Ophthalmic examination and conjunctival bacteriologic culture results from a herd of North American bison.

OBJECTIVE: To establish ocular characteristics, determine nature and prevalence of ocular lesions, and identify representative bacterial flora from the conjunctiva of North American bison (Bison bison). DESIGN: Prospective study. ANIMALS: 63 bison; 45 males and 18 females. PROCEDURE: Ophthalmic examinations were performed on 1 group of 38 bison in December 1997 and on a second group of 25 in March 1998. Eyes were examined with a penlight, magnification loop, and indirect ophthalmoscope. Two culture swabs were used to obtain samples from the inferior conjunctival sac. One swab was submitted for isolation of bacteria and the second was submitted for isolation of Mycoplasma organisms. RESULTS: 15 ocular abnormalities were observed in 13 of the 63 bison. These included minor ocular discharge in 5 animals, 1 eyelid laceration, 1 periocular Demodex spp infection, 6 corneal abnormalities, 1 anterior synechia, and 1 cataract. Seventeen species of bacteria were isolated from the 63 swabs submitted for culture. The most prevalent bacteria were of the genus Bacillus (74.6%). Mycoplasma organisms were not observed. CONCLUSIONS AND CLINICAL RELEVANCE: Corneal abnormalities were the most frequently identified ocular lesions in bison. Bacterial flora of the conjunctiva and ocular characteristics were similar to those reported for cattle.

Demodicosis in an American bison.

An 18-month-old, male American bison (Bison bison) was presented with 7- to 9-mm size nodules periorbital, perineal, and on the ventral surface of the tail. Demodex spp. were identified from the exudate by microscopic examination. Examination 6 mo later revealed that the infestation had nearly cleared without treatment.

Ultrastructure of Pasteurella haemolytica-induced changes in gnotobiotic calf lung.

Gnotobiotic calves born and maintained in a germ-free environment until inoculated with a pathogen are model animals for studying the progression of a specific disease, such as pneumonic pasteurellosis. To investigate early progression of pneumonic pasteurellosis, we compared the ultrastructure of regions of gas-exchange in the lungs of three challenge-exposed and three uninoculated control gnotobiotic calves. Three calves were inoculated endobronchially with a bolus of 7.9 x 10(10) CFU of Pasteurella haemolytica A1 and studied in a specific pathogen-free environment until severe respiratory distress occurred, at which time they were euthanized. Slices of lung tissue from the midregion of the right dorsal caudal lobe (area of lesion) of infected and control calves were fixed in glutaraldehyde and prepared for scanning (SEM) and transmission (TEM) electron microscopy. SEM revealed bacteria among long tangled strands of fibrin in pulmonary alveoli that became obliterated with cellular debris. TEM revealed areas of encapsulated and/or nonencapsulated bacteria among the cellular debris and patches of fibrin. Many neutrophils and macrophages that infiltrated the alveoli had phagocytosed bacteria and undergone degradation. Less cellular damage was present when encapsulated bacteria bordered the interalveolar septa than when nonencapsulated lysed bacteria were present. Where lysed bacteria were present, the pulmonary capillaries were dilated because of swollen, degranulated neutrophils, fibrin clots, and cellular necrosis. Both encapsulated and nonencapsulated bacteria were present in the lung tissue of gnotobiotic calves within the first 24 h after endobronchial inoculation of early log phase P. haemolytica. Loss of capsular material around individual and divided pairs of bacteria led to their consequential aggregation, lysing, and severe damage to the adjacent pulmonary capillaries and interalveolar septa.

Hereditary syndactyly in Angus cattle.

