pets disease

Veterinarians are often confronted by frustrated pet owners claiming that their pet is going deaf! Now, whether this is a valid claim or rather an actual ploy conceived by a defiant subject will not be known until a thorough ear examination is performed. A pet’s apparent inability to perceive sounds can result for a number of reasons.
First, there might be impedance to the sound waves traveling through the ear. An external ear canal clogged with wax and debris can certainly be the culprit, as can constrictive swelling of the ear canal caused by otitis externa. Torn or ruptured eardrums can also diminish the effective transmission of sound waves to the middle and inner ears.
Interestingly, some researchers feel that a dog’s eardrums are not altogether necessary for efficient conduction of sound waves; rather, sound waves permeating the bony, air-filled tympanic bullae directly fulfill a major portion of this conductive function. Regardless, researchers do know that sound waves must pass through the middle ear cavity before reaching the inner ear, and that fluid or inflammation secondary to otitis media can lead to diminished hearing.
Besides interference with the transmission of sound waves, deafness in dogs and cats can also be caused by developmental defects or damage involving the actual nerve endings within the inner ear. Congenital nerve deafness has been reported in some breeds, including dalmatians, collies, and rottweilers. Nerve deafness can also be inherited in some cats. This type of induced deafness is seen primarily in white cats with blue eyes.
Certain drugs, such as the aminoglycoside antibiotics, are well known for their adverse effects on the hearing function in dogs and cats. Chronic, untreated bacterial and fungal infections within the middle and inner ears can undoubtedly lead to nerve deafness, as can certain viral organisms.
Diagnosis of nerve deafness is based on history and special hearing tests. One such test, the brainstem auditory evoked response test (BAER), measures the brain’s response to auditory stimuli and is quite helpful in the detection of hearing defects, determining the extent of any defect, and pinpointing its location.
Unfortunately, no known treatment exists for true nerve deafness. Hearing aids designed especially for dogs are now commercially available, and may help improve hearing in select instances. Most deaf pets will adapt to their condition with time. However, because of inherent dangers associated with environmental hazards, deaf dogs and cats should not be allowed outdoors unless closely supervised or maintained on a leash and harness.

The integrity of the eyelids is vital to protect the eyes from environmental hazards. Any disruption or alteration in the normal lid anatomy can place vision in jeopardy. And certain masses involving the lids can do just that if they become large enough.
Chalazions are masses involving the eyelid that originate from the small meibomian glands that line the edge of the lid. They result from a buildup of secretion within the glands due to blockage of the ducts leading from the gland. Chalazions appear as yellow to white swellings beneath the conjunctiva on the inner lid margin. Puncturing or incising these to remove the trapped contents will afford a cure.
Hordeolums are pus-filled masses caused by infections within the meibomian glands or hair follicles lining the lid margin. As with chalazions, these can be punctured and expressed to help speed healing. Topical or systemic antibiotics are also used to eliminate infection.
Tumors that affect the eyelid can be very serious due to the inability to remove them surgically without disrupting the integrity of the lid. Sebaceous gland adenomas are common lid tumors, especially in older dogs. Others include adenocarcinomas, papillomas, and melanomas. As an alternative or adjunct to surgical removal, radiation therapy, chemotherapy, or cryotherapy (freezing) can be used as well, depending upon which type of tumor is involved.

