Dorsal Laminectomy in the Horse II. Evaluation in the Normal Horse

Subtotal dorsal cervical laminectomy was performed on nine normal horses to evaluate positioning, refine the surgical technique, and assess the immediate and long-term effects of this procedure in the horse. Funkquist type B laminectomies were performed at various levels from C3-C4 to C6-C7. Absorbable gelatin sponge or autogenous nuchal fat was placed over the exposed dura mater. Surgery times varied from 2 to 3 hours, and all horses recovered without complication. Rapid primary intention wound healing occurred, with two horses showing neck pain. All remained neurologically normal. The horses were euthanized 6 weeks, 3 months, or 6 months postoperatively. Myelograms performed just prior to euthanasia demonstrated normal or expanded dye column widths. Necropsy revealed that all surgical sites had healed well. The laminectomy membrane was soft and pliable and could be easily separated from the underlying dura mater when fat was used as interpositional material. When gelatin sponge was used, the laminectomy membrane was firmly bonded to the dura. Spinal cords at the level of laminectomy appeared normal and moved freely within the vertebral canal. Histological evaluation of the laminectomy sites and associated spinal cord revealed no abnormalities attributable to the surgery. It was concluded that dorsal cervical laminectomy can be performed in horses without untoward sequelae. The procedure may be useful for the treatment of equine cervical compressive myelopathies.     

The Effect of Storage on Ammonia Concentration in Canine Packed Red Blood Cells.

Objective: To determine the effect of storage on ammonia concentration in canine packed red blood cell (pRBC) units.
Design: In vitro and in vivo study.
Setting: University Veterinary Teaching Hospital.
Interventions: Ammonia concentration was measured in 7 units of canine pRBC prepared in citrate-phosphate-dextrose (CPD) and Adsol^a on Days 1 and 35 of storage. Ammonia was measured in 4 additional units of canine pRBC on Days 0, 7, 14, 21, 28, and 35. Plasma ammonia was also determined in 5 anemic dogs receiving pRBC.
Measurements and Main Results: Ammonia concentration increased from 73 ± 15 mmol/L (mean ± SD) on Day 1 to 800 ± 275 mmpl/L on Day (p<0.001). When measured every 7 days in 4 units of canine pRBC, ammonia concentration increased from 23 ± 8 mmol/L on Day 0 to 179 ± 13 mmol/L (Day 7), 276 ± 56 mmol/L (Day 14). 383 ± 47 mmol/L (Day21), 466 ± 30 mmol/L (Day 28), and 562 ± 27 mmol/L (Day 35) (p<0.05 for all comparisons). In a preliminary study, plasma ammonia concentration measured in blood samples from 5 anemic dogs without primary liver disease immediately before and after transfusion with 5–10 ml/kg of stored pRBC remained in the normal reference range.
Conclusions: The ammonia concentration in stored canine pRBC increased markedly with time. In this preliminary study, ammonia concentrations in dogs without primary liver disease did not increase above the reference range after transfusion with pRBC.     

MORPHOLOGIC FEATURES OF PEROSOMUS ("SHORT SPINE") IN FARMED SALMON (SALMO SALAR)

This study was done to characterize morphologically the spinal changes in stunted salmon, 1.5–2 years of age, spontaneously appearing in a Swedish fish farm. Radiographic examination and alizarin-alcian blue preparations showed compressed areas of the spine, most often near the dorsal fin. Of the average 50–52 vertebrae, 20–30 were often compressed, resulting in an average shortening of the fish by 23%. The histopathologic character of the shortened spine was a replacement of the chorda (intervertebral pad or disc) with a poorly differentiated hyaline cartilage, in which proliferative and degenerative processes produced a very irregular pattern. The origin of this cartilage, which had severely impaired ossifying capacity, was perichordal and it often had direct connections with the growth centers of the vertebrae. The disappearance of the large strongly convex (spheric) chorda and the arrest of the vertebral endochondral ossification resulted in narrow disc-like vertebrae in contrast to the normal X-shaped ones. The pathologic changes resemble those observed in chondrodystrophic types of perosomus ("short spine") in certain mammals, including humans, and in turkeys.     

