Ava M. Trent

Individual cow risk factors for clinical lameness in lactating dairy cows

Abstract A case-control study investigating relationships between clinical lameness and individual-cow (within herd) risk factors was performed in 17 Minnesota and Wisconsin dairy herds. Cases were defined as lactating cows found lame by either of two observers during farm visits in the summer of 1989 and spring of 1990 using a uniform scoring system. A single control cow (matched by herd, season, parity, and stage of lactation) was selected for each case at each visit. Assessments of body weight, body condition, dorsal claw angles, and limb lesions were made for each case and control animal. Conditional logistic regression analysis revealed positive associations between prevalent clinical lameness and heavier body weight, lower body condition score, and shallower slope of rear lateral claw angle. Lesions associated with clinical lameness included non-tarsal rear limb superficial swellings, abnormal hoof overgrowth (including corkscrew claw), and limb lacerations. Superficial tarsal swellings, intra-synovial tarsal swellings, and carpal swellings were not associated with clinical lameness.

Excretion and persistence of bovine coronavirus in neonatal calves.

SummaryFollowing oral inoculation, the excretion of a virulent or an attenuated strain of bovine coronavirus in calf feces and their persistence in spiral colon, ileum, and jejunum were studied using hemagglutination and direct fluorescent antibody tests, respectively. The virus was excreted in feces for only 3 days at high titers and then intermittently at low titers. However, viral antigen was detected in crypt or Peyers patches for at least 3 weeks after infection in 1 of 3 calves given virulent virus and 1 of 2 calves given attenuated virus.

Surgery of the Bovine Abomasum

Intensive management of cattle has resulted in an increased incidence of abomasal disorders. Many of these disorders require surgical intervention for the best outcome. This article reviews the anatomy and physiology of the abomasum, abomasal disorders that may be treated by surgery, and the advantages and disadvantages of various surgical approaches to those disorders.

Experimental Infection with a Virulent Pneumoenteric Isolate of Bovine Coronavirus

Bovine coronavirus (BCV) is 1 of the important causes of scours in young calves. Although the role of BCV in respiratory tract infections has not been clearly defined, there is increasing evidence that it causes upper respiratory tract infection in addition to the intestinal disease. Focal involvement of lungs was recently reported in 2 of 16 calves experimentally infected with BCV, but the sequence of events including clinical signs has not been clearly described for pneumotropic BCV. The present report describes a consistent, diffuse lung involvement in calves experimentally infected with a field isolate of BCV. The details of the experimental design have been described. Briefly, newborn, colostrum-deprived, unvaccinated calves were infected orally at 5 days of age with either a virulent pneumoenteric isolate of BCV (Minnesota isolate, calves 2, 6, and 7) or with an attenuated strain of BCV (Mebus strain, calves 1 and 9). The virus suspension was fed slowly to the calves with a 20-ml syringe. Although direct inoculation of the virus into the nasal cavity was unlikely, it was not possible to control the carryover of virus to the nasal cavity via insertion of the tongue into the nostril. Four calves (calves 3, 4, 5, and 8), housed in separate rooms were included as uninfected controls. One of the uninfected controls (calf 3) developed a natural infection with BCV. Nasal cells were collected by inserting cotton swabs into the anterior nasal cavity of the calves. The swabs were rotated gently to dislodge the cells of the nasal cavity. Sufficient number of cells were collected without difficulty. The swabs were placed in Hanks’ balanced salt solution (HBSS) and immediately transported to the laboratory where they were vortexed for 1 minute to separate nasal cells from the swab and the mucus. The swab was removed from the tube and the resulting suspension was centrifuged at 650 x g for 5 minutes. The pellet (approx. 0.05 ml packed cells) was mixed with equal volume of HBSS and vortexed again. The cell suspension was placed on 8-well slides with 30 μ1/well and allowed to dry at room temperature. The slides were washed with phosphate-buffered saline (PBS), pH 7.2, dried, and then fixed in acetone for 10 minutes. After drying again, the wells were covered with a drop of FITC-labeled bovine anti-BCV conjugate and incubated in a humid chamber for 1 hour. The conjugate was found to be specific for bovine coronavirus and did not react with uninfected Madin-Darby bovine kidney cells or with uninfected tissues from control calves (gut and lungs). The slides were washed with PBS (pH 8.5) and counterstained with Evan’s blue. The calves were kept under strict quarantine and were

Treatment of Infectious Arthritis and Osteomyelitis

Infectious arthritis and osteomyelitis are commonly encountered diseases of the skeletal system that can result in premature loss of an affected animal from the herd. Selection of the best possible treatment approach for an individual animal requires a solid understanding of the pathophysiologic processes involved in the infection of bone or joint; recognition of the unique aspects of the anatomy, physiology, behavior, management, and economics of the species involved; and a broad grasp of the availability and role of various therapeutic options. By recognizing the importance of all three of these areas, a clinician not only will be able to make realistic and effective judgments about care of commonly encountered cases today but also will have a sufficient basis for rational variations in therapy as pharmacologic options expand and environmental or economic pressures change.

