Publications by authors named "Francisco A Uzal"

146 Publications

Leukocyte numbers and intestinal mucosal morphometrics in horses with no clinical intestinal disease.

J Vet Diagn Invest 2021 Jul 23:10406387211031944. Epub 2021 Jul 23.

California Animal Health and Food Safety Laboratory, School of Veterinary Medicine, University of California-Davis, San Bernardino, CA, USA.

Healthy horses and other animals have large numbers of resident leukocytes in the intestinal wall, but there is scant information regarding which and how many leukocytes are normally present in the equine intestinal wall. Our aim was to provide a reference range of leukocytes in the intestinal mucosal and submucosal propria of normal horses. We included in our study intestinal tissues from 22 Thoroughbred racehorses with no clinical intestinal disease, which had been euthanized because of catastrophic musculoskeletal injuries. Neutrophils, lymphocytes, eosinophils, macrophages, and plasma cells were counted in 5 random 17,600-µm areas of villus lamina propria of the duodenum, jejunum, and ileum, and deep lamina propria of the duodenum, jejunum, ileum, right ventral colon, left ventral colon, left dorsal colon, right dorsal colon, and small colon. Other features investigated in the same intestinal segments included villus height and width (small intestine), presence of ciliated protozoa, Paneth cells number, subcryptal leukocyte layers (number of leukocyte layers between the bottom of the crypts and the muscularis mucosae), and submucosal leukocytes. Lymphocytes were the most numerous cells in all segments analyzed, followed by plasma cells, eosinophils, macrophages, and neutrophils. Eosinophil numbers were significantly higher in both lamina propria and submucosa of the large intestine than in the small intestine. The duodenum had shorter and thinner villi than either jejunum or ileum. The data provided from our study will be useful for diagnosticians examining inflammatory processes in the intestinal tract of horses.
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http://dx.doi.org/10.1177/10406387211031944DOI Listing
July 2021

infection (Tyzzer disease) in horses: retrospective study of 25 cases and literature review.

J Vet Diagn Invest 2021 Jul 8:10406387211031213. Epub 2021 Jul 8.

California Animal Health and Food Safety Laboratory, School of Veterinary Medicine, University of California-Davis, San Bernardino, CA, USA.

Tyzzer disease (TD) is caused by , a gram-negative and obligate intracellular bacterium. The disease occurs in multiple species. A triad of lesions, namely colitis, hepatitis, and myocarditis, is described in cases of TD in some species, such as rats and mice. We carried out a retrospective analysis of 25 equine cases with a diagnosis of TD; 24 of 25 cases occurred in foals <45 d old; the remaining foal was 90 d old. There were 12 males and 12 females; no sex information was available for one foal. The affected breeds were Quarter Horse, Thoroughbred, Arabian, Paint, and Hanoverian. Most of the cases (19 of 25) occurred in the spring. There were 9 cases of sudden death; the remaining animals had diarrhea, fever, distended abdomen, depression, weakness, non-responsiveness, and/or recumbency. Gross findings included icterus, hepatomegaly with acinar pattern, serosal hemorrhages, pulmonary edema, and/or fluid content in small and large intestine. Microscopically, all foals had severe, multifocal, necrotizing hepatitis. Necrotizing lymphohistiocytic colitis was observed in 10 of 25 foals, and multifocal necrotizing myocarditis was found in 8 of 25. Gram-negative, Steiner-positive, intracytoplasmic filamentous bacteria were observed in hepatocytes, enterocytes, and myocardiocytes, respectively. PCR detected DNA in the liver (24 of 24), colon (20 of 24), and heart (5 of 25). Our results indicate that necrotic hepatitis is the hallmark of TD in horses; the so-called triad of lesions is not a consistent characteristic of the disease in this species.
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http://dx.doi.org/10.1177/10406387211031213DOI Listing
July 2021

Rickets in a Thoroughbred-cross foal: case report and review of the literature.

J Vet Diagn Invest 2021 Jun 23:10406387211025232. Epub 2021 Jun 23.

California Animal Health and Food Safety Laboratory System, San Bernardino branch, University of California-Davis, CA, USA.

Rickets is a metabolic bone disease associated with failure of endochondral ossification and impaired osteoid mineralization in growing animals. As a consequence, affected individuals can develop gross and microscopic bone malformations. The most common causes of rickets in domestic species include vitamin D and phosphorus deficiency. Rickets has been described in multiple species; however, comprehensive postmortem characterizations with confirmatory histopathology in equids have not been published. A 6-mo-old, Thoroughbred-cross foal was diagnosed with rickets based on gross autopsy findings and microscopic examination of the ribs and long bones. Grossly, all costochondral junctions of the ribs were enlarged with a "rachitic rosary" appearance, and there were multiple fracture calluses in the rib bodies. Epiphyses and metaphyses of the long bones appeared widened on sagittal section, and their physes were irregularly thickened. Histologically, there were poorly organized columns of hypertrophic chondrocytes within the physes of affected bones, islands of chondrocytes embedded within the primary and secondary spongiosa, and faintly eosinophilic seams of poorly mineralized osteoid within the bone trabeculae. Areas of focally increased osteoclastic activity were observed in some of the sections, perhaps pointing to a more complex metabolic bone disease in a growing animal. Low serum concentrations of calcium and 25-hydroxyvitamin D were detected in an antemortem sample. The pathogenesis of these imbalances was not definitively established, but lack of sunlight exposure, low concentration of vitamin D precursors in the diet (perhaps secondary to malnutrition), or both, were suspected; a genetic basis cannot be ruled out.
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http://dx.doi.org/10.1177/10406387211025232DOI Listing
June 2021

[Neurotropic bovine astrovirus-associated encephalitis: An underdiagnosed disease in South America?]