The effect of colostral immunity on the active formation of antibodies in pigs after the administration of inactivated vaccine against Aujeszky's disease

In a large herd of pigs where a trial was performed to cure the animals from Aujeszky's disease (AD) by applying to all animals an inactivated vaccine, a post-vaccination antibody response was studied in piglets coming from the sows that were vaccinated several times. When the piglets were vaccinated at the age of eight weeks (the average virus-neutralizing titer (VNT) of colostral antibodies was 1:11.4) and revaccinated at the age of 11 weeks, 73% of the forty-five animals (examined at the age of 17 weeks) did not have any virus-neutralizing (VN) antibodies in the blood serum. After the third vaccination dose (at the age of 17 weeks), 11% of piglets did not have any VN antibodies if they were examined at the age of 22 weeks (the average antibody VNT was 1:15.3). Applying the ELISA procedure, the antibodies were demonstrated in the sera of all piglets after three vaccination doses. Shifting the time intervals of vaccination (at the age of 8, 13 and 19 weeks), the VN antibodies were found out after three vaccination doses in the sera of all piglets examined at the age of 23 weeks (the average VNT was 1:56.4). After three vaccination doses at the age of 12, 17 and 23 weeks, the VN antibodies were also demonstrated in all piglets at the age of 27 weeks (the average VNT was 1:208).     

Use of monoclonal antibodies in blocking ELISA detection of transmissible gastroenteritis virus in faeces of piglets

Monoclonal antibodies (mAb) to the transmissible gastroenteritis virus (TGEV) nucleoprotein (N) and membrane protein (M) were prepared and used for the comparative assessment of three blocking ELISA variants to detect TGEV. The competitive blocking ELISA format showed the highest sensitivity, allowing detection of 10(3) TCID50 TGEV/ml in culture medium. Ninety-nine porcine field faecal samples obtained from 37 herds affected with diarrhoea were examined, and various TGEV levels were found in nine samples from six herds. However, only in three samples were significant TGEV concentrations demonstrated. The relationship between incidence of TGEV gastroenteritis and the spread of porcine respiratory coronavirus infection in pig farms is discussed.     

Hepatic Encephalopathy

Hepatic encephalopathy occurs in a number of different species as a result of either congenital portacaval shunts or acquired liver disease. Despite intensive research, the neurochemical basis of the disorder has not been defined. Theories to explain the cerebral dysfunction that accompanies acute or chronic hepatic failure include 1) ammonia acting as the putative neurotoxin, 2) perturbed monoamine neurotransmission as a result of altered plasma amino acid metabolism, 3) an imbalance between excitatory amino acid neurotransmission, mediated by glutamate, and inhibitory amino acid neurotransmission, mediated by gamma-aminobutyric acid, and 4) increased cerebral concentrations of an endogenous benzodiazepine-like substance.     

Measurement of Muscle Surface Capillary Blood Flow by Laser Doppler Flowmetry

Muscle surface capillary blood flow was measured in the biceps femoris and lateral head of the triceps brachii muscles in six horses before and during halothane anesthesia by using laser Doppler flowmetry. During 90 minutes of anesthesia, muscle surface capillary blood flow was reduced to 20% to 40% of preanesthetic values. Muscle surface capillary blood flow tended to be lower in dependent muscles than in nondependent muscles, and this disparity was greater in the forelimbs than in the hind limbs.     

Use of Isobutyl-Cyanoacrylate Adhesive in Osteosynthesis A Preliminary Study

Isobutyl 2-cyanoacrylate was used to reattach partial-thickness cortical bone fragments from the femur in rabbits. Stability, apposition, callus formation, and inflammation around the fragments were evaluated at 2, 4, 8, and 12 weeks.
All glued bone fragments were stable, compared with 85% of controls. Good apposition was achieved in 95% of the glued bone fragments, compared with 19% of the controls. Analysis of the mean scores for callus formation revealed a significant difference only in the 8 week survival group.
Bony union was noted in 20 of 21 of the glued fragments. No evidence of inflammation was seen around the glue, and viable bone was seen adjacent to the adhesive in many sections. In control legs, 13 fragments had healed by osseous union, two by fibrous union, and in six the chip had resorbed.