Pathology of Clostridium perfringens type C enterotoxemia in horses.

Clostridium perfringens type C is an important cause of enteritis and enterocolitis in foals and occasionally in adult horses. The disease is a classic enterotoxemia, and the enteric lesions and systemic effects are caused primarily by beta toxin, 1 of 2 major toxins produced by C. perfringens type C. Until now, only sporadic cases of C. perfringens type C equine enterotoxemia have been reported. We present a comprehensive description of the lesions in 8 confirmed cases of type C enterotoxemia in foals and adult horses. Grossly, multifocal to segmental hemorrhage and thickening of the intestinal wall were most common in the small intestine, although the colon and cecum were also frequently affected. All horses had variable amounts of fluid, often hemorrhagic intestinal contents. The most characteristic microscopic lesion was necrotizing or necrohemorrhagic enteritis, with mucosal and/or submucosal thrombosis. Numerous gram-positive rods were occasionally seen in affected mucosa. A definitive diagnosis of C. perfringens type C enterotoxemia in all 8 cases was based on the clinical history, gross and histologic lesions, and detection of the beta toxin in intestinal contents.

Characteristics of Thoroughbred and Quarter Horse racehorses that sustained a complete scapular fracture.

REASONS FOR PERFORMING STUDY: To determine if scapular fractures occur in racehorses with distinctive characteristics. OBJECTIVES: To test the hypothesis that Thoroughbred (TB) and Quarter Horse (QH) racehorses with a scapular fracture have similar characteristics that are different from those of their respective racetrack populations. METHODS: Necropsy findings, case details, last race information and career earnings for TB and QH racehorses that had a scapular fracture in California between 1990 and 2008 were retrospectively compared between breeds. Horse signalment, career earnings, career starts and race characteristics were obtained for all California racehorses. Comparisons were made between affected horses, other racehorses that died, and all horses that raced, in California during the 19 year period. RESULTS: Seventy-three TB and 28 QH racehorses had a similar, complete comminuted scapular fracture with an articular component, and right forelimb predilection. The QHs had a higher incidence of scapular fracture incurred during racing than TBs (0.98 vs. 0.39/1000 starters). The TB and QH incident rates for musculoskeletal deaths incurred racing were 20.5 and 17.5/1000 starters, respectively; however, a greater proportion of TB musculoskeletal deaths occurred training (40% vs. 8%). Horses with a scapular fracture were more likely to be male and aged 2 or ≥ 5 years than the racetrack population. Most affected QHs (64%) were 2-year-olds; most TBs (74%) were aged ≥ 3 years. Scapular fractures occurred more commonly during racing in QHs (70%) than TBs (44%). Race-related scapular fracture was more likely to occur in a Maiden race than in a non-Maiden race. Horses with a scapular fracture had fewer career starts than the racetrack population. CONCLUSIONS AND POTENTIAL RELEVANCE: Despite breed differences for signalment and exercise distances, both breeds incur a complete scapular fracture that is more likely to occur in the right scapula of young and older, male racehorses, early in their race career or after few races. Quarter Horses sustain a catastrophic scapular fracture more frequently than TBs.

Zygomycotic lymphadenitis in slaughtered feedlot cattle.

During the 12 months of 2006, zygomycotic lymphadenitis was diagnosed in 194 of 198 feedlot steers (0.04% of cattle slaughtered during that period) in a California slaughterhouse as part of bovine tuberculosis surveillance. Mesenteric lymph nodes were involved in 190 cases. Affected lymph nodes were enlarged (2 to 42 cm in greatest dimension), firm, and mottled gray-white to yellow with multiple granular or caseocalcareous foci. Histologically, nodal architecture was effaced by necrosis, granulomatous inflammation, and fibrosis. In approximately 20% of the cases, granulomas were mainly restricted to subcapsular sinuses and afferent lymphatic vessels, causing granulomatous lymphangitis. Nonseptate, irregularly branching hyphae with nonparallel walls and bulbous enlargements were common in necrotic areas and within the cytoplasm of multinucleated giant cells. Fungal cultures were performed on 124 affected lymph nodes using 7 media, but no zygomycetes were cultured. Fungal DNA was amplified from 20 lymph nodes. Amplicons from 16 nodes had nearly 100% homology with sequences for Rhizomucor pusillus; 4 amplicons had (> 98%) homology with Absidia corymbifera sequences. Zygomycosis should be considered in the differential diagnosis for granulomatous lymphadenitis in feedlot steers.

