Investigations on the postnatal development of the macroscopic proportions and the topographic anatomy of the feline spinal cord

Morphology and morphometry of the spinal cord and meninges in Egyptian Baladi goat (Capra hircus): Stereomicroscopy of blue-stained gray matter

The study objective is to obtain normal morphology and morphometric data from Baladi goat spinal cord segments. Using Tompsett's technique for staining gray matter with a blue stain allowed us to calculate the quantity or area of gray and white matter and thus the total area of each segment. The spinal cord of the goat started at the extent of the middle-third of the occipital condyles, and the tapered end of the spinal cord terminated at the center of the first sacral vertebra. The total length of the spinal cord was 73.3 ± 2.5 cm on average. C3 was the longest spinal segment, measuring 3.95 cm. The gray matter area had a high value at the cervical and lumbar enlargements, with C8 having the highest value of gray matter cross sectional area at 12 mm2 and C7 having the highest value of white matter cross sectional area at 42 mm2 . The area of white matter of the cervical region was higher than that of the other spinal regions. At C7, the total cross section area reached its maximum of 53 mm2 . The cervical enlargement included segments from C6 to T1, while the lumbar enlargement included L5 to S1. The dura mater is connected cranially to the dens of the axis and caudally to the fourth and fifth lumbar vertebrae. The epidural space height between lumbar vertebrae was 2 mm in all lumbar spaces and 3 mm in the lumbosacral space. The normal morphology and morphometric data of the goat spinal cord segments may be useful in pathological conditions of the spinal cord and during epidural anaesthesia technique.

Fluoroscopy-Guided Surgical Removal of a Microchip from the Spinal Canal of Two Cats

Two cats were presented with acute left-sided paresis after implantation of a microchip at the referring veterinary clinic. Neurological examinations were consistent with left-sided lesions between spinal cord segments C1 and C5. Orthogonal radiographs of the cervical spine showed a microchip dorsoventrally oriented, partially embedded in the cervical vertebral canal. Fluoroscopy was used to localize and retrieve the foreign body from the cervical spinal cord in each case. Improvement in clinical condition and return to ambulation was observed in both cats within 48 hr of surgical removal of the implant. No significant perioperative adverse events were noted during the surgical retrieval of the microchip. Two previously reported cases of intraspinal canal microchip placement had been treated surgically by hemilaminectomy. This approach carries a risk of complications, including hemorrhage from the venous sinus, iatrogenic damage to the spinal cord, and improper identification of the surgical site, requires advanced surgical training, and typically has an extended surgical time. The use of fluoroscopy to assist intraoperative localization of a spinal canal foreign body may lessen the requirement for more invasive surgical procedures.

Postnatal growth of the lumbosacral spinal segments in cat: Their lengths and positions in relation to vertebrae

Cat is a prominent model for investigating neural networks of the lumbosacral spinal cord that control locomotor and visceral activity. We previously proposed an integral function, establishing the topographical relationship between the spinal cord segments and vertebrae in adult animals. Here, we investigated the dynamic of this topographical relationship through early and middle periods of development in kittens. We calculated the length of each vertebra relative to the total length of the region from 13th thoracic (T) to the 7th lumbar (L) vertebrae (V) as well as the length of each segment relative to the total region from T13 to the three-dimensional sacral (S) segment. As in our previous work, the length and position of VL2 were used to establish relationships between the characteristics of the segments and vertebrae. Cubic regression reliably approximates the lengths of segments relative to VL2 length. As the cat aged, the relative length of VT13 and VL1 decreased while the relative length of VL5 increased. The relative length of the T13 and L3 segments increased while the relative length of the S1-S2 segments decreased. The T13-L2 segments are descended monotonically relative to the VL1-VL2 border. The L3-S1 segments are also descended, though with more complex dynamics. The positions of the S2-S3 segments remained unchanged. To conclude, different spinal segments displayed different developmental dynamics. The revealed relationship between vertebrae and lumbosacral spinal segments may be helpful for clearly defining stimulation regions to invoke particular functions, both in experimental studies on the spinal cord and clinical treatment.

