Categories
Diseases

Diseases of the Ear: General Principles Of Management

The therapeutic plan for otitis externa requires identification of the primary disease process and perpetuating factors. Ideally management is aimed at thoroughly cleaning and drying the ear canal, removing or managing the primary factors, controlling perpetuating factors, administering appropriate topical or systemic therapy (or both), and evaluating response to therapy.

Ear Cleaning

Ear cleaning serves several functions: (1) it removes material that supports or perpetuates infection; (2) it removes bacterial toxins, white blood cells (WBCs), and free fatty acids that stimulate inflammation; (3) it allows complete evaluation of the external ear canal and tympanum; (4) it allows topical therapy to contact all portions of the ear canal; and (5) it removes material that may inactivate topical medications. Significandy painful ears may benefit from initial anti-inflammatory therapy to decrease pain and swelling of the ear canal prior to cleaning. Severe cases of otitis externa often require general anesthesia to facilitate complete cleaning and evaluation of the external and middle ear.

Many different solutions are available for removing cerumen, exudate, and debris from the ear canal (Table Otic Cleaning Solutions). If the tympanic membrane cannot be visualized, only physiologic saline solution or water should be used, because many topical cleaning agents are ototoxic or incite inflammation of the middle ear. An operating otoscope, ear loops, and alligator forceps facilitate manual removal of large amounts of cerumen or debris. Debris is carefully removed under direct visualization, and care is taken deeper in the ear canal (close to the tympanic membrane). Aggressive hair removal is not advised, because inflammation and damage to the epithelium can result in secondary bacterial colonization and infection. Flushing may be performed after large accumulations of cerumen and debris are mechanically removed from the ear canal.

Otic Cleaning Solutions

Trade Name Acetic Acid Boric Acid Salicylic Acid Isopropyl Alcohol Propylene Clycol Dss Other
Ace-Otic Cleanser 2%   0.1%       Lactic acid 2.7%
Adams Pan-Otic         X X Parachlorometaxylenol, tris EDTA, methylparaben, diazolidinyl urea, popylparaben, octoxynol
Alocetic Ear Rinse X     X     Nonoxynol-12, methylparaben, alovera gel
Cerulytic Ear Ceruminolytic         X   Benzyl alcohol, butylated hydroxytoluene
Cerumene             25% Isopropyl myristate
DermaPet Ear/Skin Cleanser for Pets X X          
Docusate Solution         X X  
Earmed Boracetic Flush X X         Aloe
Earmed Cleansing Solution & Wash         X   50A 40B alcohol, cocamidopropyl phosphatidyl and PE dimonium chloride
Earoxide Ear Cleanser             Carbamide peroxide 6.5%
Epi-Otic Ear Cleanser     X   X X Lactic acid, chitosanide
Fresh-Ear X X X X X   Lidocaine hydrochloride, glycerin, sodium docusate, lanolin oil
OtiCalm     X       Benzoic acid, malic acid, oil of eucalyptus
Otic Clear X X X X X   Glycerin, lidocaine hydrochloride
Oticlean-A Ear Cleaning Lotion X X X 35% X   Lanolin oil, glycerin
Oti-Clens     X   X   Malic acid, benzoic acid
Otipan Cleansing Solution         X   Hydroxypropyl cellulose, octoxynol
Otocetic Solution 2% 2%          
Wax-O-Sol 25%             Hexamethyltetracosane

Flushing and evacuation of solution is done under direct visualization through an operating otoscope. A bulb syringe and red rubber catheter system may be used to both flush and evacuate solutions and accumulations from the ear canal. The operator, avoiding drastic pressure changes within the external ear canal that could damage the tympanum, should carefully control suction and manual evacuation of the contents of the bulb syringe from the ear canal. Other alternatives include tomcat catheters (3.5 F) or flexible, intravenous catheters (14 gauge, Teflon); stiff, narrow catheters should be used cautiously and under direct visualization deep in the external ear canal. Other reservoir systems for delivery or evacuation of solutions include a 12 mL syringe or suction tubing attached to in-house vacuum systems. In-house vacuum systems should be used cautiously and under direct visualization. Care should be taken to avoid trauma to the tympanic membrane until its integrity can be assessed. Initial flushes should be done with physiologic saline solution or water until the integrity of the tympanic membrane is established.

Other solutions may aid in the removal of wax in the ear canal. Ceruminolytics are emulsifiers and surfactants that break down ceruminocellular aggregates by causing lysis of squamous cells. A ceruminolytic agent in an alkaline pH may more effectively lyse squamous cells via cell surface protein disruption. Oil-based products soften and loosen debris to aid in their removal but do not cause cell lysis. Water-based ceruminolytics are easier to remove and dry more quickly than oil-based solutions, which are occlusive if they remain in the ear canal. Water-based products include dioctyl sodium sulfosuccinate, calcium sulfosuccinate, and carbamate peroxide, which has a foaming action with the release of urea and oxygen. Oil-based products include squalene, triethanolamine polypeptide, hexamethyltetracosane, oleate condensate, propylene glycol, glycerin, and mineral oil. In a recent study only the combination of squalene and isopropyl myristate in a liquid petrolatum base had no adverse effects on hearing, the vestibular system, and histopathologic examination. Other agents tested contained glycerin, dioctyl sodium sulfosuccinate (2% or 6.5%), parachlorometaxylenol, carbamide peroxide (6%), propylene glycol, triethanolamine polypeptide oleate condensate (10%), and chlorobutanol (0.5%).

Alcohol-based drying agents added to ceruminolytics include boric acid, benzoic acid, and salicylic acid, which decrease the pH of the ear canal, cause keratolysis, and have a mild antimicrobial effect. Drying the ear canal is important to combat increased humidity, which potentiates infection.

If the tympanum is intact, the ear canal is filled with a ceruminolytic agent for at least 2 minutes and the pinna is cleaned at the same time. The solution is flushed twice with warm water, and the canal inspected. The procedure is repeated until cleaning is complete. Other solutions commonly advocated for ear flushing include dilute chlorhexidine solution (0.05%), dilute povidone-iodine, and acetic acid (2.5%). The first two agents are potentially ototoxic or induce inflammation and should not be used if the tympanum is ruptured. A combination of propylene glycol malic, benzoic, or salicylic acid; 2% acetic acid; or dilute povidone-iodine have been suggested for use in dogs with a ruptured tympanum.

Owners may clean the ears at home with mild preparations of ceruminolytics and drying agents if mild otitis is present without severe accumulation of cerumen or exudate. Aqueous solutions are usually recommended because they are less occlusive and easier to clean from the ear, dog, and home environment.

