Canine and feline intracranial meningiomas: an updated review

Meningiomas are the most common primary brain tumours in dogs and cats. There are several morphological phenotypes of this extra-axial neoplasm and they show predilections for certain anatomical locations. There have been a number of attempts to apply the current World Health Organization (WHO) classification for human meningiomas to dogs and cats and to obtain a universal classification scheme for domestic animals. Recently, certain enzymes involved in tumour growth have been recognised as biological markers and have been related to degrees of malignancy. The secondary effects of meningiomas have also been investigated, and vascular endothelial growth factor and peritumoural oedema have been reported to reduce survival rate. Breed and age predisposition are recognised in both dogs and cats and the presenting clinical signs are quite consistent. Magnetic resonance imaging and computed tomography are the techniques of choice for the presumptive diagnosis of meningiomas in domestic animals but advanced imaging techniques are constantly being developed and applied. Treatment methods for meningiomas involve a combination of de-bulking surgery, chemotherapy and radiotherapy, and detailed accounts of several treatment protocols have been reported.     

Radiation therapy for the treatment of tumours in small companion animals

Radiation is becoming widely available to treat tumours in veterinary patients. Orthovoltage machines capable of delivering low energy external beam radiation are less versatile than linear accelerators and cobalt-60 machines that deliver megavoltage radiation. In addition, electron beam capabilities that are available with some linear accelerators allow more targeted treatment in smaller patients. Acute effects of radiation are to be expected, but in nearly all cases such side effects resolve without limiting protocols. In contrast, late effects of radiation are dose limiting and are more likely with higher doses per treatment fraction. Protocols that use smaller doses per fraction have a lower risk of late effects thereby allowing higher total doses to be delivered which leads to higher tumour control rates. It is possible to provide long-term tumour control in cats and dogs using radiation therapy, particularly for mast cell tumours, soft tissue sarcomas, oral tumours and brain tumours in dogs and soft tissue sarcomas and skin tumours in cats. Individualization of treatments for tumours based on tumour staging and proliferative fraction should be considered, rather than making blanket assumptions about the behaviour of histologically determined tumour types.     

Synovial myxoma: magnetic resonance imaging in the assessment of an unusual canine soft tissue tumour

Magnetic resonance imaging (MRI) of the hindlimb of a 10-year-old Labrador retriever was performed preoperatively to define the limits and invasive nature of a synovial myxoma. This unusual tumour in dogs has also only rarely been reported in humans, although the use of advanced imaging techniques has been more widely reported in the assessment of soft tissue tumours in people. MRI was an invaluable aid in the delineation of the extensive pathological changes associated with this tumour and consequently its surgical treatment. Amputation was performed and the dog remained disease-free 18 months after surgery.     

Preliminary results of maxillectomy in the dog and cat

Maxillectomy was used in the treatment of 23 dogs and four cats with oral tumours and one dog with osteomyelitis. The major post-operative complication was wound dehiscence. All dehiscences occurred in dogs with tumour epicentres caudal to PM¹. Maxillectomy in eight dogs with oral fibrosarcoma gave disappointing results (median survival time of 7 months and a median tumour-free interval of 3½ months). Three of four dogs with squamous cell carcinoma were tumour free after a minimum follow-up period of 6 months; two of these dogs received orthovoltage radiation therapy following surgery. Maxillectomy provided excellent local control of benign tumours: three epulides and one atypical odontogenic tumour did not recur (minimum follow-up period was 10 months); an osteoma recurred after 17 months. Four cats, three with squamous cell carcinoma and one with fibrosarcoma, developed local tumour recurrence within 4 months.     

Magnetic resonance imaging findings in 40 dogs with histologically confirmed intracranial tumours

Magnetic resonance (MR) images of 40 dogs with histologically confirmed primary and secondary intracranial tumours were reviewed. Forty-one tumours were diagnosed by means of MR imaging (MRI). MRI findings allowed diagnosis of a neoplastic lesion in 37/41 cases. Based on MRI features, differentiation between neoplastic and non-neoplastic lesions was possible in 24/27 (89%) primary brain tumours and in 13/14 (92%) secondary brain tumours. Diagnosis of tumour type based on MRI features was correct in 19/27 (70%) primary tumours and in 13/14 secondary tumours. The results of this study show that MRI is a good diagnostic imaging modality to detect neoplastic lesions and to diagnose tumour type in dogs. However, as some neoplasms show equivocal MRI features the technique has limitations in the detection of some intracranial tumours and in predicting tumour type.     