Antinociceptive Effect of a Sacro-Coccygeal Epidural of Morphine and Lidocaine in Cats Undergoing Ovariohysterectomy

BACKGROUND

A commonly described analgesic protocol for ovariohysterectomy (OHE) combines systemic opioids, sedatives, and non-steroidal anti-inflammatory drugs. However, systemic analgesia does not fully prevent perioperative visceral and somatic pain triggered by the surgical stimulus.

OBJECTIVES

To compare the analgesic effects and quality of recovery of systemic analgesia with those of a sacrococcygeal epidural injection of lidocaine and morphine in cats undergoing elective OHE. Methods: Twenty domestic female cats were premedicated with dexmedetomidine (0.01 mg kg-1 IM) and alfaxalone (1.5 mg kg-1 IM) and randomly assigned to one of two analgesic protocols: methadone (0.2 mg kg-1 IM) in the control group CTR (n = 10) and methadone (0.1 mg kg-1 IM) + epidural (lidocaine 2% (0.3 mL kg-1) + morphine 1% (0.1 mg kg-1) diluted with NaCl 0.9% to a total volume of 1.5 mL in the SCC-E group (n = 10). General anaesthesia was induced with alfaxalone (1 mg kg-1 IV) and maintained with sevoflurane in 100% oxygen. Non-invasive blood arterial pressure and cardiorespiratory variables were recorded. The quality of recovery was assessed using a simple descriptive scale. Before surgery and 1, 2, 3, 4, 6, and 8 h post-op pain was assessed using the UNESP-Botucatu multidimensional composite pain scale (MCPS) and mechanical nociception thresholds (MNT). The repeated measures analysis of variance (ANOVA) was used to compare groups over time. Comparison between groups was performed using independent samples t-test if the assumption of normality was verified, or the Mann-Whitney test. The chi-square test of independence and exact Fisher's test were used to compare groups according to recovery quality.

RESULTS

Heart rate and systolic arterial pressure increased significantly from baseline values in the CTR group and did not change in the SCC-E group. In the CTR group, MNT and UNESP-Botucatu-MCPS scores increased significantly from baseline for all assessment points and the first 3 h, respectively, whereas this did not occur in the SCC-E group.

CONCLUSIONS AND CLINICAL RELEVANCE

Based on our results, the SCC-E administration of lidocaine 2% with morphine 1% is a reasonable option to provide perioperative analgesia in cats submitted to OHE, compared to a systemic protocol alone.

Neurochemical atlas of the cat spinal cord

The spinal cord is a complex heterogeneous structure, which provides multiple vital functions. The precise surgical access to the spinal regions of interest requires precise schemes for the spinal cord structure and the spatial relation between the spinal cord and the vertebrae. One way to obtain such information is a combined anatomical and morphological spinal cord atlas. One of the widely used models for the investigation of spinal cord functions is a cat. We create a single cell-resolution spinal cord atlas of the cat using a variety of neurochemical markers [antibodies to NeuN, choline acetyltransferase, calbindin 28 kDa, calretinin, parvalbumin, and non-phosphorylated heavy-chain neurofilaments (SMI-32 antibody)] allowing to visualize several spinal neuronal populations. In parallel, we present a map of the spatial relation between the spinal cord and the vertebrae for the entire length of the spinal cord.

Incidence of dural sac puncture during neuraxial anesthesia in cats: an observational, retrospective study

OBJECTIVES

The aim of this study was to determine the occurrence of dural puncture, indicated by cerebrospinal fluid (CSF) outflow, in cats receiving neuraxial anesthesia through a lumbosacral injection guided by a pop sensation method.