The ear should be filled with the solution, then massaged for 40 to 60 seconds. The pet should be allowed to shake its head to remove the majority of the solution, and the excess should be wiped from the ear canal and pinna with a tissue. Daily flushing is usually recommended, followed by every other day, weekly, then as needed, depending on the solution. Ear swabs are not recommended for home use, because cerumen and debris may be forced into the horizontal ear canal and impact against the tympanic membrane

Topical Therapy

Erythematous ceruminous otitis externa is diagnosed 2.7 times more often than acute suppurative otitis according to one report. Yeast ± cocci were identified in those cases, with cocci or rods identified in suppurative otitis. Topical therapy should be based on the cytologic examination to diminish the incidence of inappropriate treatment (Table Topical Medications Used in the Treatment of Ear Disease). Many preparations combine anti-inflammatories and antimicrobials in an attempt to decrease the inflammation and combat bacterial or yeast overgrowth. All topical medications should be considered supportive, and specific treatment should be aimed at controlling the primary disease process.

Topical Medications Used in the Treatment of Ear Disease

Generic Name Trade Name Dose Frequency Description
Fluocinolone 0.01% DMSO 60% Synotic 4-6 drops; total dose<17mL q12h initially. q48-72h maintenance Potent corticosteroid anti-inflammatory
Hydrocortisone 1.0% HB101,

Burrows H,

2-12 drops, depending on ear size q12h initially. q24-48h maintenance Mild corticosteroid anti-inflammatory
Hydrocortisone 1.0%, lactic acid Epiotic HC 5-10 drops q12h for 5 days Mild corticosteroid anti-inflammatory, drying agent
Hydrocortisone 0.5%, sulfur 2%. acetic acid 2.5% Clear X Ear Treatment 2-12 drops, depending on ear size q12-24h initially. q24-48h maintenance Mild corticosteroid anti-inflammatory, astringent, germicidal
DSS 6.5%. urea (carbamide peroxide 6%) Clear X Ear Cleansing Solution 1-2 mL per ear Once per week to as necessary Ceruminolytic, lubricating agent
Chlorhexidine 2% Nolvasan Dilute 1:40 in water As necessary Antibacterial & antifungal activity
Chlorhexidine 1.5% Nolvasan Dilute 2% in

propylene glycol

q12h Antibacterial & antifungal activity
Povidone-iodine 10% Betadine solution Dilute 1:10-1:50 in water As necessary Antibacterial activity
Polyhydroxidine iodine 0.5% Xenodyne Dilute 1:1-1:5 in water As necessary, q12h, once weekly Antibacterial activity
Acetic acid 5% White vinegar Dilute 1:1-1:3 in water As necessary; q12-24h for Pseudomonas Antibacterial activity, lowers ear canal pH
Neomycin 0.25%, triamcinolone 0.1%, thiabendazole 4% Tresaderm 2-12 drops depending on ear size q12h up to 7 days Antibacterial & antifungal activity, parasiticide (mites), moderate corticosteroid anti-inflammatory
Neomycin 0.25%, triamcinolone 0.1%, nystatin 100,000 U/mL Panalog 2-12 drops depending on ear size q12h to once weekly Antibacterial & antifungal activity, moderate corticosteroid anti-inflammatory
Chloramphenicol 0.42%. prednisone 0.17%, tetracaine 2%, squalene Liquachlor, Chlora-Otic 2-12 drops depending on ear size q12h up to 7 days Antibacterial activity, mild corticosteroid anti-inflammatory
Neomycin 1.75 & polymyxin B 5000 lU/mL, penicillin C procaine 10,000 lU/mL Forte Topical 2-12 drops depending on ear size q12h Antibacterial activity
Centamicin 0.3%, betamethasone valerate 0.1% Centocin Otic Solution, Betagen Otic Solution 2-12 drops depending on ear size q12h for 7 to 14 days Antibacterial activity, potent corticosteroid anti-inflammatory
Centamicin 0.3%, betamethasone 0.1%, clotrimazole 0.1% Otomax, Obibiotic Ointment 2-12 drops depending on ear size q12h for 7 days Antibacterial & antifungal activity, potent corticosteroid anti-inflammatory
Centamicin 0.3%, betamethasone valerate 0.1%, acetic acid 2.5% Centaved Otic Solution 2-12 drops, depending on ear size q12h for 7 to 14 days Antibacterial activity, potent corticosteroid anti-inflammatory
Polymixin B 10,000 lU/mL, hydrocortisone 0.5% Otobiotic 2-12 drops, depending on ear size q12h Antibacterial activity, mild corticosteroid anti-inflammatory
Enrofloxacin 0.5%, silver sulfadiazine 1% Baytril Otic 2-12 drops, depending on ear size q12h for up to 14 days Antibacterial activity
Carbaryl 0.5%, neomycin 0.5%, tetracaine Mitox Liquid 2-12 drops, depending on ear size   Antibacterial activity, parasiticide (mites)
Pyrethrins 0.06%, piperonyl butoxide 0.6% Ear Mite and Tick Control 5 drops q12h Parasiticide (mites)
Pyrethrins 0.05%, squalene 25% Cerumite 2-12 drops, depending on ear size q24h for 7 to 10 days Parasiticide (mites), ceruminolytic
Isopropyl alcohol 90%, boric acid 2% Panodry Fill ear canal As necessary Drying agent
Acetic acid 2%, aluminum acetate Otic Domeboro Fill ear canal q12-48h Drying agent, antibacterial activity, lowers ear canal pH
Silver sulfadiazine Silvadene Dilute 1:1 with water, 1 g powder in 100 mL water q12h for 14 days Antibacterial & antifungal activity
Tris EDTA±

gentamicin 0.03%

  2-12 drops, depending on ear size q12h for 14 days 1 L distilled water, 1.2g Tris EDTA, 1 mL glacial acetic acid; antibacterial activity
Silver nitrate   Use sparingly As necessary Cauterization of

ulcerative otitis externa

Miconazole 1%; ± topical glucocorticoid (7.5 mL of dexamethasone phosphate (4 mg/mL] to10mLof1% miconazole) Conofite 2-12 drops, depending on ear size q12-24h Antifungal activity
Ivermectin 0.01% Acarexx 0.5 mL per ear Once Parasiticide (mites)
Pyrethrins 0.15%, piperonyl butoxide 1.5% Many 2-12 drops, depending on ear size Twice at 7-day interval Parasiticide (mites)
Pyrethrins 0.05%, piperonyl butoxide 0.5%, squalene 25% Cerumite 2-12 drops, depending on ear size q24h for 7 days Parasiticide (mites), ceruminolytic
Pyrethrins 0.04%, piperonyl butoxide 0.49%, DSS 1.952%, benzocaine 1.952% Aurimite 10 drops q12h  
Rotenone 0.12%, cube resins 0.16% Many 2-12 drops, depending on ear size Every other day Parasiticide (mites)

Topical glucocorticoids benefit most cases of otitis externa by decreasing pruritus, exudation, swelling, and proliferative changes of the ear canal. The most potent glucocorticoids available in topical preparations are betamethasone valerate and fluocinolone acetonide. Less potent corticosteroids include triamcinolone acetonide and dexamethasone; the least potent is hydrocortisone. Most dogs benefit from short-term therapy with topical corticosteroids at the initiation of therapy, with concurrent therapy aimed at the primary and other perpetuating factors. Long-term therapy with topical corticosteroids can be deleterious because of systemic absorption of drug. Increased serum liver enzymes and depressed adrenal responsiveness may occur; with prolonged use iatrogenic hyperadreno-corticism is possible. Glucocorticoids alone may be of benefit for short-term therapy in cases of allergic or erythematous ceruminous otitis.