Fluorescence detection of a new photosensitizer, PAD-S31, in tumour tissues and its use as a photodynamic treatment for skin tumours in dogs and a cat: a preliminary report

We describe here the detection by fluorescence of a new photosensitizer, PAD-S31, in tumours in dogs and cats and the effect of photodynamic therapy (PDT) by using PAD-S31 for skin tumours in two dogs and one cat. PAD-S31 is a hydrophilic photosensitizer that has two peaks at absorption wavelengths 406 and 665 nm in distilled water. In a preliminary experiment in mice transplanted with SCCVII and colon 26, PAD-S31 was retained in tumour tissues rather than in other organs. The tumours resected from dogs and cats after intravenous administration of PAD-S31 at a dose of 15 mg/kg emitted strong red fluorescence under light illumination of 402 nm wavelength. Animals given PAD-S31 showed no cutaneous photosensitivity under room light illumination. Irradiation at laser light 670 nm wavelength (fluence rate 150 mW/cm2 and total light dosage 150 J/cm2) on cutaneous mast cell tumours in dogs ( n=2 ) and a cutaneous basal cell tumour in a cat induced complete remission. These results suggest PAD-S31 could be a promising photosensitizer for use in a small animal veterinary practice.     

Nerve sheath tumours in the dog and cat

Schwannomas were diagnosed in twelve dogs and five cats at Massey University Small Animal Clinic and Hospital over a 15-year period (1977-92). A further two feline cases were reported at the Batchelar Animal Health Laboratory. In six dogs, the tumour involved nerves of the brachial plexus. Clinical signs observed in these dogs were forelimb lameness, muscle wasting and pain on movement of the affected limb or neck. Hindlimb paresis was observed in two dogs. Surgical excision of the brachial plexus tumour was attempted in one dog, leading to an 8-month remission of signs. In one dog, the tumour involved the sacral nerves, and in two dogs the cranial nerves were affected. Three dogs had skin nodules. Seven of the twelve affected dogs were destroyed. In five cats, the tumours developed on the carpus, tarsus or interdigital area of a forelimb or hindlimb as a slowly developing nodular lesion. In the other two cats, the site of the tumour was the flank and the lateral thigh respectively. Surgical excision of the tumour was successful in three cats.     

Incomplete surgery, local immunostimulation, and recurrence of some tumour types in dogs and cats

Histologically confirmed inadequate treatment resulted in a lower than expected recurrence percentage in dogs with haemangiopericytoma (38%) and mastocytoma (30%). Clinical suspicion of inadequate tumour treatment did not always correlate with the histologically assessed inadequacy, nor with the appearance of local recurrence. Local recurrence did not seem to be correlated with histological grade of malignancy and tumour size. Local injection of C. parvum vaccine did not result in a lower percentage of local recurrence or longer recurrence-free intervals in any of the three tumour groups (canine haemangiopericytoma, canine mastocytoma, feline mammary carcinoma). Nor was palliative local adjuvant injection of Cp successful in dogs and cats with soft tissue sarcomas or in dogs with gingival melanoma. Re-operation of locally recurrent tumour was successful in some dogs with haemangiopericytoma, in a few with mastocytoma, but not in cats with mammary carcinoma. A trend toward histological progression of recurrences and metastases, when compared with the primary tumours, was not evident. The possible reasons for the relatively low recurrence rate of some tumour types and for the failure of Cp-treatment are discussed.     

Prognostic studies of canine and feline mammary tumours: the need for standardized procedures

For several years, veterinary oncologists have been struggling with the prognosis of mammary tumours in dogs and cats. Translation of tumour characteristics into prognostic information is an invaluable tool for the use of the most appropriate therapies, as well as for planning innovative therapeutic trials. Moreover, canine and feline spontaneous mammary gland tumours are good models for the study of human breast cancer. Collecting and interpreting information regarding the prognosis of canine and feline mammary tumours is difficult due to the fact that different methods have been applied to study various components and characteristics. This review identifies some of the challenges of prognostic studies of spontaneous canine and feline mammary tumours and suggests standardized procedures to overcome these challenges and facilitate reproducibility and assessment of results.     