Study of laryngopharyngeal pathology in Thoroughbred horses in southern California.

REASONS FOR PERFORMING STUDY: There is increasing anecdotal evidence among horse owners, trainers and equine clinicians of a high prevalence of subepiglottic ulcers, suggested to have a negative effect on racing performance. OBJECTIVES: To provide a prevalence study and pathological characterisation of laryngopharyngeal lesions with emphasis in the subepiglottic area and, in particular, subepiglottic ulcers. METHODS: The study was carried out on 91 Thoroughbred racehorses received for post mortem examination from 4 major Southern California racetracks. The most common reason for submission was catastrophic musculoskeletal injury, but others include sudden death, laminitis, colic, colitis, neurological disorders, pleuropneumonia and arytenoid chondropathy. Laryngopharyngeal specimens were collected and examined grossly; selected cases were also examined histopathologically. RESULTS: Thirteen horses (143%) had at least one type of laryngopharyngeal abnormality, 7 horses (7.7%) had lesions in the subepiglottic soft tissues, including 4 subepiglottic ulcers, 2 soft palate 'kissing lesions' and one 'subepiglottic scar'. Eight horses (8.8%) had lesions elsewhere in the laryngopharynx, including mucosal ulcerations, arytenoid chondropathy, epiglottic entrapment and partial absence of arytenoid cartilage. CONCLUSIONS AND POTENTIAL RELEVANCE: Lesions in the subepiglottic area were among the most prevalent in this study, suggesting that an important percentage of laryngopharyngeal abnormalities may be missed during routine endoscopy of the standing horse, which often does not include the examination of subepiglottic tissues. Pathologically, subepiglottic ulcers were chronic-active with viable hyperplastic epithelial margins, suggesting that proper healing and re-epithelialisation should occur with appropriate treatment. In most cases, the lesions observed do not necessarily indicate a clinical problem and more extensive prevalence studies and correlation between abnormalities found and performance are needed to assess the clinical relevance of subepiglottic soft tissue lesions accurately.

Infection of internal umbilical remnant in foals by Clostridium sordellii.

Omphalitis and the resulting septicemia contribute to perinatal mortality in several animal species. In foals, the most important causes of omphalitis are Escherichia coli and Streptococcus zooepidemicus. However to date, no information has been published about the role of Clostridium sordellii in these infections. In this paper, we describe 8 cases of perinatal mortality in foals associated with internal umbilical remnant infection by C. sordellii. The foals studied were between 12 and 21 days old at the time of death, and various breeds were represented in the group. Five of the foals were male and 3 were female. The diagnosis was established on the basis of the detection of C. sordellii by 3 methods (culture, fluorescent antibody test, and immunohistochemistry) and on gross and histopathologic findings. All foals had acute peritonitis, and the internal umbilical remnant was thickened by edema, hemorrhage, and fibrosis. A moderate amount of serosanguinous fluid with fibrin strands was present in the pericardial sac and pleural cavity. Histopathologically, the urachus and umbilical arterial walls were thickened by edema and exhibited hemorrhage, fibrin, and leukocytic infiltration. Gram-positive bacterial rods were observed in subepithelial areas of the urachus, the adventicia of umbilical arteries, and interstitium of the internal umbilical remnant. On the basis of these findings, we suggest that C. sordellii should be considered in the differential diagnosis for infections of the internal umbilical remnant in foals.

Allele frequency and likely impact of the glycogen branching enzyme deficiency gene in Quarter Horse and Paint Horse populations.