Antimicrobials are important for controlling secondary bacterial or yeast overgrowth or infection. Antimicrobials are indicated in any case with cytologic evidence of bacterial overgrowth or infection, with attention paid to the morphology and gram-staining characteristics of the bacteria. Otic preparations commonly contain aminoglycoside antibiotics. Neomycin is effective against typical otitis bacteria such as Staphylococcus intermedium. Gentamicin and polymyxin B are also appropriate initial topical treatments for gram-negative bacterial otitis externa.The significant risk of bone marrow toxicity in people limits the use of chloramphenicol for treating otitis in dogs and cats despite its antibacterial spectrum and availability.

Due to the frequency of resistant gram-negative bacteria such as Pseudomonas, other topical preparations have been developed. Enrofloxacin, ophthalmic tobramycin, and topical application of injectable ticarcillin have been used to treat otitis in dogs.< Their use should be limited to cases of resistant bacteria, and culture and susceptibility testing should be performed prior to application. Other topical agents may be used to supplement treatment of resistant Pseudomonas, such as silver sulfadiazine solution and tris EDTA. Tris EDTA can render Pseudomonas susceptible to enrofloxacin or cephalosporins by enhancing membrane permeability and altering ribosome stability. Frequent ear cleaning may also assist in the treatment of resistant bacterial otitis; ceruminolytics have antimicrobial properties, and their use in clinical cases has been evaluated. Acetic acid in combination with boric acid is effective against both Pseudomonas and Staphylococcus, depending on concentration and duration of exposure. Ear cleaning removes proinflammatory products, cells, and substances that diminish the effectiveness of topical antibiotics.

Many topical preparations control yeast organisms, which may complicate erythematous ceruminous otitis and suppurative otitis. Common active ingredients include miconazole, clotrimazole, nystatin, and thiabendazole. Preparations containing climbazole, econazole, and ketoconazole have also been evaluated. Eighty percent of yeast were susceptible to miconazole and econazole, intermediately resistant to ketoconazole, and 90% were resistant to nystatin and amphotericin B in one in vitro study. Topical ear cleaning agents have some efficacy against Malassezia organisms. Other preparations (e.g. chlorhexidine, povidone-iodine, acetic acid) are also effective in the treatment of secondary yeast overgrowth.

Response to topical therapy should be gauged by re-evaluation of physical, cytologic, and otoscopic examinations every 10 to 14 days after the initiation of therapy. Any changes in the results of these examinations should be recorded. Most cases of otitis can be managed topically; failure to respond to therapy should prompt re-evaluation of the diagnosis and treatment.

Systemic Therapy

Systemic glucocorticoid administration may be beneficial in cases of severe, acute inflammation of the ear canal, chronic proliferative changes of the ear canal, and allergic otitis. Anti-inflammatory doses should be limited to 7 to 10 days. Cases of significant thickening or proliferative changes in the external ear canal benefit from systemic antimicrobial therapy. Systemic therapy should be considered if concurrent dermatologic changes of the surrounding skin, pinna, or other regions of the body are present. Long-term administration of appropriate antimicrobials based on culture and susceptibility is required in all cases of otitis media. Systemic therapy for yeast is rarely recommended in animals with otitis alone. One study evaluated oral itraconazole therapy, and in ear samples evaluated on cytology and culture, no change in cytology score was found.

 

Categories
Horses

Heaves (Recurrent Airway Obstruction)

Practical Management of Acute Episodes and Prevention of Exacerbations

Heaves, also known as recurrent airway obstruction (RAO) and chronic obstructive pulmonary disease (COPD), is an inflammatory condition in horses that results from the inhalation of dust in moldy hay and bedding. The condition affects primarily the small airways of horses and causes bronchospasm, bronchial hyperresponsiveness, mucus plugs, and pathologic changes of the bronchiolar walls, leading to obstruction of terminal airways. The mechanisms by which dust inhalation causes lower airway inflammation remains ill-defined, although evidence exists that a hypersensitivity reaction to specific antigens present in hay may be implicated. However, a wide range of particles is present in the horse’s environment that also could be implicated in the development of heaves.

The treatment of heaves aims at (1) preventing further inhalation of offending dust in hay, (2) decreasing inflammation of the lower airways, and (3) providing symptomatic relief of airway obstruction. Although environmental dust control is pivotal to prevent the exacerbation of heaves, medications often are required for immediate improvement of airway function.

It is currently unknown whether a mechanistic relationship exists between heaves and inflammatory airway disease (inflammatory airway disease) in young performing horses and therefore findings regarding the treatment of heaves may not necessarily be appropriate for inflammatory airway disease.

Acute Episodes

The primary goal of therapy during acute exacerbation of heaves is to relieve airway obstruction primarily by the administration of antiinflammatory agents and bronchodilators.

Table Medications Recommended for the Treatment of Heaves

Medication Dosage*
Corticosteroids
dexamethasone 20-50 mg** IV, IM, or PO q24h
dexamethasone 21-isonicotinate 0.04 mg/kg IM q3d
prednisolone 2.2 mg/kg PO q24h
isoflupredone acetate 10-14 mg** IM q24h
triamcinolone acetonide 20-40 mg** IM
beclomethasone dipropionate 3500 μg/horse q12h in MDI (Equine AeroMask)
1320 μg/horse q12h in MDI (3M Equine Aerosol Delivery System)
fluticasone propionate 2000 μg/horse q12h in MDI (Equine AeroMask)
Bronchodilators
clenbuterol 0.8-3.2 μg/kg orally twice daily
0.8 μg/kg IV
aminophylline 5-10 mg/kg orally or IV twice daily
fenoterol 1-2 mg/horse in MDI (Equine AeroMask)
albuterol 0.8-2 μg/kg in MDI
ipratropium bromide 2-3 μg/kg q6h with mechanical nebulizer
90-180 μg/horse q6h in MDI (Equine AeroMask)
1200 μg/horse q6h with DPI
salmetreol 63-210 μg q8h (Equine AeroMask)
Cromones
sodium cromoglycate 80 mg/horse q24h for 4 days with a mechanical nebulizer
200 mg/horse q12h in MDI (Equine AeroMask)
nedocromil sodium 10-20 mg q8h in MDI (Equine AeroMask)

IV, Intravenous; IM, intramuscular; MDI, metered-dose inhaler; q12h, every 12 hours; DPI, dry powder inhaler.