Incomplete surgery,local immunostimulation,and recurrence of some tumour types in dogs and cats

Summary

Histologically confirmed inadequate treatment resulted in a lower than expected recurrence percentage in dogs with haemangiopericytoma (38%) and mastocytoma (30%). Clinical suspicion of inadequate tumour treatment did not always correlate with the histologically assessed inadequacy, nor with the appearance of local recurrence. Local recurrence did not seem to be correlated with histological grade of malignancy and tumour size. Local injection of C. parvum vaccine did not result in a lower percentage of local recurrence or longer recurrence free intervals in any of the three tumour groups (canine haemangiopericytoma, canine mastocytoma, feline mammary carcinoma). Nor was palliative local adjuvant injection of Cp successful in dogs and cats with soft tissue sarcomas or in dogs with gingival melanoma. Re‐operation of locally recurrent tumour was successful in some dogs with haemangiopericytoma, in a few with mastocytoma, but not in cats with mammary carcinoma. A trend toward histological progression of recurrences and metastases, when compared with the primary tumours, was not evident. The possible reasons for the relatively low recurrence rate of some tumour types and for the failure of Cp‐treatment are discussed.     

Hypertension in renal disease: diagnosis and treatment

Hypertension is a common sequela to renal disease in cats and dogs, affecting as many as 61% cats and 93% of dogs, respectively. Undiagnosed and untreated, elevations in blood pressure can have deleterious effects on the brain and heart as well as promote further renal injury. In this article, we discuss the identification of patients at risk for hypertension as well as methods for measuring blood pressure and the treatment of hypertensive patients.     

Surgical cytoreduction for the treatment of non-lymphoid vertebral and spinal cord neoplasms in cats: retrospective evaluation of 26 cases (1990–2005)

Medical records of 26 cats with non‐lymphoid vertebral and spinal cord neoplasms treated surgically were reviewed to determine outcome and prognostic factors for survival. Of the factors examined, only tumour phenotype was significantly associated with survival. Osteosarcoma (3/26 cats) and meningioma (16/26 cats) were the most common malignant and benign tumours, respectively. The median survival time for cats with malignant neoplasms was 110.5 days, compared with 518 days for cats with benign tumours. Cytoreductive surgery resulted in clinical improvement in 25/26 cats, but local treatment failure occurred in 10/26 cats. Overall, 19/26 cats died of confirmed (12/19) or suspected (7/19) tumour‐related causes, including all eight cats with malignant neoplasms. Results suggest that contemporary neurosurgical techniques commonly result in incomplete excision of feline non‐lymphoid vertebral and spinal cord tumours but are efficacious at palliation of clinical signs of spinal cord dysfunction.     

Potential tumour doubling time: determination of Tpot for various canine and feline tumours

Spontaneous tumours in dogs and cats are an excellent model for clinical human research, such as in developing proton conformation radiotherapy for humans. The kinetics of tumour cells can be used effectively to predict prognosis and response to therapy in patients with tumours. Knowledge of the kinetic parameters in these tumours is therefore important. In the present study the kinetic parameters evaluated included the labelling index (LI), relative movement (RM), mitotic index (MI), and potential doubling time (T_pot). These parameters were determined using in vivo labelling with bromodeoxyuridine, flow cytometry and histological preparation. Samples were obtained and evaluated from 72 dogs and 20 cats, presenting as patients in our clinic. Within the groups of epithelial and mesenchymal tumours from dogs and cats, the kinetic parameters LI, RM and MI were compared with T_pot. Significant correlations were observed for the comparison T_pot and LI. No correlation was found between T_pot and RM.     

