Middle Ear Infection / Otitis Media

Otitis media, commonly known as middle ear infection, is a significant health condition in guinea pigs that affects the middle ear structures including the tympanic bulla, the bony cavity that houses the middle ear, and the ossicles, the tiny bones that transmit sound vibrations. This condition occupies an intermediate position in the spectrum of ear disease, being more serious than outer ear infections but potentially less immediately devastating than inner ear involvement, though it frequently leads to inner ear disease if not treated promptly and effectively. Middle ear infections in guinea pigs are almost always bacterial in origin and require veterinary treatment.

Middle ear infections are relatively common in guinea pigs and represent a serious concern because of their tendency to progress to inner ear infection with vestibular consequences, and because they can be difficult to detect until the disease is advanced. The middle ear space is normally sterile and protected from the external environment by the tympanic membrane (eardrum). When bacteria breach this barrier, either by perforation of the eardrum from an outer ear infection or by ascending through the Eustachian tube from a respiratory infection, they can establish infection in the middle ear. The enclosed nature of the tympanic bulla makes it difficult for the body's immune system to clear infection and for antibiotics to penetrate effectively.

The impact of otitis media on affected guinea pigs can range from subtle to severe. In early or mild cases, guinea pigs may show only vague signs of discomfort or changes in behavior that owners might not immediately attribute to ear disease. As the condition progresses, more obvious signs develop including head shaking, ear scratching, pain responses when the ear area is touched, and changes in appetite and activity. If the infection spreads to the inner ear, vestibular signs such as head tilt and loss of balance develop. Hearing loss may occur if the ossicles are damaged or if fluid accumulation impairs sound transmission.

The good news is that otitis media is treatable, particularly when caught before it spreads to the inner ear. Treatment requires prolonged courses of guinea pig-safe antibiotics, often lasting several weeks to months. In some cases, particularly chronic or recurrent infections, surgical intervention to drain and clean the middle ear may be necessary. With appropriate treatment, many guinea pigs recover fully, though some may have lasting effects such as hearing impairment. Early recognition and prompt veterinary care are essential for the best outcomes, making awareness of the signs of ear disease important for all guinea pig owners.

The primary cause of otitis media in guinea pigs is bacterial infection that has reached the middle ear space. The most common route of infection is extension from an existing outer ear infection (otitis externa) where bacteria erode through or pass around a compromised tympanic membrane to enter the middle ear. The second major route is ascending infection through the Eustachian tube, the narrow passage connecting the middle ear to the nasopharynx. This route is particularly significant in guinea pigs with respiratory infections, as bacteria colonizing the upper respiratory tract can travel through the Eustachian tube to infect the middle ear. The bacteria most commonly implicated include Bordetella bronchiseptica, Streptococcus species, Staphylococcus species, and Pasteurella multocida.

While there are no known direct genetic causes of otitis media, individual anatomical variations may predispose some guinea pigs to ear infections. Differences in ear canal shape, Eustachian tube function, or immune system competence can influence susceptibility. Some guinea pigs may produce excessive ear wax or have narrower ear canals that impair natural drainage and cleaning. Conformational differences in the skull and ear structures that affect ventilation of the middle ear may also play a role. However, these individual factors are not well characterized, and any guinea pig can develop middle ear infection under appropriate conditions.

Environmental factors significantly contribute to the development of ear infections in guinea pigs. Poor husbandry is a major risk factor, including dirty bedding that harbors bacteria, high ammonia levels from inadequate cage cleaning, and dusty conditions that irritate the ear canal and respiratory tract. Inappropriate bedding materials such as cedar or pine shavings cause irritation and inflammation. Housing guinea pigs in damp or humid conditions promotes bacterial growth. Exposure to drafts or temperature extremes stresses the immune system. Overcrowded conditions increase disease transmission. Poor ventilation allows pathogens to accumulate in the environment.

Several specific risk factors increase a guinea pig's susceptibility to developing otitis media. Pre-existing outer ear infection is a significant risk factor, as untreated or inadequately treated otitis externa can progress to middle ear involvement. Respiratory infections, particularly those caused by Bordetella bronchiseptica, increase risk by providing a bacterial source that can ascend through the Eustachian tube. Immunocompromise from any cause, including stress, poor nutrition, concurrent illness, or vitamin C deficiency, impairs the ability to fight off infection. Senior guinea pigs may have decreased immune function. Guinea pigs housed with animals that have respiratory infections are at increased risk of exposure to pathogenic bacteria.

