Animal Disease Diagnostic Laboratory Research Articles

Potential for the spread of Fasciola hepatica in cattle in Oklahoma

Summary In 29 central and western Oklahoma counties, 42 ranches were investigated for indigenous Fasciola hepatica infections and their suitability for the transmission of liver fluke. A 10-year retrospective study of Oklahoma cattle based on samples submitted to the Oklahoma Animal Disease Diagnostic Laboratory also was done. Indigenous fascioliasis was found in cattle in 12 counties (9 central and western counties identified in the combined field and retrospective studies and 3 additional eastern counties identified on the basis of the retrospective study). Factors essential for survival of free-living stages of F hepatica and for snail species necessary for propagation of the fluke existed in much of Oklahoma. Snails capable of serving as intermediate hosts for transmission of the fluke reportedly have been found in 41 of the 77 Oklahoma counties. Lymnaeid snails were detected in 4 counties in the field study.

Intoxication due to Asclepias sp. (Milkweeds): George E. Burrows, 1Lanell Ogden2 and Ronald J. Tyrl3 ( 1Departments of Physiological Sciences, 2Oklahoma Animal Disease Diagnostic Laboratory and 3Botany and Microbiology, Oklahoma State University, Stillwater, OK 74078, U.S.A.)

Intoxication due to Asclepias sp. (Milkweeds): George E. Burrows, 1Lanell Ogden2 and Ronald J. Tyrl3 ( 1Departments of Physiological Sciences, 2Oklahoma Animal Disease Diagnostic Laboratory and 3Botany and Microbiology, Oklahoma State University, Stillwater, OK 74078, U.S.A.)

Ovine Abortion Due to Coxiella Burnetii Infection

9The organism is an obligate intracytoplasmic parasite in the family Rickettsiaceae. It causes Q fever in man and occasionally outbreaks of abortions in food animals such as sheep, goats, and dairy cows. The purpose of this report is to describe the pathology and microbiologic findings of a recent outbreak of abortion in sheep from northcentral California. Four aborted near-term lambs and 2 placentas were submitted for diagnostic examination to the Animal Disease Research and Diagnostic Laboratory of South Dakota State University, Brookings, South Dakota, in January 1987. They were submitted from a north-central California flock that had abortions occurring since October of the previous year. The disease appeared to be highly contagious, with the abortion rate varying from 10 to 60% within groups of the flock. Lambs were either aborted near term or born weak. Standard diagnostic procedures for ovine abortions were employed, including gross examination and collection of lung, liver, myocardium, brain, and placenta for histopathology in 10% neutral buffered formalin. For electron microscopy, formalin-fixed tissue was rinsed and postfixed in 2% glutaraldehyde and 1% osmium tetroxide and processed by standard procedures. Lung, placenta, and stomach contents were cultured by standard aerobic and microaerophilic methods. Impression smears were prepared from placental cotyledons and stained with Gimenez stain. Fluorescent antibody tests were done on frozen placental sections using Chlamydia groupspecific conjugate” and conjugate specific for C. burnetii.

A Serological Survey of Ehrlichia Canis, Ehrlichia Equi, Rickettsia Rickettsii, and Borrelia Burgdorferi in Dogs in Oklahoma

Serum samples from 259 dogs were tested for antibodies to Ehrlichia canis, Ehrlichia equi, Rickettsia rickettsii, and Borrelia burgdorferi using the indirect fluorescent antibody test. The sera were obtained from submissions to the Oklahoma Animal Disease Diagnostic Laboratory during a 14-month period from June 1986 through July 1987. The rate for positive antibody titers to E. canis was 53%, to E. equi was 33%, to R. rickettsii was 38%, and to B. burgdorferi was 18%. Higher percentages of sera serologically positive to E. canis were found in the spring through the fall months, but there were no seasonal variations for E. equi, R. rickettsii, and B. burgdorferi. There was no consistent pattern of titers to the 4 antigens when age-groups of the dogs were compared. Forty-four different breeds were tested.

Applications of a sensitive, GC-ECD analysis for anatoxin-A: Douglas K. Stevens1 and Robert I. Krieger2 ( 1University of Idaho, WOI Regional Program in Veterinary Medical Education, Washington Animal Disease Diagnostic Laboratory and Pharmacology/Toxicology Program, Moscow, Idaho 83843; and 2Department of Food and Agriculture, Worker Health and Safety Unit, 1220 N Street, Sacramento, California 95814, U.S.A.)