Glycogen Branching Enzyme Deficiency (GBED), a fatal condition recently identified in fetuses and neonatal foals of the Quarter Horse and Paint Horse lineages, is caused by a nonsense mutation in codon 34 of the GBE1 gene, which prevents the synthesis of a functional GBE protein and severely disrupts glycogen metabolism. The aims of this project were to determine the mutant GBE1 allele frequency in random samples from the major relevant horse breeds, as well as the frequency with which GBED is associated with abortion and early neonatal death using the tissue archives from veterinary diagnostic laboratories. The mutant GBE1 allele frequency in registered Quarter Horse, Paint Horse, and Thoroughbred populations was 0.041, 0.036, and 0.000, respectively. Approximately 2.5% of fetal and early neonatal deaths in Quarter Horse-related breeds submitted to 2 different US diagnostic laboratories were homozygous for the mutant GBE1 allele, with the majority of these being abortions. Retrospective histopathology of the homozygotes detected periodic acid Schiff's (PAS)-positive inclusions in the cardiac or skeletal muscle, which is characteristic of GBED, in 8 out of the 9 cases. Pedigree and genotype analyses supported the hypothesis that GBED is inherited as a simple recessive trait from a single founder. The frequency with which GBED is associated with abortion and neonatal mortality in Quarter Horse-related breeds makes the DNA-based test valuable in determining specific diagnoses and designing matings that avoid conception of a GBED foal.

The isolation of exotic Newcastle disease (END) virus from nonpoultry avian species associated with the epidemic of END in chickens in southern California: 2002-2003.

During the first 11 months of the 2002-2003 exotic Newcastle disease (END) epidemic in chickens in southern California, a total of 27,688 cloacal and tracheal (oropharyngeal) swab pools and/or tissue pools from 86 different avian species other than chickens and turkeys were submitted for Newcastle disease virus (NDV) isolation and characterization. Fifty-seven specimens (0.23%), representing 12 species of birds and 13 unspecified species, from a total of 24,409 accessions or submissions were positive for NDV. The NDV isolate was characterized as ENDV by real-time reverse transcription-polymerase chain reaction (RT-PCR). Of the 11,486 premises with other avian species, 1599 also had chickens. There were 1900 positive chicken samples from 164 premises, and 56 positive other avian species from 51 premises. Twelve premises had both positive chickens and positive other avian species. All positive other avian species were located on premises either on or within a 1 km radius of known infected premises. In this epidemic, premises with positive other avian species were significantly more likely to have chickens, and were significantly more likely to have positive chickens (OR = 3.7, P < 0.0001).

Identification by subtractive hybridization of sequences specific for Salmonella enterica serovar enteritidis.

Salmonella enterica serovar Enteritidis, a major cause of food poisoning, can be transmitted to humans through intact chicken eggs when the contents have not been thoroughly cooked. Infection in chickens is asymptomatic; therefore, simple, sensitive, and specific detection methods are crucial for efforts to limit human exposure. Suppression subtractive hybridization was used to isolate DNA restriction fragments present in Salmonella serovar Enteritidis but absent in other bacteria found in poultry environments. Oligonucleotide primers to candidate regions were used in polymerase chain reactions to test 73 non-Enteritidis S. enterica isolates comprising 34 different serovars, including Dublin and Pullorum, two very close relatives of Enteritidis. A primer pair to one Salmonella difference fragment (termed Sdf I) clearly distinguished serovar Enteritidis from all other serovars tested, while two other primer pairs only identified a few non-Enteritidis strains. These primer pairs were also useful for the detection of a diverse collection of clinical and environmental Salmonella serovar Enteritidis isolates. In addition, five bacterial genera commonly found with Salmonella serovar Enteritidis were not detected. By treating total DNA with an exonuclease that degrades sheared chromosomal DNA but not intact circular plasmid DNA, it was shown that Sdf I is located on the chromosome. The Sdf I primers were used to screen a Salmonella serovar Enteritidis genomic library and a unique 4,060-bp region was defined. These results provide a basis for developing a rapid, sensitive, and highly specific detection system for Salmonella serovar Enteritidis and provide sequence information that may be relevant to the unique characteristics of this serovar.

Comparison of VIDAS enzyme-linked fluorescent immunoassay using Moore swab sampling and conventional culture method for Salmonella detection in bulk tank milk and in-line milk filters in California dairies.