Retinal degeneration and disease can be a cause of blindness in dogs and cats. For instance, progressive retinal atrophy (PRA) is a hereditary condition that can strike middle-aged to older dogs and produce blindness over a period of several months to years. Breeds that are predisposed to this condition include Gordon setters, Irish setters, poodles, Norwegian elkhounds, Labrador retrievers, collies, cocker spaniels, and malamutes. Characterized by a slow degeneration of the receptor cells composing the retina, progressive retinal atrophy (PRA) in its early stages often leads to nightblindness in affected dogs. These dogs tend to fear or shy away from poorly lit areas. As progressive retinal atrophy (PRA) progresses, it eventually causes the pupils to remain dilated and fail to respond to light, causing complete blindness.
Retinal function may also be partially or completely lost due to underlying disease or injury. For example, glaucoma affecting an eye can place so much pressure on the blood vessels supplying the retina of that eye that secondary retinal degeneration results. Sudden acquired retinal degeneration (SARD) is another nonhereditary condition that can cause blindness in dogs, yet its exact cause remains a mystery. Interestingly, this disease is often accompanied by an increase in thirst and in appetite in those dogs so affected. Infectious diseases, such as ehrlichiosis and Rocky Mountain spotted fever, and fungi can also adversely affect the region of the retina where the optic nerve exits, leading to inflammation and subsequent loss of vision. In addition, neoplasms such as lymphosarcoma can infiltrate the retinas of dogs and cats and inhibit retinal function. Finally, trauma, immune-mediated diseases, and certain toxins can cause retinal injury and lead to blindness.
Diagnosis of retinal disease and degeneration is made using history, physical exam findings, and information obtained from an ophthalmic examination of the retinas themselves. In addition, an electroretinogram, which measures the electrical activity taking place within the retinas, will provide a definitive diagnosis of retinal degeneration and retinal blindness. If a disease condition such as glaucoma, infection, neoplasia, or toxicity is suspected, other diagnostic testing procedures specific to these conditions may be required as well to confirm a diagnosis.
Unfortunately, there are presently no known treatments for progressive retinal atrophy (PRA) and Sudden acquired retinal degeneration (SARD), and the prognosis remains grave for the restoration of sight in affected dogs. Other diseases involving the retina may respond favorably to treatments specific for the particular disorder; however, it
must be remembered that the longer such treatments are delayed or neglected, the greater the chances are of permanent loss of vision.

Glaucoma is a condition characterized by an increase in fluid pressure from the aqueous humor within the eye(s). In the normal eye, pressure and aqueous levels are maintained at a constant plateau by the continual drainage of excess aqueous humor out of the eye through tiny ports (drainage angles) located where the edge of the iris meets the cornea. If this drainage is obstructed or altered in any way, a rise in pressure within the eye can result. Unfortunately, even short-term rises in this pressure can lead to irreversible damage if not detected and treated in a timely fashion.
Conditions such as a buildup of inflammatory material within the eye, luxation of the lens due to trauma or cataracts, and synechia, where the iris “sticks” to the lens orcornea, can all effectively prevent the normal drainage of the aqueous humor from the eye.
Heredity is also thought to play a role in some cases of glaucoma in dogs, with basset hounds, beagles, and cocker spaniels having a higher incidence of the disease due to improper development of the drainage angles. In addition, a predisposition for lens luxation has been identified along family lines for many of the terrier breeds, predisposing them to glaucoma. Finally, allergies and overactive immune system responses are also thought to be important precursors to glaucoma in dogs and cats. Clinical signs of a glaucomatous eye include a marked redness affecting both the conjunctival tissue and the sclera; a blue, hazy cornea; a dilated, unresponsive pupil; and apparent blindness due to the pressure the fluid is placing on the optic nerve. In instances where the glaucoma has been present for quite some time, enlargement of the affected eyeball might become noticeable, and actual rupture of the cornea could occur.
Diagnosis of glaucoma can be easily confirmed by a veterinarian through the use of an instrument called a tonometer. This instrument, when placed directly on the surface of the cornea, measures the exact pressure within the eye. If the pressure reading is indeed elevated, then treatment should be instituted immediately to prevent lasting damage to the eye.
Treatment for glaucoma is aimed at decreasing the pressure within the eye to an acceptable level as quickly as possible, and then stabilizing this pressure to prevent future increases.
Drugs designed to quickly draw fluid out of the eye and into the bloodstream will initially be used to reduce the pressure within a pet’s eye(s). Other drugs that act by decreasing the production of aqueous humor and by increasing the size of the drainage angles are then prescribed for the long-term management and prevention of recurrence. At the same time, anti-inflammatory medications can be used topically on the eye to clear up any primary or secondary inflammation that might be aggravating the glaucoma.
In instances where a luxated lens is causing the increase in pressure, surgical removal of the offending lens should always be performed. Cryotherapy (freezing) can be used as well. This involves surgically inserting a special needle within the eye and freezing the cells within the eye responsible for the production of aqueous humor. With this technique, aqueous production can be reduced by up to 30 percent in some patients.