Rev Argent Microbiol 2021 Jun 17. Epub 2021 Jun 17.

Plataforma de Investigación en Salud Animal, Instituto Nacional de Investigación Agropecuaria (INIA), La Estanzuela, Colonia, Uruguay. Electronic address:

We describe a case of neurotropic bovine astrovirus-associated encephalitis in a Jersey dairy cow from the department of San José, Uruguay. This represents the second case of this condition reported in the Southern Hemisphere. The cow was the only one affected in a herd of 70 cows, showing neurological signs with a 2-day clinical course, before dying spontaneously. Histopathological examination revealed lymphocytic, histiocytic, and plasmacytic meningoencephalitis with neuronal necrosis, without detectable inclusion bodies. Other infectious agents, including Rabies virus(Lyssavirus), Bovine alphaherpesvirus-1 and Bovine alphaherpesvirus-5(Varicellovirus), Bovine viral diarrhea virus(Pestivirus), West Nile virus(Flavivirus), Listeria monocytogenes, Histophilus somni and other bacteria, were not detected in the brain. We propose that given the recent discovery of neurotropic astroviruses in various mammalian species, including humans, cases of astrovirus encephalitis may have gone undetected in South America. We briefly discuss the differential pathologic diagnosis of infectious bovine encephalitis.
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http://dx.doi.org/10.1016/j.ram.2021.01.006DOI Listing
June 2021

Alimentary squamous cell carcinoma in psittacines: 12 cases and review of the literature.

J Vet Diagn Invest 2021 Jun 2:10406387211021480. Epub 2021 Jun 2.

California Animal Health and Food Safety Laboratory, San Bernardino, University of California-Davis, Davis, CA, USA.

Squamous cell carcinoma (SCC), which is a neoplasm that usually arises from the integument, is reported uncommonly in pet birds. Only a few reports of SCCs in the alimentary tract of birds, including psittacines, have been published, and a detailed description of the pathology is not available in the literature. We present here 12 cases of alimentary SCC in psittacines. The average age of the birds was 22.2 y (range: 15-29 y), and affected species included 4 Amazon parrots ( sp.), 3 cockatiels (), 3 macaws ( sp.), 1 conure ( sp.), and 1 Senegal parrot ( sp.). Frequent clinical complaints included regurgitation, dysphagia, dyspnea, lethargy, and/or weight loss. SCC primarily affected the oral cavity in 6 of 12 cases, the crop alone in 2 of 12 cases, the crop and esophagus in 1 of 12 cases, the proventriculus alone in 1 of 12 cases, and the crop, esophagus, and proventriculus in 2 of 12 cases. Histologically, alimentary SCCs were locally invasive and often resulted in mucosal ulceration. Although there were no metastases in any of our cases, poor clinical outcomes were frequent and associated most commonly with complete effacement of the alimentary segment and severe inflammation with opportunistic bacterial infection. Our review of the literature records commonly affected species, variability of gross presentations and clinical signs, plausible etiologies, and current diagnostic developments.
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http://dx.doi.org/10.1177/10406387211021480DOI Listing
June 2021

Sudden death caused by spinal cord injury associated with vertebral fractures and fetlock failure in a Thoroughbred racehorse.

J Vet Diagn Invest 2021 Jul 27;33(4):788-791. Epub 2021 May 27.

Tulare, J.D. Wheat Veterinary Orthopedic Research Laboratory.

The most prevalent causes of death in racehorses are musculoskeletal injuries, causing ~83% of deaths within the racing industry in California and elsewhere. The vast majority of these injuries have preexisting lesions that predispose to fatal injury. A 4-y-old Thoroughbred colt suffered an acute suspensory apparatus failure, including biaxial proximal sesamoid bone fractures of the right front fetlock, causing loss of support of the fetlock joint and consequent fall with fractures of the cervical and sacral spine. Cervical fracture caused spinal cord damage that resulted in sudden death. A preexisting lesion in the medial proximal sesamoid bone likely predisposed to complete fracture of this bone and fetlock breakdown. Interestingly, a comparable osteopenic lesion was present in the intact medial proximal sesamoid bone of the left forelimb, which is consistent with bilateral repetitive overuse injury in racehorses. The morphologic features of the cervical and sacral spine fractures were compatible with acute injury; no evidence of preexisting lesions was seen. Most likely, these acute vertebral fractures occurred as a result of the horse falling. This case emphasizes the importance of performing a detailed autopsy in horses that suffer an appendicular musculoskeletal injury, particularly in fatal cases when the horse dies following a leg injury.
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http://dx.doi.org/10.1177/10406387211018289DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8229845PMC
July 2021

Mortality of Western Gulls (Larus occidentalis) Associated with Botulism Type a in Coastal Southern California, USA.