METHODS

This was an observational, retrospective study. Cats that were scheduled for lumbosacral neuraxial anesthesia were included. Medical records were analyzed to investigate: (1) demographic data; (2) neuraxial anesthesia performed (epidural/spinal); (3) type of needle used, including gauge and length; (4) presence of CSF (yes/no) and/or blood (yes/no) in the hub of the needle; and (5) flicking of the tail during needle advancement (yes/no).

RESULTS

A total of 94 medical records were analyzed. A 22 G 50 mm Tuohy needle was used in all cats scheduled for an epidural injection (n = 60), whereas a 22 G 40 mm Quincke needle was used in all cats scheduled for an intrathecal injection (n = 34). CSF outflow was detected in 55/60 (91.7%) cats in which a Tuohy needle was used, and 34/34 (100%) of the cats in which a Quincke needle was used (P = 0.15). Flicking of the tail was detected in 41/60 (68.3%) and in 24/34 (70.6%) injections with Tuohy and Quincke needles, respectively (P >0.99). Traces of blood, but not active blood outflow, were detected via staining of the first drops of CSF in 2/34 cats in which Quincke needles were used and in none of the cats in which Tuohy needles were used (P = 0.12).

CONCLUSIONS AND RELEVANCE

This study shows that the lumbosacral approach for neuraxial anesthesia in cats may result in a dural sac puncture when 22 G Quincke or Tuohy needles are used. The pop sensation method should be deemed effective in predicting intrathecal but not epidural needle placement.

2022 ISFM Consensus Guidelines on the Management of Acute Pain in Cats

PRACTICAL RELEVANCE

Increases in cat ownership worldwide mean more cats are requiring veterinary care. Illness, trauma and surgery can result in acute pain, and effective management of pain is required for optimal feline welfare (ie, physical health and mental wellbeing). Validated pain assessment tools are available and pain management plans for the individual patient should incorporate pharmacological and non-pharmacological therapy. Preventive and multimodal analgesia, including local anaesthesia, are important principles of pain management, and the choice of analgesic drugs should take into account the type, severity and duration of pain, presence of comorbidities and avoidance of adverse effects. Nursing care, environmental modifications and cat friendly handling are likewise pivotal to the pain management plan, as is a team approach, involving the cat carer.

CLINICAL CHALLENGES

Pain has traditionally been under-recognised in cats. Pain assessment tools are not widely implemented, and signs of pain in this species may be subtle. The unique challenges of feline metabolism and comorbidities may lead to undertreatment of pain and the development of peripheral and central sensitisation. Lack of availability or experience with various analgesic drugs may compromise effective pain management.

EVIDENCE BASE

These Guidelines have been created by a panel of experts and the International Society of Feline Medicine (ISFM) based on the available literature and the authors' experience. They are aimed at general practitioners to assist in the assessment, prevention and management of acute pain in feline patients, and to provide a practical guide to selection and dosing of effective analgesic agents.

Morphometric and volumetric analysis of the cervical spinal cord and vertebral canal using computed tomography images in normal Van cats

This study was performed on Van cats to determine the volumetric, morphometric and surface area measurement values of their cervical spinal cords (SC) and vertebral canals (CC) and the ratios between their dimensions using computed tomography (CT) images. The study also aims to reveal any biometric differences in these values between the two sexes. Spinal cord and vertebral canal CT images of 16 healthy adult Van cats (8 males and 8 females) were used in the study. First, three measurement points were selected for each vertebra on their cranial, medial and caudal sections along the sagittal axis. Next, the morphometric values were obtained using the transversal images of these measurement points. The surface areas for the SC and CC were calculated using the stereological planimetry method. The Cavalieri's principle was then used to calculate the relevant anatomic structure volumes. The obtained values were then statistically analysed. SC and CC were found to be larger in males in general, while 'SC cranial/CC cranial' and 'SC medial/CC medial' dimensions and volume ratios were found to be larger in female cats on average. Bodyweight and age values were found to have a negative correlation with SC and CC ratio, but the correlation was statistically insignificant. All SC and CC surface area and volume measurements were found to be higher in male cats (p < .05). We believe the results obtained by this study will provide valuable insight into veterinary clinicians in evaluating pathological lesions in the cervical spinal cord and vertebral canal CT scans.