Fractures or trauma to the cartilage supporting the pinna of the ear can lead to the accumulation of blood and serum within the affected flap. These aural hematomas cause the pinna to swell, sometimes to enormous sizes. In the majority of cases, the fluid accumulation occurs on the inside portion of the earflap.
Researchers don’t know what precipitates many cases of aural hematomas, but they do have a few suspicions. Since these hematomas are often accompanied by otitis externa, many feel that the trauma induced by scratching and shaking the head predisposes to aural hematomas, especially in those dogs with pendulous ears. Still others suspect that an overactive host immune system is the culprit behind this disorder. Regardless of the cause, aural hematomas are painful and irritating, and need to be surgically drained as soon as possible after initial appearance.

Entropion
Entropion is an ophthalmic condition in which the eyelids roll inward, allowing lashes and hair to irritate the surface of the eyes. The condition is inheritable, or it can occur secondary to other types of eye irritation (spastic entropion) or eyelid injury. Congenital entropion has a high incidence in chow chows, shar-peis, English bulldogs, poodles, and rottweilers.
Signs of entropion include excessive tearing, squinting, constant rubbing of the affected eye(s), excessive redness to the eye(s), and a noticeable inward roll to the eyelid, especially the lower lid.
If a pet is suffering from entropion, surgical treatment might be essential to prevent lasting damage to the surface of the eye(s). Some puppies afflicted with this disorder might outgrow it as they mature; hence, surgery is usually delayed in these young animals until they are at least 6 months old, unless the damage to the eye is severe.
In the meantime, topical lubricants designed to protect the corneas can be used on a daily basis in these patients. In some pups, especially sharpeis, temporary eversion of the offending lids with sutures implanted in the skin of the lids can also help prevent complications until they outgrow the entropion or are old enough for the surgery.
Entropion surgery involves the removal of a flap of skin just beneath (lower lid) or above (upper lid) the inverted lid. Suturing close the resulting gap of skin will then provide enough tension to roll the lid back out. In many instances, more than one surgery is necessary to achieve just the right amount of eversion.
After surgery is performed, care must be taken to prevent the dog from irritating the incision line and causing swelling. Hospitalization for a few days after the procedure is performed will help reduce this occurrence.
Because of the inheritable nature of this disorder, all dogs affected with entropion should be neutered to prevent its passing to future generations. When selecting a new pet, especially one that falls into the high-risk category, owners should examine the pup’s parents closely for any signs of entropion or for evidence that surgical correction has been previously performed.

Ectropion
Ectropion is the exact opposite of entropion; it is the outward rolling of the eyelid(s), which exposes the pink conjunctival lining within. As with entropion, this condition is inheritable, with cocker spaniels, St. Bernards, and bloodhounds having a high incidence. Facial nerve paralysis, such as that seen secondary to otitis media, can also result in ectropic lids.
Mild cases of ectropion usually cause no problems whatsoever in affected individuals. Moderate to severe cases are often accompanied by conjunctivitis, excessive lacrimation, and eye discharges. Keeping the eye(s) clean and free of discharge on a daily basis using saline solution or medicated drops or ointments will help keep minor cases of ectropion under control. For more extensive involvement, surgical correction designed to release the tension placed on the skin of the eyelid, allowing it to roll back to its correct position, might be required.

The third eyelid of dogs contains a gland that might occasionally become inflamed and protrude over the edge of the third eyelid, producing a classic “cherry eye” appearance. Certain breeds such as the cocker spaniel, Lhasa apso, Pekingese, and beagle seem to be more predisposed to this condition than others.
In the past, treatment for a prolapsed gland of the third eyelid involved complete surgical removal of the gland. However, researchers agree that the gland might play an important role in tear production; hence, complete removal of the gland might predispose a pet to keratoconjunctivitis sicca. As a result, newer surgical procedures involve removal of only a portion of the gland, or actually tacking down the prolapsed portion of the gland to the inner surface of the third eyelid.

