Clostridium spiroforme-associated enteric disease in domestic rabbits: a retrospective study of 32 cases in California, 1992-2019, and literature review.

Clostridium spiroforme has been associated with spontaneous and antibiotic-associated enteric disease (C. spiroforme-associated enteric disease, CSAED) in rabbits, which is clinically characterized by anorexia, diarrhea, or sudden death. Diagnosis is usually based on gross and microscopic lesions, coupled with finding the characteristic coiled bacteria in intestinal smears. Isolation of C. spiroforme is often challenging, and a PCR protocol has been developed. We reviewed 32 cases of CSAED submitted for autopsy to the Davis, Tulare, and Turlock laboratories of CAHFS between 1992 and 2019. The reported gross findings were soiling of the perineum, tail, and/or hind legs with diarrhea (16 of 32); gastric (16 of 32), small intestinal (6 of 32), cecal (15 of 32), and/or colonic (4 of 32) distention with brown-to-green, watery content; and serosal hemorrhages in the cecum (15 of 32). The most common microscopic finding was necrotizing enteritis (19 of 32), followed by cecal mucosal or submucosal edema (8 of 32), necrotizing or pleocellular typhlitis (6 of 32), necrotizing or heterophilic typhlocolitis (6 of 32), and cecal transmural hemorrhages (5 of 32). In all 32 rabbits, typical helically coiled, gram-positive bacilli were observed in fecal or intestinal smears. C. spiroforme was isolated from the intestinal content of 2 of 24 rabbits and detected by PCR assay in 8 of 8 rabbits.

The biology and pathogenicity of Clostridium perfringens type F: a common human enteropathogen with a new(ish) name.

SUMMARYIn the 2018-revised Clostridium perfringens typing classification system, isolates carrying the enterotoxin (cpe) and alpha toxin genes but no other typing toxin genes are now designated as type F. Type F isolates cause food poisoning and nonfoodborne human gastrointestinal (GI) diseases, which most commonly involve type F isolates carrying, respectivefooly, a chromosomal or plasmid-borne cpe gene. Compared to spores of other C. perfringens isolates, spores of type F chromosomal cpe isolates often exhibit greater resistance to food environment stresses, likely facilitating their survival in improperly prepared or stored foods. Multiple factors contribute to this spore resistance phenotype, including the production of a variant small acid-soluble protein-4. The pathogenicity of type F isolates involves sporulation-dependent C. perfringens enterotoxin (CPE) production. C. perfringens sporulation is initiated by orphan histidine kinases and sporulation-associated sigma factors that drive cpe transcription. CPE-induced cytotoxicity starts when CPE binds to claudin receptors to form a small complex (which also includes nonreceptor claudins). Approximately six small complexes oligomerize on the host cell plasma membrane surface to form a prepore. CPE molecules in that prepore apparently extend ß-hairpin loops to form a ß-barrel pore, allowing a Ca2+ influx that activates calpain. With low-dose CPE treatment, caspase-3-dependent apoptosis develops, while high-CPE dose treatment induces necroptosis. Those effects cause histologic damage along with fluid and electrolyte losses from the colon and small intestine. Sialidases likely contribute to type F disease by enhancing CPE action and, for NanI-producing nonfoodborne human GI disease isolates, increasing intestinal growth and colonization.

Lisosomal storage disease caused by ingestion of Astragalus spp in llamas: an emergent concern.

Lysosomal storage diseases are inherited or acquired disorders characterized by dysfunctional lysosomes that lead to intracytoplasmic accumulation of undegraded substrates, causing impaired cellular function and death. Many acquired lysosomal storage diseases are produced by toxic plants, which have indolizidine alkaloids, including swainsonine, that inhibits lysosomal α-mannosidase and Golgi α-mannosidase II. Swainsonine-induced nervous disease associated with various plants has been reported, including species of the genus Astragalus, Sida, Oxitropis, Swainsona, and Ipomoea. Two species of Astragalus (i.e. Astragalus garbancillo and Astragalus punae) have been found to cause neurologic disease in llamas. In addition, A. garbancillo was also associated with malformations in the offspring, and possibly abortions and neonatal mortality in llamas. The diagnosis of Astragalus spp. intoxication is established based on clinical signs, microscopic and ultrastructural findings, lectin histochemistry, abundance of these plants in the grazing area and determination of swainsonine in plant specimens.