The disease mechanism of otitis media involves establishment of bacterial infection within the normally sterile middle ear space, followed by inflammation and accumulation of purulent material. Bacteria damage the delicate structures of the middle ear including the tympanic membrane (from the inside if it was intact) and the ossicles. Pus and inflammatory debris accumulate in the tympanic bulla, which cannot drain effectively due to its enclosed nature. This creates an ideal environment for continued bacterial growth. Chronic infection can cause thickening and scarring of the bulla lining, bony changes in the bulla walls, and permanent damage to middle ear structures. If the infection is not controlled, it can erode through the bone separating the middle and inner ear, leading to the more serious condition of otitis interna.

Early warning signs of otitis media in guinea pigs can be subtle and easily overlooked. Because guinea pigs are prey animals that instinctively hide signs of illness and pain, early middle ear infection may manifest only as slight changes in behavior or demeanor. Affected guinea pigs may seem slightly less active or enthusiastic about food than usual. There may be occasional head shaking or ear scratching that the owner might attribute to normal grooming behavior. A slight reluctance to be touched around the head or ears may be noted. Appetite might decrease subtly. These early signs are nonspecific but warrant attention, particularly in guinea pigs with known ear problems or recent respiratory infections.

As otitis media becomes established, more recognizable symptoms develop. Head shaking becomes more frequent and pronounced, as the guinea pig tries to relieve discomfort or dislodge debris from the affected ear. Scratching at the ear with the hind foot increases. The guinea pig may tilt or hold the head at an unusual angle. Pain responses when the area around the ear is touched or when the ear is examined become evident. Appetite typically decreases as the guinea pig becomes increasingly uncomfortable. Activity level drops, and the guinea pig may spend more time hiding. Changes in vocalization, such as increased squeaking or grinding teeth, may indicate pain.

Behavioral changes associated with middle ear infection reflect the pain and discomfort the guinea pig is experiencing. Affected animals often become quieter and more withdrawn, showing less interest in interacting with cage mates or human caregivers. They may hide more frequently and be reluctant to come out, even for favorite treats. Decreased grooming may lead to a rougher coat appearance. Social behaviors with cage mates may change, with affected guinea pigs becoming either more irritable or more passive. Sleep patterns may be disrupted by discomfort. Some guinea pigs may show increased aggression when handled, particularly around the head.

Physical signs of otitis media may include visible changes in the ear area. The affected ear may appear red, swollen, or have a discharge that can range from waxy to purulent and may have a foul odor. The ear canal may be narrowed by swelling. If the tympanic membrane has perforated, discharge from the middle ear may be visible in the ear canal. The area around the ear may be sensitive to touch, and the guinea pig may flinch or vocalize when examined. Weight loss often develops due to decreased food intake. In some cases, facial nerve involvement causes drooping of the lip or eyelid on the affected side.

Symptom progression in untreated otitis media can lead to serious complications. If the infection extends to the inner ear, vestibular signs develop including head tilt, nystagmus (rapid eye movements), loss of balance, circling, and in severe cases, rolling. These signs indicate that the disease has progressed beyond the middle ear and carries a more guarded prognosis. Hearing loss may become apparent if it has not already. Chronic middle ear infection can cause permanent damage to middle ear structures even if infection is eventually controlled. Rarely, infection can spread to surrounding structures including bone (osteomyelitis) or brain (meningitis/encephalitis).

Emergency symptoms requiring immediate veterinary attention include sudden development of head tilt or balance problems indicating inner ear involvement, complete refusal to eat or drink lasting more than 12 hours, signs of severe pain such as teeth grinding or vocalization, discharge from the ear that is bloody or has a very foul odor, swelling extending beyond the ear to involve the face or neck, any signs of neurological deterioration, and signs of systemic illness such as lethargy, labored breathing, or collapse. Any guinea pig with suspected ear infection should be seen promptly by an exotic veterinarian, but these emergency signs require immediate attention.

