Intracranial neoplasia

A diagnosis of intracranial neoplasia in companion animals may be made by computed tomography (CT) or magnetic resonance imaging (MRI). MRI is the better method for detecting and characterizing intracranial tumors because of its superior depiction of soft tissues and relative lack of degrading artifacts, intracranial tumors may be characterized by distinct features; a systematic evaluation of these features on CT or MRI images may help to identify specific tumor types. In this article, guidelines for formulating differential diagnoses based on these imaging criteria will be discussed. Technical recommendations and protocols for CT and MR imaging will also be provided.     

Gastric neoplasia.

Gastric tumors are rare in dogs and cats but should always be considered, particularly in older dogs with chronic vomiting. The most common gastric tumor in dogs is carcinoma, although lymphoma is rare. Breeds that seem to be predisposed to gastric carcinoma are the Rough Collie, Staffordshire Terrier, and Belgian Shepherd. Lymphoma is the most common gastric malignancy in cats. Contrast radiographic examination and endoscopy are the elective procedures of choice for the diagnosis of these conditions. Biopsy is essential to confirm the diagnosis. Surgery is the only potentially curative modality for localized gastric carcinoma. Chemotherapy alone or following surgery is the elective treatment of choice for gastric lymphoma in dogs and cats. The prognosis is poor for both types of tumor, but prolonged survival times in individual animals are possible.     

Ocular neoplasia.

Except for two neoplasms, notably SCC and sarcoid, ocular and periocular tumors are uncommon in horses. The practitioner must accurately determine the type of tumor by histopathology so appropriate treatment and a legitimate prognosis can be offered. The first attempt at treatment has the greatest chance to result in a cure; an aggressive treatment regimen therefore should be selected from the start.     

Platelets and neoplasia

Numerous platelet abnormalities have been recognized in animals with malignancy. Because platelets play a key role in hemostasis, it is vital that clinicians recognize those neoplastic conditions that are associated with platelet disorders. A review of these platelet abnormalities, their underlying pathophysiology, and treatment is presented in this article.     

Angiogenesis and cerebral neoplasia

Angiogenesis is a fundamental process in reproduction and wound healing. It is a tightly regulated process causing neovascularization. However, if angiogenesis becomes unregulated, it may be responsible for several disease processes such as brain tumour growth and metastasis. An understanding of the factors implicated in angiogenesis and its inhibition is essential if they are to be exploited as possible clinical treatments for brain tumours. Unfortunately, there are multiple factors known to be involved in the regulation of angiogenesis, and hence, the clinical application of any single agent may not be effective. This article summarizes the processes of blood vessel formation in the brain, examines the angiogenic factors that are important in the nervous system and discusses their role in brain tumour development and possible treatment.     

Intestinal neoplasia in horses

BACKGROUND: Intestinal neoplasia of horses is inadequately described. HYPOTHESIS: Intestinal neoplasia of horses has characteristic clinicopathologic features. ANIMALS: Thirty-four horses with intestinal neoplasia. METHODS: Retrospective study. RESULTS: Anamnesis, clinical signs, clinicopathologic and pathologic findings in 34 adult horses diagnosed histologically with intestinal neoplasia were reviewed. The horses ranged in age from 2 to 30 years (mean 16.6 years at presentation). The Arabian breed was most represented and there was no sex predisposition. The most common presenting complaints were weight loss, colic, anorexia, and fever. The most consistent clinical signs were poor body condition, tachycardia, tachypnea, fever, and diarrhea. Useful diagnostic tools included rectal examination, routine blood analyses, abdominocentesis, ultrasonographic examination, rectal biopsy, and exploratory laparotomy. Alimentary lymphoma was the most common intestinal neoplasia identified, followed by adenocarcinoma and smooth muscle tumors. The small intestine was the most common segment of intestine affected for all neoplasms. Intestinal neoplasia was diagnosed antemortem in 13 of 34 (38%) horses. The median time from onset of clinical signs to death or euthanasia was 1.9 months. The discharge rate was 15%. Although the longest survival was observed in horses with jejunal adenocarcinoma, all horses were eventually euthanized because of intestinal neoplasia. CONCLUSIONS: Arabian horses were 4.5 times more likely to have intestinal neoplasia diagnosed than were other breeds.     