A comparison of the VIDAS Salmonella (SLM) assay using the manufacturer's recommended sampling method or a Moore swab sampling method demonstrated that the Moore swab method detected a greater number of positive samples (83.0% vs. 67.92%). When results using a conventional culture technique were compared to the VIDAS SLM assay using Moore swab sampling, there was good agreement (97.5%). When the VIDAS SLM assay was used to test in-line milk filters and compared to results from the conventional culture method, there was also good correlation between test results (95.57%). Overall, the VIDAS SLM assay using a modified sampling method compared favorably to the conventional culture method and had the advantages of taking less time to obtain a negative or presumptive positive result, being less technically complicated and requiring less screening of non-lactose fermenting colonies from negative samples.

The influence of crumble and mash feed on oral lesions of white leghorn laying hens.

The effect of crumble and mash feed on oral lesions in laying hens was investigated. Each of two groups of white leghorn hens (group A, n = 120; group B, n = 120) was separated into crumble- and mash-fed treatments. At the start of the trial, group A chickens were free of oral lesions, whereas group B chickens had nearly 100% prevalence of oral lesions. The trials began at 17.4 and 22 wk of age and ended at 32 and 33 wk of age for groups A and B, respectively. Chickens were housed in cages indoors, fed free choice, and serologically monitored. Oral lesions were periodically evaluated by visual scoring. Lesion prevalence peaked in group A chickens at 23-25 wk of age, concurrently with an outbreak of respiratory disease, and decreased to a low level at the end of the trial. For most of the trial, crumble-fed chickens had significantly lower oral lesion prevalence than mash-fed chickens (P < 0.05). Lesion prevalence in group B chickens decreased after treatments began and maintained this trend to the end of the trial. Compared with mash-fed chickens, crumble-fed chickens in group B had significantly lower oral lesion prevalence throughout the trial (P < 0.001). Neither group had significant differences in oral lesion scores between treatments. Most lesions were on the lower palate, pinpoint to 2 mm in diameter, often multiple, and bilaterally symmetrical. Feed analyses for mycotoxins and heavy metals were within normal limits. The inciting etiology of oral lesions was not elucidated in this trial. However, this work demonstrated that once lesions were present, feed type had a strong effect on persistence of oral lesions.

Glycogen branching enzyme deficiency in quarter horse foals.

Seven related Quarter Horse foals that died by 7 weeks of age were examined for glycogen branching enzyme (GBE) deficiency. Clinical signs varied from stillbirth, transient flexural limb deformities, seizures, and respiratory or cardiac failure to persistent recumbency. Leukopenia (5 of 5 foals) as well as high serum creatine kinase (CK; 5 of 5), aspartate transaminase (AST; 4 of 4), and gamma glutamyl transferase (GGT; 5 of 5) activities were present in most foals, and intermittent hypoglycemia was present in 2 foals. Gross postmortem lesions were minor, except for pulmonary edema in 2 foals. Muscle, heart, or liver samples from the foals contained abnormal periodic acid Schiff's (PAS)-positive globular or crystalline intracellular inclusions in amounts proportional to the foal's age at death. Accumulation of an unbranched polysaccharide in tissues was suggested by a shift in the iodine absorption spectra of polysaccharide isolated from the liver and muscle of affected foals. Skeletal muscle total polysaccharide concentrations were reduced by 30%, but liver and cardiac muscle glycogen concentrations were normal. Several glycolytic enzyme activities were normal, whereas GBE activity was virtually absent in cardiac and skeletal muscle, as well as in liver and peripheral blood cells of affected foals. GBE activities in peripheral blood cells of dams of affected foals and several of their half-siblings or full siblings were approximately 50% of controls. GBE protein in liver determined by Western blot was markedly reduced to absent in affected foals, and in a half-sibling of an affected foal, it was approximately one-half the amount of normal controls. Pedigree analysis also supported an autosomal recessive mode of inheritance. The affected foals have at least 2,600 half-siblings. Consequently, GBE deficiency may be a common cause of neonatal mortality in Quarter Horses that is obscured by the variety of clinical signs that resemble other equine neonatal diseases.

Pathologic and bacteriologic findings in 27-week-old commercial laying hens experimentally infected with Salmonella enteritidis, phage type 4.