Eardrums can tear or rupture as the result of direct trauma from a foreign body (a twig, cotton-tip applicator, etc.), sudden pressure changes, or, most commonly, as a secondary complication due to otitis externa. Although a serious and painful condition, a torn eardrum will heal quite quickly provided the underlying cause of the perforation is eliminated.
Medications designed for use in the ears must be used with caution if a dog or cat suffers from a ruptured eardrum. Not only can their application be painful, but also, as mentioned previously, certain antibiotics and solutions, if allowed direct access into the middle-and inner-ear chambers, can cause damage to the auditory nerve endings, resulting in deafness. As a result, be certain to follow a veterinarian’s recommendations closely.

Seen primarily in dogs, keratoconjunctivitis sicca (KCS), or “dry eye”, is a condition affecting the cornea and conjunctiva of the eye resulting from inadequate tear production. Actually, only the water portion of the tear film is deficient; the mucus portion is still produced in adequate quantities. This leads to the characteristic green, mucoid buildup in and around eyes affected with keratoconjunctivitis sicca (KCS). The lack of adequate tear moisture also predisposes the cornea to damage and ulcers. Long-term sequelae include pigmentation of the corneal surface and blindness.
keratoconjunctivitis sicca (KCS) can have a number of underlying causes. In many breeds such as Yorkshire terriers, schnauzers, cocker spaniels, bulldogs, and beagles keratoconjunctivitis sicca (KCS) can be an inherited trait. Other potential causes include canine distemper, certain medications (such as sulfa drugs), hypothyroidism, diabetes mellitus, and autoimmune disease.
Diagnosis of keratoconjunctivitis sicca (KCS) is made using tear flow tests to determine the amount of tear production. Treatment of keratoconjunctivitis sicca (KCS) involves the use of tear replacement drops, followed by an application of a tear replacement ointment to seal in the drops. These replacements must be applied every 3 to 4 hours to be truly effective. If infection or inflammation is present, antibiotics and anti-inflammatory medications should be instilled into the eyes as well.
Medications designed to stimulate more tear production have been used for treatment in the past with varying success. Also, the drug cyclosporine can be quite effective at stimulating renewed tear production in some dogs with keratoconjunctivitis sicca (KCS). For more information on cyclosporine, owners should contact their pets’ veterinarians.
In especially advanced cases of keratoconjunctivitis sicca (KCS), surgical intervention might become necessary. The standard surgical treatment used, called parotid duct transposition, involves repositioning a duct from a salivary gland to the corner of the affected eye(s), thereby providing a constant source of moisture (saliva) to the eye.

Seen primarily in dogs, keratoconjunctivitis sicca (KCS), or “dry eye”, is a condition affecting the cornea and conjunctiva of the eye resulting from inadequate tear production. Actually, only the water portion of the tear film is deficient; the mucus portion is still produced in adequate quantities. This leads to the characteristic green, mucoid buildup in and around eyes affected with keratoconjunctivitis sicca (KCS). The lack of adequate tear moisture also predisposes the cornea to damage and ulcers. Long-term sequelae include pigmentation of the corneal surface and blindness.
keratoconjunctivitis sicca (KCS) can have a number of underlying causes. In many breeds such as Yorkshire terriers, schnauzers, cocker spaniels, bulldogs, and beagles keratoconjunctivitis sicca (KCS) can be an inherited trait. Other potential causes include canine distemper, certain medications (such as sulfa drugs), hypothyroidism, diabetes mellitus, and autoimmune disease.
Diagnosis of keratoconjunctivitis sicca (KCS) is made using tear flow tests to determine the amount of tear production. Treatment of keratoconjunctivitis sicca (KCS) involves the use of tear replacement drops, followed by an application of a tear replacement ointment to seal in the drops. These replacements must be applied every 3 to 4 hours to be truly effective. If infection or inflammation is present, antibiotics and anti-inflammatory medications should be instilled into the eyes as well.
Medications designed to stimulate more tear production have been used for treatment in the past with varying success. Also, the drug cyclosporine can be quite effective at stimulating renewed tear production in some dogs with keratoconjunctivitis sicca (KCS). For more information on cyclosporine, owners should contact their pets’ veterinarians.
In especially advanced cases of keratoconjunctivitis sicca (KCS), surgical intervention might become necessary. The standard surgical treatment used, called parotid duct transposition, involves repositioning a duct from a salivary gland to the corner of the affected eye(s), thereby providing a constant source of moisture (saliva) to the eye.

