Loobani AcademyAbstract
Otitis externa is a common disease of the ear canal in dogs and cats, especially in the hot, rainy summer, more prone to infection, sometimes accompanied by auricle disease or otitis media. It often causes the affected animal ear itching, ear pinna and ear canal erythema, ear secretion (earwax) excessive and smelly, severe may be purulent and stink, and even hyperplasia blocked ear canal. This case was presented with fever by otitis externa, which is rare. Through the analysis and report of this case, looking for the regularity of otitis external, analyzes the pathogenic factors of otitis shallow such as parasites, fungi, bacteria, foreign bodies, etc., understands the characteristics and frequency of the incidence of otitis external in dogs and cats, studies and discusses treatment plans, and provides help for clinical diagnosis and treatment of otitis external in dogs and cats.
Key words：Canine,otitis externata ,fever,ear mites
Basic information
Name： A JIN
Breed： Golden Retriever
Sex： Male (no-castrated)
Age：2 months old
Body weight：4.5 kg
The owner feeds him at home without contact with other animals and humans. Bought from the pet shop one week ago, the dog appeared to have shortness of breath, loss of appetite, and weakness. The owner found it in a low spirit than usual. So decided to take him to the hospital. Vaccination history still needs to be completed.
Physical examination：
Body weight 4.5 kg， temperature 39.9℃， respiratory rate was 90/min、, heart rate：20 beats/min. Heavy and unclear murmurs in breathing. Mouth mucosa was pink， capillary refill time（CRT）=2s, and body condition score（BCS）was 5/9, which can touch the ribs in palpation. The patient presented with mild depression situation. Overall, the hair is dry, with mild dandruff, mild flushing in both ears, a small amount of dry cerumen, and a normal auricle. The dehydration was evaluated at 5%. In palpation, the rate of the femoral artery was equal to the heart rate.
Laboratory examination
Complete Blood Count (CBC) examination
Project | Result | Reference Range |
WBC | 18.2×103/uL | 6.0~17.0 |
RBC | 5.97×106/uL | 5.5~10 |
HGB | 2.8g/dL | 12.0~18.0 |
HCT | 35.4% | 37~55 |
MCV | 60.2fL | 60~77 |
MCH | 19.2pg | 19~24.5 |
MCHC | 32.5g/dL | 30~37 |
PLT | 225×103/uL | 200~500 |
LYM% | 7.9% | 12~30 |
OTHR% | 92.4% | 60~86 |
EO% | 4.4% | 2~10 |
LYM# | 0.4×103/uL |
|
OTHR# | 12.6×103/uL |
|
EO# | 0.3×103/uL |
Interpretation:There was a mild increased in the WBC and OTHER%. Red blood cell count is normal.
Idexx Catalyst biochemistry CHEM17
Project | Result | Reference Range |
ALB | 2.8g/dL | 2.3-4.0 |
ALT | 102U/L | 10-100 |
ALKP | 200U/L | 23-212 |
AMYL | 643U/L | 500-1500 |
BUN/CREA | 10 | |
UREA | 7.1mg/dL | 7-27 |
CREA | 1.7mg/dL | 0.5-1.8 |
GGT | 0U/L | 0-7 |
LIPA | 553U/L | 200-1800 |
PHOS | 0.97mg/dL | 2.5-6.8 |
TP | 6.5g/dL | 5.2-8.2 |
TBIL | <2mg/dL | 0-15 |
GLOB | 3.0g/dL | 2.5-4.5 |
ALB/GLOB | 1.0 | |
GLU | 5.85mg/dL | 74-143 |
CHOL | 3.43mmol/L | 2.84-8.26 |
CA | 2.50mmol/L | 1.98-3 |
Interpretation: There was a noticeable increase in ALT, which is a cue for the cell injury.No apparent abnormalities in other biochemical indicators.
The result of the CRP testing
Project | Result | Reference Range |
CRP | 40 mg/L | <10mg/L |
Interpretation: The result of CRP was higher than usual.
The PCR result of infectious examination
The microscope and otoscopy of ears
Picture 1.There were a lot of Malassezia in ear canal secretion cytology, but no bacteria and white blood cells was seen.
Picture 2.Hand-held otoscopy showed flushing of the ear canal wall, a small amount of earwax, a crawling ear itch mite, and an intact eardrum
Diagnosis
Canine otitis externa, Malassezia infection, ear mite infection
The diagnosis methods in Canine otitis externa usually used in veterinary clinical consist of the physical examination findings or history, laboratory examination such as complete blood count, cytology of ear canal, and otoscopy.
