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Biomedical subjects

W C Rebhun

Publications and source records attributed to W C Rebhun.

At least 19 recordsLinked to original sources

Selective IgM deficiency and abnormal B-cell response in a foal.

Selective IgM deficiency was diagnosed in a 3-month-old Standardbred colt that was referred for chronic respiratory tract disease. Immunoglobulin quantification revealed normal IgG and IgA concentrations, but undetectable IgM concentration. Stimulation of blood lymphocytes with the T-cell mitogens concanavalin A and phytohemagglutinin yielded results within the normal range. However, stimulation with the B-cell mitogen lipopolysaccharide produced no response. A B-cell defect similar to that associated with several immunodeficiency disorders in people was suggested as the cause of the IgM deficiency in this colt.

Animals

Chronic frontal sinusitis in dairy cattle: 12 cases (1978-1989).

Chronic frontal sinusitis in 12 dairy cattle most often was associated with a history of dehorning, in which the sinus was entered (67%), or with respiratory tract disease (25%). The most common organisms isolated were Actinomyces pyogenes and Pasteurella multocida. Signs of infection did not develop for months in some cattle and were often intermittent. The most common clinical signs included anorexia, lethargy, fever, frontal bone distortion, exophthalmos, abnormal posture, nasal discharge, and neurologic abnormalities. Treatment consisted of trephination at 2 sites, drainage and lavage of the sinus cavity, and administration of antibiotics and analgesics. Eight cattle responded well to treatment and were discharged, but 4 others had signs of CNS involvement and died or were euthanatized. Trephination of the frontal sinus cavity at carefully chosen sites and antibiotic treatment are indicated when sinusitis is suspected. Drainage of the sinus cavity is imperative to avoid extension of the infection into the CNS.

Animals

Thoracotomy in adult dairy cattle: 14 cases (1979-1991).

Fourteen cows were subjected to thoracotomy as an aid in the treatment of either septic pericarditis (n = 7) or unilateral pleuritis (fibrous or purulent; n = 7). Thoracic lesions were primary in 4 cows, secondary to traumatic reticuloperitonitis in 9 cows, and secondary to extension of a liver abscess in 1 cow. Thoracotomy was performed on 9 cows under local anesthesia. Surgery was performed on 5 cows under general anesthesia; 2 died during anesthesia, and 2 others were euthanatized. Of the 10 cows allowed to recover from surgery, 4 had pericarditis and 6 had pleuritis. Four cows with pleuritis had thoracic abscesses. All but 1 cow with pericarditis died or were euthanatized, and 5 of the 6 cows with pleuritis were discharged from the hospital. A year after surgery, 1 cow was culled because of infertility, and the other 5 cows were returned to production.

Anesthesia, General

Retinal and optic nerve diseases.

Basic knowledge of the normal appearance and variations of the equine fundus coupled with frequent practice in ophthalmology will allow equine practitioners to be confident when assessing the equine fundus during ophthalmic examinations. Once the normal variations are mastered, appreciation of retinal, choroidal, optic nerve, and vitreal abnormalities is possible. Congenital and acquired lesions of the equine retina, optic nerve, and vitreous are discussed and illustrated.

Animals

Factors associated with the risk of developing sarcoid tumours in horses.

A retrospective case-control study was conducted to identify risk factors in horses associated with the development of the common skin tumours known as sarcoids. The study involved 503 sarcoid cases diagnosed (January 1980-December 1989) at New York State College of Veterinary Medicine and a similar number of controls (non-sarcoid cases). Data on age, breed and sex of cases and controls were obtained from computerised records. Multiple logistic regression analysis was used to identify risk factors. Separate data were obtained for the same 10-year period from the Veterinary Medical Data Program to determine the proportional morbidity rate at different veterinary colleges in North America. Appaloosa, Arabian and Quarter horses were at a higher risk of developing sarcoid tumours than were Thoroughbred horses. Standardbred horses had a lower risk of developing sarcoids. Geldings were at a higher risk of developing sarcoids in comparison with stallions. There was no significant difference in the risk of developing sarcoids between stallions and mares. The risk of developing sarcoid increased with age up to 15 years and then declined. The proportional morbidity rate of sarcoids among the veterinary colleges ranged between 0 and 14 per 1,000 cases, with an average of 6 per 1,000.