An opacity involving the lens of the eye that prevents light from reaching the retina is termed a cataract. Cataracts can be inherited (juvenile cataracts) or might develop secondary to eye trauma, infections, or metabolic disease, such as diabetes mellitus. As lens opacity increases, the amount of light allowed to reach the retina is diminished, and partial blindness ensues.
Cataracts can also predispose to rotation or luxation of the lens. Such lens movement can disrupt normal fluid flow within the eye and lead to secondary glaucoma.
True cataracts must be differentiated from lenticular sclerosis seen in older pets. Lenticular sclerosis is a lens opacity caused by a normal hardening of the lens material due to age. It is a normal aging change seen in some dogs, and rarely leads to loss of sight as can occur with cataracts. As a result, no specific treatment is required for most cases of lenticular sclerosis. Lenticular sclerosis and cataracts can be differentiated with an ophthalmologic examination performed by a veterinarian.
Treatment for cataracts usually involves surgical removal of the offending lens. A less invasive surgical technique for cataract removal is called phacofragmentation. This procedure employs the use of ultrasound to break up the lens material into small pieces, which can then be drawn or sucked out of the eye using special instrumentation. Once cataracts are removed, vision is effectively restored in the affected pet.

Otitis media, infection involving the middle ear, usually results from a chronic, untreated or recurring otitis externa. In such cases, the eardrum might become so diseased as to tear or rupture completely, allowing direct access of infectious organisms into the middle-ear chamber.
The clinical signs of otitis media are essentially the same as those for otitis externa, with a few notable additions. Pets so afflicted will usually exhibit a head tilt toward the side of the affected ear. In severe cases, paralysis of the facial muscles on the side of the lesion might be seen as the nerves passing through the middle ear become involved. This can result in a characteristic drooping of the eyelids, cheeks, and lips. In addition, a decreased tear production, pinpoint pupil, and protrusion of the third eyelid might be noted in the eye on the affected side.
If the infection extends from the middle ear into the inner-ear apparatus, the signs become even more pronounced. Since the inner ear functions in maintaining balance and equilibrium as well as hearing, pets suffering from otitis interna tend to become very uncoordinated and might fall down frequently or move in circles toward the affected side. A characteristic twitching of the eyeball, called nystagmus, also becomes more noticeable.
Although the clinical signs seen are often diagnostic, radiographs of the skull are quite helpful at confirming a diagnosis of otitis media or interna and determining the extent of the disorder.
Therapy for otitis media or interna must be instituted promptly to prevent permanent damage to the hearing apparatus. Oral antibiotics should be started immediately. In cases of otitis interna, continued treatment with antibiotics might be required for up to 30 days to afford a complete cure. In select cases, anti-inflammatory medications have been used to reduce signs associated with inflammation. If not already ruptured, the eardrum on the affected side is usually punctured to allow for thorough drainage of the middle-ear cavity and for the direct infusion of medications. Of course, such treatment steps must be carried out in a veterinary hospital under heavy sedation or anesthesia. In tough, refractory cases, surgical placement of a drain in the bony tympanic bulla affords excellent exposure to the middle and inner ear spaces.

