Fractionation of cock spermatozoa

An account is given of the methodology for fractionation of cock spermatozoa into head and tail fractions by ultrasonication, followed by sucrose density gradient centrifugation. Quantitative estimates of DNA attested to 89.4% purity of the head fraction and low contamination of tails with heads. Recovery of protein and malic dehydrogenase (MDH) activity, following sperm fractionation, averaged 94.3% and 95.7%, respectively. Contamination of the head fraction with tails, as assessed by MDH assay, was only 4.65%, and the purity of the tail fraction was 91%. Intensive succinic dehydrogenase (SDH) activity was histochemically localised in the separated tail fraction and in the tail portion of intact spermatozoa. However, SDH activity was discernible neither in the head fraction nor in the head of intact spermatozoa.     

Effect of xylazine on cerebrospinal fluid pressure in conscious horses.

Lumbosacral CSF pressure was measured in 6 horses via a catheter inserted through the lumbosacral space. Heart rate, facial artery pressure, central venous pressure, and CSF pressure were measured before IV injection of a saline solution control, for 15 minutes after saline solution injection, and for 60 minutes after the IV injection of 1.1 mg of xylazine/kg of body weight. Arterial pH and blood gases were analyzed before saline solution injection, 15 minutes after saline solution injection, and at 15, 30, and 60 minutes after xylazine injection. Constant craniocervical posture was maintained during sedation. Lumbosacral CSF pressure was significantly decreased for 15 minutes after xylazine injection. Diastolic arterial pressure was significantly increased 4 minutes after xylazine administration and diastolic and mean arterial pressure were increased at 6 and 8 minutes after xylazine administration. Small increases in systolic arterial blood pressure and central venous pressure, and a small decrease in heart rate were observed. There were no significant differences in the arterial blood gas values. It was concluded that IV injection of xylazine causes a decrease in intracranial pressure in healthy conscious horses. The effects may be different in horses with neurologic disease or cerebral trauma.     

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.     

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.     

Severe mortality in broiler chickens associated with Mycoplasma synoviae and Pasteurella gallinarum.

Severe economic loss due to high mortality and condemnation rates occurred on two commercial broiler facilities. Chickens had moderate-to-severe airsacculitis, pericarditis, perihepatitis, tracheitis, and synovitis. Pasteurella gallinarum was isolated from 16 of 18 pericardia, four of 14 livers, 11 of 16 air sacs, six of seven joints and one of 28 tracheas in pure culture. In addition, Mycoplasma synoviae was isolated from trachea and air sac. Lesions were suggestive of an Escherichia coli septicemia, but E. coli was isolated from only four of 28 tracheas and one of 14 livers in pure culture. A coronavirus was isolated from trachea and lung. Whether this coronavirus represented a vaccine or field strain of infectious bronchitis was not determined. These findings suggested that the severe lesions were due to a concomitant infection with an atypical strain of P. gallinarum.     

Acute selenium toxicosis in a dog

A toxic dose of selenium administered by IM injection to a 3-year-old Chihuahua resulted in pulmonary edema and death. The compound had been dispensed to the owner inadvertently in combination with a vitamin E preparation. Vitamin and mineral products often are considered safe for use in megadoses by the uninformed public. The potential danger of selenium overdosage should not be underestimated.     

Pathology of infectious diarrhea of infant rats (IDIR) induced by an antigenically distinct rotavirus

Suckling rats were inoculated with a group B rotavirus to determine the progression of the morphologic changes induced in the intestine by this virus. Several changes were observed by light microscopy 1 day after viral inoculation: shortening of small intestinal villi, villous epithelial necrosis, and villous epithelial syncytia. The lesions were most often present in the distal small intestine, although other small intestinal segments were affected to a lesser degree. By day 3 post-inoculation, epithelial necrosis, and syncytia were no longer present; however, the villous epithelium was disorganized and irregularly vacuolated, and intestinal crypt epithelium was hyperplastic. Alterations in villous height to crypt depth ratios were present in portions of the small intestine for the remainder of the 12-day study period. Epithelial syncytia appeared to form by the breakdown of the lateral interdigitating membranes of the absorptive villous epithelium. Viral particles, abundant in the syncytia, appeared to form from amorphous or reticular arrays of viral precursor material. Group B rotaviral antigens, as detected by indirect immunofluorescence, were present in large amounts in the small intestinal villous epithelium only on the first day after viral inoculation. These studies show that two important diagnostic features of group B rotaviral infections of rats, epithelial syncytia and viral antigen as determined by immunofluorescence, are present only on the first day of disease. These findings should be taken into consideration when attempting to diagnose disease induced by this agent.