Neuromuscular and cardiovascular effects of atracurium, a nondepolarizing neuromuscular blocking agent, were evaluated in 10 halothane-anesthetized adult horses. Hind limb digital extensor tension (hoof twitch) was measured with a strain gauge to quantitate the muscle relaxant effects of atracurium. Response of facial muscles was compared with hoof twitch. Five injections of atracurium were given. Initial mean (+/- SEM) dosage of 0.07 +/- 0.01 mg of atracurium/kg of body weight caused 98.6 +/- 0.8% reduction of the preinjection hoof twitch. Subsequent dosages of 0.04 +/- 0.003 mg/kg induced a degree of relaxation similar to that induced by the initial dose. Duration of paralysis from maximal effect to 10% recovery of twitch was 12.2 +/- 1.5 minutes for the first injection. This was significantly (P less than 0.05) different from subsequent paralysis periods, which lasted approximately 7 miutes. The 10% to 75% recovery time after all injections was similar--approximately 16 minutes. The facial muscles were less affected objectively by atracurium than was the hind limb. Atracurium did not cause cardiovascular changes. When the hoof twitch had recovered to 95% of its tension before atracurium administation, 0.5 mg of edrophonium/kg, was given to antagonize neuromuscular blockage. Within 5 minutes of edrophonium administration, twitch tension exceeded that measured before atracurium administrations. Within 2 minutes of edrophonium administration blood pressure began to increase and continued to increase approximately 10 mm of Hg above the value measured before edrophonium administration. Heart rate was not affected by edrophonium. Other muscarinic side effects of edrophonium were not observed. Of the 10 horses, 9 had good, unremarkable recovery to standing position. One horse had a violent recovery period.

Microvascular permeability characteristics were evaluated in digits of 7 adult horses. After capillaries were isolated and an extracorpeal perfusion circuit for the digit was established, a lymphatic vessel draining the distal portion of the phalangeal region was cannulated at the level of the coronary band. Venous pressure was increased in a stepwise manner, and lymph flow, lymph protein concentration (Cl), and plasma protein concentration (Cp) were determined after measured variables were allowed to reach steady state. Lymph-to-plasma protein concentration ratios (Cl/Cp) and lymph and plasma oncotic pressures were determined from samples collected during steady state. The osmotic reflection coefficient was determined after Cl/Cp became constant, regardless of increasing lymph flow, and was expressed as 1 - Cl/Cp. The osmotic reflection coefficient for the digit was 0.67. Seemingly, the microvasculature bed of the digit was relatively permeable and could maintain only 67% of the endogenous macromolecules within the vasculature.

The patency of mammary papillae was reestablished after surgically induced injury. Perforated prosthetic tubes with affixed Dacron tubing or Teflon strips were implanted in 18 abrabed papillae of lactating dairy cows and were secured with sutures. Wound healing was assessed by palpation and visual inspection. All wounds, with one exception, healed by first intention. Machine milking, reinstituted on day 5 after surgery, caused no apparent discomfort. Grossly and histopathologically, all implants stimulated a variable degree of mucosal metaplasia and hyperplasia. Only implants with Teflon strips became anchored by fibrotic invasion. Mastitis, tube migration, and milk fistulas were complications of the procedure.

A percutaneous biopsy technique for the study of endochondral bone formation in the dog was developed. With the dogs under general anesthesia or sedated with a combination of a tranquilizer and a local anesthetic, biopsy specimens were obtained from the proximal growth plate of the humerus with the use of a Jamshidi bone biopsy needle. Biopsy specimens were structurally intact, and contained epiphysis, growth plate, and metaphysis. The procedure proved to be a simple, safe technique, which caused minimal discomfort for the patient and did not affect the growth of the proximal end of the humerus, even after multiple biopsies.

Nine 7-month-old Beagle dogs were inoculated with 200 third-stage larvae of Dirofilaria immitis. The development of cardiac disease secondary to heartworm infection was confirmed by thoracic radiography, echocardiography, and angiography with blood pressure measurements. The only indication of renal disease was mild-to-moderate proteinuria. The dogs were euthanatized approximately 18 months after inoculation. The mean microfilarial count in blood at the time of euthanasia was 88,700/ml, with a mean of 89 adult heartworms in the vena cavae, heart, and pulmonary arteries. The kidneys were perfused for microangiographic and correlative histologic examination of the intrarenal microvasculature and associated renal morphologic features. Angiograms of whole kidneys from 6 dogs revealed attenuation or truncation of the major renal vessels. Microangiograms of all kidney slices revealed attenuation in the microangiographic appearance of the glomerular capillaries. Histologic examination of all kidney slices revealed mild-to-intense, diffuse, chronic interstitial nephritis and generalized membranoproliferative glomerulonephritis. Microfilariae were observed within the glomerular capillaries and the medullary vessels. The microangiographic changes correlated with and were explained in part by the histologic changes in the renal parenchyma.