Inflammation of the thin, transparent mucous membrane lining the inner portion of the eyelids and front part of the sclera is termed conjunctivitis. Conjunctivitis is the most common cause of “red eyes” in dogs and cats. Other signs seen with conjunctivitis include discharge, swelling, and pain.
The type of discharge present can sometimes give a clue as to the underlying cause of the conjunctivitis. For instance, a watery discharge can indicate irritation from an allergy, virus (canine distemper or feline rhinotracheitis), or contact with dirt or dust; a mucuslike discharge often links the problem to abnormal tear formation (“dry eye”) or to a bacterial infection, either primary or secondary to any of the causes previously mentioned.
Because conjunctivitis can be secondary to other problems, diagnostic tests performed by veterinarians should be directed at identifying any underlying causes. Corneal staining using a fluorescent stain is usually performed to determine whether the cornea is affected. In dogs, if a mucuslike discharge is present, a tear flow test should be performed to rule out “dry eye” as the cause of the conjunctivitis.
In cases of conjunctivitis that don’t respond to conventional therapy, a bacterial culture or sensitivity test should be performed to be sure treatment measures being used are correct.
Treatment of conjunctivitis is aimed at treating or eliminating any inciting causes, and at controlling the localized inflammation. If dust or pollens are the source of the conjunctivitis, daily flushing of the eyes with a sterile saline solution designed for use in the eyes or daily application of a sterile ophthalmic lubricant can help reduce the irritation caused by these offenders.
Ophthalmic drops or ointments containing antibiotics are necessary if a bacterial infection is present. In addition, ophthalmic preparations containing steroids can be used to reduce the inflammation present, provided the surface of the cornea is intact. Preparations containing both antibiotics and steroid compounds for use in the eyes are readily available for pets through a prescription from a veterinarian.

Otodectes cynotis is the mite that most commonly inhabits the ear canals of dogs and cats. These tiny parasites, which are transmitted by close contact with other infected animals, live on the skin surface within the ear and feed on body fluids. Their presence irritates the glands lining the ear canal, leading to an increased cerumen production. Secondary infections with the Malassezia yeast are not uncommon, leading to the brown, crusty discharge so often seen with ear mite infestations. In isolated cases, intense allergic reactions to ear mites can occur, causing severe inflammation and secondary infection.
Diagnosis of an ear mite infestation is confirmed by identification of the mites directly on otoscopic exam or through a microscopic examination of an ear swab. Treatment involves the use of medications containing antiparasitic compounds, such as pyrethrins, rotenone, ivermectin, or thiabendazole. Mineral oil has also been employed as a home remedy for killing mites by suffocation. Since secondary yeast infections are commonly found with ear mite infestations, an antiyeast medication should be used concurrently with antimite preparations.
Ear mites can be difficult pests to eliminate. Depending on the medication used, daily treatment for 3 to 4 weeks might be needed to ensure a complete kill. All animals in the household, regardless of whether they are exhibiting signs of infestation, should be treated at the same time. In addition, to prevent reinfestation from the haircoat, an insecticidal spray or shampoo should be used at least twice during the treatment period.

Deep corneal ulcerations are treated the same way that superficial ulcerations are, yet these require close observation for progression or worsening of the ulcer. Bacterial cultures of such ulcers are necessary to be certain that the antibiotics being used are effective against any organisms involved.
For deep ulcers that worsen or fail to respond to conventional treatment, additional procedures might be necessary to speed healing or to prevent the cornea from actually rupturing. A favorite procedure among veterinarians consists of surgically freeing and extending a portion of the thin conjunctiva over the ulcer and actually tacking it down against the ulcer using suture material (conjunctival flap). The flap of conjunctiva provides nutrition and speeds healing to the ulcer, and also allows any medications applied directly to the eye(s) to reach the ulcer without hindrance. Once healing has been accomplished, the flap is released, and excess conjunctival tissue is trimmed away from the healed surface.
Special contact lenses and/or corneal tissue adhesives can also be applied over the damaged surface of the cornea. These serve to protect it from further degradation and help promote rapid healing. For difficult ulcers, actual grafts using fresh or frozen corneal tissue may be required.

