Archive for May, 2012

Normally dogs’ eyes are clear, bright and usually have only a clear, watery discharge, but some breeds with normal eyes may accumulate a light gray material on the corners of their eyes. You can just clean these off with clean cotton swabs. If your dog’s eyes are red (inflamed) and/or have significant accumulations of yellowish or greenish material, it could indicate conjunctivitis, inflammation of the conjunctival membranes. The conjunctiva, are light pink membranes that cover the front of the eyeball and the inside of the eyelids. Conjunctivitis can be a problem in one eye (unilateral) or both eyes (bilateral) and can be chronic, infectious or non-infectious. Other signs of conjunctivitis include swollen eyelids, pawing or rubbing at the eyes, excessive blinking, squinting, and protrusion of the third eyelid, also known as the nictitating membrane, usually seen as a reddish mass extending over part of the eye from the inner corner.

In this area, allergies to pollen, dust and mold are a major cause of conjunctivitis in dogs. Other causes include viral infections such as canine distemper, bacterial infections, especially from Staphylococci and Streptococci. A lack of tears can result in keratoconjunctivitis sicca or dry eye. This is an inflammation of both the cornea and the conjunctiva and can be caused by trauma, inflammation of the conjunctival glands and ducts and/or scarring of these structures. Dry eye can also be the result of certain immune diseases or diabetes mellitus. Foreign objects such as grass seeds, hair, and eyelashes can result in conjunctivitis as can injury, some parasites, fungal infections, tumors and certain anatomical abnormalities. Sometimes we just cannot determine a cause, and assign the name idiopathic conjunctivitis.

Follicular, also known as mucoid, conjunctivitis occurs when the small mucous glands (follicles) on the underside of the third eyelid react to an irritant or infection and change to a raised, rough surface that irritates the eye further and produces a thick off colored mucous discharge. Sometimes even after the initiating cause has been removed this thickened follicles persist and may require surgical treatment. Purulent conjunctivitis is a serious form of conjunctivitis characterized by secondary bacterial contamination and requires veterinary diagnosis and prescribed treatment.

Your veterinarian can diagnose dry eye by using the Schirmer Tear Test. The treatment does require that you continue to treat the condition throughout the dog’s life. The treatment of purulent conjunctivitis requires a proper diagnosis by your veterinarian who will instruct you about safely removing mucous and pus from the dog’s eyes as well as any pus and crust that may adhere to the eyelids. Your veterinarian will also prescribe an appropriate antibiotic ointment or drops to use as directed. Conjunctivitis from allergies, but not complicated by a bacterial infection, may be treated with drops or ointments containing corticosteroids but these should not be used if there is a corneal ulcer or injury because the corticosteroids prevent the local inflammatory response that helps fight the infection. Your veterinarian may find it necessary to do culture and sensitivity testing to determine the most appropriate treatment. If your veterinarian suspects injury to the cornea s(he) may apply a dye (fluorescein) to the eyeball that stains and demonstrates scratches or ulcers. Antiviral eye medications are available to treat viral conjunctivitis and L-Lysine may be beneficial in some cases. Anti-fungal medications are available for fungal eye infections.

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There is some evidence that Polybrominate Diphenyl Ethers (PBDEs) may be involved in hyperthyroidism in cats. Feline hyperthyroidism may be the most common endocrine disorder in cats. It is associated with benign tumor(s) of the thyroid gland and usually appears in middle-aged to older cats, without preference to breed or gender. The signs of hyperthyroidism are weight loss, hyperactivity accompanied by a voracious appetite. Cats can also demonstrate increased water intake, more frequent urination, along with intermittent vomiting and/or diarrhea. Cats with severe hyperthyroidism suffer from increased heart rates, arrhythmias (irregular beats) and congestive heart failure. About 10% of cats with hyperthyroidism develop a condition known as apathetic hyperthyroidism. These animals show depression and lack of appetite with fast weight loss.

The diagnosis of hyperthyroidism is by measuring increased circulating levels of the two thyroid hormones. Your veterinarian can verify the diagnosis by the use of special thyroid imaging called planar thyroid scintigraphy. Hyperthyroidism can be treated successfully with anti-thyroid drugs, surgery or the administration of radioactive iodine, the latter is currently the most commonly employed and probably the most successful.

There are three different types of PBDE compounds commonly used as flame retardants. They can migrate out of the flame retardant products then accumulate in indoor air and house dust and eventually contaminate the environment. Since the PBSEs do not break down quickly in the environment they accumulate in air, soils, sediments, fish, marine mammals, birds and other wildlife and well as in meat, poultry and dairy products. We should expect a decrease in these contaminants in this country since two of the most commonly used types were discontinued in 2004 and the third will be phased out in 2013. However, exposure from existing building materials, furnishings and consumer products, especially those imported from countries still using these products will continue.

A paper recently published in the Journal of Toxicology and Environmental Health suggested a link between PBDEs and hyperthyroidism. The researchers studied 21 normal cats, 41 cats diagnosed as hyperthyroid and 10 normal feral cats with no exposure to household dust. Although the total PBDE concentrations in the serum of normal and hyperthyroid cats were not significantly different, the total PBDE in dust from homes of hyperthyroid cats was significantly higher than the dust from homes of normal cats. The levels of PBDE in dust and one of the thyroid hormones (T4) were significantly correlated. Although this study does not prove a cause and effect between PBDE levels in household dust and hyperthyroidism in cats it is another indication that household pets could serve as sentinels for environmental toxicants that could affect humans. A major problem with most toxicology studies is that the effects of low levels of toxicants, over long periods of time, are too expensive to conduct and therefore are almost never done.

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