J Wildl Dis 2021 Jul;57(3):657-661

California Animal Health and Food Safety Laboratory System, University of California, Davis, 620 W Health Sciences Drive, Davis, California 95616, USA.

A mortality event involving at least 14 Western Gulls (Larus occidentalis) was observed on 10 October 2019 on Huntington State Beach, Orange County, California, US. Clinical signs of affected gulls included generalized weakness and difficulty standing and flying. Six additional Western Gulls with similar clinical signs were admitted for rehabilitation between 24 October and 7 November, including birds from Newport Beach and Laguna Beach, south of Huntington Beach. Eleven carcasses were submitted for postmortem examination, including nine gulls collected on 10 October from Huntington Beach, one collected on 24 October from Laguna Beach, and one collected on 6 November from Newport Beach. Six of seven gulls tested were positive for Clostridium botulinum toxin type A by mouse bioassay, including five collected on 10 October from Huntington Beach and one from Laguna Beach, approximately 23 km south, on 24 October, suggesting the toxin was available to scavenging birds for nearly 2 wk following the original exposure. Botulism type C, and less commonly type E, are most frequently documented in wild birds, including waterfowl and fish-eating birds, respectively. In contrast, botulism type A is the most common cause of foodborne botulism in humans, acquired from food contaminated with C. botulinum spores, but it has not previously been associated with mortality in free-ranging wild birds.
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http://dx.doi.org/10.7589/JWD-D-20-00153DOI Listing
July 2021

Pathology of cryptosporidiosis in raccoons: case series and retrospective analysis, 1990-2019.

J Vet Diagn Invest 2021 Jul 6;33(4):721-727. Epub 2021 May 6.

California Animal Health and Food Safety Laboratory (CAHFS), University of California-Davis, San Bernardino, CA, USA.

Cryptosporidiosis is an intestinal protozoal disease of public health importance caused by spp. Despite the high synanthropism of raccoons, studies describing the pathology of spp. infections in this species are lacking. Therefore, we characterized the pathology of cryptosporidiosis in 2 juvenile raccoons. In addition, we conducted a retrospective search of the database of the California Animal Health and Food Safety laboratory for 1990-2019 and found 6 additional cases of cryptosporidiosis in raccoons. Sequencing of cryptosporidia was performed in one autopsied raccoon, and PCR on formalin-fixed, paraffin-embedded tissues in archived cases. The skunk genotype (CSkG), a strain of zoonotic relevance, was detected in 6 of 8 cases (75%). Frequently, cryptosporidiosis was associated with enteritis, eosinophilic infiltrates, villus atrophy or blunting and/or fusion, and crypt abscesses or necrosis. In 7 of the 8 cases, there was confirmed concurrent coinfection with canine distemper virus; 1 case was coinfected with canine parvovirus. Although crypt necrosis is considered a classic lesion of canine parvoviral infection in mesocarnivores and not a hallmark of cryptosporidiosis, results suggest that canine distemper virus is capable of mimicking such lesions in combination with cryptosporidia and immunosuppression.
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http://dx.doi.org/10.1177/10406387211011949DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8229841PMC
July 2021

Placentitis and abortion caused by a multidrug resistant strain of Campylobacter fetus subspecies fetus in a sheep in Uruguay.

Rev Argent Microbiol 2021 Apr 16. Epub 2021 Apr 16.

Plataforma de Investigación en Salud Animal, Instituto Nacional de Investigación Agropecuaria (INIA), Ruta 50 Km 11, Estación Experimental La Estanzuela, Colonia, Uruguay. Electronic address:

Campylobacter fetusfetus (Cff) is a major infectious cause of abortion in sheep worldwide, and an opportunistic human pathogen. Information on Cff as an ovine abortifacient in South America is limited. We describe a case of abortion caused by a multidrug resistant strain of Cff in a sheep in Uruguay. In August 2017, 3/57 pregnant ewes (5.3%) aborted whithin one week. Histopathologic examination of the placenta of an aborted ewe revealed severe neutrophilic and fibrinonecrotizing placentitis with vasculitis and thrombosis of the chorionic arterioles. Cff was isolated on microaerobic culture in Skirrow agar, and further confirmed by 16S rDNA PCR amplification and sequencing, and endpoint and real time PCR assays. Antimicrobial sensitivity testing revealed resistance to tetracyclines, nalidixic acid, telithromycin and clindamycin. Other abortifacients were not detected. Further studies are necessary to determine the geographic distribution, ecology, epidemiology, economic impact, and antimicrobial resistance of Cff in sheep flocks in Uruguay.
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http://dx.doi.org/10.1016/j.ram.2021.02.005DOI Listing
April 2021

Outbreak of rabbit hemorrhagic disease virus 2 in the southwestern United States: first detections in southern California.

J Vet Diagn Invest 2021 Jul 2;33(4):728-731. Epub 2021 Apr 2.

California Animal Health and Food Safety Laboratory System, San Bernardino, USA.