* Suggestive dosages are indicative only.

** The usual dose for a horse that weighs 450 to 500 kg.

Corticosteroids Recommended for the Treatment of Heaves

Bronchodilators Recommended for the Treatment of Heaves

Expectorant, Mucolytic, and Mucokinetic Agents

Expectorants are drugs that increase pulmonary secretion, whereas mucolytic agents loosen secretions. The term mucokinetic agent may be preferred because it indicates that the therapy is aimed at increasing the clearance of the respiratory tract secretions. Although the administration of mucokinetic agents may help loosen the secretions in the large airways, evidence of their efficacy in improving the clinical signs of heaves is sparse. Clenbuterol, because of its bronchodilator and mucokinetic properties, may be preferred to clear mucus from the airways. Dembrexine (Sputolysin) and potassium iodide also improve clearance of bronchial secretions. Potassium iodide should be administered with caution to heavey horses because it is irritating for the respiratory tract and can induce or worsen bronchospasm. Nebulization with N-acetylcysteine (1 g/horse q12h via mechanical nebulizer) depolymerizes mucus by breaking disulfide bridges between macromolecules and has been advocated in the treatment of horses.

Overhydration by the massive administration of isotonic saline solution combined with bronchodilators or mucokinetic agents has been used to treat airway obstruction of horses with heaves. Although in a controlled laboratory setting this author failed to find an improvement in the pulmonary mechanics of heaves-affected horses with overhydration alone, it occasionally was associated with improved airway function of some clinical cases particularly when heaves-affected horses were refractory to other modes of therapy including potent corticosteroids. The proposed beneficial effects of this treatment are improved mucus transport and removal of mucus plugs related to the liquefaction of excessively viscous mucus. This treatment should be administered with caution as a number of side effects, including dyspnea and colic, have been observed with its use.

Antitussive agents are rarely indicated in the treatment of equine heaves because cough is a mechanism essential for the clearance of respiratory secretions.

Prevention Of Exacerbation

Environmental Changes

Clinical exacerbation of heaves occurs when susceptible horses are exposed to environmental dust particles. Drugs administered to heaves-affected horses will have only transitory effects if concurrent strict dust control measures are not applied. A wide diversity of particles may be found in a barn, including molds, noxious gases, endotoxins, and other irritants. The greatest exposure to particles small enough to be inhaled deep into the lungs of horses occurs when they are eating hay. For this reason, long-term management of heaves depends primarily on the replacement of hay in the diet by non-dusty hay alternatives. The airways of heaves-affected horses are hyperreactive, and therefore any inhaled irritants also potentially could contribute to the airway obstruction in susceptible horses.

The reversal of clinical signs of heaves with strict environmental changes may take up to 3 to 4 weeks. The remission time correlates with age and the duration and severity of illness. Horses kept permanently outdoors and fed grass or other hay substitutes usually remain free of clinical signs. Horses do well when kept outdoors even in very cold conditions, as long as they have access to enough food, fresh water (heated water tub), and shelter. The replacement of hay by less dusty feed can induce clinical remission in stabled horses. Pelleted hay, hay silage, and hydroponic hay are well tolerated and free of dust. Hay soaked in water for 2 to 4 hours before feeding may control heaves in some horses, whereas in others only partial improvement often is noted. Wood shavings, shredded paper, peanut kernels, and peat moss are good substitutes for straw, although a recent study failed to find differences in airway function in heaves-susceptible horses fed silage that were bedded on good quality straw or shavings. Other commonly made recommendations include removing the horse from the stable when cleaning the box stalls and watering the aisles before sweeping to decrease the amount of dust particles suspended in air. Proper ventilation is also important, although identifying the proper ventilation system, which would minimize dust, is problematic.

Aerosol Medications

Aerosol medications, in particular steroids such as BDP and FDP, are quite effective to prevent relapses, if given long term (see “Aerosolized Drug Delivery Devices” and “Use of Aerosolized Bronchodilators and Corticosteroids”). These drugs prevent the cascade of inflammation that is the hallmark of the allergic process and may reduce the previous remodeling of the airway (airway wall thickening via epithelial hyperplasia and goblet cell metaplasia). Although little information exists in the literature, the use of 10 puffs of BDP (84 meg/puff) or FDP (220 μg/puff) given daily or every other day has been reported to be an effective means to prevent exacerbations during periods of susceptibility but does not replace the need for environmental changes.

Alternatively, the prophylactic administration of sodium cromoglycate (Intal, 80 mg q24h for 4 days) by inhalation in heaves-susceptible horses in clinical remission prevented the appearance of clinical signs for up to 3 weeks after they were introduced to a dusty environment. The administration of sodium cromoglycate using a dose metered inhaler and a treatment mask facilitated drug administration and therefore decreased treatment failure resulting from inadequate drug administration. A similar mast cell blocker is nedocromil sodium (Tilade) that is given at a dose of 10 to 20 puffs (1 mg/puff) three times per day. These two mast cell blockers may be effective in preventing exacerbations in horses that do not respond to inhaled steroids, or as supplements to reduce the need for steroids. The problem with mast cell blockers is the need for large and frequent dosing.

Categories
Horses

Corticosteroids Recommended for the Treatment of Heaves

Corticosteroids are the most potent drugs currently available for the treatment of heaves (Table Medications Recommended for the Treatment of Heaves). The mechanisms of action of corticosteroids include decreasing smooth muscle contraction and epithelial damage by inhibiting the effects of inflammatory cells and their mediators, potentiation of the bronchodilating effects of catecholamines and reduction of mucus production. Corticosteroids with potent antiinflammatory effects are also more likely to result in detrimental effects. Corticosteroids have been commonly administered systemically, and more recently, by inhalation. An advantage of inhaled medication is achievement of a high local concentration of drug in the lungs while minimizing systemic effects. A number of corticosteroid drugs have been proposed for the treatment of heaves but objective information concerning their comparative efficacy and toxicity is sparse. Drug selection depends on the severity of the clinical signs and the ability to improve the environment. The minimal effective dose should be used, and the prolonged systemic administration of corticosteroids usually is avoided to prevent side effects.

