, and undifferentiated round cell or spindle cell sarcomas account for approximately 59% of sarcomas in the breed. In an attempt to classify these tumors further, formalin-fixed, paraffin-embedded sections from 14 undifferentiated sarcomas from Flat-Coated Retrievers were reviewed and examined with a panel of histologic and immunohistochemical stains. The panel included vimentin, desmin, Myo D1, smooth muscle actin, cytokeratin, S100, von Willebrand factor (factor VIII), Mac 387, CD3, major histocompatibility complex (MHC) class II, and CD79a. The majority of the sarcomas showed greater than 70% staining for MHC class II. We conclude that these undifferentiated sarcomas in Flat-Coated Retrievers belong to a spectrum of tumors with varying proportions of characteristic cell types and morphologic features, some of which fit the diagnostic criteria for malignant fibrous histiocytoma. Many of these sarcomas seem to have a significant myofibroblast component and a mild or moderate T cell infiltrate but the precise cell lineage is still uncertain.