An outbreak of rabbit hemorrhagic disease virus 2 (RHDV2)-associated disease occurred in the southwestern United States following its first detection in New Mexico in March 2020. The disease spread throughout several states and was diagnosed for the first time in California on May 11, 2020, in a black-tailed jackrabbit (). The following day, the California Department of Food and Agriculture (CDFA) issued an order banning the entrance into California of several lagomorph species and their products from any state in which the disease had been detected in the last 12 mo. RHDV2 is a threat to wild lagomorph species in California, including the endangered riparian brush rabbit (). Therefore, the California Department of Fish and Wildlife (CDFW) started tracking any mortality event in wild lagomorph populations. As of August 9, 2020, RHDV2 had been detected in wild and domestic lagomorphs of several counties in southern California that were submitted to the California Animal Health and Food Safety laboratory system by the CDFA or the CDFW. These positive cases included 2 additional black-tailed jackrabbits and 3 desert cottontail rabbits (). In addition, the infection spilled over to domestic populations, whereby it was confirmed on July 10, 2020, in a domestic rabbit ().
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http://dx.doi.org/10.1177/10406387211006353DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8229834PMC
July 2021

Nutritional Wasting Disorders in Sheep.

Animals (Basel) 2021 Feb 15;11(2). Epub 2021 Feb 15.

California Animal Health and Food Safety Laboratory (CAHFS), San Bernardino Branch, University of California, Davis, CA 95616, USA.

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.
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http://dx.doi.org/10.3390/ani11020501DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7918192PMC
February 2021

Toxic Wasting Disorders in Sheep.

Animals (Basel) 2021 Jan 18;11(1). Epub 2021 Jan 18.

California Animal Health and Food Safety Laboratory (CAHFS), San Bernardino Branch, University of California, Davis, CA 95616, USA.

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.
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http://dx.doi.org/10.3390/ani11010229DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7831912PMC
January 2021

Protothecosis and chlorellosis in sheep and goats: a review.

J Vet Diagn Invest 2021 Mar 15;33(2):283-287. Epub 2020 Dec 15.

California Animal Health and Food Safety Laboratory, University of California-Davis, San Bernardino, CA.

Protothecosis and chlorellosis are sporadic algal diseases that can affect small ruminants. In goats, protothecosis is primarily associated with lesions in the nose and should be included in the differential diagnosis of causes of rhinitis. In sheep, chlorellosis causes typical green granulomatous lesions in various organs. Outbreaks of chlorellosis have been reported in sheep consuming stagnant water, grass from sewage-contaminated areas, and pastures watered by irrigation canals or by effluents from poultry-processing plants. and are widespread in the environment, and environmental and climatic changes promoted by anthropogenic activities may have increased the frequency of diseases produced by them. The diagnosis of these diseases must be based on gross, microscopic, and ultrastructural lesions, coupled with detection of the agent by immunohistochemical-, molecular-, and/or culture-based methods.
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http://dx.doi.org/10.1177/1040638720978781DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7953102PMC
March 2021

Intestinal Myxoid Leiomyosarcoma in a Sambar Deer (Rusa unicolor).

J Comp Pathol 2020 Oct 1;180:69-72. Epub 2020 Oct 1.

California Animal Health and Food Safety Laboratory, School of Veterinary Medicine, University of California Davis, San Bernardino, California, USA.

A 9-year-old male sambar deer (Rusa unicolor) that died during sedation had a large and firm polypoid mass, which expanded the small intestinal wall and partially obstructed the duodenal lumen. Histopathology revealed a pleomorphic sarcoma composed of stellate to spindloid cells loosely arranged in an abundant myxoid matrix. The cytoplasm of the neoplastic cells was strongly immunopositive for vimentin and smooth muscle actin, but negative for c-KIT, desmin and myoglobin. The findings are consistent with intestinal myxoid leiomyosarcoma, which is rare in cervids and has not been described in the sambar deer, which is an endangered species.
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http://dx.doi.org/10.1016/j.jcpa.2020.08.008DOI Listing
October 2020

-Associated Necrotic Enteritis-Like Disease in Coconut Lorikeets ().

Vet Pathol 2021 Mar 19;58(2):423-427. Epub 2020 Nov 19.

Institute of Animal Pathology, Vetsuisse Faculty, 27210University of Bern, Bern, Switzerland.

Several outbreaks of necrotic enteritis-like disease in lorikeets, from which was consistently isolated, are described. All lorikeets had acute, segmental, or multifocal fibrinonecrotizing inflammatory lesions in the small and/or the large intestine, with intralesional gram-positive rods. The gene encoding alpha toxin was detected by PCR (polymerase chain reaction) on formalin-fixed, paraffin-embedded (FFPE) tissues in 20 out of 24 affected lorikeets (83%), but it was not amplified from samples of any of 10 control lorikeets ( < .0001). The second most prevalent toxin gene detected was the beta toxin gene, which was found in FFPE from 7 out of 24 affected lorikeets (29%). The other toxin genes were detected inconsistently and in a relatively low number of samples. These cases seem to be associated with , although the specific type involved could not be determined.
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http://dx.doi.org/10.1177/0300985820971788DOI Listing
March 2021

Nonenteric Lesions of Necrotic Enteritis in Commercial Chickens in California: 25 Cases (2009-2018).

Avian Dis 2020 09;64(3):356-364

California Animal Health and Food Safety Laboratory System, University of California, Davis, Tulare, CA 93274.