Diagnosis of otitis media in guinea pigs requires a thorough examination by a veterinarian experienced with exotic animals. The examination begins with assessment of overall health status and a detailed history from the owner, including information about symptom onset and progression, any previous ear or respiratory problems, diet and husbandry conditions, and exposure to other animals. The external ears are examined visually for swelling, discharge, or other abnormalities. Otoscopic examination of the ear canals allows visualization of the ear canal lining and, if visible, the tympanic membrane. An abnormal, bulging, discolored, or perforated tympanic membrane suggests middle ear involvement. A neurological examination assesses for signs of inner ear involvement.

Diagnostic tests help confirm the diagnosis and guide treatment. If ear discharge is present, samples should be collected for bacterial culture and sensitivity testing to identify the causative organism and determine which antibiotics will be effective. Cytology of ear discharge provides rapid preliminary information about the type of infection. Blood work including complete blood count and serum biochemistry panel assesses overall health and may reveal signs of systemic infection. Imaging is particularly important for diagnosing otitis media, as the middle ear cannot be directly visualized. Skull radiographs can reveal changes in the tympanic bullae such as thickening, increased opacity (suggesting fluid or pus accumulation), or bony changes indicating chronic infection. CT scan provides much more detailed evaluation of the middle ear structures and is the imaging modality of choice when available.

Differential diagnosis considers other conditions that can cause similar symptoms. Otitis externa alone can cause ear pain, head shaking, and discharge, but does not involve the middle ear. Ear mites, though uncommon in guinea pigs, can cause ear irritation and scratching. Dental disease can cause referred pain to the ear area and may need to be ruled out. Foreign bodies in the ear canal can cause localized inflammation. Tumors affecting the ear or surrounding structures are possible, particularly in older guinea pigs. If vestibular signs are present, inner ear involvement must be considered, as must central nervous system causes of vestibular dysfunction.

Once the diagnosis is confirmed, severity assessment helps guide treatment planning. The veterinarian will consider whether one or both ears are affected, the degree of bulla involvement on imaging, the presence or absence of inner ear involvement, the overall health of the guinea pig, and how long symptoms have been present. Mild cases caught early may respond well to medical management alone, while severe or chronic cases may require more aggressive intervention including surgery. This assessment also helps establish prognosis and allows for realistic discussions with the owner about expected treatment duration and outcomes.

Treatment of otitis media in guinea pigs begins with addressing immediate concerns and may include pain management and supportive care for guinea pigs in significant discomfort. Non-steroidal anti-inflammatory medications safe for guinea pigs, such as meloxicam, help reduce inflammation and provide pain relief. If the guinea pig is not eating well, syringe feeding with Critical Care or a similar recovery formula maintains nutrition and prevents GI stasis. Fluid therapy addresses dehydration if present. The environment should be kept calm and comfortable to reduce stress on the recovering guinea pig. If outer ear infection is also present, ear cleaning may be performed carefully, though this can be painful and may require sedation.

Medical management centers on antibiotic therapy, which must use guinea pig-safe antibiotics. This point cannot be overemphasized: many common antibiotics including penicillins, amoxicillin, ampicillin, cephalosporins, clindamycin, lincomycin, and erythromycin are potentially fatal to guinea pigs because they disrupt the essential gut flora, causing antibiotic-associated enterotoxemia. Safe antibiotic options include enrofloxacin (Baytril), trimethoprim-sulfa, chloramphenicol, and azithromycin. Antibiotic selection should ideally be guided by culture and sensitivity results, but empirical treatment with a broad-spectrum safe antibiotic should begin immediately while awaiting results. Systemic antibiotics are essential for treating middle ear infections, as topical ear medications cannot effectively penetrate to the middle ear space. Treatment courses are typically prolonged, often 4-8 weeks or longer.

Surgical intervention may be necessary for cases that do not respond adequately to medical management or for chronic, recurrent middle ear infections. Bulla osteotomy is a surgical procedure where the tympanic bulla is opened to allow drainage of accumulated pus and debris and to provide access for direct treatment of the infection. This surgery improves antibiotic penetration and allows the immune system better access to clear the infection. Total ear canal ablation with bulla osteotomy (TECA-BO) may be recommended for severe chronic disease affecting the entire ear. These surgeries should only be performed by surgeons with experience in guinea pig surgery. Post-operative care is intensive but outcomes can be very good for appropriate candidates.