Failure to detect and treat inflammation within the external ear canal early enough can lead to the establishment of a bacterial infection within the ear. Often, these infections result when the harmless bacteria that normally inhabit the ear are overwhelmed by the inflammation, allowing their not-so-peaceful counterparts to proliferate and take over.
A creamy brown to yellow discharge carrying a foul odor is characteristic of a bacterial disorder within the ear. Bacterial infections can even be found together with yeast infections within the same ear(s), leading to a discharge having characteristics of both types.
If not treated promptly and vigorously, bacterial infections can become firmly entrenched within the ear canal, making a complete cure difficult. For this reason, veterinary practitioners rely heavily on bacterial cultures and sensitivity tests to tell them which bacteria are involved and which antibiotics will be most effective.
Otic preparations containing appropriate antibiotics, often combined with anti-inflammatory medications, are used to combat cases of bacterial otitis externa. Bacteria within the ear have been effectively treated with 5% vinegar (acetic acid) solutions.
If a ruptured eardrum is suspected, selection of treatment agents must be done carefully. For example, antibiotics belonging to the class known as aminoglycosides (examples include gentamycin and neomycin) should not be used in the ear directly, since they can cause nerve deafness if exposed to the inner ear. The same holds true for astringent preparations and acetic acid solutions. In addition, if a ruptured eardrum is suspected, only water-soluble treatment solutions should be used. Ointments should be avoided, as they can become entrapped within the middle ear.
In especially severe cases of bacterial otitis, oral antibiotics might be given concurrently with topical ear medications to afford faster results. In chronic longstanding infections that can’t be cleared up with antibiotics, a surgical procedure known as a lateral ear resection might be necessary to increase the treatment effectiveness. This involves the surgical reconstruction of the external ear canal to eliminate the vertical portion, allowing easy, direct access to the horizontal portion and the eardrum. Although the results might not be the most cosmetic, a lateral ear resection can mean the difference between a life of misery or comfort for a dog afflicted with chronic otitis externa.

Malassezia pachydermatis is the yeast organism most commonly involved in otitis externa. This is not surprising, since Malassezia is normally found within the ear canals of healthy dogs and cats, causing no problems whatsoever. However, if inflammation strikes for whatever reason, the yeast takes advantage of a good situation and begins to proliferate. When this growth reaches a certain level, it too can promote inflammation. A characteristic brownish discharge is seen with a buildup of yeast within the ears.
Ear ointments or solutions containing miconazole, thiabendazole, or nystatin can be used to effectively treat yeast infections in the ear. Treating the ears twice daily for 10 to 14 days will clear up most infections. Because Malassezia is considered an opportunist, it is important that the underlying source of the inflammation that led to the yeast infection be identified and treated concurrently.

The transparent cornea enclosing the front portion of the eye is a remarkable organ in itself. Responsible for gathering light and directing it into the eye, healthy corneas are essential for proper vision. It stands to reason, then, that ulcerations (loss of surface epithelium) or scratches involving one or more corneal surfaces can seriously threaten eyesight if not managed promptly.
Corneal ulcerations in dogs and cats can occur secondary to poor tear production, entropion or ectropion, dust and foreign debris in the eye(s), nail scratches and other direct trauma, and infections.
Some of the most common sources of corneal ulceration seen by veterinarians are soap or shampoo burns caused by inadequate eye protection when bathing. Pet owners should always apply a sterile ophthalmic ointment to their pet’s eyes prior to any procedure that involves potentially caustic substances around the eyes. Since corneas are so sensitive, even shampoos with touted “no tears” formulations should never be used without applying this protection first.
Clinical signs of a corneal ulcer include squinting and aversion to light, ocular discharge, and obvious discomfort, often signified by pawing at or rubbing the affected eye. A change in the normal color or transparency of the corneal surface is also an indicator that something is wrong.
Definitive diagnosis of a corneal ulcer is made by veterinarians using special fluorescein dyes to stain the corneal surfaces. Dead, diseased corneal tissue will readily take up such stains whereas healthy tissue will not.
Fortunately, the cornea is one organ that will heal quite rapidly if treatment is administered quickly and vigorously. For ulcers involving only the superficial layers of the cornea, topical antibiotic ointments or solutions designed for use in the eyes and applied three to six times daily will help speed healing.
Of course, if an underlying cause, such as foreign debris, still exists in the eye, it must be removed before proper healing can take place. Superficial ulcers can heal in 36 to 48 hours with proper treatment applied.