Clinical signs, imaging features, neuropathology, and outcome in cats and dogs with central nervous system cryptococcosis from California

Background: Cryptococcus spp. is a fungal pathogen with a predilection for the central nervous system (CNS). Objectives: To compare the clinical, advanced imaging, and neuropathologic findings in dogs and cats with CNS cryptococcosis, and to evaluate outcome of treatment in these animals. Animals: Twenty‐six cats and 21 dogs with CNS cryptococcosis. Methods: Medical records were reviewed for clinical findings and results of CNS imaging. Archived cerebrospinal fluid and CNS tissue specimens were reviewed for pathology. Findings in cats were compared with those in dogs and the effects of variables on survival were determined by survival curve analysis. Results: When present, pain was localized to the cervical region in dogs and was generalized or localized to the thoracolumbar spine or pelvic limbs in cats. Magnetic resonance imaging (MRI) findings were variable but correlated with CNS histopathological findings of meningitis, meningitis with gelatinous pseudocyst formation, and granulomatous mass lesions. Peripherally enhancing brain lesions were seen only in cats. Histopathologically, the inflammatory response was milder in cats compared with dogs. Remissions of ≥1 year occurred in 32% of treated animals. Altered mentation was associated with negative outcome. Glucocorticoid use after diagnosis was associated with improved survival in the first 10 days. Conclusions and Clinical Importance: Lesions seen on MRI reflected neuropathological findings and were similar to those reported in human patients. The immune response to infection may differ between cats and dogs, or relate to the infecting cryptococcal species. Long‐term (>6 month median survival time) survival may be possible in animals surviving ≥4 days after diagnosis.     

Temporomandibular joint ankylosis in cats and dogs. A report of 10 cases.

Temporomandibular joint (TMJ) ankylosis is characterized by difficulty or inability to open the mouth. The ankylosis may be articular ('true') or extra-articular ('false'). Clinical signs, radiographic studies, treatment and follow-up are presented in a retrospective study involving five cats and five dogs. The findings were compared with TMJ ankylosis in humans. CT imaging with three-dimensional reconstruction proved to be of great value in determining the extent of the abnormalities and helped with preoperative planning. Articular TMJ ankylosis occurred in six animals and extra-articular TMJ ankylosis was found in the other four cases. In three cats and in three dogs, the TMJ ankylosis was trauma related; the remaining patients were diagnosed with a tumour. Resection of ankylosing tissue in false ankylosis or gap arthroplasty in true ankylosis was successful in all of the trauma induced cases. In the two cats, with tumour related ankylosis, the ankylosis was caused by an osteoma and resection had a good prognosis, whereas the two dogs had to be euthanatized.     

Prevalence and anatomopathological characterization of cutaneous squamous cell carcinomas with regional and distant metastases in dogs and cats: 20 cases (1985–2020)

The aim of this study was to assess the prevalence of regional and distant metastases from cutaneous squamous cell carcinomas (SCCs) in dogs (n = 11) and cats (n = 9) in a retrospective case series over 36 years (1985–2020), as well as to characterize its macroscopic aspects (location and size), degree of differentiation (well, moderately and poorly differentiated [WD, MD and PD, respectively]) and the rate of cell proliferation, by counting the AgNORs. Immunohistochemistry (IHC) was used to identify patterns of tumour migration and invasion (islands, ribbons, cords, small aggregates, individual cells [fusiform and amoeboid]) and to evaluate the intensity of desmoplasia and the amount of myofibroblasts. The prevalence of metastatic SCCs was 4.39% (21/478), being 3.8% in dog (12/309) and 5.3% in cat (9/169). Metastases affected lymph nodes in all dogs and 66% (6/9) of cats, and less frequently distant organs. Primary tumours predominantly affected the abdominal skin in dogs and the nasal planum in cats. Among the 20 cases, 52% were MDs, 34% were WDs, and 14% were PDs. Histological lesions suggestive of exposure to chronic solar radiation were present in 57% (8/14). The main patterns of tumour migration and invasion were islands for WD SCCs and individual cells for PD SCCs. MD SCCs had a mix of patterns. In cats, individual spindle cells were restricted to PDs. A marked desmoplastic reaction was more associated with PD SCCs and often with MDs. This study highlights that the prevalence of SCC metastases in dogs and cats is predominantly regional. The IHC was essential in the identification of individual fusiform keratinocytes, whose presence in surgical margins may represent a greater risk of recurrence. Although the presence of myofibroblasts was observed in all infiltrative and metastatic tumours, further studies evaluating these cells may be important to better understand their role in the tumour microenvironment of cutaneous SCCs with metastasis in dogs and cats.     