Applications of a sensitive, GC-ECD analysis for anatoxin-A: Douglas K. Stevens1 and Robert I. Krieger2 ( 1University of Idaho, WOI Regional Program in Veterinary Medical Education, Washington Animal Disease Diagnostic Laboratory and Pharmacology/Toxicology Program, Moscow, Idaho 83843; and 2Department of Food and Agriculture, Worker Health and Safety Unit, 1220 N Street, Sacramento, California 95814, U.S.A.)

A survey of eastern equine encephalomyelitis in Florida horses: Prevalence, economic impact, and management practices, 1982–1983

In spite of the availability of vaccines, eastern equine encephalomyelitis (EEE) virus continues to cause significant death losses in Florida horses. Veterinarians engaged in equine practice in Florida were surveyed regarding their experiences with EEE, and their responses were compared with serologic data available from the State of Florida Animal Disease Diagnostic Laboratory for 1982 and 1983. On the assumption that most cases of encephalitis in Florida are caused by EEE virus, considerable under-reporting was apparent. Clinical cases of EEE were comfirmed in every month of the year with the highest incidence observed in June and July. Northern and central Florida had the highest number of cases reported. Most deaths (78%) occurred in unvaccinated animals, indicating that greater horse owner awareness is needed. Deaths in vaccinated animals raised questions of the efficacy of current vaccines or their schedule of administration particularly in young horses. Vaccination schedule recommendations were variable between veterinarians with regard to annual versus semiannual EEE vaccination and age of first vaccination for foals. A conservative estimate of the cost to EEE to the state equine industry was greater than $1 000 000 per year.

Canine granular cell tumour (myoblastoma): a report of four cases and review of the literature

ABSTRACTFour cases of canine granular cell tumour (myoblastoma) were diagnosed at the Washington Animal Disease Diagnostic Laboratory between 1977 and 1981. Two of the tumours occurred in the tongue, one in the lip and one in the larynx. Three cell types were found in the tumours. Granular cells, with abundant periodic acid‐Schiff (PAS)‐positive cytoplasmic granules, were most numerous. Interstitial cells resembled fibroblasts and were often adjacent to collagen fibrils. Angulate body cells contained PAS‐positive, ovoid cytoplasmic inclusions composed of microtubular subunits. Review of these and reported cases indicates no breed or sex predisposition for this rare tumour. The tongue is the most common site and all but one tumour have occurred in or adjacent to the oral cavity. There have been no reports of recurrence or metastasis of granular cell tumours except the recurrence of a disputed case in the subcutis of a dog.

Quaternary Ammonium Compound Toxicity in Chickens

Two commercial White Leghorn flocks of 41,000 and 57,000 25-week-old hens experienced death losses of 676 and 1,089 birds in a week. Six birds from each flock were presented for necropsy to the Animal Disease Diagnostic Laboratory at Purdue University with a clinical history of excessive deaths, unsatisfactory production, and dehydration. Gross lesions were present on the tongue and on oral and pharyngeal mucosa as uniformly pale or white areas with interspersed multifocal sites of ulceration. Other changes were cyanotic, shriveled combs and wattles and ruptured ovarian follicles with concurrent egg yolk peritonitis. Microscopic examination revealed large areas of coagulative necrosis with multifocal epithelial ulceration of the oral and pharyngeal mucosae. There was an intense inflammatory, heterophilic response at the periphery of affected areas. Alterations in the abdominal viscera were limited to egg yolk peritonitis. The high death rate and oral lesions were attributed to accidental use of excessive levels of a quaternary ammonium disinfectant in the drinking water.