Age Factors

Severe masseter myonecrosis in a horse.

A 6-year-old Quarter Horse was examined because of acute, severely swollen masseter muscles (palpation of which elicited pain response), exophthalmos, severe chemosis, and protrusion of the third eyelids. Blood selenium and vitamin E concentrations, and results of feed analysis and muscle biopsy supported a diagnosis of nutritional myopathy. The horse was treated and was clinically normal 2 weeks after discharge from the hospital.

Animals

Emphysematous gastritis in a horse.

A 12-year-old Morgan gelding was examined for colic of 3 days duration. Signs of depression, colic, diarrhea, and endotoxemia persisted despite aggressive medical therapy and surgical exploration. Culture results from gastric fluid and feces yielded many colonies of Clostridium perfringens. This organism also was recovered from peritoneal fluid 10 days after admission; consequently, the horse was euthanized. At necropsy, a localized gas-filled, necrotic stomach wall was found; many mucosal and submucosal gas blebs were visible. Culture of this tissue yielded Clostridium perfringens. Emphysematous gastritis is a fulminant infection of the stomach wall caused by gas-forming organisms that gain access to the submucosa via mucosal defects such as ulcers. This condition has been reported infrequently in people, and the case reported herein represents the first instance of emphysematous gastritis in the horse.

Animals

Pyelonephritis in cows: 15 cases (1982-1986).

Medical records of 15 adult cows with a final diagnosis of pyelonephritis were evaluated retrospectively. Only 3 cows had obvious clinical signs that indicated urinary tract disease. Physical examination, including rectal and vaginal examinations, and urine chemical reagent strip screening detected abnormalities in all 15 cows and allowed subsequent confirmation by culture results of urine samples obtained using a catheter. Bacteriologic cultures of urine revealed Corynebacterium renale infection in 6 cows and Escherichia coli infection in 9 cows. Long-term treatment with antimicrobial drugs resulted in recovery in 9 of 11 treated cows. Of these, 4 of 4 cows with C renale infection and 5 of 7 cows with E coli infection recovered; the remaining 2 cows with E coli infection died.

Animals

Failure of omasal transport attributable to perireticular abscess formation in cattle: 29 cases (1980-1986).

During a 7-year period, failure of omasal transport attributable to a perireticular abscess was diagnosed in 29 cows. Affected cattle were examined because of anorexia, hypogalactia, and bilateral abdominal distention. The cows were all female Holsteins, 15 months to 10 years old. The abscess was identified during exploratory celiotomy and rumenotomy or at necropsy. Traumatic reticuloperitonitis was believed to be the cause. Twenty-seven cattle (93%) were treated surgically. The abscess was drained into the reticulum or omasum in 25 cows (86%). Twenty-four cows (83%) survived to the time of discharge from the hospital, and 20 (69%) survived for at least 1 year and became productive members of the herd. This is a better survival rate than that reported for other causes of vagal indigestion.

Abscess

An epizootic of blindness and encephalitis associated with a herpesvirus indistinguishable from equine herpesvirus I in a herd of alpacas and llamas.

Blindness characterized by dilated unresponsive pupils and funduscopic evidence of varying degrees of vitritis, retinal vasculitis, retinitis, chorioretinitis, and optic neuritis developed in 21 alpacas and 1 llama within a 30-day period. The animals were part of a group of approximately 100 animals imported from Chile one year earlier. The animals had spent 6 months in quarantine and then, for the 6 months preceding the epizootic, were housed at an exotic animal import-export farm, where the disease developed. Four of the affected animals also had signs of neurologic dysfunction. A herpesvirus indistinguishable from equine herpesvirus I was isolated from 4 of the affected animals, and antibody titers diagnostic for equine herpesvirus I were demonstrated in the serum of all but one of the affected animals.

Animals

Atypical actinobacillosis granulomas in cattle.

Actinobacillus lignieresii is well recognized as the cause of "wooden tongue." We have encountered Actinobacillosis as the cause of granulomas in unusual locations. These lesions have been confused with neoplasms, nasal polyps, or exuberant granulation tissue. Four such cases constitute this report.