Some clinical signs are common, such as afebrile, alopecia, central nervous system(CNS), cutaneous crusts, ulcers, dermatitis, hematoma of the ear, pain, head shaking, pruritus, and fever.The main etiology is malassezia spp. And the breed predilection includes:
- An American cocker spaniel.
- Gold retriever.
- English springer spaniel.
- Labrador retriever.
- Wachtelunhd.
- Welsh springer spaniel.
- Wirehaired is pointing to griffin.
There is no sex predilection in this disease. Fever is not a common symptom of this disease. After excluding the usual infectious disease, it was considered acute inflammation in this case. And the fever was controlled after the treatment.
Treatment
SPECIFIC THERAPY
Treatment of related causes
Specific treatments must be made for related causes (e.g., ear mites, atopic reactions, food allergies, hypothyroidism, immune-mediated diseases, keratosis disorders, etc.), significant, and persistent factors.
1、Clean the ear with Chlorhexidine twice a day
2、Oridermyl(nystatin) after cleaning the ear for external using
3、Amoxicillin clavulanic acid 20mg/kg q.d
4、0.9%NaCL 150ML for subcutaneous injection
Tips：
Ear Cleaning
Ear canal cleaning is an essential step in the treatment of otitis externa. Debris in the ear canal can disable some topical medications; Prevent drugs from touching the external auditory canal; And prevent a complete evaluation of the tympanum. Residue protects microbes, perpetuates infections, and contains bacterial toxins, pro-inflammatory mediators, and free fatty acids that stimulate inflammation. If there is only a small or moderate amount of debris and the tympanum is intact, you can teach the owner to clean the ear at home with a mild copper solution/desiccant. Fill the ear canal with the solution and massage for 60 seconds. Then let the pet shake its head to help remove excess solution and debris. Tissue or cotton ball can wipe the residual solution and debris on the ear canal and auricle. Do not use cotton swabs at home, as they can push debris deep into the horizontal ear canal. If a large amount of waste is present or the tympanum cannot be assessed, deep ear cleaning is necessary for the patient under sedation or general anesthesia. Sedation or anesthesia is usually required for a thorough, deep ear cleaning and to obtain an ideal sample for cytology and culture. Deep ear irrigation is performed by looking directly into the ear canal through an otoscope. Earrings, a light bulb syringe, a red rubber catheter attached to the needle, and a tomcat catheter can all be used to remove debris from the root canal. Deep ear cleaning must be done carefully to avoid damage to the ear canal and tympanum. If the tympanum is ruptured, it can be rinsed with warm saline or water.
The choice of ear cleaner:
Wax-dissolving agents are surfactants and detergents emulating waxes and lipids, thereby facilitating their removal. Common sulfur-dissolvers include sodium dioctyl (DSS), calcium sulfosuccinate, squalene, propylene glycol, peroxide carbamate, hexamethyl carbon tetrachloride, and glycerol. Many sulfur-dissolving agents are ototoxic and should not be used when the tympanic cavity ruptures. A study that evaluated four different sulfur-dissolving agents showed that squalene-containing washes did not cause proliferative ear disease. The other three products stopped triethanolamine, propylene glycol, or DSS, which caused proliferative changes when left in the middle ear. Rinsing the ear canal with water or saline after using the sulfur-dissolving agent can help reduce ototoxicity.
Desiccant is usually added to the solution. They include boric acid, salicylic acid, benzoic acid, acetic acid, lactic acid, and malic acid. Desiccant lowers the pH of the ear, causes keratosis, and has a slight antibacterial effect. The antibacterial activity is related to the presence of isopropyl alcohol, chloromethyl (PCMX), and the low pH of the solution. Chlorhexidine also has antibacterial effects. Tris-EDTA makes antibiotics more effective by inducing changes in membrane permeability. Tris-EDTA is also effective against many Malassezia isolates, and chelating agents can enhance the effectiveness of antifungal agents. In addition to treating bacterial infections, studies have shown that some cleaners are very active against Malassezia, including CleanAural Dog®, Epi-Otic®, MalAcetic Aural®, Sancerum®, and TrizUltra+Keto.