Spontaneous intoxication of sheep by the pollen beetle Astylus atromaculatus: 4 outbreaks in Uruguay and Argentina.

Astylus atromaculatus Blanchard is a native beetle of South America that feeds on pollen. During the summer of 2022-2023 in Argentina and Uruguay, an explosive infestation of these insects occurred in pastures in which ruminants were grazing. This was believed to be associated with a severe drought, which had significantly reduced the flowering of crops. Three farms in Uruguay and one in Argentina were visited to examine the flocks and perform autopsies. Affected sheep had watery diarrhea, anorexia, depression, and ruminal atony. The average morbidity, mortality, and case fatality rates were 7.5%, 4.3%, and 68%, respectively. The main gross findings in all animals were in the jejunum; the serosa had multifocal hemorrhages, and the mucosa was necrotic and covered by a pseudomembrane. Microscopically, the mucosa had partial-to-complete necrosis of the lamina propria, as well as loss of villus and crypt epithelium with neutrophilic infiltration. Overlying the necrotic mucosa was a pseudomembrane of fibrin, cell debris, desquamated epithelial cells, degenerate neutrophils, and bacteria. Many specimens of A. atromaculatus were in all paddocks in which sheep grazed, as well as in the ruminal content of the autopsied animals.

Overexpressing the cpr1953 Orphan Histidine Kinase Gene in the Absence of cpr1954 Orphan Histidine Kinase Gene Expression, or Vice Versa, Is Sufficient to Obtain Significant Sporulation and Strong Production of Clostridium perfringens Enterotoxin or Spo0A by Clostridium perfringens Type F Strain SM101.

The CPR1953 and CPR1954 orphan histidine kinases profoundly affect sporulation initiation and Clostridium perfringens enterotoxin (CPE) production by C. perfringens type F strain SM101, whether cultured in vitro (modified Duncan-Strong sporulation medium (MDS)) or ex vivo (mouse small intestinal contents (MIC)). To help distinguish whether CPR1953 and CPR1954 act independently or in a stepwise manner to initiate sporulation and CPE production, cpr1953 and cpr1954 null mutants of SM101 were transformed with plasmids carrying the cpr1954 or cpr1953 genes, respectively, causing overexpression of cpr1954 in the absence of cpr1953 expression and vice versa. RT-PCR confirmed that, compared to SM101, the cpr1953 mutant transformed with a plasmid encoding cpr1954 expressed cpr1954 at higher levels while the cpr1954 mutant transformed with a plasmid encoding cpr1953 expressed higher levels of cpr1953. Both overexpressing strains showed near wild-type levels of sporulation, CPE toxin production, and Spo0A production in MDS or MIC. These findings suggest that CPR1953 and CPR1954 do not function together in a step-wise manner, e.g., as a novel phosphorelay. Instead, it appears that, at natural expression levels, the independent kinase activities of both CPR1953 and CPR1954 are necessary for obtaining sufficient Spo0A production and phosphorylation to initiate sporulation and CPE production.

Experimental oral administration of pollen beetle (Astylus atromaculatus) to cattle results in an acute lethal gastrointestinal disease.