Effect of tetrathiomolybdate administration on the excretion of copper, zinc, iron and molybdenum in sheep bile

The copper (Cu), zinc (Zn), and iron (Fe) excreted daily in the bile of three sheep were estimated at 0.20, 0.10 and 0.36 mg respectively. Intravenous administration of tetrathiomolybdate (TM) increased bile Cu excretion and reduced liver Cu concentration. Tetrathiomolybdate had no significant effect on the excretion of Zn and Fe. These findings indicate that at least one of the mechanisms by which TM induces hypocuprosis is by increasing biliary Cu excretion. Hence it has a possible use in the treatment of Cu storage diseases in man and animals.

A LONGITUDINAL STUDY OF SALMONELLA FROM SNAKES USED IN A PUBLIC OUTREACH PROGRAM

Snakes are considered to be a source of Salmonella infection for humans, but little is known about the actual serotype prevalence in healthy snakes over time. Twelve snakes involved in a public outreach program, representing seven different species, were tested weekly for shedding of Salmonella sp. over a period of 10 consecutive weeks. The snakes were housed in close proximity but in separate exhibits. Fresh fecal samples (when available) or cloacal swabs were cultured for Salmonella sp., and subsequent Salmonella isolates were serotyped. As representatives of the feed source, the feces of two mice and the intestines of one rat were cultured weekly. Fecal samples from 11 of the 12 snakes were positive for Salmonella at least once. Seven (58%) of 12 snakes were culture positive five times or more. The weekly prevalence of Salmonella shedding varied between 25% and 66%. Two or more different serotypes were isolated from nine snakes over time; however, a predominant serotype was generally isolated from each of these snakes. Altogether 15 different serotypes were identified. Serotypes of public health concern included Newport, Oranienburg, and Muenchen. Two samples from feeder rodents were positive for Salmonella. The results are consistent with previous studies showing high intestinal colonization rates with Salmonella sp. in snakes. Frequent and intermittent shedding of multiple serotypes was evident. Feeder rodents might serve as a source for intestinal colonization. Appropriate handling protocols should be implemented for all reptiles associated with public outreach programs to minimize risk of Salmonella transmission to the public.

Antibody responses in spiral colon, ileum, and jejunum of bovine coronavirus-infected neonatal calves

Abstract A preliminary study was conducted to compare the regional intestinal immune responses of neonatal calves inoculated with virulent or attenuated bovine coronavirus (BCV) to determine the cause of reported vaccine failures. A group of 9 newborn, colostrum-deprived calves was used; two calves were inoculated with attenuated virus, four calves were infected with virulent virus (including one naturally infected calf), and three calves were uninfected controls. Calves inoculated with virulent virus produced higher titers of BCV antibodies in the intestines than those inoculated with the attenuated virus. The failure of the calves to respond to the attenuated virus was apparently due to the inability of the virus to replicate to high titers. Spiral colon, ileum, and jejunum were found to be immunologically distinct; the highest anti-BCV antibody responses were detected in spiral colon, the primary site of infection, and involved all four isotypes of bovine immunoglobulins. The antibody response in ileum was lower than in spiral colon. The immune responses developed slowly in jejunum and were associated primarily with the IgG subtypes.

OMENTAL TORSION IN A CAPTIVE POLAR BEAR (URSUS MARITIMUS)

Abstract: This is the first case report of an omental torsion in a polar bear (Ursus maritimus). A captive, 23-yr-old, 250-kg, intact female polar bear presented to the University of Minnesota Veterinary Medical Center with a 2-day history of lethargy, depression, and vomiting. Abdominal ultrasound identified large amounts of hyperechoic free peritoneal fluid. Ultrasound-guided abdominocentesis was performed and yielded thick serosanguinous fluid compatible with a hemoabdomen. An exploratory laparotomy revealed a large amount of malodorous, serosanguineous fluid and multiple necrotic blood clots associated with a torsion of the greater omentum and rupture of a branch of the omental artery. A partial omentectomy was performed to remove the necrotic tissue and the abdomen was copiously lavaged. The polar bear recovered successfully and is reported to be clinically well 6 mo later. This condition should be considered as a differential in bears with clinical signs of intestinal obstruction and hemoabdomen.

Fecal Steroid Analysis for Evaluating Ovarian Function in the Greater Kudu (Tragelaphus strepsiceros) and Lesser Kudu (Tragelaphus imberbis)

Abstract: Seasonal reproductive-endocrine norms have not been described for the genus Tragelaphus, which consists of seven species of African antelope. Longitudinal patterns of progesterone metabolite excretion were assessed by radioimmunoassays in fecal samples collected noninvasively (three to seven samples per week) from greater kudu (Tragelaphus strepsiceros, n = 4) and lesser kudu (Tragelaphus imberbis, n = 4). Progesterone metabolite excretion patterns revealed seasonal estrous cycles in both species, and discrimination of pregnant versus nonpregnant females was achieved in lesser kudu. These data reveal the value of fecal progesterone metabolites for establishing reproductive-endocrine norms in both zoo-maintained and free-living antelopes of the genus Tragelaphus.