Topical Therapy
Antifungal drugs: commonly used medications include clotrimazole, ketoconazole, miconazole, Posaconazole, thiabendazole, nystatin, etc. In one study, 80% of yeast were sensitive to miconazole and econazole but moderately resistant to ketoconazole. Another study assessing the sensitivity of M. pachyderma to miconazole and clotrimazole indicated that the bacterium was unlikely to develop clinically relevant resistance.
Systemic Therapy
Anti-inflammatory drugs: Systemic glucocorticoids are beneficial in cases of severe inflammation or edema of the ear canal and are used in a proliferative response that causes lumen obstruction. Prednisone can be administered 0.5-1 mg/kg/day for 2 weeks and then tapered off with oclacitinib (Apoquel®) administered in conjunction with topical combination products shows promise in the treatment of otitis externally in allergic dogs.
The symptoms of breath have been a relief after seven days of therapy
Conclusion
Definition and signalment
One of the most common ailments in dogs in veterinary practice is ear disease. From mild erythema to severe otitis media, about 15 to 20 percent of dog patients and about 6 to 7 percent of cat patients have some ear disease. In humid climates, the incidence of otitis media in dogs is close to 50%. It is estimated that more than half of dogs with chronic recurrent otitis externa also have otitis media. Determining the cause of ear disease is often a difficult task. Currently, it is believed that there is only one kind of ear pruritus mite parasitic on dogs and cats, namely canine ear pruritus mite. The insect body was elliptic, the size of male mites was 0.274 — 0.362mm, and that of female mites was 0.345 — 0.451mm.
Mouthparts are short and conical. There are four pairs of long feet. The ends of each couple of feet of male mites and the first and second pairs of feet of female mites have suckers with handles. The handles are short and have no nodes. The fourth pair of female mite feet is underdeveloped and cannot extend out of the body edge. The tubercles at the posterior end of the male mite body were underdeveloped. Each tubercle had four long, four short, and four bristles, and there were two obscure anal suckers in front of the tubercles. The egg is white and oval; one side is relatively straight, the length between 166 — 206um. The development of pruritus auricularia is incomplete metamorphosis, which goes through four stages: egg, larva, nymph, and adult—Parasitic on the surface of the skin and the external ear canal. After mating, the female produces eggs, which adhere to the ear canals of dogs and cats by laying secretions.
Depending on the temperature of the environment, the time it takes for the mite to develop from egg to adult varies. It takes 13 to 15 days in the warm season and three weeks in the cold season. The survival time of pruritus auricularia was longer when the relative humidity was higher. The mite can survive for months at a temperature of 35 degrees Celsius and a relative humidity of 80%. Animals can also become infected through indirect contact with the ear itch mite that lives in the environment. Ear mites, parasitic dogs, and cats generally have foul ears. Dogs always keep scratching the ear, ear wax in particular. The severe inner ear has the phenomenon of redness and fever, light, not redness and fever. Generally, big-eared dogs, lop-eared dogs, and long-eared dogs are more common. Ear itch mites mainly cause ear canal mite infections in dogs and cats. As shown in Figure 2, the ear canal of infected animals is pruritus severely, which often scratches the outer ear, face, and neck. It is contagious, and severe cases may lead to otitis media. Secondly, as shown in FIG. 3, scabies infestation will result in the outer ear margin’s proliferation and increased dander. The female mite digs a tunnel, burrows into the skin, and lays eggs in the tunnel after finding the right site, which will cause extreme itching, sleep, food insecurity, increased dander, rough coat, and often secondary bacterial infection.
Prognosis
Patients treated for otitis externa need to be revisited frequently, and the ear cytology evaluated to determine if a change in treatment is required. Major factors must be adequately controlled. Otherwise, otitis will recur. Common causes of treatment failure include failure to identify and address significant and persistent factors; Improper ear cleaning; Inappropriate treatment; Treatment time is not enough.
Otitis exterior in dogs and cats is one of the most common clinical cases. Over-intensive pet rearing, abuse of antibiotics, and excessive nutrition intake are the reasons for the increasing incidence of otitis exterior is in dogs and cats. The peak season of otitis exteriors is summer, and there is no significant difference in the incidence of otitis exterior in dogs and cats. According to clinical statistics, the leading causes of the disease were mites, fungi, and bacteria infection; mites were infected with ear drops stolen, ivermectin injection had a noticeable effect, and yellow cedar extract has a dangerous impact, fungal drugs itraconazole, clotrimazole, and ketoconazole had a good product, and drugs with good antibacterial effect included cephalosporins and aminoglycosides.