Systemic Corticosteroids

Systemic corticosteroid administration for a minimum of 2 weeks usually is recommended for the control of heaves. A delay of a week can be expected between the initiation of therapy and the maximal clinical response, although some improvement may be observed within a few days of drug administration. Therefore in horses with severe respiratory dysfunction, corticosteroids should be combined with drugs such as bronchodilators, which can provide symptomatic relief more rapidly. If concurrent environmental control is not performed, the respiratory signs are likely to recur soon after cessation of drug administration. For a severe attack, dexamethasone (initial dose 0.05-0.1 mg/kg, IV, followed by decremental doses and alternate day dosing) has proven efficacious to control clinical signs.

Isoflupredone acetate has the advantage that it can be administered by the intramuscular route and is as effective as dexamethasone in improving the airway function of horses with heaves. The dose used is 10 to 14 mg intramuscularly daily for 5 days; the drug is then administered on alternate days and tapered to a low dose over a period of 10 to 20 days. Although hypokalemia may occur after the administration of isoflupredone acetate to horses, the severe hypokalemic myopathy reported in cattle and in people apparently does not occur when this drug is used in horses.

Triamcinolone acetonide (20-40 mg IM) also reverses clinical signs of airway obstruction in horses with severely impaired airway function. Because long-acting corticosteroids are more likely to be associated with detrimental side effects, triamcinolone administration is recommended when short-acting corticosteroids cannot be administered. Even in severe cases when no improvement has been made in the horse’s environment, the clinical improvement lasts up to 5 weeks.

Prednisone and prednisolone are less potent and less toxic than the above corticosteroids and have been used for the treatment of mildly affected horses. Recent studies have shown that oral prednisone is absorbed poorly in horses and, when administered in conjunction with environmental changes, provides no additional benefit over management alone.

Inhaled Corticosteroids

Inhalation therapy is well-suited to corticosteroid administration because of the large number of glucocorticoid receptors at the level of bronchial epithelial cells and vascular endothelial cells. Inhalation therapy allows a maximal concentration of drug at the effector sites and minimizes side effects. Inhaled corticosteroids may therefore be preferable when prolonged therapy would be required.

Beclomethasone dipropionate (BDP) in metered-dose inhalers (MDIs) improves respiratory mechanics parameters within 3 to 4 treatment days. The maximal beneficial effects usually are observed during the first week of therapy. Fluticasone propionate (FDP) administered from a MDI and a mask also results in a decrease in airway obstruction, in neutrophil counts, in bronchoalveolar lavage fluid, and in bronchial hyperresponsiveness.

The information available to date in horses suggests that the short-term administration of inhaled corticosteroids is both efficacious and well tolerated but has little residual effect when the treatment is discontinued. Because a delay in response is expected with inhaled corticosteroids, they should be combined with faster acting drugs, such as bronchodilators or systemic corticosteroids in horses with respiratory distress. Bronchodilator administration also may improve pulmonary distribution of aerosolized surface-active antiinflammatory preparations. Masks used in combination with MDIs or dry powder inhalers (DPIs) increase the resistance to airflow and therefore may not be suitable and well tolerated for the initial treatment of horses with labored breathing. This author has treated a few horses that became reluctant to inhale the medication after a few days. Replacing the poorly tolerated drug with another of the same class often corrects this problem.

Chronic airway inflammation in heaves results in airway remodeling. The dosages and duration of corticosteroid administration required to restore the normal lung morphology in heaves are unknown but are likely to exceed, by far, the usually recommended posology.

Side effects of corticosteroids are uncommon based on the available literature. Detrimental findings that have been reported after systemic corticosteroid administration to heaves-affected horses include laminitis, suppression of the hypothalamo-pituitary-adrenal axis, altered bone metabolism, and bacterial pneumonia. To date, the only side effect attributed to inhaled corticosteroids is a decrease in serum cortisol.

Categories
Horses

Treatment of Cutaneous Lymphosarcoma

Glucocorticoids remain the mainstay of treatment of cutaneous T cell-rich, B cell lymphoma. Tumor regression is typically noted following the systemic administration of dexamethasone (0.02-0.2 mg/kg IV, IM or PO q24h) or prednisolone (1-2 mg/kg PO q24h). In these authors’ experience, dexamethasone proves more effective than prednisolone in treating lymphosarcoma. Once cutaneous lesions have regressed in size and number, the glucocorticosteroid dose can be gradually tapered. However, a rapid decrease or discontinuation of glucocorticosteroid administration may result in recurrence of cutaneous lesions. Relapses are anecdotally reported to be sometimes more refractory to treatment. Long-term maintenance therapy may be required in these cases. These authors prefer to use a dose of 0.04 mg/kg of dexamethasone (approximately 20 mg for an average-size horse) once daily until significant regression of tumors has occurred; the dose then is reduced to 0.02 mg/kg daily and then to every 48 hours. Intralesional injections of betamethasone or triamcinolone can also be performed with success; this may be impractical when presented with a large number of cutaneous lesions. Topical application of corticosteroid preparations may result in clinical improvement in cases with ulceration; however, results of its use have not been reported. In addition to im-munosuppression, laminitis is a potential side effect of corticosteroid administration.

Exogenous progestins may demonstrate an antiproliferative effect on lymphosarcoma tumors. The exact mechanism of action has not been determined; however, it is believed to be due to the presence of progesterone receptors, which have been demonstrated on both neoplastic and normal equine lymphoid tissues. Progestogens also have glucocorticoid-like activity, which may also account for the response observed in some cases of lymphosarcoma. In one study, progesterone receptors were identified on 67% of the subcutaneous lymphosarcoma tumors that were evaluated (primarily representing T cell-rich, B cell tumors). In the mare diagnosed with simultaneous cutaneous histiolymphocytic lymphosarcoma and a granulosatheca cell ovarian tumor, partial regression of the skin lesions occurred following a ten-day course of the synthetic progestin, altrenogest (0.044 mg/kg q24h PO). A temporary response was also observed after unilateral ovariectomy. The ovarian tumor stained positive for estradiol and led the authors to believe it was estrogen-secreting. The authors speculated that the steroid hormones secreted by the ovarian tumor may have influenced growth of the T cell-rich, B cell tumors by leading to low progesterone concentrations. Anecdotal reports of tumor regression during pregnancy also exist. In one mare with cutaneous T cell lymphosarcoma, regression of nodules was noted after surgical excision, a single intralesional injection of betamethasone (0.04 mg/kg), and an 8-day course of the oral progestogen, megestrol acetate (0.2 mg/kg q24h). Surgical excision may be efficacious in cases in which a single or a small number of cutaneous nodules exists.