Supportive care throughout treatment is essential for recovery. Syringe feeding every 4-6 hours is necessary for guinea pigs that are not eating adequately, as even 24 hours without food can trigger life-threatening GI stasis in guinea pigs. Vitamin C supplementation at 50-100 mg daily supports immune function and tissue healing. Probiotic supplementation helps maintain healthy gut flora during antibiotic treatment. The cage should be kept very clean to reduce bacterial exposure. Stress reduction through a quiet environment and, when appropriate, social contact with bonded cage mates supports recovery. Pain management continues as needed throughout treatment.

Complementary approaches may support primary medical treatment. Anti-inflammatory medications reduce pain and inflammation. Some practitioners use topical treatments in the ear canal if the infection extends to the outer ear, though these alone are insufficient for middle ear disease. Keeping the affected ear clean and dry is important. A warm, comfortable environment supports healing. Maintaining normal routines as much as possible reduces stress. Some owners find that providing extra comfortable bedding and hiding spots helps their guinea pig feel more secure during recovery.

Treatment decisions should be made in partnership with the veterinarian, considering the severity and extent of disease, the guinea pig's overall health and age, the response to initial treatment, the owner's ability to provide necessary care including medication administration and potential syringe feeding, and financial considerations for what may be prolonged treatment. Most guinea pigs with otitis media respond well to appropriate treatment, though some require extended courses of antibiotics or surgical intervention. In cases where disease is very advanced or the guinea pig is suffering despite treatment, quality of life considerations may lead to difficult decisions.

The recovery timeline for otitis media in guinea pigs depends on the severity and duration of infection before treatment began, the underlying cause, and how well the guinea pig responds to treatment. Improvement in clinical signs such as reduced head shaking and improved appetite may be seen within the first one to two weeks of antibiotic therapy. However, complete resolution of middle ear infection typically requires prolonged treatment, usually 4-8 weeks minimum, and some cases require even longer courses. Follow-up imaging may be recommended to confirm that changes in the tympanic bulla are resolving. The veterinarian will guide decisions about treatment duration based on clinical response and any repeat diagnostics.

Post-treatment care remains important throughout recovery and beyond. Antibiotics must be given for the entire prescribed course, even if the guinea pig seems to have improved, as stopping treatment early can allow infection to recur and potentially become resistant. Regular veterinary rechecks, typically every 2-4 weeks during active treatment, monitor progress and allow treatment adjustments. Nutritional support continues until the guinea pig is eating well on its own. Vitamin C supplementation continues indefinitely at maintenance doses. The cage environment is kept clean to reduce bacterial exposure. Close monitoring at home watches for any signs of recurrence or complications such as the development of vestibular symptoms suggesting spread to the inner ear.

Prognosis for otitis media is generally good when the condition is caught early and treated appropriately, before spread to the inner ear. Factors influencing prognosis include the duration of infection before treatment, the severity of bulla changes on imaging, whether inner ear involvement has developed, the guinea pig's overall health and immune function, and compliance with the treatment regimen. Guinea pigs whose middle ear infection is caught and treated before inner ear involvement typically have excellent outcomes. Cases that have progressed to involve the inner ear or have developed chronic bony changes carry a more guarded prognosis.

The long-term outlook for guinea pigs that recover from otitis media is generally favorable. Many guinea pigs recover completely with no lasting effects. Some may have residual hearing impairment if middle ear structures were damaged, though this is often not obvious in daily life as guinea pigs rely heavily on other senses. Recurrence is possible, particularly if predisposing factors such as chronic outer ear disease or respiratory infections are not addressed. Guinea pigs that have had otitis media should receive regular veterinary monitoring and owners should be vigilant for any signs of ear problems. With appropriate ongoing care, most guinea pigs that recover from middle ear infection go on to live normal, comfortable lives.

Primary prevention of otitis media focuses on preventing the infections that lead to middle ear disease and maintaining overall ear health. Since middle ear infection usually develops from outer ear infection or respiratory infection, preventing these conditions is key. Excellent husbandry practices form the foundation of prevention: keeping the cage clean with regular spot cleaning and bedding changes, using appropriate non-dusty bedding materials, and maintaining good environmental conditions. Regular ear checks allow early detection of outer ear problems before they can spread to the middle ear. Prompt treatment of any ear discharge, head shaking, or other signs of ear problems prevents progression to more serious disease.