In the summer of 2023, ingestion of Astylus atromaculatus (pollen beetle) was linked to spontaneous fatal disease in grazing cattle and sheep in Argentina and Uruguay. While the disease was experimentally reproduced in sheep and guinea pigs in the 1970's, no experimental reproductions have been attempted in cattle, and controversy exists as to whether this insect is indeed noxious to cattle and at which dose. Here, we demonstrate that A. atromaculatus causes acute fatal disease in Hereford calves at single oral dosages of 2.5, 4.5, 10.0, and 15.0 g of insect/kg body weight. Death or severe disease necessitating euthanasia occurred at 38 to 48 hours postinoculation regardless of the dose, suggesting that the single fatal dosage is likely <2.5 g/kg body weight (this dose representing approximately 850 mL of intact beetles in a 100 kg calf). Clinically, the disease was characterized by acute anorexia, prolonged recumbency, reluctance to move, listlessness/apathy, depression, ruminal hypomotility and tympany, hypothermia, bruxism with frothing at the mouth, and mucoid diarrhea progressing to death. Hematologic and biochemical alterations included hemoconcentration, stress/acute inflammatory leukogram, negative energy balance, and ketosis. The pathological hallmark of this experimental disease is acute necrotizing omaso-reticulo-rumenitis, fibrinohemorrhagic enteritis, and exfoliative colitis with intralesional chitinous insect fragments. While A. atromaculatus might contain a gastrointestinal toxin or pathogen, extensive toxicological testing failed to identify a causative toxin. Other pathomechanisms such as direct physical damage caused by insect fragments on the alimentary tract seem plausible, although further studies are needed to elucidate the pathogenesis of A. atromaculatus-associated disease.

Mannheimia haemolytica-associated fibrinonecrotizing abomasitis in lambs.

Mannheimia haemolytica-associated abomasitis has been clinically described as a cause of sudden death in lambs, but it is poorly characterized. We describe the pathological features of a severe fibrinonecrotizing abomasitis in 3 lambs that died suddenly. All 3 abomasums had a thickened submucosa due to edema and necrotic areas delimited by bands of degenerate neutrophils with slender nuclei (oat cells) and angiocentric distributions. The overlying mucosa was congested. Myriads of gram-negative coccobacilli were observed within the oat cell bands. M. haemolytica was isolated from the abomasum in all 3 animals and was serotyped as A2 in one of them. Pericarditis and pleuritis were observed in 2 of the lambs. Clostridium spp. were isolated in 1 lamb and detected by immunohistochemistry in the 3 animals, suggesting clostridial co-infection. M. haemolytica should be considered among the differential diagnoses of necrotizing abomasitis in lambs.

Botulism in fish: a review.

Published information about fish botulism is scant. We review here the current literature on fish botulism. Freshwater fish are susceptible to botulism. Only anecdotal evidence exists about possible botulism cases in saltwater fish. With only a few exceptions, the etiology of all cases of fish botulism reported is Clostridium botulinum type E, although fish are sensitive to, and may carry, various C. botulinum types. Clinical signs of botulism in fish include loss of equilibrium and motion, abducted opercula, open mouths, dark pigmentation, and head up/tail down orientation in which attempts to swim result in breaching the surface of the water. Dark pigmentation is thought to be associated with acetylcholine imbalance in botulinum neurotoxin (BoNT)-affected fish. Rarely, but similar to the situation in other animal species, fish can recover from botulism. Fish botulism can cause secondary outbreaks of the disease in birds, as botulism-affected fish stand out from normal fish, and are selectively preyed upon by fish-eating birds, which thus become intoxicated by the BoNT present in sick fish. The source of BoNT in fish has not been definitively confirmed. Fish may ingest C. botulinum spores that then germinate in their digestive tract, but the possibility that fish ingest preformed BoNT from the environment (e.g., dead fish, shellfish, insects) cannot be ruled out. The presumptive diagnosis of botulism in fish is established based on clinical signs, and as in other species, confirmation should be based on detection of BoNT in intestinal content, liver, and/or serum of affected fish.

Gingival squamous cell carcinoma in 2 lions under managed care.

Neoplasia is one of the main causes of euthanasia in geriatric captive nondomestic felids. However, few studies have examined oral tumors in these animals. We describe here the clinicopathologic features of gingival squamous cell carcinoma (SCC) in 2 lions (Panthera leo) from separate zoologic collections. In both cases, the lions had a history of sialorrhea, bloody oral discharge, and anorexia. Autopsy findings in both lions were similar and were characterized by poorly circumscribed, friable, and bloody gingival masses with grossly apparent invasion of the mandibular bone; a pathologic fracture was observed in 1 case. Histologically, the masses consisted of poorly circumscribed, unencapsulated, densely cellular proliferations of neoplastic epithelial cells arranged in irregular islands, cords, and anastomosing trabeculae with formation of keratin pearls, which, coupled with positive immunohistochemistry for pancytokeratin, were diagnostic for SCC. Although no metastases were found in either animal, both lions were ultimately euthanized because of poor prognosis.