Etiology and Epidemiology of Verminous Encephalitis in an Emu

Verminous encephalitis was reported in 1978 in an emu (Dromaius novaehollandiae) from Indiana (8). The bird was the second of two emus that had developed severe ataxia followed by bilateral leg paralysis, which resulted in natural death of the first bird. The second emu was presented alive but unable to stand to the Purdue Animal Disease Diagnostic Laboratory. No gross lesions were found, but on histologic examination, focal malacic lesions and inflammatory changes were seen in the cerebellum, in association with an ascarid larva. No generic or specific identification of the parasite was made, nor was information presented concerning the possible source or mode of infection of the birds. Of the four other known outbreaks or cases of cerebrospinal nematodiasis in avian species (1,3,4,5), the two most extensive were positively linked to migrating larvae of Baylisascaris procyonis, the common roundworm of raccoons (3,4). In one of these, 622 chickens died following a single exposure to contaminated bedding (4), and in the other, all 85 quail died following exposure to a contaminated run (3). A third case involved central nervous system (CNS) disease in a chukar partridge; B. procyonis was suggested as the cause (5). In the fourth case, no identification was made of the ascarid species responsible for CNS disease in tumbler pigeons (1). The present report is based on a retrospective evaluation of a case of verminous encephalitis in an emu (8). New information is presented concerning the etiology and epidemiology of the parasite involved. Examination of sections of cerebellum revealed an ascarid larva within a focus of reactive malacia. The larva had prominent

Chlamydia psittaci Infection in Companion Birds Examined in Florida

Over a two-year period, companion birds, submitted mostly by small-animal practitioners to the Animal Disease Diagnostic Laboratory, Kissimmee, Florida, were examined for chlamydia. Chick embryo yolk sac and mouse brain inoculations were used for isolation. Chlamydiae were isolated in 58 (20%) of 287 birds examined. Although twice as many birds were examined in 1980 as in 1979, the percentage of positive isolations was 20% for each year. This suggests a constant level of chlamydial infection in companion birds. Most of the isolations were made in psittacine birds; the only positive isolations in passerine birds were in finches.

Nonhematopoietic gastrointestinal neoplasia in cats: a retrospective study of 44 cases.

Gastrointestinal neoplasms other than lymphosarcomas and mast cell tumors were diagnosed in 44 cats during a 14-year period at the Washington Animal Disease Diagnostic Laboratory. All the tumors were malignant; 31 metastasized or recurred. One cat had fibrosarcoma; another, leiomyosarcoma. The other 42 cats had adenocarcinomas, which were subclassified into three histologic patterns: tubular adenocarcinoma; undifferentiated carcinoma; and mucinous adenocarcinoma. The cats averaged 10.6 years of age. There was no sex predisposition. Siamese cats had a higher frequency of adenocarcinomas than other breeds. Osseous and chondroid metaplasia occurred in nine adenocarcinomas.

Forensic toxicology and the bovine practitioner

The Oklahoma Animal Disease Diagnostic Laboratory investigates a large number of cases each year, many of which have legal implications. The majority of bovine cases with legal implications involve oil field wastes, feed additives such as urea, feed contaminants such as mycotoxins, pesticides, drugs and malicious poisoning. The laboratory has also investigated cases of insurance fraud and animal mutilation cases where unusual drug residues were identified.

Rapid qualitative procedure for the identification of petroleum products in animal tissue by gas-liquid chromatography

The Oklahoma Animal Disease Diagnostic Laboratory has investigated many cases of suspected petroleum hydrocarbon intoxication. The potential for litigation required that the laboratory develop analytical procedures for the identification and quantitation of petroleum hydrocarbons in interstinal contents and tissues. This analytical procedure is a reasonably rapid, extremely accurate, qualitative test that lends itself to modification as a quantitative procedure. Petroleum compounds from water, stomach contents, lung and feces may be positively matched with implicated petroleum products by a method of chromatographic fingerprinting. Each petroleum mixture, when separated by gas-chromatography, will be represented by a specific reproduceable recorder tracing or fingerprint. When recovered from biological samples, the petroleum mixture will retain this fingerprint and can be identified by direct comparison.

