Reference values for activated coagulation time in cats

OBJECTIVE: To establish reference values for activated coagulation time (ACT) in cats by use of jugular venipuncture and direct collection of blood into ACT vacuum tubes. ANIMALS: 100 clinically normal cats that were to have elective surgery performed at a private practice. PROCEDURE: Collection of 3 blood samples for ACT measurement was attempted for each cat at the time of elective surgery: sample 1, obtained before sedation; sample 2, tube 1 of 2 consecutive samples obtained from a single venipuncture of the contralateral jugular vein after sedation with acepromazine and ketamine hydrochloride; and sample 3, tube 2 collected immediately following collection of sample 2 without removing the needle from the vein. Venipuncture quality was rated subjectively on a 3-point scale. RESULTS: Median ACT were 95 seconds for each sample group. The middle 95% of values ranged inclusively from 55 to 185 seconds (sample 1), 65 to 135 seconds (sample 2), 45 to 145 seconds (sample 3), and 55 to 165 seconds overall (samples 1, 2, and 3). Significant differences in ACT values were not detected between sample groups. Significant relationships between ACT and venipuncture quality or sex of cat were not detected. CONCLUSIONS AND CLINICAL RELEVANCE: With the ACT protocols used, clinically normal cats had ACT of < 165 seconds. The ACT in cats does not appear to be significantly affected by sex, sedation with acepromazine and ketamine, or by moderately traumatic venipunctures. These results refute widespread statements that ACT should be < 65 seconds in healthy cats. Cats with ACT repeatedly > 165 seconds should be further evaluated for hemostatic disorders.     

Reference values of respiratory and peripheral muscle function in rats

Skeletal muscle dysfunction is a common systemic manifestation in several prevalent diseases. Predictive values are useful tools for the diagnosis and prognosis of diseases. In experimental animals, no reference values of muscle function evaluation have been so far reported. The objective was to obtain predictive values of maximal inspiratory pressure (MIP) and grip strength measurements in healthy rats. In 70 healthy rats, MIP and grip strength were measured in vivo weekly for five consecutive weeks using non‐invasive methodologies. Three ranges of rat body weights (250–299, 300–349 and 350–399 g) and lengths (37.0–41.0, 41.1–42.0 and 42.1–44.0 cm) were established. MIP and grip strength measurements falling within the ranges of weight 350–399 and 300–349 g and length 42.1–44.0 cm were significantly greater than values falling within 250–299 g and 37.0–41.0 cm ranges respectively. Specific weight‐ and length‐percentile distributions for MIP and grip strength measurements were calculated. As significant direct correlations were observed between rat weights and lengths and either MIP or grip strength measurements, regression equations relating all these variables were also determined. Skeletal muscle dysfunction is frequently associated with highly prevalent conditions. The significant predictive equations described for both MIP and grip strength measurements will enable scientists to better estimate the respiratory and peripheral muscle dysfunctions of laboratory animals, especially when conducting follow‐up and/or intervention investigations.     

Transcranial magnetic stimulation of the motor cortex and percutaneous magnetic stimulation of the peripheral nervous structures in the dog

The motor cortex was transcranially and peripheral nervous structures (motor roots, plexus, peripheral nerves) were percutaneously stimulated by magnetic pulses in awake dogs and in dogs awaking from general anesthesia. The compound muscle action potentials were recorded by surface or needle electrodes. The central motor conduction time as an information about central motor tracts was obtained by subtracting the peripheral latency from the corticomuscular latency. The peripheral latency was assessed by high voltage electrical and magnetic stimulation of motor roots and by the F-wave technique. The motor conduction velocity of the tibial nerve was measured by percutaneous magnetic and by electrical stimulation and the resulting values were compared.     

Use of electrical nerve stimulation to monitor lumbosacral epidural needle placement in cats

ObjectiveTo determine the minimal electrical threshold (MET) necessary to elicit muscle contraction of the pelvic limb or tail when an insulated needle is positioned outside (MET_out) and inside (MET_in) the lumbosacral epidural space in cats.Study designProspective, blinded study.AnimalsTwelve mixed-breed healthy adult cats, scheduled for a therapeutic procedure where lumbosacral epidural administration was indicated.MethodsUnder general anesthesia, an insulated needle was advanced through tissues of the lumbosacral interspace until its tip was thought to be just dorsal to the interarcuate ligament. An increasing electrical current (0.1 ms, 2 Hz) was applied through the stimulating needle in order to determine the MET necessary to obtain a muscle contraction of the pelvic limb or tail (MET_out), and then 0.05 mL kg^?1 of iohexol was injected. The needle was further advanced until its tip was thought to be in the epidural space. The MET was determined again (MET_in) and 0.2 mL kg^?1 of iohexol was injected. The cats were maintained in sternal position. Contrast medium spread was determined through lateral radiographic projections.ResultsThe radiographic study confirmed the correct needle placement dorsal to the interarcuate ligament in all cats. When the needle was placed ventrally to the interarcuate ligament, iohexol was injected epidurally in ten and intrathecally in two cats. The MET_out and MET_in was 1.76 ± 0.34 mA and 0.34 ± 0.07 mA, respectively (p < 0.0001).Conclusion and clinical relevanceNerve stimulation can be employed as a tool to determine penetration of the interarcuate ligament but not the piercing of the dura mater at the lumbosacral space in cats.     

