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Tumors

  • Ocular melanomas in cats may be benign or malignant. Malignant tumors, called diffuse iris melanomas, present as multifocal iridial pigmentation, and benign tumors, called limbal melanomas, present as a discernable limbal mass. The diagnosis of these tumors is in large part by clinical signs and tumor appearance. Treatment for diffuse iris melanomas may include close monitoring, laser surgery, iridectomy, and enucleation. As some iris melanomas progress slowly (over years) intervention may not be required for some time. Metastasis has been reported in about 60% of cases of diffuse iris melanoma, with spread most commonly to the regional lymph nodes, kidneys, liver, and lungs, but unlike other cancers, metastatic disease may not become evident for years. Treatment for limbal melanomas may include close monitoring, and surgery (with or without grafting) sometimes combined with cryosurgery, laser surgery, or radiation therapy. Enucleation is an option if the treatment is unsuccessful or the tumor regrows. Histopathology is always recommended for a definitive diagnosis.

  • Ocular melanomas, although rare, are the most common eye tumor in dogs. Ocular melanomas can originate from the uvea or the limbus. About 80% of uveal melanomas (and all limbal melanomas) are benign. The rate of metastasis is less than 5%. Ocular melanomas are at least in part heritable and caused by one or more genetic mutations. Uveal melanomas can become discrete, raised pigmented masses that damage the intraocular structures of the eye and cause hyphema, uveitis, and glaucoma. Limbal melanomas can invade the cornea and cause keratitis, grow outwards and cause conjunctivitis, and penetrate and damage the eye as with uveal tumors. Treatment for ocular melanomas may include close monitoring, surgery, iridectomy, laser surgery, cryotherapy, radiation therapy, and enucleation, depending on the type and size of the tumor and how it is affecting the eye. All tissues removed should be sent for histopathology for a definitive diagnosis. The overall prognosis is good.

  • A 'tumor' is a lump. Some tumors are cancerous and some are benign. There are several different types of tumors that occur in the tissues around the eye. Many of these tumors have physical effects on the eye, causing soreness, redness and weeping. The most common treatment for tumors around the eye is surgical removal of the lump.

  • Mast cell tumors are the most common skin tumor found in ferrets. They can also be found internally on the spleen. They arise from a cell type called a mast cell. In dogs and less so in cats, these tumors can vary from benign to highly malignant.

  • Fibrosarcomas and spindle cell tumors originate from the connective tissue of, or beneath, the skin. The tumor is diverse in appearance and several different cell lines produce tumors of similar appearance.

  • This tumor is a disordered and purposeless overgrowth of modified sebaceous (sweat) glands known as the hepatoid glands. These glands only occur in dogs.

  • There are four major hormonal diseases in ferrets. This handout covers adrenal gland disease and diabetes mellitus. Adrenal gland disease occurs in a large number of ferrets in North America, while diabetes mellitus is a rare, but an important problem.

  • An insulinoma is a tumor that involves the beta cells of the pancreas. Beta cells are the cells that produce the hormone insulin. Insulinomas are surprisingly common in ferrets.

  • It is important to recognize that multiple tumors in the liver are not always cancers. The livers of older dogs may become nodular without causing any clinical effects.

  • Lung tumors are considered rare in cats and dogs. Certain breeds are more predisposed to develop pulmonary tumors than others. Not all pets with pulmonary tumors exhibit clinical signs and are often diagnosed incidentally from routine chest X-rays. Ultrasound-guided fine needle aspiration or biopsy will confirm the diagnosis. Pulmonary carcinomas have a high tendency to metastasize, so full staging is recommended. Surgery is by far the most common treatment, though radiation therapy may be considered if surgery is not possible.