Brain hypoperfusion post-resuscitation

Post-resuscitation brain hypoperfusion is an all too common problem following successful CPR in dogs and cats. The deterioration of neurologic status may occur, regardless of the clinician's ability to restore and maintain heart rate and rhythm, mucous membrane color, capillary refill time, and arterial blood pressure. New insight has been gained into the mechanisms responsible for post-resuscitation brain hypoperfusion, which has improved current treatment regimens and the development of new therapeutic modalities. Proper use of fluids (isotonic or hypertonic saline, oncotic solutions), diuretics, corticosteroids, and sedatives, combined with appropriate CPR techniques, can improve outcome. New drugs and therapeutic techniques offer exciting potential for the future limitation of this problem.     

A retrospective study of twenty-nine spinal tumours in the dog and cat

In a retrospective study of twenty-nine spinal tumours in dogs and cats approximately equal numbers of extradural and intradural tumours were found. The most prominent tumour type was the group of primary tumours of bone which included osteosarcomas, fibrosarcomas, hemangiosarcomas and multiple cartilagenous exostoses. Primary sarcomas of the spinal cord were the next most prominent type of tumour identified. A close clinicopathological correlation was found for tumour localization; however, intradural and extradural tumours could not be differentiated clinically. In comparison with extramedullary tumours which were evenly divided between acute and insidious onset, the majority of animals with intramedullary tumours had acute onset of neurological signs. In general, the intramedullary tumours had the shortest duration of clinical signs (1.7 weeks) whereas the extradural tumours had a mean duration of 3.4 weeks and intradural-extramedullary tumours had the longest mean duration (5.7 weeks). Contrast radiography was the most useful diagnostic aid. It confirmed the regional localization in twenty-two of twenty-four animals     

Three‐dimensional conformal radiation therapy alone or in combination with surgery for treatment of canine intracranial meningiomas

Treatment protocols, treatment planning methods and tumour types in studies evaluating radiotherapy for canine brain tumours have been varied. This case series retrospectively evaluated the outcome of definitive, three‐dimensional conformal radiation therapy (3D‐CRT) as either a sole modality or as an adjuvant to surgery in 31 dogs diagnosed with meningioma by histopathology (n = 10) or cross‐sectional imaging of the head (n = 21, assessed independently by two board certified radiologists). Prescribed dose ranged from 45 to 54 Gy in 2.5 to 3 Gy fractions. Median overall survival was 577 days (interquartile range = 272–829 days; range = 30–1942 days) when all deaths were considered and 906 days (interquartile range = 336–912 days; range = 101–1942 days) when only dogs dying due to meningioma were considered. No significant difference in survival time was detected for the defined clinical or imaging findings or between treatment with radiotherapy alone versus adjuvant radiotherapy, suggesting that 3D‐CRT may be a viable alternative to surgery.     

Prognostic and predictive markers in canine tumours: rationale and relevance. A review

Cancer is one of the most common causes of death in dogs. The availability of multiple treatment modalities and novel therapeutic targets make the correct diagnosis, prognostic stratification, and the identification of treatment effect predictive factors an issue of major debate in cancer management. Selection of high and low risk patients and the type of systemic or local treatment is important in cancer management. The search for better prognostic markers and predictive factors is now focused on the molecular mechanisms which underlie tumour behaviour, such as altered cell cycle progression, proliferation, apoptosis, and angiogenesis. The ultimate goal is to identify reliable markers that can accurately diagnose and stage a tumour and predict tumour's clinical behaviour, prognosis and response to therapy. In this review, the current state of prognostication in canine tumours and promising new molecular markers are discussed. The markers are allocated to four groups according to their function: (i) proliferation markers, (ii) apoptosis, (iii) extracellular matrix and cell adhesion molecules, (iv) angiogenesis and (v) cell cycle regulators. Clinicopathological factors and histopathological grading remain the most practical parameters in decision-making. Although experimental research has shown that molecular markers have a good potential to be used as diagnostic, prognostic or predictive markers in canine tumours, insufficient evidence exists on their efficacy for routine use in veterinary oncology.