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Objective—To determine magnetic resonance imaging (MRI) vertebral ratio values representing vertebral canal height, vertebral canal shape, and vertebral body shape in Doberman Pinschers with and without disk-associated cervical spondylomyelopathy (DACSM) and clinically normal English Foxhounds. Animals—Doberman Pinschers with (n = 18) and without (20) DACSM and clinically normal English Foxhounds (18). Procedures—All dogs underwent low-field MRI of the cervical vertebral column. From 5 specific measurements made at C3 through C7, 4 linear vertebral ratios were calculated and assessed for correlation: vertebral canal height-to-body height ratio (CBHR), vertebral canal height-to-body length ratio (CBLR), caudal canal height-to-cranial canal height ratio (CCHR), and vertebral body length-to-height ratio (BLHR). The CBHR and CBLR described vertebral canal height, CCHR described vertebral canal shape, and BLHR described vertebral body shape. A midvertebral canal-occupying ratio (mVCOR) for the spinal cord was calculated at C5. Results—Compared with both groups of unaffected dogs, CBHR, CBLR, and BLHR for Doberman Pinschers with DACSM were significantly smaller. The C7 CCHR was significantly larger in DACSM-affected Doberman Pinschers, compared with clinically normal English Foxhounds. Ratios did not differ significantly between unaffected Doberman Pinschers and clinically normal English Foxhounds. Correlation coefficients between CBHR, CBLR, and mVCOR were low and not significant. Conclusions and Clinical Relevance—Doberman Pinschers with DACSM had significantly smaller vertebral canal heights and more square-shaped vertebral bodies, compared with unaffected Doberman Pinschers, combined with a funnel-shaped vertebral canal at C7. Breed-specific differences were not evident. Linear MRI vertebral canal-to-body ratios do not appear to predict relative vertebral canal stenosis.

Objective—To determine the spectrum and frequency of abnormalities for low-field magnetic resonance imaging (MRI) examinations of clinically normal Doberman Pinschers and Foxhounds. Animals—37 clinically normal dogs (20 Doberman Pinschers and 17 Foxhounds). Procedures—For each dog, MRI of the cervical vertebrae (sagittal, dorsal, and transverse T1- and T2-weighted images) was performed. Variables assessed were intervertebral disk degeneration, disk-associated compression, compression of the dorsal portion of the spinal cord, vertebral body abnormalities, and changes in intraparenchymal signal intensity. Associations between these variables and age, breed, sex, and location of the assessed intervertebral disk spaces were evaluated. Results—Severe MRI abnormalities were detected in 17 dogs, including complete disk degeneration (n = 4 dogs), spinal cord compression (3), or both (10). Vertebral body abnormalities were detected in 8 dogs, and hyperintense signal intensity was detected in 2 dogs. Severity of disk degeneration and disk-associated compression was significantly associated with increased age. There was a significant association between disk degeneration, disk-as-sociated compression, and compression of the dorsal aspect of the spinal cord and location of the assessed intervertebral disk space, with the intervertebral disk spaces in the caudal portion of the cervical region being more severely affected. Conclusions and Clinical Relevance—Abnormalities were commonly seen on MRI examinations of the caudal portion of the cervical vertebral column and spinal cord of clinically normal Doberman Pinchers and Foxhounds. Such lesions were probably part of the typical spinal cord degeneration associated with the aging process of dogs.

Circulating ghrelin, the natural ligand of GHS-R 1a, is synthesized primarily in the stomach in mammals. The distribution of these receptors is consistent with the role of ghrelin in promoting secretion of GH; receptors are highly expressed in the hypothalamus and pituitary gland and are also distributed in other central and peripheral tissue sites. In addition to strong GH-releasing activity, ghrelin has other actions, including stimulation of lactotroph and corticotroph function, stimulation of appetite, regulation of energy homeostasis, stimulation of gastric motility and gastric acid secretion, regulation of insulin secretion and glucose metabolism, cardiovascular effects, and antiproliferative activity. These properties make ghrelin a candidate for future diagnostic and clinical applications. In mammals, secretion of GH from the adenohypophysis is regulated by 2 hypothalamic hormones with antagonistic actions: a stimulatory GHRH that is produced in the arcuate nucleus and an inhibitory hormone, somatostatin, synthesized in the paraventricular nucleus. 1 Both hormones are transported from the hypothalamus to target cells in the pituitary gland via the hypothalamo-hypophyseal portal system in the median eminence. Alternation in secretion of GHRH and somatostatin is responsible for the pulsatile pattern of GH release. 2,3 Measurement of GHRH and somatostatin in hypophyseal-portal blood in humans and other animals reveals that the episodic pattern of GHRH and somatostatin secretion does not fully account for all pulses of GH secretion. 4 The amplitude and frequency of GH secretory pulses are regulated by a complex array of external and internal stimuli, including body composition, age, sleep, gender, disease status, menstrual cycle phase, genetic background, and nutritional status. 5–7

Objective—To determine the usefulness of magnetic motor-evoked potentials (MMEPs) for assessing the integrity of the cervical, thoracic, and thoracolumbar spinal cord in horses with bilateral hind limb ataxia. Animals—9 horses and 1 donkey with bilateral hind limb ataxia of various degrees. Procedure—The motor cortex was stimulated magnetically, and MMEPs were recorded bilaterally from the extensor carpi radialis and cranial tibial muscles. Results—In 5 horses and 1 donkey, MMEPs with normal onset latencies and peak-to-peak amplitude were recorded from the extensor carpi radialis muscles, whereas abnormal onset latencies and peak-topeak amplitudes were recorded from the cranial tibial muscles. In these animals, a spinal cord lesion in the thoracic or thoracolumbar segments was suspected. In 4 horses, onset latencies and peak-topeak amplitude of MMEPs recorded from the extensor carpi radialis and cranial tibial muscles were abnormal. In these horses, a cervical spinal cord lesion was suspected. Conclusions and Clinical Relevance—Transcranial magnetic stimulation can be considered a valuable diagnostic tool for assessing the integrity of the spinal cord, and MMEPs may be used for differentiating thoracic or thoracolumbar spinal cord lesions from mild cervical spinal cord lesions that cause ataxia in the hind limbs only. (Am J Vet Res 2003;64:1382–1386)