Comparison of media to isolate Staphylococcus aureus from teat skin and milking unit liners.

Four procedures were compared for isolation of Staphylococcus aureus from swabbing solutions of teat skin and milking unit liners from commercial dairies. In 2 procedures, 0.1 ml of swabbing solutions were added to either 5 ml Vogel-Johnson or Baird Parker broth media and enriched at 37 degrees C, 4 h. Following enrichment, 0.1 ml culture was transferred to modified Baird-Parker agar and incubated at 37 degrees C, 48 h. In the other 2 procedures, 0.1 ml of swabbing solution was directly placed on either blood or modified Baird-Parker agar plates and incubated at 37 degrees C 48 h. Combining results from all methods, Staphylococcus aureus were isolated from 72 of 913 (7.9%) skin samples, and 34 of 268 liners (12.6%). On average, 43.1% (31/72) of the S. aureus isolates were found by the enrichment in liquid Vogel-Johnson procedure. The average isolation percentage for other methods ranged from 19.4% to 25.0%. Isolation of S. aureus from milking unit liner or teat skin swabbing solutions was approximately twice as likely after enrichment in Vogel-Johnson liquid media as opposed to other methods of isolation. This indicates that enrichment in Vogel-Johnson liquid media improved recovery of S. aureus from swabbing solutions.     

Congenital deafness and vestibular deficit in the dobermann

A condition characterised by the early onset of vestibular deficit and hearing loss was investigated in the dobermann breed of dog. Affected pups showed behavioural signs of head tilt, circling and ataxia and there was a total absence of vestibular response to rotation or caloric stimulation. Severe deafness, as assessed by brainstem auditory evoked response testing, was present by three weeks of age in all affected animals. The inner ears showed a progressive neuroepithelial type of cochlear degeneration with loss of the auditory sensory cells. In the vestibular system, however, there was no equivalent sensory cell loss and the only abnormal feature was the absence or abnormality of the otoconia in some of the affected animals. Pedigree analysis suggested that the condition was inherited as an autosomal recessive trait.     

Plasma and extracellular volume in calves: comparison between isotopic and 'cold' techniques.

While isotopic techniques have largely superseded traditional markers for the determination of the volume of fluid compartments in vivo, they are not always convenient, especially with diarrhoeic animals. A direct comparison was therefore made in week-old calves between Evans blue and radio-iodinated serum albumin as measures of plasma volume and thiocyanate or 24sodium as measures of extracellular fluid space. The correlation coefficients were excellent (1.00, 0.96; P < 0.001) and the calves had plasma and extracellular fluid volumes of 72 +/- 2 and 438 +/- 2 ml kg-1, respectively. The latter value is, though high, typical of young animals and comparable with other data in calves.     

Isolation of Mycobacterium paratuberculosis after oral inoculation in uninfected cattle.

Feces from cows naturally infected with Mycobacterium paratuberculosis was given to 6 uninfected heifers by orogastric intubation, to determine whether ingested organisms could be passively excreted and detected by bacteriologic culture of feces (ie, false-positive result). Heifers were paired, and each pair received a different dose of feces on days 1 and 2. Fecal samples were collected from the heifers 3 times daily. Mycobacterium paratuberculosis was detected in fecal samples of all heifers within 18 hours of being given the first dose of feces. The number of colony-forming units peaked on days 3 or 4, and organisms were no longer detected by day 7. The number of colony-forming units in fecal samples from the heifers was approximately proportional to the dose given. On days 15 and 16, the experiment was repeated with feces from a second infected cow. Results were similar to those in the first experiment. All heifers remained seronegative (agar-gel immunodiffusion test and ELISA) and had negative results to the intradermal johnin test throughout the experiment. Lymph node and intestinal tissues were obtained from all 6 heifers at slaughter on day 28. Mycobacterium paratuberculosis was not isolated from mesenteric lymph nodes from the ileocecal valve region, but was isolated from ileal mucosal samples from each heifer.     