Two strains of 27-wk-old commercial laying chickens (strain A, brown-egg-laying type and strain B, white-egg-laying type) were inoculated either orally (PO) or intravenously (IV) with a field isolate of Salmonella enteritidis phage type 4. Chickens were sequentially necropsied at regular intervals throughout the 17-wk observation period. Gross and microscopic lesions were most evident between 1 and 14 days postinoculation (DPI). Gross lesions consisted of enlarged livers with white foci, enlarged and mottled white spleens, fibrinous exudate in the peritoneum, and atretic, misshapen ovarian follicles. Microscopic lesions included multifocal coagulative necrosis of hepatocytes and inflammation, fibrinous exudation in vascular sinuses of the spleen, and fibrinosuppurative inflammation of the peritoneum and ovarian follicles. The proportion of reproductive organ infections (ovary and oviduct) in the IV group, 83% (20/24, P = 0.007; 50% and 33% for strains A and strain B birds, respectively), was higher than that of the PO group, 46% (11/24; 29% and 17% for strains A and B, respectively), for the first 16 days of observation postinoculation. The proportion of fecal shedding for the IV group of birds was significantly (P = 0.009) lower, 29% (7/24; 33% and 25% respectively for strain A and strain B birds, respectively), than the PO group, 67% (16/24; 75% and 58% for strain A and strain B birds, respectively). Three (2.6%) of 234 egg pools were culture-positive for group D Salmonella from strain A chickens (1 of 119 pools from the IV group and 2 of 115 pools from the PO group of birds). Chickens infected with the field strain of S. enteritidis phage type 4 harbored the organism in tissues only for a brief time, most clearing within 8 DPI and nearly all within 16 DPI. Overall the percentage of culture-positive birds did not differ significantly (P > 0.05) between birds with and without lesions, but isolation of S. enteritidis tended to be more frequent when lesions were evident. This experiment also demonstrated that brown-egg-laying-type chickens were more susceptible than white-egg-laying-type chickens to S. enteritidis phage type 4 isolated from California based on gross and microscopic lesions and bacteriologic findings.

Halicephalobus gingivalis (H. deletrix) infection in two horses in southern California.

Two horses, a 16-year-old male Holsteiner and a 5-year-old male miniature horse, were diagnosed with halicephalobiasis at the California Veterinary Diagnostic Laboratory System, San Bernardino Branch, in April and June of 1998. Over a period of 4 weeks, the Holsteiner horse developed renal dysfunction, blepharospasm, and blindness in the right eye. A 15-cm-diameter mass was detected on ultrasound examination in the right kidney. Terminally, the animal developed seizures and was euthanized. The miniature horse had a 6-week-long illness characterized by testicular enlargement and uveitis. This animal developed ataxia and died. Necropsy examination revealed bilateral enlargement of the kidneys in both horses, petechial hemorrhages of the optic nerve (Holsteiner), and a diffusely firm and enlarged left testicle (miniature horse). Microscopic evaluation of tissues revealed granulomatous nephritis, optic neuritis, retinitis, and encephalitis in both horses and orchitis in only the miniature horse with intralesional rhabditiform nematodes. Halicephalobus gingivalis was found in the urine sediment of both animals and in semen of the Holsteiner horse.

Desert bighorn sheep mortality due to presumptive type C botulism in California.

During a routine telemetry flight of the Mojave Desert (California, USA) in August 1995, mortality signals were detected from two of 12 radio-collared female desert bighorn sheep (Ovis canadensis) in the vicinity of Old Dad Peak in San Bernardino County (California). A series of field investigations determined that at least 45 bighorn sheep had died near two artificial water catchments (guzzlers), including 13 bighorn sheep which had presumably drowned in a guzzler tank. Samples from water contaminated by decomposing bighorn sheep carcasses and hemolyzed blood from a fresh bighorn sheep carcass were tested for the presence of pesticides, heavy metals, strychnine, blue-green algae, Clostridium botulinum toxin, ethylene glycol, nitrates, nitrites, sodium, and salts. Mouse bioassay and enzyme-linked immunosorbent assay detected type C botulinum toxin in the hemolyzed blood and in fly larvae and pupae. This, coupled with negative results from other analyses, led us to conclude that type C botulinum poisoning was most likely responsible for the mortality of bighorn sheep outside the guzzler tank.

