Journal of Veterinary Internal Medicine 2000,14:105-109.

Journal of Veterinary Internal Medicine 2000;13:606-612.

Even though the drugs delivered by metered dose inhalers are only absorbed systemically in minute quantities, veter­inarians should be aware that treated horses may still test positive for these medications.

Compendium 1999;21 :4:353-355.

318

Hemangiosarcoma Dr. Louise Southwood and others recently reported on disseminated heman-

giosarcoma in 35 horses. According to Dr. Southwood hemangiosarcoma occurred in middle aged horses, with no apparent sex predilection. Thirteen of the cases were Thoroughbred horses. The disease affected the respiratory and musculoskel­etal systems most commonly. Presenting complaints included dyspnea (26%), subc).ltaneous or muscular swelling (24%), epistaxis (17%), and lameness (12%). In addition, horses usually presented with pale or icteric mucus membranes and

I had elevated heart and respiratory rates. Eighty-eight percent of the cases were anemic and over half had a leukocytosis or neutrophilia. About half of the cases had a thrombocytopenia as well. An antemortem diagnosis using biopsy or fine needle aspirate was only established in 4/35 cases. The lung, skeletal muscle and spleen were most commonly affected. Hemangiosarcoma should be included as a differential diagnosis for horses with evidence of hemorrhage into body cavities, skeletal muscle or subcutaneous locations.

Eosinophilic granulomas A report concerning injection site eosinophilic granulomas and collagenoly­

sis in 3 horses was recently published by Dr. Nathan Slovis and others. In '[ this report the 3 horses presented with a history of having developed cutaneous

nodules 24-48 hours after injections. The injections were made using silicone­coated hypodermic needles. Histopathic evaluation of the nodules confirmed that they were equine eosinophilic granulomas. The lesions were thought to have arisen as a result of a hypersensitivity reaction to the silicone or another component of the coating formulation. Subsequently 2 horses were experimentally injected using coated needles and the site of injection was biopsied 14 days later. On histopathology there was severe eosinophilic granulomatous inflammation with and without collagenolysis. The eosinophilic response likely represented a complex immunologic response to the silicone based coating of the needles.

COPO and small airway disease

Dr. Rob MacKay recently published a brief review on inhalant therapies for inflammatory airway disease in horses. According to Dr. MacKay, metered dose inhalers which are also known as "puffers" are commonly used to treat respiratory diseases in humans. These same devices have been used to effectively deliver medication to the small airways of horses.

For horses with chronic obstructive airway disease or COPD, Dr. MacKay , recommends using albuterol, ipratropium bromide, salmeterol, fluticasone and , dexamethasone. The goals of treatment are to relieve severe dyspnea and exert

a broad spectrum anti-inflammatory effect. Albuterol acts as a beta-2 adrenergic agent to cause bronchodilation. Effects are immediate but do not last a long time. Ipratropium bromide is an antimuscarinic agent which blocks parasympathetic nerve-mediated airway spasm. It lasts for up to 6 hours. The greatest anti-

I inflammatory effect is seen with glucocorticoids such as fluticasone propionate or beclomethasone dipropionate and dexamethasone. During the first week of therapy Dr. MacKay recommends using systemic dexamethasone in conjunction with inhaled albuterol (day I only), ipratropium bromide (days 1-7), salmeterol (days 2-7), fluticasone (days 1-14 and then as needed). Dr. MacKay also recom­mended adding the mast cell-stabilizing drug cromolyn sodium in a metered dose

, inhaler during the time of year when attacks are most common. ! For younger racehorses with sterile bronchiolitis which limits training and

racing Dr. MacKay also recommends metered dose inhalers. In such cases the final common pathway of inflammation is granUlocytic inflammation, mucus secretion and small airway constriction. Use of albuterol immediately before train­ing may be very helpful in conjunction with longer term therapy with fluticasone which may put the disorder into remission. Systemic corticosteroids or low dose oral alpha interferon may be used concurrently.

JOURNAL OF EQUINE VETERINARY SCIENCE