Eleven miniature dachshunds with a herniated intervertebral disc were examined by CT, first before and then after contrast enhancement of the subarachnoid space. The images were classified into three grades by three veterinarians. In four cases, lesions observed on the scans obtained after contrast enhancement had not been observed on the preliminary scans and in one case a lesion observed on the preliminary scan was not observed on the scan obtained after contrast enhancement. Hemilaminectomies were performed on the basis of the enhanced CT results, and a clinical improvement was observed in each of the dogs. Calcification was detected in all the samples of herniated intervertebral disc material.

Computed tomographic angiography was performed on nine normal Holstein calves in a crossover method to investigate the effect of a saline chaser for enhancement of the maxillary arteries and dorsal sagittal sinus. One group was administered a contrast injection (600 mg iodine/kg at 4 ml/s) followed by 50 ml of a saline chaser at the same rate as the contrast material. The second group was administered a contrast injection without a saline chaser. Addition of the saline chaser to the contrast material resulted in a higher peak attenuation in the maxillary artery (244.45 +/- 36.19 v 202.20 +/- 27.07, P<0.05) and dorsal sagittal sinus (241.2 +/- 31.51 v 198.88 +/- 21.09, P<0.05). These results indicate that a contrast injection followed by saline chaser increased uptake in contrast-enhanced CT.

To investigate the effectiveness of a saline chaser in reducing the required dose of contrast material while carrying out dynamic CT scans in cattle, six clinically normal Holstein calves were subjected to CT scans of the head in a study using a crossover design. The calves were studied as three groups: group A received only contrast material (600 mgI/kg); group B received a 30 per cent lower dose of the same contrast material followed by 50 ml of saline solution; and group C received a 40 per cent lower dose of the same contrast material followed by 50 ml of saline solution. In all the animals, a power injector was used for administering the contrast material, with an injection rate of 4 ml/s and a pressure of 4.7 to 5.7 kg/cm(2). Attenuation values were obtained from the right and left maxillary arteries and dorsal sagittal sinus. There were no significant differences in the maximum enhancement value (MEV) of the maxillary arteries and dorsal sagittal sinus between groups A and B. The MEVs of the maxillary arteries and dorsal sagittal sinus in groups A and B were significantly greater than the MEV in group C (P<0.05). The use of a saline chaser allowed a 30 per cent reduction in the dose of contrast material without decreasing vascular enhancement.

Dynamic CT was performed in five normal Holstein calves to investigate the effect of saline chasers on intravascular contrast enhancement when administered at three different rates. The five calves were imaged using dynamic CT in a crossover study design. Group A was administered only contrast medium (600 mg iodine/kg, 4 ml/s), while groups B, C and D were administered contrast medium at 30 per cent reduction followed by saline chasers injected at 2, 4 and 8 ml/s, respectively. Attenuation values were obtained from the right and left maxillary arteries and dorsal sagittal sinus. Maximum enhancement value and mean value of the enhancement plateau obtained from the maxillary arteries were significantly lower in group B than in the other groups. The duration of the enhancement plateau was longer in group C than in groups B and D (P<0.05).