Morphometry of cervical spinal cord in cat using design-based stereology

The spinal cord harbours nerve fibres that facilitate reflex actions and that transmit impulses to and from the brain. The cervical spinal cord is an area of particular interest in medicine and veterinary due to frequent pathologic alterations in this region. This study describes the morphometric features of the cervical spinal cord in cat using design-unbiased stereological methods. The cervical spinal cords of four male cats were dissected and samples were taken according to systematic uniform random sampling. Each sample was embedded in agar and cut into 60-µm thick sections and stained with cresyl violet 0.1% for stereological estimations. The total cervical spinal cord volume obtained by the Cavalieri estimator was 2,321.21 ± 285.5 mm³ . The relative volume of grey matter and white matter was 23.8 ± 1.3% and 76.1 ± 1.3%. The dorsal horn and ventral horn volume were 12.3 ± 1.2% and 11.4 ± 0.7% of the whole cervical spinal cord. The volume of central canal was estimated to 3.8 ± 1 mm³ . The total number of neurons was accounted 3,405,366.2 ± 267,469.4 using the optical disector/fractionator method. The number of motoneurons and interneurons was estimated to be 1,120,433.2 ± 174,796.7 and 2,284,932.9 ± 127,261.5, respectively. The average volume of the motoneurons and interneurons was estimated to 1980 µm³ and 680 µm³ , respectively, using the spatial rotator method. This knowledge of cat spinal cord findings may serve as a foundation as a translational model in spinal cord experimental research and provide basic findings for diagnosis and treatment of spinal cord disorders.

Analgesia: What Makes Cats Different/Challenging and What Is Critical for Cats?

Cats have unique anatomic, physiologic, and behavioral considerations that may influence analgesia and pain management. They present specific challenges that require an individualized, feline-specific approach. This article presents an overview of recent advances in feline pain management and their differences in relation to other species and evolves on its future challenges. The main specific anatomy and physiology of the cat and how it may affect analgesia is discussed. Validated pain assessment tools including the UNESP-Botucatu Multidimensional Composite Pain Scale, Glasgow Feline Composite Measure Pain Scale, and the Feline Grimace Scale are summarized.

Prediction Algorithm of the Cat Spinal Segments Lengths and Positions in Relation to the Vertebrae

Detailed knowledge of the topographic organization and precise access to the spinal cord segments is crucial for the neurosurgical manipulations as well as in vivo neurophysiological investigations of the spinal networks involved in sensorimotor and visceral functions. Because of high individual variability, accurate identification of particular portion of the lumbosacral enlargement is normally possible only during postmortem dissection. Yet, it is often necessary to determine the precise location of spinal segments prior to in vivo investigation, targeting spinal cord manipulations, neurointerface implantations, and neuronal activity recordings. To solve this problem, we have developed an algorithm to predict spinal segments locations based on their relation to vertebral reference points. The lengths and relative positions of the spinal cord segments (T13-S3) and the vertebrae (VT13-VL7) were measured in 17 adult cats. On the basis of these measurements, we elaborated the estimation procedure: the cubic regression of the ratio of the segment's length to the lengths of the VL2 vertebra was used for the determination of segment's length; and the quadratic regression of the ratio of their positions in relation to the VL2 rostral part was used to determine the position of the segments. The coefficients of these regressions were calculated at the training sample (nine cats) and were then confirmed at the testing sample (eight cats). Although the quality of the prediction is decreased in the caudal direction, we found high correlations between the regressions and real data. The proposed algorithm can be further translated to other species including human. Anat Rec, 302:1628-1637, 2019. © 2018 American Association for Anatomy.