Necrotic enteritis (NE) is an important enteric disease affecting a wide variety of avian species, including poultry, caused by Clostridium perfringens type G and, rarely, type C. Significant economic losses can result from elevated mortality rates and poor performance, such as decreased weight gain associated with intestinal damage and impaired absorption of nutrients. Additional losses can result from elevated condemnation at the processing plant because of a high incidence of cholangiohepatitis. Nonenteric lesions associated with NE have been rarely reported. This paper describes uncommon presentations of NE in commercial chickens received by the California Animal Health and Food Safety Laboratory (Turlock and Tulare branches) between 2009 and 2018. Overall, extraintestinal lesions associated with C. perfringens were diagnosed in 25 cases of NE involving commercial broiler chickens. The extraintestinal sites most commonly affected included liver, followed by gizzard, bursa of Fabricius, gall bladder, and spleen. The etiology of these lesions, C. perfringens, was confirmed from a combination of gross, bacteriologic, microscopic, and immunohistochemical findings. The most common predisposing factors for NE identified were coccidiosis (56%, 14/25) and immunosuppressive disease agents, including infectious bursal disease virus (16%, 4/25) and fowl adenovirus group 1 (4%, 1/25). Additionally, four cases (16%) had microscopic lesions compatible with cystic enteritis, probably of viral etiology. This study describes the incidence of extraintestinal lesions of NE in chickens, underlying the role of enteric disorders and immunosuppression as major predisposing factors for the development of NE.
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http://dx.doi.org/10.1637/aviandiseases-D-19-00129DOI Listing
September 2020

Diseases caused by in sheep and goats: a review.

J Vet Diagn Invest 2021 Jan 6;33(1):20-24. Epub 2020 Nov 6.

Instituto Nacional de Investigación Agropecuaria (INIA), Plataforma de Investigación en Salud Animal, Estación Experimental INIA La Estanzuela, Colonia, Uruguay.

Pythiosis is characterized most commonly by ulcerative dermatitis, mainly in the limbs of sheep and occasionally of goats. In sheep, is also responsible for necrotizing rhinitis characterized by marked enlargement and deformity of the nasal region, severe respiratory difficulty, and bloody nasal discharge. A third form of pythiosis in sheep affects the digestive tract, involving ulceration of the esophagus, forestomachs, and abomasum. Pythiosis in sheep and goats has been reported only in Brazil where it occurs mainly in the semiarid region of the country, when animals congregate and stay for longer periods of time within or around water reservoirs. However, it has been reported as well in areas of humid environments, such as the Pantanal of Mato Grosso and in the Brazilian Cerrado. The diagnosis of the different presentations of pythiosis is based on gross and microscopic findings, coupled with detection of the agent by immunohistochemical, molecular, and/or culture-based methods.
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http://dx.doi.org/10.1177/1040638720968937DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7758700PMC
January 2021

Equine dental and skeletal fluorosis induced by well water consumption.

J Vet Diagn Invest 2020 Nov 14;32(6):942-947. Epub 2020 Oct 14.

North Dakota State University Veterinary Diagnostic Laboratory, Fargo, ND.

Two horses that consumed well water with high fluoride content exhibited clinical signs of chronic dental and skeletal fluoride toxicosis and were later euthanized and autopsied. Both horses had degenerative disease of multiple joints and multiple dental defects. Elevated fluoride concentrations were found in bone and tooth samples of both horses, well water, and feed. Microscopically, abnormalities were noted in bone and tooth samples, and consisted mostly of foci of cement necrosis and hypercementosis. Horses exhibiting bilateral, highly symmetrical dental and/or skeletal lesions, with chronic lameness, should be evaluated for the possible presence of fluoride toxicosis.
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http://dx.doi.org/10.1177/1040638720962746DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7649535PMC
November 2020

Characteristics of complete tibial fractures in California racehorses.

Equine Vet J 2020 Oct 29. Epub 2020 Oct 29.

Department of Surgical and Radiological Sciences, University of California Davis, Davis, CA, USA.

Background: Tibial fractures cause ~3% of racehorse deaths. Pre-existing stress fractures have been associated with multiple racing and training fractures, but not complete tibial fractures.

Objectives: To describe racehorse tibial fractures and compare signalment and exercise histories of affected and control racehorses.

Study Design: Retrospective analysis of necropsy reports.

Methods: Racehorses that had a complete tibial fracture (1990-2018) were retrospectively reviewed. Signalment and exercise histories of affected horses were compared to 1) racehorses that died because of non-tibial musculoskeletal injuries or 2) non-musculoskeletal cause and 3) age, sex, event-matched control racehorses. Tibial fracture prevalence was described relative to California racehorses that had at least one official work or race. Age, sex and limb distributions were compared between affected and control horses (Chi-square, Fisher's Exact test). Exercise history data were reduced to counts and rates of official high speed works, races and layups (periods without an official high speed work or race >60 days). Variables were compared among groups using matched logistic regression (P ≤ .05).