Somatosensory-evoked and spinal cord-evoked potentials in response to pudendal and tibial nerve stimulation in cats

Somatosensory-evoked potentials (SEP) and spinal cord-evoked potentials (SCEP) were recorded in clinically normal adult cats in response to electrical stimulation of pudendal and tibial nerves to provide normative data that can be used in a clinical evaluation of pudendal nerve function in cats after sacral or sacrococcygeal luxations or fractures. Responses to tibial nerve stimulation were included in the study as an internal control because it is usually not involved in these types of injuries and because its SEP and SCEP are easily recorded. Evoked potentials were characterized by the latencies (ms) of positive (P or p) and negative (N or n) peaks. The SEP resulting from percutaneous pudendal nerve stimulation consisted of a prominent P-N-P potential in the 30- to 80-ms range. The pudendal SCEP was not successfully recorded because of large muscle artifacts evoked from the sacral area. The tibial SEP was similar to the pudendal SEP, except that the prominent P-N-P series in the 35- to 81-ms range was preceded by a smaller p-n-p-n sequence in the 7- to 23-ms range. The tibial SCEP consisted of a P-N-P series in the 2- to 4-ms range.     

Muscle potentials evoked by magnetic stimulation of the sciatic nerve in unilateral sciatic nerve dysfunction

Magnetic stimulation of the sciatic nerve and subsequent recording of the muscle-evoked potential (MEP) was performed in eight dogs and three cats with unilateral sciatic nerve dysfunction. Localisation of the lesion in the sciatic nerve was based on the history, clinical neurological examination and on results of electromyography examination. Aetiology of the sciatic nerve lesion was diverse. A significant difference was found in MEP between the normal and the affected limbs. In addition, absence of conscious pain sensation, absence of voluntary motor function and a poor outcome seemed associated with the inability to evoke an MEP in the affected limb.     

The use of muscle relocation techniques in the treatment of peripheral nerve injuries in dogs and cats

The authors describe certain muscle relocation techniques for the treatment of peripheral nerve injuries (radial and peroneal) in small animals. Six clinical cases are related illustrating the usefulness of the techniques. It is stressed that only a functional muscle can be relocated and that the majority of peripheral nerve lesions in the dog and cat are too extensive, involving a number of nerves, to allow the application of such techniques. However, the procedures can be of great value in certain selected cases, avoiding limb amputation or euthanasia of the patient.     

Porencephaly in dogs and cats: magnetic resonance imaging findings and clinical signs

Magnetic resonance imaging (MRI) features of brain lesions in 5 dogs and 2 cats characterized by extensive cystic changes of the cerebral hemispheres in terms of a porencephaly are presented. Age at diagnosis ranged from 12 weeks to 7 years. MRI findings were confined to the forebrain. Porencephalic lesions appeared as wedge-shaped parenchymal defects connecting the ventricular system and the subarachnoid space or as large cystic defects in the cerebral hemispheres. Although in two adult dogs the porencephalic lesions were asymptomatic, the other animals showed clinical symptoms depending on the affected cerebral area. Three animals had seizures. Interestingly, four animals showed neurological signs normally not localized to the forebrain (nystagmus, hypermetria, ataxia). Whether these clinical signs are related to impaired function of the cerebral cortex or to not recognizable lesions in the cerebello-vestibular system could not be further clarified. Although the defects develop intrauterine or postnatal, the clinical symptoms can occur later in life. The definition of porencephaly as well as its subclassification is not uniform in veterinary medicine. We suggest the term encephaloclastic porencephaly unregarding the underlying cause of the defect, which cannot be further specified by diagnostic imaging.     