Hepatic and renal lesions in sheep intoxicated with Urochloa hybrid Mulato II in Argentina.

A flock of 48 sheep in Argentina grazing on a pasture of hybrid Urochloa (formerly Brachiaria) Mulato II (Urochloa ruziziensis × Urochloa decumbens × Urochloa brizantha) developed facial dermatitis, severe jaundice, and weakness after brief physical activity. Blood biochemistry of 3 animals revealed azotemia, elevated aspartate aminotransferase activity, and increased direct, indirect, and total bilirubin concentrations. The urine was markedly turbid and contained large concentrations of bile pigments and protein. At autopsy of 2 animals, there was severe jaundice and subcutaneous submandibular edema. The livers were enlarged, intensely yellow, and had a marked acinar pattern. Gallbladders were distended, and the kidneys were diffusely dark in one animal and yellow-green in the other. Microscopically, there was lymphoplasmacytic and histiocytic cholangiohepatitis with abundant crystals in the lumen of bile ducts and in the cytoplasm of macrophages. The proximal and distal convoluted renal tubules had protein casts in their lumens, and crystals were observed in the lumen and epithelial cells. Lectin histochemistry showed strong affinity for Arachis hypogaea agglutinin in hepatic macrophages. In the one sheep that was tested for heavy metals, copper concentrations in the liver and kidney were within the RIs. Despite the immediate change of pasture, morbidity and mortality were 100% within 3 mo. The association between the consumption of this pasture, and the clinical, biochemical, pathology, and lectin histochemistry findings confirmed intoxication with Urochloa hybrid Mulato II. To our knowledge, intoxication by this hybrid of Urochloa has not been reported previously.

Pollen beetle (Astylus atromaculatus)-associated gastroenteric disease in cattle: report of 6 natural outbreaks.

Astylus atromaculatus is a pollen beetle native to South America, commonly found in crop flowers. Experimental intoxication of sheep and guinea pigs by this beetle resulting in fibrinonecrotizing enteritis has been reported. We describe here 6 natural outbreaks of intoxication in cattle associated with consumption of alfalfa (5 of 6) and mixed native (1 of 6) pastures heavily contaminated with A. atromaculatus. The outbreaks occurred during the summer (January-February) of 2023 in Argentina (n = 4) and Uruguay (n = 2), in beef cattle under extensive or semi-extensive rearing systems, with overall cumulative incidence and mortality of 22.3% and 17.8%, respectively. The main clinical signs included acute onset of anorexia, lethargy, hyperthermia, hindlimb weakness, reluctance to move, and diarrhea, for up to 15 d. In 2 outbreaks, sudden death was observed. Eight Hereford, Angus, and/or crossbreed heifers, cows, steers, and/or calves were autopsied. Gross and microscopic findings included multifocal necrosis with fibrinous pseudomembranes in the forestomachs and/or small and large intestines. Fragments or whole specimens of A. atromaculatus were identified in the ruminal content of all animals. Testing for multiple gastroenteric pathogens was negative as was testing of A. atromaculatus for cantharidin and batrachotoxin. GC-MS and LC-MS/MS performed on the beetles did not identify any known toxic compounds. Based on the exposure to A. atromaculatus-contaminated pasture, gross and microscopic lesions, and negative results of all testing for multiple gastroenteric pathogens, a diagnosis of intoxication by A. atromaculatus is proposed. Disease caused by A. atromaculatus consumption has not been reported previously in cattle, to our knowledge.

Epizootic of enterocolitis and clostridial overgrowth in NSG and NSG-related mouse strains.