The administration of autologous tumor cell vaccines may benefit horses with cutaneous lymphosarcoma. In one report, tumor regression was achieved by using a combination of low-dose cyclophosphamide and autologous tumor cells infected with vaccinia virus. Cyclophosphamide is thought to potentiate the immune response by decreasing suppressor T cell activity. Infection of tumor cells with the vaccinia virus was performed to augment the host antitumor immune response. The treatment protocol included intravenous administration of cyclophosphamide (300 mg/m2) via a jugular catheter over a period of 2 to 3 minutes on days 1 and 36. Immunization with tumor-cell vaccine was performed on days 4 and 21. Response to immunostimulation was confirmed by development of a delayed-type hypersensitivity response to autologous tumor cells injected intradermally in the horse. Potential side effects of cyclophosphamide administration in other species include immunosuppression, enterocolitis, myelosuppression, and hemorrhagic cystitis. No side effects were noted in the horse in this report.

Treatment of epitheliotropic (cutaneous T cell lymphosarcoma) in horses remains speculative because of a paucity of reported cases. Surgical excision of small lesions may be curative. Retinoids and vitamin A analogs inhibit malignant lymphocyte proliferation in human and canine patients with epitheliotropic lymphosarcoma. No reports of the use of retinoids in horses have been published. However, these authors noted no gross or histologic improvement in treating one case of equine epitheliotropic lymphosarcoma with retinoid cream. Side effects included local erythema and signs of irritation after repeated applications.

Investigations as to the effectiveness of radiation therapy and systemic chemotherapy in the management of equine cutaneous lymphosarcoma are needed. Local therapy that consists of intralesional injection of cutaneous nodules with cisplatin has been used successfully in horses with a small number of lesions. Combination chemotherapy that consists of cytosine arabinoside, chlorambucil or cyclophosphamide, prednisone, and vincristine has been reported for use in horses with multicentric lymphosarcoma, as has L-asparaginase.

Categories
Horses

Collagenolytic Granuloma

The second clinical presentation of nodules is that of a more slowly progressive, infiltrative lesion. Collagenolytic granuloma (nodular necrobiosis, equine eosinophilic granuloma with collagen degeneration) is the most common nodular skin disease of horses within this category. The etiology of these nodules is unknown; however, it is probably a type IV hypersensitivity reaction to insect bites. Other theories include trauma and atopy as causes for these nodules. Recently, eosinophilic granuloma that arises in areas of previous injection sites has been described and is thought to be a hypersensitivity reaction to the silicone or other component of the coating of hypodermic needles. Thus it appears that multiple etiologies exist.

Collagenolytic Granuloma: Clinical Signs

Collagenolytic granulomas usually occur during the warmer months of the year; however, some stables report occurrence of lesions during the winter months as well. No apparent breed, age, or sex predilection exists. The lesions consist of one to several firm dermal nodules that range in size from 0.5 to 5 cm in diameter and usually are located on the sides of the neck, withers, and back. A generalized form consisting of numerous pea-sized nodules on the face, neck, and thorax has been described in Arabian horses. The overlying skin surface and hair coat are usually normal in appearance; however, the surface may ulcerate, especially if it is frequently traumatized by tack. No pruritus or pain is associated with the lesions.

Diagnosis of Collagenolytic Granuloma

The primary differential diagnoses include bacterial furunculosis, fungal granuloma, neoplasia, tick reaction, and hypodermiasis. A definitive diagnosis of collagenolytic granuloma requires biopsy; however, a tentative diagnosis can be made based on history and physical examination. Cytology of an aspirate may be used to help confirm a diagnosis by revealing a primarily eosinophilic inflammation with varying numbers of lymphocytes and histiocytes. No infectious organisms should be identified on cytology or culture.

The primary change on histopathology is an eosinophilic granulomatous reaction that surrounds one to several foci of necrobiosis in which the collagen fibers have an amorphous, granular appearance. In older lesions many of these foci have become mineralized.

Treatment of Collagenolytic Granuloma

Treatment options depend on the number, size, and location of the lesions. Many of the lesions will spontaneously regress with time. Therefore lesions that are not unsightly or are not in a location that is bothersome to the horse can be left alone. Single lesions can be surgically excised. If the horse has only a few lesions, triamcinolone acetonide may be injected intralesionally or sublesionally at 3 to 5 mg/lesion (not to exceed 20 mg total dose). This treatment may be repeated 2 to 3 times at 10-day intervals. Multiple lesions should be treated with oral prednisolone at a dose of 1 mg/kg daily for 10 to 14 days. If lesions respond, the dosage can be slowly decreased over a 2-week period. If lesions recur once corticosteroid therapy has been discontinued, an underlying cause should be pursued. Mineralized lesions will not resolve completely with steroid therapy. The mineralized core can eventually reach the surface but may require surgical excision. Because these lesions are likely a hypersensitivity to insect bites, strict insect control with 2% permethrin spray may help prevent recurrence (see “Fly Control”).

Categories
Horses

Treatment of Cutaneous Habronemiasis

Antiinflammatory Drugs

Because a hypersensitivity reaction to the larvae is believed to be one of the major causes in the pathogenesis of this skin disease, treatment usually involves some form of either topical or systemic steroid therapy. The most common steroids used in topical preparation are dexamethasone and triamcinolone. These steroids are most commonly combined with other medications such as dimethyl sulfoxide (DMSO), fenthion, and/or nitrofurazone. Oral steroids have also been used to minimize or control the hypersensitivity reaction. The usual antiinflammatory steroid dose used to treat cutaneous habronemiasis is prednisolone (1 mg/kg q24h) for 10 to 14 days and then tapered off over a 2-week period. If this mode of therapy is advocated then the owners need to be warned of possible side effects such as laminitis and enterocolitis that are associated with steroid use in horses.

Eliminating Parasites from the Skin

Systemic parasiticidal treatment is used to eliminate the parasite from the skin. The most commonly used parasiticide is ivermectin, which is almost 100% effective in killing Habronema larvae. However, the half-life for orally administered ivermectin in horses is 66.3, plus or minus 4.7 hours; thus it is almost completely eliminated from the body in five half-lives or approximately 14 days. The manufacturer recommends that horses be treated with ivermectin every 2 months for control of internal parasites such as Habronema varieties. However, one study demonstrated that such a frequency of drug administration might not always be adequate in controlling Habronema spp. In this report, 5 of 31 horses required additional intramuscular treatment within 2 to 4 weeks with ivermectin to clear the Habronema infection. Parenterally administered ivermectin has a longer half-life than orally administered ivermectin (88.2, ±9.1 hours for subcutaneous injection, versus 66.3 ±, 4.7 hours for oral administration). Therefore in cases of recurring cutaneous habronemiasis, ivermectin may need to be given more frequently than every 2 months.