Serum antibody titers to canine parvovirus (CPV), canine adenovirus-1 (CAV-1), and canine distemper virus (CDV) were measured in dogs with known immunization status. The dogs represented 3 groups: nonvaccinated dogs less than 12 months old; vaccinated dogs less than 12 months old; and adult dogs greater than 12 months old. For practical reasons, the population from which the specimens were obtained could be considered as free from natural infection with CAV-1 and CDV. In nonvaccinated dogs less than 12 months old, antibodies against all 3 viruses were measured at the time the dogs were given their first vaccination. Altogether, 50.7% of the dogs had titer greater than or equal to 1:10 to CPV, and 26.1 and 46.2% had titer greaterthan or equal to 1:8 to CAV-1 and CDV, respectively. The concentration of maternal antibody seemed to be of major importance for failure of immunization with use of inactivated CPV vaccine, but not with CAV-1 and CDV vaccination. In dogs less than 12 months old and vaccinated against CPV infection with inactivated virus, only 11.5% had titer greater than or equal to 1:80. In dogs vaccinated against infectious canine hepatitis and canine distemper, 63.2 and 78.3%, respectively, had titer greater than or equal to 1:16. In adult dogs greater than 2 months old and vaccinated against CPV infection, less than 50% had titer greater than or equal to 1:80, regardless of time after vaccination. There was no significant difference in titer between vaccinated and nonvaccinated dogs. Approximately 60% of these dogs had titer greater than or equal to CAV-1 at all time intervals after vaccination. There was only a weak correlation between decrease of titers and time; this correlation could be explained by the fact that a proportion of the dogs had been vaccinated with inactivated CAV-1 virus. There was, however, no correlation between titer to CDV and time. The percentage of dogs with titer greater than or equal to 1:16 was at least 60%.

Thirty-four preweaning pigs with induced enteropathogenic Escherichia coli diarrhea were treated with electroacupuncture, traditional acupuncture, or neomycin. In the group treated with electroacupuncture, points GV-1, bilateral ST-36, and Bai-hui were stimulated electrically. In the group treated with traditional acupuncture, points GV-1, bilateral ST-36, BL-20, bulb points, bilateral ear tip, and Shan-gen were used. Acupuncture points CV-12 and bilateral ST-25 also were treated with moxibustion (applying heat generated by a burning herb, Artemisia argyi). Hemoacumpuncture also was applied to Shan-gen, bilateral ear tip, and bulb points. Pigs in the third group were given neomycin orally. Five pigs were inoculated with E coli, but were not treated and served as nontreated controls. At postinoculation day 5, 60% of control pigs and greater than 80% of pigs in treated groups recovered from diarrhea. However, at postinoculation day 3, recovery rates for pigs in the control and group treated with electroacupuncture were only 20 and 27.3%, respectively; whereas pigs treated with acupuncture or neomycin attained 81.8 and 71.4% of recovery rates, respectively. Seemingly, traditional acupuncture, but not electroacupuncture, was effective in controlling induced E coli diarrhea in pigs at its early stage.

Kinetics of large-scale production of naturally derived bovine leukocyte interferon (IFN) was investigated using Sendai virus, Newcastle disease virus, and infectious bovine rhinotracheitis virus inducers. Cultures were tested for IFN production every 6 hours for 66 hours. The effect of varying the priming dose of Sendai virus from 0 to 50% of total virus dose and the effect of varying the priming time from 0 to 4 hours before induction also were investigated. Other factors explored were effects of varying the fetal bovine serum concentration (from 0 to 8%) and individual cow donors on bovine IFN titers. Highest bovine leukocyte IFN titers (15,314 U/ml) were obtained using Sendai virus (priming dose, 60 hemagglutinating units/ml;inducing dose, 240 hemagglutinating units/ml) and incubating for 12 hours. Up to 24 L (over 360 million U) of naturally derived leukocyte IFN were produced at one time.

The fiber type, fiber size, and capillary geometric features were determined from the center of the proximal half of the left and right semitendinosus muscles in 5 mixed-breed dogs, 5 hound-type dogs, and 5 Beagles. There were no significant differences between the left and right muscles of each dog. Comparisons among the 3 groups of dogs revealed that the hound-type dogs had the largest fibers (type I and type II); however, the 3 groups were similar in their fiber-type percentages and their capillary geometric features.

The efficacy of a single dose of ivermectin (0.2 mg/kg), in injectable or paste formulations, against microfilariae of Onchocerca cervicalis and associated skin lesions was evaluated in 20 naturally infected horses during midsummer months in Louisiana. All horses had clinical signs of dermatitis of the ventral midline and/or limbs, shoulders, thorax, and withers. Efficacy was monitored at 21, 42, and 63 days after treatment. Procedures done at these intervals included microfilarial counts of 6-mm skin biopsy specimens of affected ventral midline, grading of gross lesions, and photography and histologic assessment of ventral midline biopsy specimens. Microfilarial numbers were reduced to 0 by 21 days after treatment in all but one horse. Active lesions improved or were resolved completely by 63 days after treatment. Total inflammation, as judged by histologic methods, was reduced in all horses by 63 days after treatment, but there was a residual population of inflammatory cells in all horses. Adverse reactions after treatment were not observed in any of the horses.