Twenty-five syndactylous Angus cattle, characterized pathologically, were reported from 16 herds in 10 states from 1979 to 1994. Twenty-one (84%) had all 4 legs syndactylous, 3 (12%) had 3 legs syndactylous, and 1 (4%) had 2 legs syndactylous. All syndactylous cattle walked with considerable difficulty. Hooves of aged animals became curled and bent laterally or medially. Affected hooves had the appearance of a truncated cone, the base of which was located at the coronary band. Most hooves were fused completely with no indication of dual anlage. An occasional hoof had a distal notch, and other hooves had a dorsally located groove indicating dual embryonic origin. Lateral dewclaws were enlarged in most cases. Radiographs and dissections of limbs of 19 animals revealed a consistent pattern of fusion in most affected calves. Lesions included 1 or more of the following: disappearance of the large metacarpal and metatarsal intertrochlear notches, horizontal fusion of 1 or more carpals and tarsals, fusion of proximal sesamoids, 1 distal sesamoid, and fusion of paired phalanges. Evidence of a genetic cause consisted of 11 syndactylous calves among 70 offspring of 4 3/4 sib families, 8 preterm syndactylous fetuses among 148 preterm fetuses and 13 calves in progenies of 19 animals tested for possible heterozygosity, and 5 syndactylous calves from matings of an Angus syndactylous bull with 1 Angus and 4 Holstein syndactylous cows. Data were consistent with recessive inheritance at a single locus. Angus cattle with sydactytly had a larger number of affected limbs than did syndactylous Holsteins and their Angus crosses, suggesting existence of 2 recessive alleles. The allele of Holsteins (syH) appeared to influence phenotypic expression in a dominant pattern over the Angus allele (syA). Both syA and syH alleles acted as recessives to the normal SY allele. Phenotypic effects on limb development were most dramatic in calves with the syA/syA genotype.

Respiratory problems of newborn calves.

Cardiopulmonary development of fetus is a timely event that proceeds to the point that birth can take place. Calves may be born premature, and because of surfactant deficiency, develop the respiratory distress syndrome. More research needs to be done on fetal lung development in calves to determine the age when maturity has been reached for compatibility with extrauterine life. Also, more specific therapy regimens need to be developed that will enhance lung development. The birthing process is a major event that must proceed in a timely fashion. Any delay in delivery will compromise further the already hypoxic fetus. Practitioners need to recognize the severely hypoxic/ asphyxiated calf and be prepared to therapeutically support the cardiopulmonary systems.

Passive protection of calves with Pasteurella haemolytica antiserum.

Four colostrum-deprived calves each were immunized passively with antisera to whole Pasteurella haemolytica, leukotoxin-containing supernatants of P haemolytica, P haemolytica lipopolysaccharide, or newborn calf serum. Calves were challenge exposed intrabronchially with 5 x 10(9) P haemolytica, and 24 hours later, the resulting lesions were evaluated. The greatest protection against challenge exposure was provided by the antiserum to whole P haemolytica (lesion score = 6.3), whereas newborn calf serum provided the least protection (lesion score = 28.3). Calves that received antiserum to P haemolytica supernatants were moderately protected (lesion score = 16.3), and the antiserum to lipopolysaccharide provided minimal protection (lesion score = 21.8). Antibodies that were unique to whole P haemolytica antiserum and produced dense bands on immunoblots were detected to antigens at 66, 50, and 30 kd. Antibodies in the supernatant preparation that produced prominent bands reacted to antigens between 100 and 90 kd. Collectively, antibodies to these antigens may be responsible for enhancing resistance to experimentally induced pneumonic pasteurellosis. Antibodies to antigens in P haemolytica lipopolysaccharide provided little to no protection.

Multifocal subacute necrotizing encephalomyelopathy in Simmental calves.

In 24 cases of multifocal necrotizing encephalopathy (MNE) in Simmental and Simmental-cross cattle, clinical features varied, consisting of mild rear limb ataxia, caudal paresis, and, less often, sudden death. Bilateral and symmetric malacic lesions were present in the brain stem (olivary nucleus) of all affected calves. Foci of malacia affecting thoracic spinal cord and additional brain stem sites were common. Neuronal cell bodies and hypertrophied capillaries were present within malacic foci. Rarefaction of neuropil, progressing to complete parenchymal loss, characterized advanced lesions. Pathologic features were similar to those of Leigh syndrome in humans, and a similar defect in aerobic metabolism is hypothesized. Occurrence of the syndrome within 1 breed over a wide geographic area suggests that hereditary factors contribute to development of MNE.

Penile hematoma in bulls: 60 cases (1979-1990).