Hoof size, shape, and balance as possible risk factors for catastrophic musculoskeletal injury of Thoroughbred racehorses.

OBJECTIVE: To evaluate hoof size, shape, and balance as risk factors for catastrophic musculoskeletal injuries (CMI), including suspensory apparatus failure (SAF) and cannon bone condylar fracture (CDY) in Thoroughbred racehorses. ANIMALS: 95 Thoroughbred racehorses that died between 1994 and 1996. PROCEDURE: 38 quantitative measures of hoof size, shape, and balance were obtained from orthogonal digital images of the hoof and were compared between case horses with forelimb CMI (70), SAF (43), and CDY (10) injuries and control horses whose death was unrelated to the musculoskeletal system (non-CMI, 25). Comparison of group means between cases and controls was done using ANOVA, and multivariable logistic regression was used to estimate odds ratios. RESULTS: Odds of CMI were 0.62 times lower for a 5mm increase in ground surface width difference and 0.49 times lower for a 100-mm2 increase in sole area difference. Odds of SAF were 6.75 times greater with a 10 degrees increase in toe-heel angle difference and 0.58 times lower with a 100-mm2 increase in sole area difference. Odds of CDY were 0.26 times lower with a 3 degrees increase in toe angle, 0.15 times lower with a 5-mm increase in lateral ground surface width, and 0.35 times lower with a 100-mm2 increase in sole area difference. CLINICAL RELEVANCE: Decreasing the difference between toe and heel angles should decrease risk of SAF for Thoroughbred racehorses and should be considered in addition to increasing toe angle alone to help prevent catastrophic injury. Trimming the hoof to perfect mediolateral symmetry may not be a sound approach to avoiding injury.

Relationship between race start characteristics and risk of catastrophic injury in thoroughbreds: 78 cases (1992).

OBJECTIVE: To investigate relationships of several racehorse characteristics and race conditions with risk of a catastrophic musculoskeletal injury (CMI) resulting in euthanasia in Thoroughbreds during racing in California in 1992. DESIGN: Retrospective longitudinal study. ANIMALS: Thoroughbreds that incurred CMI during racing and all California race entrants in 1992. PROCEDURE: Necropsy records were reviewed, and race start information was obtained. Incidence risk of CMI/1,000 race entrants was estimated. Relationships between CMI during racing and race-meet, entrant age and sex, race type and length, and racing surface type and condition were evaluated by use of logistic regression. RESULTS: Incidence risk of CMI was 1.7/1,000 entrants. A higher risk of CMI was found at 2 fair race-meets, with incidence risks of 4.9 and 5.5/1,000 entrants. Risk of injury in male horses was 1.7 times greater than that in female horses, and influence of age on risk depended on race type. Risk of injury for horses 2 to 5 years old was two times greater for claiming horses than for maiden horses. Race length or racing surface type (dirt vs turf) or condition (fast, muddy, yielding) were not significantly associated with risk of CMI. CLINICAL IMPLICATIONS: Incidence of CMI was similar among 12 of 14 major and fair race-meets and among various race lengths and racing surface types and conditions, whereas incidence of CMI was influenced by entrant age and sex as well as race type. Investigators should consider controlling for age and sex, race-meet, and race type whenever possible in studies of risk of CMI.

Prevalence of Salmonella in municipal sewage treatment plant effluents in southern California.

Effluents from 12 sewage treatment plants in southern California were examined for Salmonella using a Moore swab technique. Eight of the 12 plants were positive for Salmonella when sampled at the chlorination/dechlorination site (inside the plant). Effluents from 11 of 12 sewage treatment plants were positive for Salmonella when samples were analyzed downstream of the chlorination/dechlorination site, before effluents merge with the receiving stream (outside the plant). Two of the three control sites, an urban runoff, a raw potable water reservoir, and two other sites were also positive for Salmonella. A total of 683 Salmonella isolations were represented by 11 serogroups and 54 serotypes from 26 of 32 sampling sites. Effluents from three treatment plants and one control site (raw potable water resevior) yielded Salmonella enteritidis phage type 4, in addition to other serotypes.