Toxicity of blue-green algae in livestock

Blue-green algae (Phylum Cyanophyta) occur in nearly every pond, stream, and lake in Oklahoma. Under proper conditions in ponds or lakes certain toxic species may accumulate in such quantities that a hazard to livestock develops. At least one case of algae toxicity has been confirmed at the Oklahoma Animal Disease Diagnostic Laboratory since the summer of 1977.
 Algae accumulate from population explosions called "water blooms" or simply "blooms". A bloom usually contains only one or 2 species. The algae will accumulate to the point of tinting the water bright breen or covering the surface with a thick gelatinous mass. When these blooms are dominated by a toxic species of blue-green algae poisonings may occur. Poisoning may occur during a bloom from species producing an exotoxin or immediately following a bloom when dying cells release their endotoxins. Toxic conditions may be very short lived so samples of water should be taken and refrigerated at the first sign of animal distress.
 There are five genera of blue-green algae that are universally accepted as toxic or capable of producing toxins. They are Microcystis, Nodularia, Anabaena, Aphanizomenon, Gloeatrichia. Microsystis is generally the most noxious and is the only genus known to produce an exotoxin. Along with Anabaena and Aphanizomenon it is the most common form of toxic algae in substantiated cases of blue-green algae poisoning. All toxic algae contain pseudovacuoles which tend to bouy them to the surface.

Spontaneous neoplasms of pigs—A study of 31 cases

Thirty-one porcine neoplasms were examined at the Animal Disease Diagnostic Laboratory of Purdue University, from January 1st 1966 to december 31st 1976. The series comprised 8 lymphosarcomas, a granulocytic sarcoma, 7 melanomas, 2 haemangiosarcomas, 3 haemangiomas, 3 papillomas, 2 embryonal nephromas, a glioblastoma, an ameloblastoma, a lipoma, a chondroma, and a leiomyoma.

Mixed glioma and rhabdomyosarcoma in brain of a wild deer.

Tumors of the central nervous system occur in the horse, cow, pig, cat, dog, chicken and laboratory rats and mice, but there are few reports of these tumors in other mammals [2, 8, 91. We found an unusual brain tumor in a wild deer and suggest a new concept for the pathogenesis of tumors that arise in the nervous system and contain muscle. A young adult female white-tailed wild deer was found wandering in a wooded area of Tennessee. She was weak and dazed and died 24 hours later. The deer was necropsied at the Tennessee Animal Disease Diagnostic Laboratory. Tissues were fixed in 10 percent buffered neutral formalin, embedded in paraffin, sectioned at 6 micrometers, and stained with hematoxylin and eosin (HE) and phosphotungstic acid-hematoxylin (PTAH). Formalin-fixed tissues were processed for electron microscopic study. Lesions were confined to the central nervous system. The frontal lobes of the brain contained a gelatinous mass 3.8 centimeters at its greatest diameter. The tumor was in the midline in the region of the frontal lobes (fig. 1). The upper part of the mass was sharply demarcated, but the neoplasm infiltrated part of the brain below, leaving a rim of uninvolved brain inferiorly. The fixed brain weighed 170 grams and was otherwise normal. The histologic pattern of the tumor correlated with the gross appearance. There were some zones of abrupt demarcation between neoplasm and affected brain, and other regions in which the tumor merged gradually with surrounding normal brain. Mild degenerative changes of neurons and a slight increase in astrocytes were noted in the adjacent compressed brain. At the border of the tumor in the regions abruptly demarcated from normal brain or within 2 to 3 millimeters of normal brain in gradually merging zones, the tumor had a regular population of cells with a delicate neurofibrillary background and small, round nuclei with a stippled pattern of chromatin. In many foci near the borders, these small nuclei were perivascular (fig. 2) and were more densely packed than elsewhere. Proliferation of vascular endothelial cells and focal zones of necrosis occasionally were seen. The more central parts of the tumor also contained small, undifferentiated cells

Case Report: Umbilical Hernias in Turkeys from Two Flocks

On May 30, 1972, six 11-week-old Nicholas turkeys from a flock of 5500 birds on range were presented to the Southern Indiana-Purdue Animal Disease Diagnostic Laboratory. One hundred and forty birds had died in a two-week period at a rate averaging 15 to 20 a day. The history indicated a 15% morbidity, with signs described as lameness, coughing, and some birds staggering. No mention was made of subcutaneous abdominal masses or hernias. However, two of the six birds presented had umbilical hernias. Pictures were taken of one bird before the skin was dissected off the abdominal area (Fig. 1) and also after (Fig. 2). Five of the six birds had airsacculitis, swollen livers, and pericarditis. Escherichia coli was isolated from the livers and was considered a probable pathogen. Serologic tests for Mycoplasma gallisepticum were negative. The hernias did not become a flock problem.