Actinobacillosis

Listeriosis.

The signs of bovine listeriosis include depression and variable cranial nerve deficits indicative of brain stem inflammation. Because a wide range of cranial nerve deficits exists in bovine listeriosis patients, a thorough neurologic examination and cerebrospinal fluid analysis are essential to accurate diagnosis. Treatment should consist of intensive antibiotic therapy owing to the intracellular location of the causative organisms and should also address metabolic acidosis in those patients with loss of buffer because of excessive salivation. The public health implications of bovine listeriosis require the veterinarian to protect all persons attending the bovine patient affected with listeriosis.

Animals

Successful management of malignant edema caused by Clostridium septicum in a horse.

The clinical course and successful therapeutic management of a horse with malignant edema caused by Clostridium septicum is described. This is believed to be the first report of a horse surviving malignant edema caused by C. septicum. A discussion of this disease syndrome, including etiology, pathogenesis, clinical signs, therapy, and diagnostic methods is presented.

Animals

Healing of experimentally induced corneal ulcers in horses.

Corneal ulcers to the depth of the anterior third of the stroma were created surgically in both eyes of 10 ponies. One eye in each pony was treated topically with chloramphenicol and 1% atropine ophthalmic ointments 3 times per day; the contralateral eye was not treated topically. All ponies were given phenylbutazone orally for relief of ocular pain. Fluorescein-stained ulcers were measured once a day. The median healing time of the treated eyes (11 days) and the median healing time of the nontreated eyes (13.5 days) were found not to be significantly different. Clinically, however, more severe complications arose in the nontreated eyes.

Animals

Rumen collapse in cattle.

Simultaneous auscultation and percussion of the bovine abdomen is a standard physical diagnostic tool employed to detect gas and fluid distention within an organ such as a displaced abomasum or dilated cecum. Such distension results in an area of tympanic resonance or ping. A previously unreported condition--rumen collapse--may also cause a left-side abdominal ping that can easily be misdiagnosed as left displacement of the abomasum. Associated medical problems causing complete anorexia may lead to the rumen collapse syndrome in cattle. Differentiation of rumen collapse from displacement of the abomasum is important since cattle with rumen collapse require only medical therapy, and surgical intervention is not necessary.

Abomasum

Bovine virus diarrhea--clinical syndromes in dairy herds.

Bovine Virus Diarrhea (BVDV) was diagnosed as the major etiological agent in 10 dairy herd disease outbreaks. The outbreaks varied between herds in time of onset in individual cattle, signs, morbidity, and clinical course. A definitive diagnosis was obtained by viral isolation from whole blood samples in each herd. Each herd problem and its clinical course was described in detail. A discussion of current knowledge pertaining to BVD--the disease and the virus--follows. The importance of strain variation relative to disease production and prophylaxis was highlighted.

Animals

Thymic lymphosarcoma in three heifers.

Three heifers with the thymic form of lymphosarcoma were examined. In each of the 3 cases, fever, bloat, and jugular venous distention had developed. Detectable antibody to bovine leukosis virus was not found on agar gel immunodiffusion testing in any of the cases. Thymic lymphosarcoma was confirmed by necropsy and histologic examination. Thymic lymphosarcoma must be considered in the differential diagnosis in heifers with fever, bloat, and jugular venous distention.

Animals

Complications of blind-stitch abomasopexy: 20 cases (1980-1985).

Over a 5-year period, 20 adult Holstein cows were admitted to the New York State College of Veterinary Medicine because of complications following blind-stitch percutaneous abomasopexy for correction of left-displaced abomasum. Of the 20 cows, 16 were treated surgically, 2 were treated medically, and 2 were admitted to the pathology service for necropsy. Complications associated with the blind-stitch technique included peritonitis, cellulitis, abomasal displacement or evisceration, complete forestomach obstruction, and thrombophlebitis of the subcutaneous abdominal vein. Because of the various complications associated with blind-stitch percutaneous abomasopexy, we concluded that it is not an appropriate procedure for correction of left displaced abomasum in valuable cattle, but may be used as an alternative for salvage in less valuable cows.

Abomasum