Ionized calcium concentration in horses with surgically managed gastrointestinal disease: 147 cases (1988-1990).

Packed cell volume, total plasma protein, serum sodium, potassium, and ionized Ca2+ concentrations, and blood pH were determined at the time of admission and following surgery in 147 horses with acute abdominal crisis. Horses were allotted to 3 categories on the basis of the surgical lesion: (1) nonstrangulating obstruction of the ascending or descending colon (category A, n = 76), (2) strangulating and nonstrangulating infarction of the cecum or ascending colon (category B, n = 37), and (3) strangulating and nonstrangulating infarction of the small intestine (category C, n = 25). Horses with low serum ionized Ca2+ concentration following surgery were given 23% calcium gluconate (100 to 300 ml) IV to effect, and ionized Ca2+ concentration was determined following treatment. The serum ionized Ca2+ concentrations of horses in categories A, B, and C before and after surgery were lower than our normal laboratory reference range. Prior to surgery, serum ionized Ca2+ concentration measured from horses in category B and C was lower than that in horses in category A. There was no difference in ionized Ca2+ concentration in serum samples obtained before surgery in horses from category B and C, and in serum samples obtained following surgery. There was a decrease in ionized Ca2+ concentration during surgery in horses in category A. There was no change between preoperative and postoperative ionized Ca2+ concentration in the samples obtained from horses in category B and C. After calcium gluconate administration, all horses with low serum ionized Ca2+ after surgery had concentrations within our normal range. Measurement of serum ionized Ca2+ in horses with an acute abdominal crisis is recommended.(ABSTRACT TRUNCATED AT 250 WORDS)     

Dual-Energy X-Ray Absorptiometry and Force-Plate Analysis of Gait in Dogs With Healed Femora After Leg-Lengthening Plate Fixation

Dual-energy x-ray absorptiometry was used to measure bone mineral density of four regions in healed femora of nine dogs after fracture fixation with a leg-lengthening plate. Six to 85 months (mean, 46 months) after surgery, the bone mineral density of healed femora was not significantly different from the contralateral uninjured femora ( P >.05; power = 0.8 at Δ= 15%). Radio-lucencies around the proximal screws, apparently associated with screw loosening, were seen on radiographic views of the healed femora of three dogs. In one of these dogs, one screw in the proximal metaphysis had broken. Force-plate analysis of gait was also performed on dogs at the time of bone mineral density measurement. Peak vertical force was decreased in the pelvic limb with the healed fracture compared with the contralateral unoperated limb ( P < 0.05). Clinically apparent lameness in three dogs did not appear to be associated with altered bone mineral density and may have been caused by hip osteoarthritis, a nondisplaced hairline diaphyseal fracture, and screw loosening in conjunction with extensive post-traumatic soft tissue injury.     

Evaluation of Tissue Adhesive to Contain Axonal Regeneration in Horses

Bilateral palmar and plantar digital neurectomies were completed in 10 horses (a total of 80 neurectomies) using one of three methods: (1) simple transection (guillotine method); (2) epineural capping; (3) n-butyl cyanoacrylate injected into the epineural sheath to act as a nerve sealant. Horses were regularly evaluated clinically for tenderness in and around the surgical site, as well as skin sensation at the coronary band in the heel region, during the 12-week course of the study. None of the surgical sites exhibited any signs of drainage or infection. Horses were then euthanatized, the nerve stumps were dissected from surrounding tissues, and the length and width of the tissue mass that had formed on the end of the nerve was recorded. Longitudinal and transverse sections of the nerve endings were examined histologically for numbers of proliferating axon sprouts (neuroma formation); whether the axons had penetrated the epineurium; degree of Schwann cell proliferation; degree of chronic inflammation; extent of foreign body reaction; extent of retrograde degeneration of the nerve bundles; and amount of fibro vascular proliferation. The proportion of legs exhibiting tenderness or heel sensation did not differ significantly between the three different treatments at any of the six different times they were examined. There was no difference between the three treatments in the length or width of the fibrous tissue scar on the ends of the nerves or in the number of sprouting axons from the ends of the nerves. Of 80 nerves examined, only two nerves were not confined to the epineurium. Both these nerves had been treated by simple transection. Statistically there was more chronic inflammation and foreign body reaction in the acrylic treated nerves, but no difference in Schwann cell proliferation or retrograde degeneration between the three treatments. There was slightly less fibrovascular proliferation in the transected nerves than in those subjected to epineural capping or acrylic, but the difference was not statistically significant. The use of the tissue adhesive n-butyl cyanoacrylate to prevent the continuous growth of axons after digital neurectomy seems to offer little advantage over more traditional methods of neurectomy.     