A newer parasiticidal agent, moxidectin, has a similar efficacy against Habronema organisms as ivermectin and may be considered for some of the more difficult cases of cutaneous habronemiasis. The recommended dose for moxidectin is 0.4 mg/kg orally. The half-life of this orally administered drug is similar to ivermectin, but, unlike ivermectin, the parent compound has been detected in the plasma for extended periods of time (ivermectin — 30 days, whereas moxidectin — 75 days) after treatment. This longer retention time provides a longer anthelmintic effect, which may be advantageous for treating difficult cases of habronemiasis.

Fly control with various sprays is usually recommended to prevent recontamination of the lesion with larvae. Because of longer residual activity, an oil-based fly spray is preferred over the water-based fly sprays.

Surgery is another method of eliminating the parasite from the skin. Surgical excision is especially useful in the treatment of large proliferative cutaneous habronemiasis lesions that have not reduced in size when the horse has been treated with systemic steroids. Surgery can also be used to debulk a lesion. For example, when proliferative lesions that involve the prepuce or urethral opening cause dysuria, routine surgical methods, cryosurgery, or lasers may remove the affected tissue. Success has been reported with each of these methods.

Topical or systemic parasiticidals used to eliminate Habronema larvae from the skin include fenthion, trichlorfon, thiabendazole, ronnel, echothiophate (phospholine iodide) ophthalmologic drops, and ivermectin. These ingredients are used either by themselves or in combination with other ingredients.

The author has had the best results when topical and systemic treatments, which contain anti-inflammatory agents and/or antiparasiticidal agents, have been used in combination. Fly control is essential to maximize the chances for success in treating and preventing recurrence of cutaneous habronemiasis in horses.

Categories
Veterinary Medicine

Selected Acquired Diseases Of The Lips, Cheeks, And Palate

Feline eosinophilic granuloma complex (FEGC) comprises an eosinophilic ulcer, plaque, and a linear granuloma. Oral lesions are usually a linear granuloma or an eosinophilic ulcer; the latter has a predisposition for the maxillary lips (80%). Intraoral lesions appear as one or more discrete, firm, raised nodules. Clinical signs include dysphagia and / or ptyalism. Although the etiology of this disease is unknown, bacterial and viral infections and immune-mediated and hypersensitivity diseases have been associated with feline eosinophilic granuloma complex. Biopsy of the lesion, with the aforementioned diseases in mind, should be performed to confirm the diagnosis and to differentiate it from neoplastic disease. Ancillary tests should include a complete blood count, which usually shows an absolute eosinophilia. Concurrent or potentially causative hypersensitivity diseases should be considered during the diagnostic phase of treatment. The mainstay of feline eosinophilic granuloma complex treatment is corticosteroid therapy. Intralesional triamcinolone (3 mg weekly), oral prednisolone (1. 0 to 2. 0 mg / kg given twice daily), and subcutaneous methylprednisolone acetate (20 mg every 2 weeks), administered until feline eosinophilic granuloma complex resolves, are efficacious treatments. Progestational compounds (progesterone or medroxyprogesterone) are often used to treat feline eosinophilic granuloma complex These compounds are not approved for use in cats and have potential side effects that make them undesirable, including adrenocortical suppression, polydipsia, polyuria, polyphagia, obesity, personality change, reproduction abnormalities, mammary hypertrophy, neoplasia, and diabetes mellitus. Cats with untreated chronic lesions, responsive previous lesions, and lesions refractory to corticosteroid therapy have a 50% recurrence rate within 5 months. Failure of treatment is usually related to inadequate dosage or premature cessation of therapy. Animals that do not respond to either corticosteroids or progestational compounds have a poor prognosis and are candidates for more aggressive therapy, such as irradiation, cryosurgery, laser therapy, or immunotherapy.

The term stomatitis refers to an inflammation of the oral mucosa. Oral inflammatory lesions in dogs and cats have multiple causes, necessitating a consistent and logical diagnostic approach. A complete history and thorough physical examination are essential. Dogs and cats with no evidence of debilitating systemic disease should receive a short-acting intravenous anesthetic to allow an unimpeded visual and tactile oral examination. Oral ulcerations occur in at least four different immunemediated diseases, including systemic lupus erythematosus, bullous (pemphigus) disease, idiopathic vasculitis, and toxic epidermal necrosis. The many infectious diseases that are manifested by lesions in the oral cavity include feline leukemia virus, feline immunodeficiency virus, feline syncytium-forming virus, feline calicivirus, feline herpes virus, and feline infectious peritonitis. fis Canine distemper and feline panleukopenia virus may cause stomatitis, although other organs are more severely affected. Candidiasis (infection with Candida albicans) may cause severe stomatitis in dogs and cats. Many cats with stomatitis have immunosuppressive disease or systemic debilitation or have received chronic immunosuppressive therapy. Although the oral manifestation may appear as a white, pseudomembranous covering of the tongue, the lesions are usually irregular, ulcerated areas in zones of inflamed mucosa.

Feline oral inflammatory disease ranges from simple gingivitis to varying degrees of stomatitis in which inflammation extends beyond the mucogingival junction into the oral mucosa. Cats with chronic gingivitis / stomatitis may have ulceration and extension of granulation tissue involving the palatoglossal folds and fauces. Clinical signs include halitosis, ptyalism, dysphagia, inappetence, and weight loss. Extensive disease is marked by root resorption and possibly bony sequestrae in edentulous areas. Unfortunately, because the causation is usually unknown, treatment is symptomatic, including professional cleaning of the teeth, therapy with antimicrobials or with systemic or local corticosteroid agents similar to those used for feline eosinophilic granuloma complex, and laser therapy to stimulate re-epithelialization over inflamed, ulcerated areas. It is not unusual for refractory cases to require extraction of all molars and premolars or all teeth to alleviate the symptoms of this disorder.

Stomatitis may be described as idiopathic despite a thorough diagnostic evaluation. Immunemediated ulcerativc gingivitis / stomatitis afflicts Maltese terriers, although the etiology is verified in only 20% of animals. If diagnostic test results are negative in idiopathic stomatitis, it is appropriate to assume a possible immune-mediated component. A prudent treatment plan includes regular cleaning of the teeth, oral preventive medicine at home, and intermittent or chronic provocative corticosteroid therapy. Antimicrobial therapy emphasizing anaerobic pathogens (e. g. , metronidazole, amoxicillin, clavulanic acid / amoxicillin) may he administered on an intermittent, chronic basis.