While the immunodeficient status of NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ (NSG) and NSG-related mice provides utility for numerous research models, it also results in increased susceptibility to opportunistic pathogens. Over a 9-week period, a high rate of mortality was reported in a housing room of NSG and NSG-related mice. Diagnostics were performed to determine the underlying etiopathogenesis. Mice submitted for evaluation included those found deceased (n = 2), cage mates of deceased mice with or without diarrhea (n = 17), and moribund mice (n = 8). Grossly, mice exhibited small intestinal and cecal dilation with abundant gas and/or digesta (n = 18), serosal hemorrhage and congestion (n = 6), or were grossly normal (n = 3). Histologically, there was erosive to ulcerative enterocolitis (n = 7) of the distal small and large intestine or widespread individual epithelial cell death with luminal sloughing (n = 13) and varying degrees of submucosal edema and mucosal hyperplasia. Cecal dysbiosis, a reduction in typical filamentous bacteria coupled with overgrowth of bacterial rods, was identified in 18 of 24 (75%) mice. Clostridium spp. and Paeniclostridium sordellii were identified in 13 of 23 (57%) and 7 of 23 (30%) mice, respectively. Clostridium perfringens (7 of 23, 30%) was isolated most frequently. Toxinotyping of C. perfringens positive mice (n = 2) identified C. perfringens type A. Luminal immunoreactivity to several clostridial species was identified within lesioned small intestine by immunohistochemistry. Clinicopathologic findings were thus associated with overgrowth of various clostridial species, though direct causality could not be ascribed. A diet shift preceding the mortality event may have contributed to loss of intestinal homeostasis.

Gastrointestinal Impaction and Necrotic Enteritis in a Backyard Chicken.

The carcass of a 4-mo-old, female, mixed-breed backyard chicken was submitted for postmortem evaluation and diagnostic workup. The bird was previously presented to a veterinary clinic because of chronic weight loss and loose stool, and was euthanized before submission to the California Animal Health and Food Safety, Turlock lab. On gross examination, the proventriculus, gizzard, and duodenum were markedly distended and impacted with a mixture of fibrous plant material, cereal grain, and litter material. The koilin layer of the gizzard was eroded. There were multifocal to coalescing, 0.2-1-cm diameter white nodules on the serosal surface of the duodenal loop and lesions extended into the distal jejunum. The duodenum had multifocal, transmural, umbilicated, and ulcerated mucosal lesions, which were covered with a white pseudomembrane. Microscopically, there was segmental, transmural necrosis of the intestinal wall with diffuse sloughing of villi epithelium and accumulation of fibrino-hemorrhagic exudate with numerous bacterial colonies in the lumen. The gross and microscopic findings were indicative of gastrointestinal impaction and necrotic enteritis. Proliferation of Clostridium perfringens within the intestine was demonstrated by anaerobic bacterial culture, intestinal gram stains, and immunohistochemistry. The C. perfringens isolate was type F (encoding the gene for alpha toxin -cpa- and for enterotoxin -cpe) by PCR toxinotyping. Overgrowth of C. perfringens was likely exacerbated by the rough fibrous forage and highly fermentable grain diet. To our knowledge, gastrointestinal impaction concurrent with necrotic enteritis has not been described in backyard chickens. In addition, to our knowledge, C. perfringens type F has not been associated with necrotic enteritis in chickens.

