Toxic Wasting Disorders in Sheep

Infectious and parasitic agents have been frequently associated with debilitating and wasting conditions in sheep. The prevalence of these agents has probably undermined the role of toxic causes as contributors to such disorders. In addition, many of these intoxications frequently produce acute clinical disease with specific and characteristic lesions, thus a causal relationship with the toxic substance may be relatively easy to establish. However, persistent exposure to some of these organic or inorganic toxic substances may lead to emaciation, ill-thrift, and poor external aspect. The anti-nutritional factors and alkaloids of several plants, including pyrrolizidine alkaloids, among others, have also been associated with emaciation and/or poor general performance in sheep flocks. In this review, some of these disorders are discussed with an emphasis on clinical signs and lesions, relevant diagnostic aspects, and available therapeutic approaches. In most cases, demonstrating a history of exposure should be one of the most relevant aspects of the diagnostic approach, and removing the animals from the toxic source is the cornerstone of the majority of the treatment strategies

Nutritional Wasting Disorders in Sheep

The different ovine production and breeding systems share the cornerstone of keeping a good body condition to ensure adequate productivity. Several infectious and parasitic disorders have detrimental effects on weight gains and may lead to emaciation. Flock health management procedures are aimed to prevent such conditions. Nutritional management is equally important to guarantee adequate body condition. Persistent bouts of low ruminal pH due to excess concentrate in the diet may lead to subacute ruminal acidosis. Pre-stomach motility disorders may also lead to ill-thrift and emaciation. An adequate mineral supplementation is key to prevent the effects of copper, selenium, and other micronutrients deprivation, which may include, among others, loss of condition. This review elaborates on the clinico-pathologic, diagnostic, and therapeutic aspects of some of these conditions, and highlights the necessity of considering them as contributors to states of wasting in sheep flocks

Exophiala Infection in Aquaria: Identification, Environmental Study and Challenge Experiments

Exophiala species are melanized fungi considered widely distributed in the environment, particularly in soil, decaying wood, polluted water and sewage; however, these fungi are recovered at low frequency from low-nutrient or hydrocarbon-polluted environments. Naturally occurring Exophiala species infection has been reported in both captive marine and freshwater teleosts, and in cartilaginous fish, with high mortality. E. salmonis and E. pisciphila are the most commonly isolated species, although more recently, novel species have been associated with infection in multiple fish species. ^ In two geographically distant commercial aquaria, ulcerative cutaneous lesions and disseminated fungal infections were identified in two separate captive populations of weedy and leafy seadragons. Culture of the lesions and molecular analyses of the sequences generated identified a novel Exophiala species, Exophiala sp. nov. Characteristic microscopic features of lesions in these fish were ulcerative skin lesions, renal necrosis and fungal vascular invasion. Exophiala sp. nov. isolates, that had greater than 99% nucleotide sequence identity to that isolated from seadragons, were later identified from similar ulcerative skin lesions and visceral lesions in a captive population of sandlance. While the source of the infection in these two separate populations of fish was thought to be environmental, culture of multiple tank environment sites and the water column during the phaeohyphomycotic outbreak in sandlance did not yield any Exophiala spp. isolates. ^ Experimental infections of chinook salmon in saltwater aquaria were conducted using Exophiala sp. nov. isolated from lesions in sandlance. Confirmation of melanized fungus in ulcerative skin lesions and in foci of renal necrosis, recovery of the fungus by culture from lesions, and identification of Exophiala species nov. by molecular testing of isolates fulfilled Koch\u27s postulates for associating a pathogen with disease and indicated that Exophiala sp. nov. can be a primary pathogen of salmon. In a separate pilot study, we confirmed that salmon in freshwater aquaria were susceptible to Exophiala sp. nov. infection by intraperitoneal inoculation and produced lesions in all the exposed fish. Experimental infection studies and taxonomic classification of Exophiala sp. nov. are useful in understanding the pathogenesis, epidemiology and treatment options for aquarium fish.