Results: Tibial fractures in 115 horses (97% unilateral; 50% left, 47% right) occurred most commonly during training (68%) and in 2- to 3-year-old horses (73%). Fractures were predominantly comminuted (93%), diaphyseal (44%) and oblique (40%). Of 61 cases examined for callus, 64% had periosteal callus associated with fracture, most commonly in proximal (65%) and distal diaphyseal (27%) locations. Of 28 racehorses with known exercise history, 57% never raced and 36% had a layup. Affected horses had fewer official-timed works and events (official high speed works and races), number of active days and accumulated less distance in events and works (P < .05) than control horses.

Main Limitations: Retrospective review of necropsy reports by multiple pathologists over 28 years.

Conclusions: Tibial fractures were associated with pre-existing stress fracture early in career. Most fractures were associated with proximolateral stress fractures.
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http://dx.doi.org/10.1111/evj.13375DOI Listing
October 2020

Cardiopulmonary Lesions in Sheep Produced by Experimental Acute Type D Enterotoxemia.

Vet Pathol 2021 01 15;58(1):103-113. Epub 2020 Oct 15.

8789University of California at Davis, San Bernardino, CA, USA.

Enterotoxemia caused by type D is one of the most prevalent clostridial diseases of sheep. The lesions of the acute form of this disease, particularly the cerebral lesions, are well characterized; however, detailed descriptions of the cardiac and pulmonary lesions are lacking. Here we describe cardiopulmonary lesions in experimental acute type D enterotoxemia in sheep and determine the role of epsilon toxin (ETX) in the development of these lesions. Four groups of 6 sheep were intraduodenally inoculated with either a wild-type type D strain; its knockout mutant, which is unable to produce ETX; the mutant complemented with the wild-type gene, which regains the ETX toxigenic ability; or sterile culture medium as a control. All sheep were subjected to postmortem examination within 24 hours of inoculation. Lesion scores were compared between groups for pulmonary edema; hydrothorax; ascites; hydropericardium; endocardial, myocardial and epicardial hemorrhages; microscopic lesions of acute myocardial degeneration and necrosis; and myocardial, endocardial, and epicardial edema, hemorrhage, and inflammation. Only sheep inoculated with the wild-type and complemented ETX-toxigenic bacterial strains developed cardiopulmonary lesions, which were present in varying degrees of severity and proportions. These lesions were not present in sheep inoculated with the mutant or in the negative control. We conclude that severe acute cardiopulmonary lesions in sheep with experimental enterotoxemia are associated with the capacity of the strains to produce ETX. These changes are likely contributors to the clinical signs and even death of affected animals.
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http://dx.doi.org/10.1177/0300985820965554DOI Listing
January 2021

Conidiobolomycosis, cryptococcosis, and aspergillosis in sheep and goats: a review.

J Vet Diagn Invest 2020 Nov 14;32(6):826-834. Epub 2020 Sep 14.

Instituto Nacional de Investigación Agropecuaria (INIA), Plataforma de Investigación en Salud Animal, Estación Experimental INIA La Estanzuela, Colonia, Uruguay.

We review herein infections by spp., spp., and spp. in sheep and goats. spp. are common causes of rhinitis in sheep and are less frequent in goats, in which spp. also cause skin lesions. spp. cause rhinitis, meningitis, encephalitis, and pneumonia in goats, and are rarely observed in sheep. spp. may cause rhinitis in goats, and pneumonia and mastitis in sheep and goats. Gross and microscopic lesions caused by these 3 fungal infections may be similar to each other. The diagnosis of these diseases must be based on gross and microscopic lesions, coupled with detection of the agent by immunohistochemical, molecular, and/or culture-based methods.
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http://dx.doi.org/10.1177/1040638720958338DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7649532PMC
November 2020

The Agr-Like Quorum-Sensing System Is Important for Type A Strain ATCC 3624 To Cause Gas Gangrene in a Mouse Model.

mSphere 2020 06 17;5(3). Epub 2020 Jun 17.

California Animal Health and Food Safety Laboratory System, School of Veterinary Medicine, University of California, Davis, San Bernardino, California, USA

type A is involved in gas gangrene in humans and animals. Following a traumatic injury, rapid bacterial proliferation and exotoxin production result in severe myonecrosis. alpha toxin (CPA) and perfringolysin (PFO) are the main virulence factors responsible for the disease. Recent studies have identified an Agr-like quorum-sensing (QS) system in that regulates the production of both toxins. The system is composed of an AgrB membrane transporter and an AgrD peptide that interacts with a two-component regulatory system in response to fluctuations in the cell population density. In addition, a synthetic peptide named 6-R has been shown to interfere with this signaling mechanism, affecting the function of the Agr-like QS system In the present study, type A strain ATCC 3624 and an isogenic -null mutant were tested in a mouse model of gas gangrene. When mice were intramuscularly challenged with 10 CFU of wild-type ATCC 3624, severe myonecrosis and leukocyte aggregation occurred by 4 h. Similar numbers of an -null mutant strain produced significantly less severe changes in the skeletal muscle of challenged mice. Complementation of the mutant to regain expression restored virulence to wild-type levels. The burdens of all three strains in infected muscle were similar. In addition, animals injected intramuscularly with wild-type ATCC 3624 coincubated with the 6-R peptide developed less severe microscopic changes. This study provides the first evidence that the Agr-like QS system is important for type A-mediated gas gangrene. type A strains produce toxins that are responsible for clostridial myonecrosis, also known as gas gangrene. Toxin production is regulated by an Agr-like quorum-sensing (QS) system that responds to changes in cell population density. In this study, we investigated the importance of this QS system in a mouse model of gas gangrene. Mice challenged with a strain with a nonfunctional regulatory system developed less severe changes in the injected skeletal muscle compared to animals receiving the wild-type strain. In addition, a synthetic peptide was able to decrease the effects of the QS in this disease model. These studies provide new understanding of the pathogenesis of gas gangrene and identified a potential therapeutic target to prevent the disease.
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http://dx.doi.org/10.1128/mSphere.00500-20DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7300355PMC
June 2020

Subchondral focal osteopenia associated with proximal sesamoid bone fracture in Thoroughbred racehorses.