Reporte de caso- Impactación gastrointestinal y enteritis necrótica en un pollo de traspatio. Para realizar una evaluación post mortem y estudios de diagnóstico, se recibió un pollo de traspatio muerto, hembra, de raza mixta y de cuatro meses de edad. El ave fue presentada previamente a una clínica veterinaria debido a la pérdida de peso crónica y heces acuosas y fue sacrificada antes de ser enviada al Laboratorio de Salud Animal y Seguridad Alimentaria de California con sede en Turlock. En el examen macroscópico, el proventrículo, la molleja y el duodeno estaban marcadamente distendidos e impactados con una mezcla de material vegetal fibroso, granos de cereal y material de hojarasca. La capa de koilin de la molleja estaba erosionada. Había nódulos blancos de 0.2 a 1 cm de diámetro, multifocales a coalescentes, en la superficie serosa del asa duodenal y las lesiones se extendían hacia el yeyuno distal. El duodeno presentaba lesiones mucosas multifocales, transmurales, umbilicadas y ulceradas, las cuales estaban cubiertas por una pseudomembrana blanca. Microscópicamente, había necrosis transmural segmentaria de la pared intestinal con desprendimiento difuso del epitelio de las vellosidades y acumulación de exudado fibrino-hemorrágico con numerosas colonias bacterianas en el lumen. Los hallazgos macroscópicos y microscópicos fueron indicativos de impactación gastrointestinal y enteritis necrótica. La proliferación de Clostridium perfringens dentro del intestino se demostró mediante cultivo de bacterias anaerobias, tinciones de Gram intestinales e inmunohistoquímica. El aislado de C. perfringens fue tipo F (que codifica el gene de la toxina alfa ­cpa- y de la enterotoxina ­cpe) por tipificación de toxina mediante PCR. El crecimiento excesivo de C. perfringens probablemente fue exacerbado por el forraje áspero y fibroso y la dieta de granos altamente fermentables. Hasta donde se conoce, la impactación gastrointestinal concurrente con enteritis necrótica no se ha descrito en pollos de traspatio. Además, hasta donde se sabe, C. perfringens tipo F no se ha asociado con enteritis necrótica en pollos.

Yellow oleander (Thevetia peruviana) toxicosis in 4 goats.

Four alpine goats developed diarrhea soon after the owner placed plant clippings believed to be yellow oleander (Thevetia peruviana) into their pen on a suburban property near Palm Desert, CA, USA. A 1-y-old female goat died suddenly ~1 h after eating the plant clippings and was submitted to the San Bernardino Branch of the California Animal Health and Food Safety Laboratory System for postmortem examination. The main autopsy and histopathologic findings were myocardial hemorrhage and necrosis, consistent with cardiac glycoside intoxication. Rumen contents were analyzed by LC-MS/MS; peruvoside, a cardiac glycoside, was detected, but oleandrin, the cardiac glycoside of common oleander (Nerium oleander), was not. An LC-high-resolution MS (LC-HRMS) analysis revealed the presence of peruvoside and neriifolin in the rumen contents and in a tested plant fragment, indicating that the plant was a member of the Thevetia genus. A clipping from the plant fed to the goats and submitted by the owner was identified as yellow oleander, Thevetia peruviana (also known as Cascabela thevetia).

Bovine respiratory syncytial virus infection in feedlot cattle cases in Argentina.

Although bovine respiratory syncytial virus (BRSV) infection has been reported in cattle in Argentina, it has not been associated with pneumonia in Argentina. We report here 5 cases of bovine pneumonia associated with BRSV. Autopsies were performed on 35 beef cattle with gross and/or microscopic lesions of pneumonia from 3 commercial feedlots. Lung samples in 5 of 35 animals were BRSV-positive by reverse-transcription nested PCR. The lungs of 2 of these 5 animals were coinfected with Mannheimia haemolytica, and 1 with bovine viral diarrhea virus 1. Microscopically, the lungs of 3 of the 5 BRSV PCR-positive animals had fibrinosuppurative bronchopneumonia, with or without pleuritis; 2 of the 5 had interstitial pneumonia. We conclude that BRSV is part of the bovine respiratory disease complex in Argentina.

Identification of orphan histidine kinases that impact sporulation and enterotoxin production by Clostridium perfringens type F strain SM101 in a pathophysiologically-relevant ex vivo mouse intestinal contents model.