Sixty bulls with penile hematomas were examined from 1979 through 1990. Thirty-eight bulls underwent surgical correction, 17 bulls were managed by medical treatment, and 5 bulls were not treated. Hereford and Polled Hereford breeds represented the majority (n = 37, 62%) of the bulls, with 10 other breeds representing the remainder (n = 21, 35%) in this study; breed was not reported in 2 bulls. Follow-up information was obtained from owners (40/60) through conversation on the success or failure of treatment, interval of sexual rest, duration of breeding soundness, and final outcome of the bull. Surgical correction was successful in 19 (70%) of 27 cases; medical treatment was successful in 6 (46%) of 13 cases. Of the 8 bulls that had penile hematomas with swelling measuring > 20 cm in width, 6 were successfully treated surgically, compared with 1 of 3 successfully treated medically. Of the bulls with penile hematomas having a swelling measuring < or = 20 cm in width, 7 of 9 were successfully treated surgically, compared with 4 of 5 successfully treated medically. Duration of the penile hematoma had little effect on the success of surgical correction. Of the bulls allowed sexual rest for > 2 months after treatment was initiated, 6 (25%) of 24 had a recurrence of penile hematoma. Four (40%) of 10 bulls allowed sexual rest for < or = 2 months had a recurrence of penile hematoma.

Upper motor neurone and descending tract pathology in bovine spinal muscular atrophy.

The extent of neuropathology in a recently reported disease of Brown Swiss cattle, spinal muscular atrophy (SMA), was investigated with light and electron microscopy. Many regions of the central nervous system were sampled from 10 SMA-affected and three normal Brown Swiss calves. In addition to extensive necrosis of lower motor neurones there was extensive upper motor neurone degeneration and descending tract pathology. Since these abnormalities are also hallmarks of amyotrophic lateral sclerosis (ALS), SMA may be an animal model for that disease. There was also considerable vacuolar degeneration, which is a feature of the wobbler mouse and murine type C RNA virus-induced paralytic disease models of ALS.

Serologic survey for selected microbial pathogens in bison from Kansas.

A serologic survey was conducted on an American bison (Bison bison) herd in Kansas for antibodies against Brucella spp., Leptospira interrogans serovar canicola, pomona, grippotyphosa, icterohaemorrhagiae, and hardjo, Anaplasma spp., bluetongue virus, infectious bovine rhinotracheitis virus and bovine viral diarrhea virus. There was an increase in prevalence of bluetongue antibodies from 38% in 1987 to 100% in 1989 in animals greater than or equal to 24-mo-old. Prevalences of antibodies against the other livestock pathogens were either negative or at levels associated with previous vaccination.

Hematological and blood chemistry profiles of American bison grazing on Konza Prairie of Kansas.

Normal hematological and blood chemistry parameters were measured in 45 American bison (Bison bison) that were divided into three age groups for comparison. There was a statistically significant (P less than 0.05) increase with advancing age in mean corpuscular volume, mean corpuscular hemoglobin, absolute neutrophil and eosinophil counts, total protein, globulin, creatinine, and blood urea nitrogen. There was a statistically significant (P less than 0.05) decrease with advancing age in levels of sorbital dehydrogenase, alkaline phosphatase, glucose, sodium, calcium and phosphorus.

The effects of stressful exercise on leukocytes in cattle with experimental pneumonic pasteurellosis.

Seven yearling bulls were treated with stressful exercise and intrabronchial Pasteurella haemolytica A1. Group 1 bulls (nos. 1-4) underwent treadmill exercise and, 24 days later, intrabronchial instillation of P. haemolytica A1. Group 2 bulls (nos. 5-7) underwent treadmill exercise, followed 30 min later by intrabronchial P. haemolytica A1. Blood lactic acid values were raised (p less than 0.05) by treadmill exercise only, but plasma cortisol was raised (p less than 0.05) by treadmill exercise and by P. haemolytica A1 infection. Neutrophils in bronchoalveolar lavage (BAL) differed from control values 24 h after treadmill exercise, and 1 h and 4 h after P. haemolytica A1 infection. Respiratory disease was more severe and the gross lung lesions were larger in group 2 bulls than in group 1 bulls. P. haemolytica A1 was recovered from the livers, spleens and mesenteric lymph nodes of group 2 but not group 1 bulls, suggesting that group 2 bulls had experienced bacteraemia. Decreased neutrophils in BAL fluid from group 2 bulls at 1 h and 4 h after infection suggests that exercise transiently inhibited neutrophil egress from the blood to the alveoli; BAL neutrophils peaked at 1 h and 4 h after infection in group 1 bulls but declined at 24 h. We conclude that group 2 bulls were made more susceptible to experimental pneumonic pasteurellosis by stressful exercise.