Distribution of ASFV antigens in pig tissues experimentally infected with two different Spanish virus isolates.

Lymph nodes, spleen, liver, lung and kidney obtained from pigs experimentally infected with two African Swine Fever Virus (ASFV) isolates of differing virulence were fixed by perfusion with glutaraldehyde and embedded in paraffin. An immunoperoxidase technique using a polyclonal anti-ASFV serum was performed on tissue sections in order to detect ASFV antigen. The distribution of ASFV antigen in such infected organs is shown and the differences between both infections compared and discussed. Monocytes, macrophages, hepatocytes, endothelial cells, neutrophils and epithelial cells were found to contain ASFV antigens.     

Growth patterns of two lines of Angus cattle selected using predicted growth parameters.

Linear functions of body weight and condition score at weaning and 18 mo of age were used to predict the mature weight (A) and maturing rate (k) parameters of an asymptotic growth model of Angus cows at the Subtropical Agricultural Research Station, Brooksville, FL. From 1981 through 1988 a heavy-mature-weight line (Line A) and a rapid-maturing line (Line K) were selected based on predicted A and k values. Linear contrasts (A-K) of least squares means for weight at fixed ages indicated that the weight difference between lines increased from birth to maturity during the period of the study. Animals from Line A were heavier (P less than .01) at all ages. A negative response in maternal ability, relative to increased growth potential of their calves, seems to have occurred in the cows of Line A. Mature weight was reached at approximately 4.5 yr of age in Line K and at approximately 5.5 yr in Line A. Brody's three-parameter and Richards' four-parameter functions were fitted to 2,855 quarterly weights of cows, from birth to 6.5 yr of age, to estimate the average growth curve for each line. Brody's model gave better estimates of weights from 18 mo to maturity, but the asymptotic residual mean squares were slightly higher because early weights were overestimated. Linear and nonlinear regression analyses of weight-age data and comparisons of degree of maturity at different premature ages showed differences in the growth patterns of the two lines selected for early predicted values of A and k.     

Detection with nonradioactively labeled probes of the toxin genes of different E. coli pathotypes from swine]

We tested hemolytic E. coli from 86 pigs with edema disease or colidiarrhea. They were tested serologically and with nonradioactive digoxigenin-dUTP labelled probes for the presence of enterotoxin or Shiga-like-toxin genes. By slide-agglutination we detected 38 cases with E. coli O149:K88, 28 with E. coli O139:82B and 20 with E. coli O141. E. coli of serogroup O149:K88 isolated from diarrheic pigs, reacted with the probes for LT and STb genes. Edema disease E. coli O139:82B reacted with the SLTII probe. E. coli O141, isolated from colidiarrhea or edema disease showed a diversity of toxin gene patterns. All the E. coli O141 from diarrheic pigs reacted with the probes for LT and STap in addition to SLTII. No strains isolated from pigs with edema disease possessed any of these enterotoxin genes. Gene probe technique confirmed the serological method as useful tool for diagnosing E. coli O149:K88 and O139:82B as ETEC or VTEC, respectively. On the other hand only the demonstration of toxin genes with probes could explain the pathological findings in the pigs shedding E. coli of serogroup O141.