Equine Vet J 2021 Mar 23;53(2):294-305. Epub 2020 Jul 23.

Department of Surgical and Radiological Sciences, University of California-Davis, Davis, CA, USA.

Background: Proximal sesamoid bone (PSB) fracture is the most common fatal injury in Thoroughbred (TB) racehorses in the United States. Epidemiological and pathological evidence indicates PSB fracture is likely the acute culmination of a chronic stress-related process. However, the aetiopathogenesis of PSB fracture is poorly understood.

Objective: To characterise bone abnormalities that precede PSB fracture.

Study Design: Two retrospective case-control groups of PSBs from TB racehorses with, and without, unilateral biaxial PSB fracture.

Methods: Proximal sesamoid bones were harvested post-mortem from TB racehorses subjected to euthanasia for unilateral biaxial PSB fracture (cases) or causes unrelated to PSB fracture (controls) while racing or training. The fractured medial PSB (FX-PSB) and contralateral intact medial PSB (CLI-PSB) from racehorses that sustained PSB fracture, and an intact medial PSB (CTRL-PSB) from racehorses that did not have a PSB fracture were collected as case and control specimens. Study 1 distributions of morphological features were compared among case and control groups using visual examination, photographs, radiographs and histology of whole PSBs and serial sagittal sections (10 FX-PSB, 10 CLI-PSB and 10 CTRL-PSB). Study 2 local bone volume fraction and mineral densities were compared among case and control PSBs using microcomputed tomography (9 FX-PSB, 9 CLI-PSB and 9 CTRL-PSB).

Results: A focal subchondral lesion characterised by colocalised focal discoloration, radiolucency, osteopenia, low tissue mineral density and a surrounding region of dense cancellous bone was identified in most case horses but not in controls. This subchondral lesion was found in a slightly abaxial mid-body location and was bilaterally present in most case horses.

Main Limitations: The post-mortem samples may not represent the spectrum of abnormalities that occur throughout the development of the subchondral lesion. Lateral PSBs were not examined, so their contribution to biaxial PSB fracture pathogenesis is unknown.

Conclusion: Abaxial subchondral lesions are consistent with pre-existing injury and likely associated with PSB fracture.
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http://dx.doi.org/10.1111/evj.13291DOI Listing
March 2021

Ibex-Associated Malignant Catarrhal Fever in Duikers ().

Vet Pathol 2020 07 14;57(4):577-581. Epub 2020 May 14.

University of California, Davis, CA, USA.

Eight duikers, representing 3 different species cohoused in a single zoological collection, died in a 10-month period. Black, red-flanked, and yellow-backed duikers were affected, appearing clinically with a combination of anorexia, diarrhea, ataxia, tremors, and/or stupor, followed by death within 72 hours of onset of clinical signs. Consistent gross findings were pulmonary ecchymoses (8/8), generalized lymphadenomegaly (6/8), ascites (5/8), and pleural effusion (4/8). Dense lymphocyte infiltrates and arteritis affected numerous tissues in most animals. Ibex-associated malignant catarrhal fever (MCF) viral DNA was detected in all cases by polymerase chain reaction and in situ hybridization. Identical ibex-MCF virus sequence was detected in spleen of a clinically healthy ibex () housed in a separate enclosure 35 meters away from the duikers.
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http://dx.doi.org/10.1177/0300985820918313DOI Listing
July 2020

Intoxication by var. in llamas.

J Vet Diagn Invest 2020 May 1;32(3):467-470. Epub 2020 Apr 1.

Facultad Ciencias Agrarias, Universidad Nacional de Jujuy, Jujuy, Argentina (Marin, Vignale).

Lysosomal storage diseases are inherited and acquired disorders characterized by dysfunctional lysosomes. Intracytoplasmic accumulation of undegraded substrates leads to impaired cellular function and death. Several plant species are toxic to livestock because of the presence of indolizidine alkaloids, including swainsonine, which cause a storage disease. Swainsonine-induced nervous disease (i.e., locoism) of sheep and cattle is well recognized in several parts of the world, particularly in the western United States and in parts of Australia. Spontaneous intoxication by var. was suspected in a group of 70 llamas () in Jujuy Province, northwestern Argentina. The animals grazed an area dominated by stands of var. . Clinical signs were staggering, ataxia, hypermetria, and progressive weight loss. The clinical course in individual animals was ~50 d. The main microscopic changes were Purkinje cell degeneration, necrosis, and loss, associated with intracytoplasmic vacuolation, meganeurite formation, and Wallerian degeneration. Specific positive labeling for ubiquitin was observed in axonal spheroids. Composite leaf and stem samples of var. analyzed by high-performance liquid chromatography contained 0.03% swainsonine. Based on the microscopic lesions, clinical history, and plant analysis, a diagnosis was made of storage disease caused by consumption of swainsonine-containing var. .
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http://dx.doi.org/10.1177/1040638720914338DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7377608PMC
May 2020

Focus issue on clostridial disease.