A review of the pharmacology and clinical application of alfaxalone in cats

Alfaxalone-2-hydroxpropyl-β-cyclodextrin (alfaxalone-HPCD) was first marketed for veterinary use in Australia in 2001 and has since progressively became available throughout the world, including the USA, where in 2012 Food and Drug Administration (FDA) registration was granted. Despite the growing body of published works and increasing global availability of alfaxalone-HPCD, the accumulating evidence for its use in cats has not been thoroughly reviewed. The purpose of this review is: (1) to detail the pharmacokinetic properties of alfaxalone-HPCD in cats; (2) to assess the pharmacodynamic properties of alfaxalone-HPCD, including its cardiovascular, respiratory, central nervous system, neuromuscular, hepatic, renal, haematological, blood-biochemical, analgesic and endocrine effects; and (3) to consider the clinical application of alfaxalone-HPCD for sedation, induction and maintenance of anaesthesia in cats. Based on the published literature, alfaxalone-HPCD provides a good alternative to the existing intravenous anaesthetic options for healthy cats.     

The use of a nerve stimulation test to confirm sacrococcygeal epidural needle placement in cats

ObjectiveTo determine if a nerve stimulation test (NST) could act as a monitoring technique to confirm sacrococcygeal epidural needle placement in cats.Study designProspective experimental trial in a clinical setting.AnimalsTwenty-four adult cats, scheduled for a therapeutic procedure where epidural anesthesia was indicated.MethodsUnder general anesthesia, an insulated needle was inserted through the S₃-Cd₁ intervertebral space guided by the application of a fixed electrical current (0.7 mA) until a motor response was obtained. The NST was considered positive when the epidural nerve stimulation produced a motor response of the muscles of the tail, whereas it was considered negative when no motor response was evoked. In the NST positive cases, 0.3 mL kg⁻¹ of 0.5% bupivacaine was administrated before needle withdrawal. Ten minutes after injection, epidural blockade was confirmed by the loss of perineal (anal), and pelvic limbs reflexes (patellar and withdrawal).ResultsThe use of a fixed electrical stimulation current of 0.7 mA resulted in correct prediction of sacrococcygeal epidural injection, corroborated by post bupivacaine loss of perineal and pelvic limb reflexes, in 95.8% of the cases.Conclusion and clinical relevanceThis study demonstrates the feasibility of using, in a clinical setting, an electrical stimulation test as an objective and in real-time method to confirm sacrococcygeal epidural needle placement in cats.     

Clinical and magnetic resonance imaging findings in 92 cats with clinical signs of spinal cord disease

Medical records of 92 cats presented with clinical signs of spinal cord disease, which had undergone magnetic resonance imaging (MRI), were reviewed. The cats were grouped into seven categories based upon the diagnosis suggested by results of MRI, cerebrospinal fluid analysis and other diagnostic procedures: neoplastic (n=25), inflammatory or infectious (n=13), traumatic (n=8), vascular (n=6), degenerative (n=5), anomalous (n=3) and those with an unremarkable MRI (n=32). There were two independent predictors of abnormal MRI findings: severity of clinical signs and presence of spinal pain. Abnormal MRI findings and speed of onset of disease were significantly associated with survival. For the 32 cats with unremarkable MRI findings, only nine died due to spinal disease and, therefore, the median survival time (MST) was not reached (lower 95% confidence interval (CI)=970 days). For the 60 cats with abnormal MRI findings, 37 died due to their disease and the MST was 138 days (95% CI: 7-807).     

Magnetic stimulation of the radial nerve in dogs and cats with brachial plexus trauma: a report of 53 cases

Brachial plexus trauma is a common clinical entity in small animal practice and prognostic indicators are essential early in the course of the disease. Magnetic stimulation of the radial nerve and consequent recording of the magnetic motor evoked potential (MMEP) was examined in 36 dogs and 17 cats with unilateral brachial plexus trauma.Absence of deep pain perception (DPP), ipsilateral loss of panniculus reflex, partial Horner’s syndrome and a poor response to MMEP were related to the clinical outcome in 29 of the dogs and 13 of the cats. For all animals, a significant difference was found in MMEP between the normal and the affected limb. Absence of DPP and unilateral loss of the panniculus reflex were indicative of an unsuccessful outcome in dogs. Additionally, the inability to evoke a MMEP was associated with an unsuccessful outcome in all animals. It was concluded that magnetic stimulation of the radial nerve in dogs and cats with brachial plexus trauma may provide an additional diagnostic and prognostic tool.     

Change in M-mode echocardiographic values in cats given ketamine

Determination was made of changes in heart rate and certain M-mode echocardiographic values in healthy cats given ketamine (3 to 5 mg/kg, IM). Heart rate and septal and left ventricular posterior wall thickness in diastole increased, and left ventricular internal diameter in diastole and shortening fraction decreased (P less than 0.02) after ketamine was given. With the adjustment for heart rate by analysis of covariance, left ventricular internal diameter in diastole, shortening fraction, and velocity of circumferential fiber shortening were significantly decreased (P less than 0.05) from base-line values.     