Pneumonic pasteurellosis induced experimentally in gnotobiotic and conventional calves inoculated with Pasteurella haemolytica.

Experimental pneumonia caused by Pasteurella haemolytica was induced in 2-week-old gnotobiotic (n = 4) and conventional (n = 6) calves by endobronchial inoculation into the right caudal lung lobe of 7.9 x 10(10) +/- 0.6 x 10(10) (mean +/- SD) colony-forming units of P haemolytica in the 6-hour log phase of growth. The calves were studied for 24 hours or less. Regression lines for the relationship between clinical index and time for the gnotobiotic group and conventional group of calves were compared, and the clinical index was found to be significantly (P less than or equal to 0.005) more rapid in the gnotobiotic group. There was also a significant difference in the preinoculation, absolute segmented neutrophil count (P less than or equal to 0.05), and in the total serum protein, albumin, and globulin values (P less than or equal to 0.05). Comparison of the preinoculation and post inoculation blood cell and blood chemical values revealed a significant increase (P less than or equal to 0.05) in the numbers of band neutrophils and fibrinogen in conventional calves, and a significant decrease (P less than or equal to 0.05) in the total WBC count in gnotobiotic calves. Necropsy of both groups of calves revealed a circular to oblong lesion that was congested, edematous, and firm, and which occupied 20% to 100% of the right caudal lung lobe and involved the remaining lung lobes to a more minor degree. When mean lesion scores of the 2 groups of calves were compared, no significant difference (P less than or equal to 0.05) was found.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical and pathologic studies of experimentally induced Pasteurella haemolytica pneumonia in calves.

Pasteurella haemolytica pneumonia of the right caudal lung lobe was experimentally induced in 2-week-old Holstein calves (n = 11) by endobronchial inoculation of 7.9 x 10(10) colony-forming units of 6-hour log-phase bacteria. Calves were studied for 72 hours after inoculation. The challenge procedure consistently induced a lesion in the right caudal lung lobe, which was consistent radiographically with results of pathologic examination and a similar volume of bronchography contrast medium. Clinically, the calves developed a significant increase in rectal temperature within 24 hours after inoculation. Seventy-two hours after inoculation, the total WBC counts, absolute band neutrophil counts, monocyte counts, and blood fibrinogen concentrations were significantly higher than normal and albumin concentration was significantly decreased. Necropsy revealed a circular to oblong lesion that was congested, edematous, and firm and occupied 20 to 40% of the right caudal lung lobe. Histologic examination revealed a severe acute inflammatory reaction characterized by cellular exudate and proteinaceous fluid in the alveoli, interlobular septa, and pleura.

The etiology and surgical management of tracheal collapse in calves.

The mean ages of 10 calves with tracheal collapse were 2.7 weeks at onset of clinical signs and 9.4 weeks at presentation for treatment. Inspiratory and expiratory dyspnea and stunted growth were the most common clinical signs. There were abnormalities of the cranial ribs consistent with healing fractures with redundant callus in eight lateral thoracic radiographs. Tracheal collapse in calves may result from cranial thoracic trauma during or soon after birth. Short polypropylene ring prostheses made from 60 ml syringe barrels were placed on the tracheas of four calves with cervical tracheal collapse. There were cranial rib masses in all calves and resection of the right first and second ribs was necessary in one calf to allow placement of prostheses. Dyspnea was relieved in all calves. One calf died of unrelated causes in year 3, and one calf had recurrence of clinical signs at month 5 and was euthanatized. In both calves, tracheal stenosis resulted from continued growth and infolding of the trachea within the constraints of the prostheses. One calf was alive at month 11, and one calf died of acute bronchopneumonia on day 2. Removal of tracheal prostheses in calves is recommended after 2 to 3 months if clinical signs recur.