Primary brain tumors in two dogs treated by surgical resection in combination with postoperative radiation therapy

Domestic Animal Models of Central Nervous System Tumors: Focus on Meningiomas

Intracranial primary tumors (IPTs) are aggressive forms of malignancies that cause high mortality in both humans and domestic animals. Meningiomas are frequent adult IPTs in humans, dogs, and cats, and both benign and malignant forms cause a decrease in life quality and survival. Surgery is the primary therapeutic approach to treat meningiomas, but, in many cases, it is not resolutive. The chemotherapy and targeted therapy used to treat meningiomas also display low efficacy and many side effects. Therefore, it is essential to find novel pharmacological approaches to increase the spectrum of therapeutic options for meningiomas. This review analyzes the similarities between human and domestic animal (dogs and cats) meningiomas by evaluating the molecular and histological characteristics, diagnosis criteria, and treatment options and highlighting possible research areas to identify novel targets and pharmacological approaches, which are useful for the diagnosis and therapy of this neoplasia to be used in human and veterinary medicine.

Evaluation of nanoparticle delivered cisplatin in beagles

Intracranial neoplasia is a significant cause of morbidity and mortality in both human and veterinary patients, and is difficult to treat with traditional therapeutic methods. Cisplatin is a platinum (Pt)-containing chemotherapeutic agent approved by the Food and Drug Administration; however, substantial limitations exist for its application in canine brain tumor treatment due to the difficulty in crossing the blood-brain barrier (BBB), development of resistance, and toxicity. A modified Pt(iv)-prodrug of cisplatin, Platin-M, was recently shown to be deliverable to the brain via a biocompatible mitochondria-targeted lipophilic polymeric nanoparticle (NP) that carries the drug across the BBB and to the mitochondria. NP mediated controlled release of Platin-M and subsequent reduction of this prodrug to cisplatin allowed cross-links to be formed with the mitochondrial DNA, which have no nucleotide excision repair system, forcing the overactive cancer cells to undergo apoptosis. Here, we report in vitro effects of targeted Platin-M NPs (T-Platin-M-NPs) in canine glioma and glioblastoma cell lines with results indicating that this targeted NP formulation is more effective than cisplatin. In both the cell lines, T-Platin-M-NP was significantly more efficacious compared to carboplatin, another Pt-based chemotherapy, which is used in the settings of recurrent high-grade glioblastoma. Mitochondrial stress analysis indicated that T-Platin-M-NP is more effective in disrupting the mitochondrial bioenergetics in both the cell types. A 14-day distribution study in healthy adult beagles using a single intravenous injection at 0.5 mg kg(-1) (with respect to Platin-M) of T-Platin-M-NPs showed high levels of Pt accumulation in the brain, with negligible amounts in the other analyzed organs. Safety studies in the beagles monitoring physical, hematological, and serum chemistry evaluations were within the normal limits on days 1, 7, and 14 after injection of either 0.5 mg kg(-1) or 2 mg kg(-1) or 2.2 mg kg(-1) (with respect to Platin-M) of T-Platin-M-NPs. At all doses over the 14-day period, no neurotoxicity was observed based upon periodic neurological examinations and cerebrospinal fluid analysis. These studies demonstrated the translational nature of T-Platin-M-NPs for applications in the treatment of brain tumors.

Evaluation of progesterone and estrogen receptor expression in 15 meningiomas of dogs and cats

OBJECTIVE

To evaluate progesterone and estrogen receptor expression in meningiomas of the CNS in dogs and cats.

ANIMAL

8 dogs (1 of which was treated with gestrinone) and 5 cats with intracranial meningiomas and 2 dogs with spinal cord meningiomas; tissue samples were also obtained from 1 clinically normal dog and 1 clinically normal cat.

PROCEDURE

Meningioma tissue was obtained during surgery or at necropsy; samples were processed for histologic classification and immunohistochemical evaluation of the proportion of tumor cells with progesterone and estrogen receptors. Correlation among receptor expression, tumor grade, and histologic subtypes was determined.

RESULT

Several histologic subtypes of intracranial meningiomas were detected among tissue samples. In the cats, all intracranial meningiomas were benign. Progesterone receptor immunoreactivity was detected in 14 of 15 meningiomas. Progesterone receptor expression was identified in > 80% of cells in 8 intracranial meningiomas (4 dogs and 4 cats) and 2 spinal cord meningiomas. In samples of malignant transitional and granular cell meningiomas in dogs, progesterone receptors were detected in 32 and 4.8% of cells respectively. In 1 cat, 38% of tumor cells had progesterone receptors. In a dog treated with gestrinone, no progesterone receptors were detected in the intracranial meningioma. Estrogen receptors were only detected in the tumor of 1 dog.

CONCLUSIONS AND CLINICAL RELEVANCE

Results indicate a high proportion of progesterone receptors in cells of meningiomas of the CNS in dogs and cats. Antiprogesterone treatment may have a role in the treatment of unresectable or recurrent meningiomas in dogs and cats.

Contrast enhancement in magnetic resonance imaging using intravenous paramagnetic contrast media: a review

Interest in magnetic resonance (MR) imaging as a major diagnostic tool in veterinary clinical medicine is increasing. Most MR studies are performed with the use of contrast enhancement via intravenous injection of paramagnetic gadolinium-containing contrast media. A vast number of publications are available regarding the use of contrast media in humans. The purpose of this paper is to assist practicing veterinary radiologists in understanding mechanisms of MR contrast enhancement. This paper reviews certain aspects of MR contrast enhancement, including physical, chemical and biologic characteristics of most common MR contrast media targeted primarily at the central nervous system (CNS). Authors also describe processes that explain changes in signal intensity on the MR images.

The advantage of magnetic resonance imaging in diagnosis of cauda equina syndrome in dogs

Three dogs were evaluated in our study using magnetic resonance imaging (MRI) to reveal the anatomical deformity and the degree of the lesion of cauda equina. In all dogs, MRI revealed soft tissue, such as cauda equina, epidural fat, and intervertebral disc, at the lumbosacral region clearly without contrast medium. Our results suggest that MRI has some advantages in evaluating cauda equina syndrome in dogs.