Environmental prevention involves optimizing the guinea pig's living conditions to minimize infection risk. The cage should be cleaned frequently with spot cleaning daily and complete bedding changes at least weekly. Appropriate bedding such as paper-based products or fleece should be used, avoiding dusty materials and aromatic wood shavings that can irritate the respiratory tract and ears. Temperature should be maintained between 65-75°F with moderate humidity. Good ventilation without drafts prevents buildup of ammonia and airborne pathogens. The cage should be located away from sources of stress and environmental irritants. Overcrowding should be avoided as it increases stress and disease transmission.

Dietary prevention supports immune function to help the guinea pig resist infections. Unlimited timothy hay should form the bulk of the diet, providing essential fiber for digestive and dental health. Fresh vegetables high in vitamin C, such as bell peppers, dark leafy greens, and tomatoes, should be offered daily. A measured amount of quality guinea pig pellets supplements the diet. Fresh, clean water must always be available. Vitamin C supplementation of 25-50 mg daily is recommended for all guinea pigs since they cannot synthesize this essential nutrient. Adequate vitamin C is crucial for immune function, and deficiency significantly increases susceptibility to infections of all types.

Regular health maintenance helps prevent ear problems and catch them early when they do occur. Guinea pigs should have wellness examinations with an exotic veterinarian at least annually, with more frequent visits for senior animals or those with health issues. Ears should be examined at each veterinary visit. Any signs of ear problems, including head shaking, scratching, discharge, or odor, warrant prompt evaluation. Respiratory infections should be treated promptly and completely, as they can lead to middle ear infection via the Eustachian tube. Maintaining dental health is important as dental problems can sometimes contribute to ear issues. Quarantine protocols when introducing new guinea pigs help prevent introducing infectious diseases.

Early intervention is crucial for preventing outer ear infections from progressing to middle ear disease. If an outer ear infection is diagnosed, treatment should begin immediately with appropriate guinea pig-safe antibiotics. The full prescribed course of medication must be completed even if symptoms resolve early. Follow-up examinations confirm that infection has fully resolved. Any recurrence or treatment failure should prompt further investigation and potentially more aggressive treatment. If a guinea pig has respiratory infection, awareness that this could spread to the ears helps owners monitor for early signs of ear involvement. The key message is that ear problems in guinea pigs should be taken seriously and treated promptly to prevent progression to more serious conditions.

Daily management for guinea pigs being treated for or recovering from otitis media requires attention to their comfort, nutrition, and medication needs. The cage should be kept exceptionally clean to minimize bacterial exposure, with spot cleaning daily and bedding changes every few days during active treatment. Soft, absorbent bedding provides comfort. Food and water should be easily accessible, and favorite foods can be offered to encourage eating in guinea pigs with decreased appetite. Medications must be administered as prescribed, which typically means oral antibiotics given once or twice daily. Many guinea pig owners find it helpful to establish a consistent medication routine, giving medications at the same times each day combined with a small treat afterward.

The home environment should be optimized for recovery. The cage should be located in a quiet area away from loud noises and household bustle that could cause stress. Temperature should be kept stable and comfortable, around 68-72°F. If the guinea pig has cage mates, they should generally be kept together as social support reduces stress and encourages normal behaviors including eating. However, monitoring is needed to ensure the affected guinea pig is not being bullied and can access food and water without competition. If necessary, temporary separation with visual contact provides a middle ground. A hiding house or tunnel provides security.

Maintaining quality of life during treatment is important for both physical recovery and emotional well-being. Guinea pigs being treated for ear infections may feel unwell and behave differently than usual, but efforts to maintain normal routines and positive interactions help. Gentle handling can continue, being careful around the affected ear. Offering favorite foods and treats encourages eating and provides positive interaction. Floor time can continue if the guinea pig seems up to it, in a clean, safe area. Attention to the guinea pig's social needs, whether with other guinea pigs or human companionship, supports recovery.

Ongoing monitoring throughout treatment and beyond helps ensure successful recovery and catches any complications early. Daily observation should note appetite, activity level, any ear discharge, head shaking or scratching, and general demeanor. Any worsening of symptoms, development of new symptoms like head tilt or balance problems, or failure to improve despite treatment should prompt veterinary consultation. Weight should be monitored, with any significant loss reported to the veterinarian. After treatment is completed, ongoing vigilance for signs of recurrence is important, particularly in the weeks immediately following the end of antibiotics.