Infectious necrotic hepatitis caused by Clostridium novyi type B in a horse: case report and review of the literature

A 14-y-old bay Quarter Horse gelding was presented with progressive neurologic signs, elevated rectal temperature, and icterus for 3 d prior to death. Postmortem examination revealed icterus, large amounts of serosanguineous fluid in the abdominal cavity, widespread petechiae and ecchymoses in several organs, and a large, pale, and well-demarcated focus of necrosis in the liver. Histologically, there was coagulative necrosis surrounded by a rim of inflammatory cells and large numbers of gram-positive rods, which were identified as Clostridium novyi by immunohistochemistry. Liver samples tested by PCR were positive for C. novyi type B flagellin and alpha toxin genes, but negative for Clostridium haemolyticum and other clostridia. Based on postmortem findings and ancillary tests, a definitive diagnosis of infectious necrotic hepatitis (INH) was made. Mostly a disease of ruminants, also known as black disease, INH has rarely been reported in horses, and a definitive etiologic diagnosis has not been achieved previously; the etiology of all cases reported to date was identified as C. novyi but the type was not determined. Animals are predisposed to clostridial hepatitis when hepatic anaerobiosis is established. Such conditions allow germination and proliferation of bacterial spores, resulting in production and release of toxins. INH, caused by C. novyi type B, and bacillary hemoglobinuria, caused by C. haemolyticum, are mechanistically and pathologically almost indistinguishable. Because these 2 microorganisms are closely related, differentiation requires molecular tools

Streptococcus equi subspecies zooepidemicus septicemia in alpacas: three cases and review of the literature.

Streptococcus equi subspecies zooepidemicus septicemia of alpacas and llamas, also called alpaca fever, is characterized clinically by fever, depression, recumbency, and death, and pathologically by polyserositis. Although a few natural and experimental cases of the disease have been reported, very little information about the pathology of spontaneous cases has been published. We present a detailed gross and microscopic description of 3 spontaneous cases of alpaca fever and review the literature on this condition. Typical of spontaneous and experimental infections with S. equi ssp. zooepidemicus, the 3 animals had disseminated fibrinosuppurative polyserositis with vascular thrombosis and intralesional gram-positive cocci. In addition, 2 of the animals had severe fibrinosuppurative pneumonia, endocarditis, and myocardial necrosis; the third animal had transmural pleocellular enteritis with prominent lymphangitis. The enteric lymphangitis observed in the latter suggests that dissemination of S. equi ssp. zooepidemicus occurred through lymphatic circulation and that, at least in this animal, the portal of entry of infection was the alimentary system

Cluster of cases of massive hemorrhage associated with anticoagulant detection in race horses.

Five horses originating from 4 different California race tracks were submitted to the California Animal Health and Food Safety Laboratory for necropsy and diagnostic workup. The 5 horses had a history of sudden collapse and death during exercise. In all of them, massive hemoperitoneum and hemorrhages in other cavities or organs were observed. The liver from these 5 animals and from 27 horses that had been euthanized due to catastrophic leg injuries (controls) were subjected to a rodenticide anticoagulant screen. Traces of brodifacoum, diphacinone, or bromadiolone were detected in the 5 horses with massive bleeding (5/5), and no traces of rodenticides were detected in control horses (0/27). Other frequent causes of massive hemorrhages in horses were ruled out in 4 of the cases; one of the horses had a pelvic fracture. Although only traces of anticoagulants were found in the livers of these horses and the role of these substances in the massive bleeding remains uncertain, it is speculated that exercise-related increases in blood pressure may have reduced the threshold for toxicity of these anticoagulants

Paeniclostridium (Clostridium) sordellii-associated enterocolitis in 7 horses.

Enteric disease in horses may be caused by a variety of microorganisms, including several clostridial species. Paeniclostridium sordellii (previously Clostridium sordellii) has been frequently associated with gas gangrene in humans and several animal species, including horses. However, its role in enteric diseases of animals has not been fully determined. We describe herein 7 cases of enteric disease in horses associated with P. sordellii infection. Grossly, the small and/or large intestines were necrotic, hemorrhagic, and edematous. Microscopically, there was severe mucosal necrosis and hemorrhage of the small and/or large intestine of all horses. P. sordellii was isolated and/or demonstrated by immunohistochemistry and/or PCR in the intestine of all horses. All other known causes of enteric disease in horses were ruled out in these 7 cases. P. sordellii should be considered among the differential diagnoses in cases of enteric disease in horses