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in Journal of the American Veterinary Medical Association

Abstract

Objectives

To establish intracranial pressure (ICP) measurements in healthy cats under isoflurane anesthesia, using a fiberoptic monitoring system; to assess brain lesions associated with such monitoring; and to determine whether decompressive intracranial surgery decreases ICP in healthy cats.

Animals

6 healthy cats.

Procedure

Craniectomy and durotomy were performed, and the effect of these procedures on ICP was determined. ICP was monitored by use of a fiberoptic monitoring system. Gross and microscopic evaluations of brain tissues were performed after data collection.

Results

ICP decreased significantly after craniotomy and durotomy. After wound closure, ICP remained significantly reduced relative to initial pressures. However, postsurgical pressures were significantly increased, compared with those associated with ICP after durotomy. Gross and histologic abnormalities associated with placement of the ICP monitoring cable included mild focal acute hemorrhage and mechanical cortical disruption.

Conclusions

Craniectomy and durotomy significantly decreased ICP in healthy cats. ICP increased after wound closure, but remained significantly lower than initial pressures.

Clinical Relevance

Craniectomy and durotomy may be used to decrease ICP in cats. (Am J Vet Res 1996;57:1659–1661)

Free access
in American Journal of Veterinary Research

Summary

Urethral smooth muscle tone in response to treatment with phenylephrine, a selective α1-adrenergic receptor agonist, and prazosin a selective α1-adrenergic receptor antagonist, was evaluated in 12 anesthetized healthy adult sexually intact male cats. Intravenous administration of prazosin (20 to 30 μg/kg of body weight) decreased the average preprostatic and prostatic intraurethral pressure, compared with baseline and postphenylephrine (20 to 30 μg/kg) administration, values. Neither prazosin nor phenylephrine administration had an effect on functional urethral length. Results have implications for the pharmacologic management of lower urinary tract disorders in male cats.

Free access
in American Journal of Veterinary Research

Summary

Quantitative electroencephalography was assessed in 6 dogs anesthetized with 1.8% end-tidal halothane, under conditions of eucapnia, hypocapnia, and hypercapnia. Ventilation was controlled in each condition. Heart rate, arterial blood pressure, core body temperature, arterial pH, blood gas tensions, end-tidal CO2 tension, and end-tidal halothane concentration were monitored throughout the study. A 21-lead linked-ear montage was used for recording the eeg. Quantitative electroencephalographic data were stored on an optical disk for analysis at a later date. Values for absolute power of the eeg were determined for δ, θ, α, and β frequencies. Hypocapnia was achieved by hyperventilation. Hypercapnia was achieved by titration of 5% CO2 to the inspired gas mixture. Hypercapnia was associated with an increase in the absolute power of the δ band. Hypocapnia caused an increase in the absolute power of δ, θ, and α. frequencies. Quantitative electroencephalographic data appear to be altered by abnormalities in arterial carbon dioxide tension. Respiratory acidosis or alkalosis in halothane-anesthetized dogs may obscure or mimic electroencephalographic abnormalities caused by intracranial disease.

Free access
in American Journal of Veterinary Research

Objective

To determine the prevalence of various clinical signs in dogs with brain tumors.

Design

Retrospective study.

Animals

97 dogs with brain tumors.

Procedure

Medical records were reviewed for signalment, tumor type and location, and clinical signs.

Results

33 breeds were represented; Golden Retrievers were most commonly affected. Most dogs were older (median age, 9 years); 95% of dogs were ≥ 5 years old. Seventy-six percent of dogs had tumors in the supratentorial region. Seizures were the most common clinical sign at initial examination, with lower prevalence for circling, ataxia, and head tilt. Meningioma was the most common tumor.

Conclusions and Clinical Relevance

Brain tumors develop most often in dogs ≥ 5 years old and are uncommon in dogs < 5 years old. Seizures are a common clinical sign, and a brain tumor should be considered in dogs that have their first seizure after they are 4 years old. (J Am Vet Med Assoc 1999;215:818–819)

Free access
in Journal of the American Veterinary Medical Association

Abstract

Objectives

To determine systemic and local platinum concentrations released from subcutaneously implanted cis-diamminedichloroplatinum (cisplatin)-impregnated polymethylmethacrylate (PMMA) and to evaluate systemic or local adverse reactions.

Animals

6 healthy dogs.

Procedure

Cisplatin (20 mg) was inserted into PMMA that was fashioned into cylinders and placed into subcutaneous tissue chambers overlying the thorax (treated site). An empty tissue chamber was placed over the opposite side (control site). Plasma samples were obtained for platinum determination before implantation, at 3, 6, and 12 hours after implantation on day 0, and once daily on days 1, 2, 3, 7, 14, 21, and 29. At similar times on similar days, tissue chamber fluid samples also were obtained for platinum determination. Complete blood count, serum urea nitrogen and creatinine concentration determinations, and urinalyses were performed on days 1, 2, 3, 7, 14, 21, and 29. Complete necropsy was performed at conclusion of the study.