Categories
Veterinary Drugs

Corticosteroids

The anti-inflammatory effects of corticosteroids are based upon their ability to suppress capillary dilatation, vascular exudation, leucocyte migration, and immunosuppression regardless of the causative agent. In chronic conditions they inhibit neovascularisation and fibroblastic activity in the eye. This may be useful in preventing scarring and pigment deposition in the cornea but disadvantageous by retarding healing. In general, topical preparations readily penetrate the cornea. The ester of the corticosteroid used influences corneal penetration, for example, prednisolone acetate has a superior corneal penetration to prednisolone sodium phosphate.

Topical corticosteroids are particularly useful in the treatment of uveitis, various specific and non-specific inflammatory disorders of the cornea, such as chronic superficial keratitis (CSK, pannus) in the German Shepherd dog. They also assist in the reduction of post-surgical inflammation, such as that following cataract or lens extraction. Following administration, therapeutic levels remain in the eye for only about three hours and this may necessitate frequent application to prevent treatment failure. Low levels of systemic absorption will occur after frequent application of topical steroids and this should be considered in animals of low body-weight and those with metabolic diseases such as diabetes mellitus. Topical corticosteroids should not be used in the presence of corneal ulceration; systemic NSAIDs should be considered. Corticosteroids may be used in the presence of glaucoma in animals but care should obviously be taken in the differential diagnosis of a ‘red eye’. All corticosteroids should be used with care in pregnant animals because there is a slight risk of intra-uterine growth retardation.

Subconjunctival injections may augment, or replace, topical instillation. Preparations of methylprednisolone acetate or triamcinolone acetonide may be effective for up to three weeks. Their use may sometimes be effective for owners experiencing difficulty in applying drops. Subconjunctival therapy may be used for the treatment of bovine iritis. Beta-methasone sodium phosphate (2 mg) or dexamethasone sodium phosphate (2 mg) every 3 days or methylprednisolone (10 to 20 mg, depot injection) every 7 to 14 days may be administered by subconjunctival injection for the treatment of inflammatory ocular conditions in horses. However, subconjunctival granulomas, plaques, or mineralisation can occur at the injection site. It is recommended that specialist advice be sought before using subconjunctival corticosteroid treatment in equines. Care must be taken with the use of topical corticosteroids in horses because the alteration in ocular micro-environment can predispose to fungal infections. Similar caution must be exercised in cats with suspected herpetic keratitis because local immunosuppression caused by the corticosteroid can allow recrudescence of the herpes virus. The use of systemic corticosteroids for ophthalmic therapy is limited because lower ocular concentrations are achieved than with topical application. However, systemic therapy may be useful for idiopathic partial serous retinal detachments, posterior uveitis, and optic neuritis. There is an association between cataractogenesis and steroid therapy in humans but this has not been described in animals. The adverse effects of prolonged administration of systemic corticosteroids may be minimised by alternate day therapy. Equine recurrent uveitis (periodic ophthalmia) is a disease of horses resulting in recurrent photophobia, lacrimation, conjunctival injection, corneal changes (such as oedema and vascularisation), hypopyon, miosis, synechiation, and even blindness due to extensive synechiae, cataract formation, or phthisis bulbi. Some forms of the disease have been linked to Leptospira infection, although in many instances the aetiology remains obscure. Treatment consists of topical and possibly subconjunctival corticosteroids, NSAIDs, and if bacterial infection is suspected, systemic antibacterials. Topical atropine is used to achieve a mid-dilated pupil.

BETAMETHASONE

Indications. See notes above

Contra-indications. Corneal ulceration, fungal or viral infections, see notes above

Warnings. Care in pregnant animals

Dose: Apply every 2-3 hours

Prescription-only medicine:® Betnesol (Celltech) UK

Drops (for eye, ear, or nose), betamethasone sodium phosphate 0.1%

Eye ointment, betamethasone sodium phosphate 0.1%

Prescription-only medicine: ® Vista-Methasone (Martindale) UK Eye drops, betamethasonesodium phosphate 0.1%

DEXAMETHASONE

Indications. See notes above

Contra-indications. Corneal ulceration, see notes above

Warnings. Care in pregnant animals

Dose: Apply every 2-3 hours

Prescription-only medicine:® Maxidex(Alcoa) UK

Eye drops, dexamethasone 0.1%, hypromellose 0.5%

Prescription-only medicine: ® Minims Dexamethasone (Chauvin) UK Eye drops, dexamethasone sodium phosphate 0.1%

FLUOROMETHOLONE

Indications. See notes above

Contra-indications. Corneal ulceration, see notes above

Warnings. Care in pregnant animals

Dose: Apply 4 times daily

Prescription-only medicine: ® FML (Allergan) UK

Eye drops, fluorometholone 0.1%, polyvinyl alcohol 1.4%

PREDNISOLONE

Indications. See notes above

Contra-indications. Corneal ulceration, see notes above

Warnings. Care in pregnant animals

Dose: Apply 4 times daily

Prescription-only medicine: ® Pred Forte (Allergan) UK Eye drops, prednisolone acetate 1%

Prescription-only medicine:® Predsol (Celltech) UK

Drops (eye drops or ear drops), prednisolone sodium phosphate 0.5%

Prescription-only medicine: ® Minims Prednisolone (Chauvin) UK

Eye drops, prednisolone sodium phosphate 0.5% (single use)

RIMEXOLONE

Indications. Treatment of local inflammation

Warnings. Care in pregnant animals

Dose: Apply 1 drop 2-4 times daily for up to 4 weeks. May be used more frequently for severe uveitis

Prescription-only medicine:® Vexol (Alcon) UK Eye drops, rimexolone 1%

COMPOUND CORTICOSTEROID AND ANTIBACTERIAL OPHTHALMIC PREPARATIONS

Preparations containing antibacterial and glucocorticoid agents in combination can be useful in cases of infected inflammatory processes such as bacterial keratitis, and for prophylaxis, for example following intra-ocular surgery where control of inflammation is important but a risk of infection also exists. A specific diagnosis and rationale for combination therapy should always be established.

Indications. See notes above

Contra-indications. Corneal ulceration

Warnings. Care in pregnant animals

Dose: See preparation details

Prescription-only medicine:® Maxitrol (Alcoa) UK

Eye drops, dexamethasone 0.1%, hypromellose 0.5%, neomycin (as suifate) 0.35%, polymyxin B suifate 6000 units/mL

Dose: Apply 4 times daily

Prescription-only medicine:® Maxitrol (Alcon) UK

Eye ointment, dexamethasone 0.1%, neomycin (as suifate) 0.35%, polymyxin B suifate 6000 units/g

Dose: Apply 3 times daily

Prescription-only medicine:® Vista-Methasone N (Martindale) UK

Eye drops, betamethasone sodium phosphate 0.1%, neomycin suifate 0.5%