Hepatic encephalopathy

Hepatic encephalopathy is a neurometabolic syndrome caused by altered hepatic blood flow patterns and/or hepatic disease. This article describes current thoughts on its pathogenesis and diagnosis. Treatment principles are emphasized.     

Hepatic Encephalopathy

Hepatic encephalopathy occurs in a number of different species as a result of either congenital portacaval shunts or acquired liver disease. Despite intensive research, the neurochemical basis of the disorder has not been defined. Theories to explain the cerebral dysfunction that accompanies acute or chronic hepatic failure include 1) ammonia acting as the putative neurotoxin, 2) perturbed monoamine neurotransmission as a result of altered plasma amino acid metabolism, 3) an imbalance between excitatory amino acid neurotransmission, mediated by glutamate, and inhibitory amino acid neurotransmission, mediated by gamma-aminobutyric acid, and 4) increased cerebral concentrations of an endogenous benzodiazepine-like substance.     

Hepatic biopsy

Hepatic biopsy plays an integral part in the formation of the diagnosis, selection of the therapy, and determination of the prognosis in clinical cases of hepatic disease. It has been shown that results of hepatic biopsy correlate well with postmortem findings and findings of liver function tests. Hepatic biopsy is not difficult to perform and the benefits usually outweigh the risks and costs. The techniques described have many variations that are influenced by the experience and skill of the practitioner and the equipment available to the practitioner. It is the authors' opinion that, with the proper training, every practitioner can obtain hepatic biopsies and, thus, increase the quality of medical care to their patients.     

Melanocytic neoplasia in the cat

Clinical features and histopathological details from 13 cases of melanocytic neoplasia in the cat are presented. The series includes cases of intraocular melanoma (n=5), limbal melanoma (n=2), dermal melanoma (n=5) and one case of metastatic melanoma for which a primary site was not identified. In the case of the intraocular tumours, there was apparent correlation between the degree of cellular pleomorphism, the mitotic rate and the extent of local infiltration. Such an association was not identified for the melanomas arising from the limbus or skin.     

Primary renal neoplasia of dogs

BACKGROUND: Primary renal tumors are diagnosed uncommonly in dogs. HYPOTHESIS: Signs and survival will differ among different categories of primary renal tumors. ANIMALS: Data were collected from the medical records of 82 dogs with primary renal tumors diagnosed by examination of tissue obtained by ultrasound-guided biopsy, needle aspiration, surgery, or at postmortem examination. METHODS: This was a multi-institutional, retrospective study. RESULTS: Forty-nine dogs had carcinomas, 28 had sarcomas, and 5 had nephroblastomas. The dogs were geriatric (mean 8.1 years; range: 1-17) with a weight of 24.9 kg (range: 4.5-80). Tumors occurred with equal frequency in each kidney with 4% occurring bilaterally. Initial signs included one or more of hematuria, inappetance, lethargy. weight loss, or a palpable abdominal mass. Pain was reported more frequently in dogs with sarcomas (5/28). The most common hematologic abnormalities were neutrophilia (22/63), anemia (21/64), and thrombocytopenia (6/68). Polycythemia was present in 3 dogs and resolved with treatment. Hematuria (28/49), pyuria (26/49), proteinuria (24/50), and isosthenuria (20/56) were the most frequently observed abnormalities on urinalysis. Pulmonary metastases were noted on thoracic radiographs in 16% of dogs at diagnosis. Seventy-seven percent of dogs had metastatic disease at the time of death. Median survival for dogs with carcinomas was 16 months (range 0-59 months), for dogs with sarcomas 9 months (range 0-70 months), and for dogs with nephroblastomas 6 months (range 0-6 months). CONCLUSIONS AND CLINICAL IMPORTANCE: Primary renal tumors in dogs are generally highly malignant with surgery being the only treatment that improves survival.