Results

Tissue chamber platinum concentrations at the treated site were significantly greater than plasma and control site tissue chamber concentrations on days 2, 3, 7, 10. Mean plasma platinum concentration at 3 (0.735 µg/ml), 6 (0.691 µg/ml), 12 (0.534 µg/ml), 24 (0.131 µg/ml), 48 (0.2 µg/ml), 72 (0.1 µg/ml), and 158 (0.014 µg/ml) hours was significantly greater than pretreatment values (0.0 µg/ml). Plasma platinum concentration 10 days after treatment (0.011 µg/ml) did not significantly differ from pretreatment values. Local or systemic adverse reactions were not apparent.

Conclusions

The route of cisplatin administration was safe. Greater concentration of platinum was released locally relative to plasma concentration for an extended period. (Am J Vet Res 1999;60:280–283)

Free access
in American Journal of Veterinary Research
in Journal of the American Veterinary Medical Association

SUMMARY

During 2 separate studies, intracranial pressure (icp) was measured in 13 healthy dogs (group A, n = 7; group B, n = 6), using a fiberoptic monitoring system implanted surgically in the right superficial cerebral cortex. Average icp was measured for 15 minutes after a 15-minute post-implantation period of equilibration. Intracranial pressure was measured in group-A dogs at 2.0 and 1.3% end-tidal isoflurane concentrations. Mean ± 1 sd icp in group-A dogs at 2.0 and 1.3% end-tidal isoflurane concentrations was 11 ± 2 and 11 ± 3 mm of Hg, respectively. Dogs of group A were euthanatized immediately after measurements were obtained. Mean icp ± 1 sd in group-B dogs was 11 ± 3 mm of Hg. After monitoring, but prior to euthanasia, group-B dogs underwent callosotomy, and were maintained for 30 days after surgery. The brain was removed from all dogs, formalin fixed, and examined grossly and microscopically for lesions associated with fiberoptic cable implantation. Variable degrees of hemorrhage and mechanical brain damage were seen focally around the catheter site in all brains from group-A dogs, especially when the cable entered through a sulcus. In 1 dog, local vacuolation was seen in the brain immediately adjacent to the tract associated with implantation of the fiberoptic catheter. In all other dogs, the additional cortex was histologically normal. Histologic lesions associated with cable implantation were not observed in group-B dogs.

Free access
in American Journal of Veterinary Research

Abstract

Objective—To determine whether magnetic resonance imaging (MRI) features correlated with histologic diagnosis in dogs with nasal disease.

Design—Retrospective case series.

Animals—78 dogs undergoing MRI for evaluation of nasal disease.

Procedures—Medical records and MRI reports of dogs were reviewed to identify MRI features associated with histologic diagnosis. Features evaluated were presence of a mass effect, frontal sinus involvement, sphenoid sinus involvement, maxillary recess involvement, nasopharyngeal infiltration by soft tissue, nasal turbinate destruction, vomer bone lysis, paranasal bone destruction, cribriform plate erosion, and lesion extent (ie, unilateral vs bilateral).

Results—33 dogs had neoplastic disease, 38 had inflammatory rhinitis, and 7 had fungal rhinitis. Lesion extent was not significantly associated with histologic diagnosis. Absence of a mass effect was significantly associated with inflammatory disease. However, presence of a mass was not specific for neoplasia. In dogs with evidence of a mass on magnetic resonance (MR) images, nasal turbinate destruction, frontal sinus invasion, and maxillary recess invasion were not useful in distinguishing neoplastic from nonneoplastic disease, but cribriform plate erosion, vomer bone lysis, paranasal bone destruction, sphenoid sinus invasion, and nasopharyngeal invasion were.

Conclusions and Clinical Relevance—Results suggested that in dogs with nasal disease, the lack of a mass effect on MR images was significantly associated with inflammatory disease. In dogs with a mass effect on MR images, vomer bone lysis, cribriform plate erosion, paranasal bone destruction, sphenoid sinus invasion by a mass, and nasopharyngeal invasion by a mass were significantly associated with a diagnosis of neoplasia.

Full access
in Journal of the American Veterinary Medical Association

Abstract

OBJECTIVE To compare the effects of conventional and slanted ventral slot procedures on the biomechanical behavior of the C5-C6 vertebral motion unit (VMU) in dogs.

SAMPLE 14 vertebral columns (C4 through C7) from canine cadavers.

PROCEDURES Specimens were assigned to a conventional or slanted ventral slot group (n = 7/group). For each specimen, the C5-C6 VMU was tested in ventral and dorsal bending and positive and negative axial torsion before and after surgery. Range of motion (ROM), stiffness, and energy absorption were compared between the 2 groups.

RESULTS Both procedures significantly increased the ROM and stiffness and significantly decreased the energy absorption of the C5-C6 VMU in ventral and dorsal bending. Both procedures also increased the ROM in positive and negative axial torsion. In negative torsion, total stiffness and stiffness over the maximum ROM tested decreased less for the slanted slot procedure than for the conventional slot procedure. There were no significant differences between procedures for any of the other biomechanical outcomes examined.

CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that the biomechanical response of the C5-C6 VMU to the conventional and slanted ventral slot procedures was not significantly different, especially when considering postsurgical instability induced by both procedures. This was most likely due to disruption of the nucleus pulposus and dorsal annulus fibrosus of the disk with both procedures. On the basis of these findings, neither procedure appeared biomechanically superior. Comparative clinical studies are warranted to further evaluate the 2 procedures.

Full access
in American Journal of Veterinary Research