Inflammation involving the external ear canal is called otitis externa. It is estimated that up to 20 percent of the dog population in the United States alone suffers from some form of otitis externa. Anatomical features that predispose certain breeds to ear disorders include long, pendulous ears (cocker spaniels), long, narrow ear canals (poodles), and excessive hair within the ear canal which entraps wax and restricts air circulation (poodles). Dogs that spend a lot of time in the water, such as hunting retrievers and spaniels, are also prone to otitis externa. Otitis externa is relatively rare in cats, unless it occurs secondary to trauma or to ear mites.
Since the external canals are nothing more than inward extensions of the skin, conceivably anything that can cause skin inflammation can cause otitis externa. This can include allergies, metabolic diseases (hypothyroidism, seborrhea), trauma, foreign bodies such as grass awns and twigs, and parasites such as ticks and mites. Anal sac disease has even been implicated in cases of otitis externa, even though the exact mechanism of involvement is not completely understood.
Signs of otitis externa involving one or both ears include head shaking, itching, painful ears, person ality changes, and/or odifer ous discharges coming from the ear canal(s). Hair loss might be noticed around the pinnae due to scratching. Aural hematomas might also develop in the wake of such self-trauma.
Diagnosis of otitis externa is based on clinical signs, physical exam, and selected laboratory tests if needed to determine the underlying cause of the inflammation. An otoscopic (ear) exam performed by a veterinarian will help rule out foreign bodies and parasites. This exam is also needed to assess the health of the eardrums. Since many medications cannot be used if the eardrum is torn or ruptured, never attempt to treat otitis externa at home without first having a veterinarian perform this otoscopic exam.
The type of medications prescribed by a veterinarian for the treatment of otitis externa will vary, depending on the nature and extent of the causative agent or condition.

The Ears
The sense of hearing in the average dog and cat is much more fine-tuned than that of a human, allowing it to detect much higher sound pitches. The upper range of hearing is thought to be around 50,000 kilohertz for dogs and 60,000 kilohertz for cats, well above the 20,000-kilohertz norm for people.
Silent dog whistles were invented on the basis of this principle, and the pitch emitted was just above human hearing range but well within that of the dog being summoned. Unfortunately, the high pitch emitted by many of the new electronic flea collars available on the market often falls within the dog and cat’s hearing range, raising serious questions as to their safe use.

Anatomy and Physiology
The canine and feline hearing apparatus can be divided into three portions: the inner ear, the middle ear, and the external ear canal and associated structures.
The inner ear is that portion containing the nerve endings responsible for the sensation of hearing. It also plays a leading role in maintaining balance and equilibrium in your pet (dogs and cats get carsick, too). The inner ear apparatus lies protected within the bony confines of the skull. The nerves and associated structures within the inner ear are very sensitive and can be damaged through continued exposure to loud, high-pitched noises, infections, and/or toxic medications.
The middle ear communicates directly with the inner ear and is contained within a pear-shaped bony cavity originating from the skull called the tympanic bulla. This middle-ear cavity is normally filled with air and contains blood vessels and nerves that supply the face and the rest of the head. Inflammation involving the middle ear can adversely affect these nerves, leading to paralysis of the muscles of the face.
The eardrum, or tympanic membrane, separates the middle ear from the external ear canal. This external canal directly communicates to the outside world, but not without first going through some significant anatomical changes along the way. A horizontal portion of the canal courses a short distance directly away from the eardrum before angling sharply upward (especially in dogs) to form a long vertical portion. This distinct bend has medical significance in that it can lead to the entrapment of wax, hair, and debris deep within the ear, predisposing to inflammation and infection. These substances can be removed by application of a liquid cleansing agent.
The vertical external ear canal and to a lesser extent, the horizontal ear canal are lined with special glands that produce ear wax, or cerumen. In the past, cerumen was thought to exert some beneficial antibacterial effects in the ear. Yet research has disproved this and has shown that too much of a waxy buildup can actually promote bacterial growth and infections. In the healthy ear with normal amounts of cerumen produced, this doesn’t present much of a problem. Yet when an ear becomes inflamed, wax production increases, and can predispose to infectious complications.
Surrounding the opening of the external ear canals is the earflap, or pinna, which, in dogs, comes in all sorts of sizes and shapes, both natural and synthetic. Each pinna is supported by a sturdy band of cartilage that courses from the vertical ear canal to the tip of each flap. Long droopy earflaps that hang down over the ear openings can effectively cut off proper air circulation within the ear canal; this can potentially lead to ear problems in these dogs unless preventive measures are instituted on a rountine basis. Thus, dogs with shorter, more erect pinnae are less likely to develop this condition.