J Vet Diagn Invest 2020 03 28;32(2):173-174. Epub 2020 Feb 28.

California Animal Health and Food Safety Laboratory, University of California-Davis, San Bernardino, CA (Uzal, Navarro).

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http://dx.doi.org/10.1177/1040638720908420DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7081497PMC
March 2020

Gas gangrene in mammals: a review.

J Vet Diagn Invest 2020 Mar 21;32(2):175-183. Epub 2020 Feb 21.

Veterinary School, Federal University of Minas Gerais, Brazil (Oliveira Junior, Silva, Lobato).

Gas gangrene is a necrotizing infection of subcutaneous tissue and muscle that affects mainly ruminants and horses, but also other domestic and wild mammals. type A, type A, and are the etiologic agents of this disease, acting singly or in combination. Although a presumptive diagnosis of gas gangrene can be established based on clinical history, clinical signs, and gross and microscopic changes, identification of the clostridia involved is required for confirmatory diagnosis. Gross and microscopic lesions are, however, highly suggestive of the disease. Although the disease has a worldwide distribution and can cause significant economic losses, the literature is limited mostly to case reports. Thus, we have reviewed the current knowledge of gas gangrene in mammals.
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http://dx.doi.org/10.1177/1040638720905830DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7081496PMC
March 2020

Alimentary necrobacillosis in alpacas.

J Vet Diagn Invest 2020 Mar 18;32(2):339-343. Epub 2020 Feb 18.

California Animal Health and Food Safety Laboratory System, San Bernardino (Carvallo, Uzal) branches, University of California-Davis, Davis, CA.

Ulcers of the oral cavity, esophagus, and gastric compartments of South American camelids are uncommon. Multifocal-to-coalescing ulcers were identified in the oral cavity, esophagus, and/or gastric compartments of 5 alpacas submitted for postmortem examination. was isolated from the lesions in all alpacas, in combination with other aerobic and anaerobic bacteria. In 4 of these cases, -associated lesions were considered secondary to neoplasia or other chronic debilitating conditions; in 1 case, the alimentary ulcers were considered the most significant autopsy finding. It is not known if this agent acted as a primary or opportunistic agent in mucosal membranes previously damaged by a traumatic event, chemical insult, immunodeficiency, or any other debilitating condition of the host.
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http://dx.doi.org/10.1177/1040638720906409DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7081513PMC
March 2020

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

J Vet Diagn Invest 2020 Mar 13;32(2):239-245. Epub 2020 Feb 13.

California Animal Health and Food Safety Laboratory System, University of California-Davis, San Bernardino (Nyaoke, Navarro, Fresneda, Moore, Uzal) and Davis (Diab) branches, CA.

Enteric disease in horses may be caused by a variety of microorganisms, including several clostridial species. (previously ) 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 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. 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. should be considered among the differential diagnoses in cases of enteric disease in horses.
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http://dx.doi.org/10.1177/1040638720903738DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7081492PMC
March 2020

Fatal intestinal inflammatory lesions in equids in California: 710 cases (1990-2013).

J Am Vet Med Assoc 2020 Feb;256(4):455-462

Objective: To determine incidences and underlying causes of fatal intestinal inflammatory lesions (FIILs) and demographic characteristics of affected equids necropsied at any of the California Animal Health and Food Safety Laboratory facilities between January 1, 1990, and April 16, 2013.

Animals: 710 equids with FIILs, including colitis, duodenitis, enteritis, enterocolitis, enteropathy, enterotyphlitis, gastritis, gastroenteritis, ileitis, jejunitis, typhlitis, or typhlocolitis, alone or in combination.

Procedures: The medical records were reviewed, and data collected included animal age, sex, geographic origin, necropsy submission date, and breed, purpose, or characteristic of use. Descriptive statistics were compiled and reported as numbers and percentages.

Results: Colitis (323/710 [45.5%]), enteritis (146/710 [20.6%]), and typhlocolitis (138/710 [19.4%]) were the most common FIILs, and the underlying cause of most FIILs was categorized as either undetermined (465/710 [65.5%]) or bacterial (167/710 [23.5%]). The most common bacteria responsible for FIILs were spp and spp.

Conclusions And Clinical Relevance: Results indicated that the underlying cause for most FIILs could not be identified; however, when it was identified, it was most commonly bacterial and typically spp or spp, which could be useful information for practitioners when evaluating and managing horses and other equids with intestinal distress. In addition, results underscored the need for improved diagnostic procedures and strategies to determine underlying causes of FIILs in equids. Knowledge of the most common FIILs and their underlying causes may help in diagnosing and mitigating intestinal disease in equids.
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http://dx.doi.org/10.2460/javma.256.4.455DOI Listing
February 2020
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