Reference range values of regional left ventricular myocardial velocities and time intervals assessed by tissue Doppler imaging in young nonsedated Maine Coon cats

OBJECTIVE: To describe and analyze the left ventricular free wall (LVFW) radial and longitudinal motions in a population of healthy Maine Coon cats by use of quantitative 2-dimensional color tissue Doppler imaging (TDI). ANIMALS: 23 healthy young Maine Coon cats (mean +/- SD: age, 2.1 +/- 0.9 years; weight, 5.0 +/- 1.0 kg). PROCEDURE: TDI was performed by the same trained observer (VC) on all cats. Radial LVFW velocities were recorded in endocardial and epicardial LVFW segments, and longitudinal velocities were recorded in the mitral annulus and in basal and apical LVFW segments. Isovolumic contraction and relaxation times were calculated in each myocardial segment, and the coefficients of variation (CVs; %) were determined for each TDI parameter. RESULTS: LVFW velocities were significantly higher in the endocardial layers than in the epicardial layers and also significantly higher in the basal than in the apical segments. Annular velocities were significantly higher than basal myocardial velocities in systole and early diastole. Coefficient of variation values were lower for radial velocities, particularly in systole, and were also lower for time intervals (16% to 22%) than for myocardial velocities (19% to 62%). CONCLUSIONS AND CLINICAL RELEVANCE: Because Maine Coon cats are predisposed to an inherited hypertrophic cardiomyopathy, which is a common cause of death in this breed, TDI could provide a useful tool for early detection of the disease. Tissue Doppler imaging indices may complete the conventional analysis of the left ventricular function in Maine Coon cats. However, the usefulness of TDI indices in the early detection of myocardial dysfunction needs to be clarified.     

Transcranial magnetic stimulation: normal values of magnetic motor evoked potentials in 84 normal horses and influence of height, weight, age and sex

REASONS FOR PERFORMING STUDY: Cervical spinal cord dysfunction is a common problem in equine medicine and the currently available tests give no objective information about the functionality of the nervous tracts. Therefore, transcranial magnetic stimulation (TMS) was performed in 84 healthy horses of different height in order to have an objective measure for the integrity of the descending motor tracts in normal horses. OBJECTIVES: To obtain reference values for onset latency and peak-to-peak amplitude of magnetic motor evoked potentials (MMEPs) and to evaluate the possible effect of height, age and gender on the neurophysiological measures. METHODS: All horses were sedated and stimulated transcranially by using a magnetic coil placed on the forehead. The stimulator triggered the sweep of an electromyogram machine that recorded MMEPs bilaterally from needle electrodes in the extensor carpi radialis and cranial tibial muscles. In that way, it was possible to measure latency between stimulus and onset of response. RESULTS: A significant difference was found between recordings made in the fore- and hindlimbs; MMEPs recorded in the front legs had a shorter onset latency and higher peak-to-peak amplitude. Mean +/- s.d. normal values for onset latency of 19.32 +/- 2.50 and 30.54 +/- 5.28 msecs and peak-to-peak amplitude values of 9.54 +/- 3.73 and 6.62 +/- 3.62 mV were obtained for extensor carpi radialis and cranial tibial muscles, respectively. The left-to-right difference in onset latency and peak-to-peak amplitude was not significant. In the same horse, differences up to 0.82 and 1.53 msecs for the extensor carpi radialis and cranial tibial muscles, respectively, lie within the 95% confidence limit and are considered normal. In contrast to onset latency, peak-to-peak amplitude showed a very large intra- and interindividual variability, even in the same muscle. To reduce the variability and predict normal values of new individual cases, influence of height, weight, age and sex on the MMEPs were determined. No significant effects of sex were observed on onset latency and peak-to-peak amplitude. The age of the horse had only a small but significant effect on peak-to-peak amplitude, with larger responses in older horses. Height at the withers and weight of the horse, parameters that strongly correlate with the size of the horse, had an important significant influence on onset latency but not on peak-to-peak amplitude. The age of the horse and height at the withers were used to predict peak-to-peak amplitude and onset latency, respectively, in normal horses. CONCLUSIONS AND POTENTIAL RELEVANCE: TMS is an excellent addition to the few tools we have for noninvasive imaging of the equine nervous system. Magnetically evoked potentials are highly reproducible and recent advances suggest that the applications of TMS in horses will continue to grow rapidly.