Caregiver support and resources help owners manage the demands of caring for a guinea pig with ear infection. Online guinea pig communities provide support, advice, and shared experiences from other owners who have dealt with similar situations. Developing a good relationship with an exotic veterinarian provides access to guidance and reassurance throughout treatment. Learning proper techniques for administering oral medications, which many guinea pigs resist, makes daily treatment easier. Keeping a log of medication doses, symptoms, weight, and any concerns helps track progress and provides useful information for veterinary appointments. Recognizing that treating ear infections can be a prolonged process helps caregivers pace themselves and maintain the consistency needed for successful treatment.

Otitis media can affect guinea pigs of any breed, as the condition is primarily caused by bacterial infection rather than genetic factors. No specific breeds have been identified as having significantly higher inherent susceptibility to middle ear infections. However, certain breed characteristics may influence the overall risk of ear problems that could potentially lead to otitis media. Long-haired breeds including Peruvians, Silkies, Coronets, Texels, and Lunkarya have abundant hair that may grow around the ear area, potentially trapping debris and moisture. These breeds require diligent grooming to keep the ear area clean and dry. Regular trimming of hair around the ears can help reduce this risk factor.

Individual factors are likely more important than breed in determining susceptibility to ear infections. Guinea pigs with narrow ear canals, those who produce excessive ear wax, or those with anatomical variations affecting drainage may be more prone to ear problems regardless of their breed. Animals with compromised immune systems from any cause are at higher risk. Respiratory health is a significant factor since bacteria from respiratory infections can spread to the middle ear. Guinea pigs with chronic respiratory issues are at increased risk for ear complications. A history of previous ear problems increases the risk of future episodes. Age may play a role, with senior guinea pigs potentially being more susceptible.

For breeders, maintaining ear health throughout the breeding colony contributes to producing healthy animals. All breeding stock should receive regular veterinary examinations including ear assessment. Guinea pigs with chronic or recurrent ear problems should be carefully evaluated before being used for breeding, as while otitis media itself is not hereditary, conformational factors that might predispose to ear problems could have a genetic component. Excellent husbandry and nutrition throughout the breeding facility supports overall health. Quarantine and health screening for new animals prevents introducing infectious diseases. Long-haired breeds in the breeding program should receive appropriate grooming attention to their ear areas.

Otitis media exists as part of a continuum of ear disease in guinea pigs, closely related to infections at other levels of the ear. Otitis externa (outer ear infection) frequently precedes and accompanies middle ear infection, as bacteria from the outer ear can spread through a compromised tympanic membrane to invade the middle ear. Conversely, otitis media can lead to otitis interna (inner ear infection) if bacteria erode through the bone separating the middle and inner ear spaces. This progression from superficial to deep ear infection is common, and guinea pigs presenting with otitis media often have concurrent outer ear infection and may be at imminent risk for inner ear involvement. Upper respiratory infections are frequently associated, particularly those caused by Bordetella bronchiseptica, as bacteria can ascend through the Eustachian tube from the nasopharynx to the middle ear.

Several conditions can present with symptoms similar to otitis media and may need to be differentiated through veterinary evaluation. Otitis externa alone can cause similar symptoms of head shaking and ear discomfort but does not involve the middle ear structures. Dental disease, particularly affecting the molars, can cause referred pain to the ear area and changes in eating behavior. Ear mites, though uncommon in guinea pigs, can cause ear irritation. Foreign bodies lodged in the ear canal cause localized inflammation. If vestibular signs are present, inner ear disease or central nervous system conditions must be considered. Tumors affecting the ear region are possible, particularly in older guinea pigs.

Potential complications of otitis media include progression to otitis interna with resultant vestibular dysfunction, which is the most common serious complication. Hearing loss can result from damage to the tympanic membrane and ossicles, fluid accumulation in the middle ear, or extension to the cochlea. Facial nerve paralysis can occur if the infection involves the facial nerve where it passes through the middle ear region, causing drooping of the lip or eyelid. Chronic otitis media can lead to permanent scarring and bony changes in the tympanic bulla. Rarely, infection can extend to involve bone (osteomyelitis) or, in severe cases, spread intracranially to cause meningitis or brain abscess. Long-term antibiotic therapy carries a risk of disrupting gut flora, necessitating probiotic support during treatment.