When causing food poisoning or antibiotic-associated diarrhea, Clostridium perfringens type F strains must sporulate to produce C. perfringens enterotoxin (CPE) in the intestines. C. perfringens is thought to use some of its seven annotated orphan histidine kinases to phosphorylate Spo0A and initiate sporulation and CPE production. We previously demonstrated the CPR0195 orphan kinase, but not the putative CPR1055 orphan kinase, is important when type F strain SM101 initiates sporulation and CPE production in modified Duncan-Strong (MDS) sporulation medium. Since there is no small animal model for C. perfringens sporulation, the current study used diluted mouse intestinal contents (MIC) to develop an ex vivo sporulation model and employed this model to test sporulation and CPE production by SM101 CPR0195 and CPR1055 null mutants in a pathophysiologically-relevant context. Surprisingly, both mutants still sporulated and produced CPE at wild-type levels in MIC. Therefore, five single null mutants were constructed that cannot produce one of the previously-unstudied putative orphan kinases of SM101. Those mutants implicated CPR1316, CPR1493, CPR1953 and CPR1954 in sporulation and CPE production by SM101 MDS cultures. Phosphorylation activity was necessary for CPR1316, CPR1493, CPR1953 and CPR1954 to affect sporulation in those MDS cultures, supporting their identity as kinases. Importantly, only the CPR1953 or CPR1954 null mutants exhibited significantly reduced levels of sporulation and CPE production in MIC cultures. These phenotypes were reversible by complementation. Characterization studies suggested that, in MDS or MIC, the CPR1953 and CPR1954 mutants produce less Spo0A than wild-type SM101. In addition, the CPR1954 mutant exhibited little or no Spo0A phosphorylation in MDS cultures. These studies, i) highlight the importance of using pathophysiologically-relevant models to investigate C. perfringens sporulation and CPE production in a disease context and ii) link the CPR1953 and CPR1954 kinases to C. perfringens sporulation and CPE production in disease-relevant conditions.

Enterotoxemia produced by lambda toxin-positive Clostridium perfringens type D in 2 neonatal goat kids.

Enterotoxemia caused by Clostridium perfringens type D usually affects sheep and goats ≥ 2-wk-old. The main clinical signs and lesions of the disease are produced by the epsilon toxin (ETX) elaborated by this microorganism. However, ETX is produced in the form of a mostly inactive prototoxin that requires protease cleavage for activation. It has traditionally been believed that younger animals are not affected by type D enterotoxemia given the low trypsin activity in the intestinal content associated with the trypsin-inhibitory action of colostrum. Two Nigerian dwarf goat kids, 2- and 3-d-old, with a history of acute diarrhea followed by death, were submitted for postmortem examination and diagnostic workup. Autopsy and histopathology revealed mesocolonic edema, necrosuppurative colitis, and protein-rich pulmonary edema. Alpha toxin and ETX were detected in intestinal content, and C. perfringens type D was isolated from the colon of both animals. The isolates encoded the gene for lambda toxin, a protease that has been shown previously to activate ETX in vitro. Type D enterotoxemia has not been reported previously in neonatal kids, to our knowledge, and we suggest that lambda toxin activated the ETX.

Experimental acute Clostridium perfringens type D enterotoxemia in sheep is not characterized by specific renal lesions.

Type D enterotoxemia, caused by Clostridium perfringens epsilon toxin (ETX), is one of the most economically important clostridial diseases of sheep. Acute type D enterotoxemia is characterized by well-documented lesions in the nervous, cardiocirculatory, and pulmonary systems. However, discrepancies and confusion exist as to whether renal lesions are part of the spectrum of lesions of this condition, which is controversial considering that for many decades it has been colloquially referred to as "pulpy kidney disease." Here, the authors assess renal changes in an experimental model of acute type D enterotoxemia in sheep and evaluate the possible role of ETX in their genesis. Four groups of 6 sheep each were intraduodenally inoculated with either a wild-type virulent C. perfringens type D strain, an etx knockout mutant unable to produce ETX, the etx mutant strain complemented with the wild-type etx gene that regains the ETX toxin production, or sterile culture medium (control group). All sheep were autopsied less than 24 hours after inoculation; none of them developed gross lesions in the kidneys. Ten predefined histologic renal changes were scored in each sheep. The proportion of sheep with microscopic changes and their severity scores did not differ significantly between groups. Mild intratubular medullary hemorrhage was observed in only 2 of the 12 sheep inoculated with the wild-type or etx-complemented bacterial strains, but not in the 12 sheep of the other 2 groups. The authors conclude that no specific gross or histologic renal lesions are observed in sheep with experimental acute type D enterotoxemia.