If your vet told you that he or she found rod bacteria in your dog's ears, you my be wondering what this means exactly. When a dog has an ear infection, the vet will take a swab of the gunk that is found in the dog's ear canal. The gunk will then be looked under a microscope so to determine what bacteria is present. If your vet told you that he or she found rod bacteria in your dog's ears, this can be indicative of an ear infection caused by pseudomonas, a particular strain of bacteria which can be challenging to treat.
About Rod Bacteria
When bacteria are looked at under the microscope, your vet will be able to differentiate some types from others courtesy of their diverse shapes. Blessed with a rigid cell wall, bacteria come in different shapes and sizes which makes identifying them under a microscope quite easy.
Bacteria generally fall under three shape variations: rod-shaped bacillus, sphere-shaped cocci and spiral-shaped spirillum. As the name implies, rod-shaped bacteria tend to have a cylindrical shape as the main distinguishing factor. All rod-shaped bacteria are considered bacilli bacteria.
If rods were found in your dog's ears, there are chances that your dog is affected by pseudomonas, which can be resistant to many types of medications, explains veterinarian Dr. Andy. Getting a culture ad sensitivity test when rods are found is important so to determine exactly what type of antibiotics may be needed to kill the bacteria and treat the infection.
Challenging to Treat
While the presence of rods can be suggestive of several different species of bacteria, often rod bacteria are antibiotic resistant and pseudomonas bacteria is something to be concerned about, points out veterinarian Dr. Scarlett.
Pseudomonas are opportunistic bacteria that tend to flourish in an ear where normal, beneficial flora have been wiped out from previous use of antibiotics. This bacteria thrives in moist, humid environments.
Affected dogs tend to have a lot of ear discharge, an odor to the ears, presence of ulcers and erosions along the walls of the ear canal and are often in a lot of pain. Head shaking and ear scratching are common manifestations in affected dogs.
Pseudomonas bacteria tend to be resistant to the use of commonly used ear drops and oral antibiotic treatments. Also, because pseudomonas tend to form biofilms that adhere to the ear's skin surface, the efficacy of ear drops may be reduced. It's therefore important that the ear is cleaned well removing exudate and debris from the ears of affected dogs.
Dog Pseudomonas Treatment
For this type of bacteria, Dr. Scarlett likes to use Baytril Otic along with an ear cleanser called TrizEDTA. TrizEDTA works well in combination with the Baytril because it pokes holes in the bacterial cell wall so that the Baytril can penetrate better.
TrizEDTA therefore is used to pre-soak the ear followed by the Baytril. Baytril is antibiotic made with enrofloxacin and silver sulfadiazine.
Other topical antibiotics often used include neomycin, polymyxin, gentamicin, marbofloxacin, amikacin and ticarcillin. Another ear cleanser option that has good success rates includes Epi-Otic by Virbac which has good antibacterial activity. In one study, the use of Epi-Otic alone used for flushing the dog's ears twice day resolved Pseudomonas ear infectionswithin two weeks in four dogs.
In severe infections, the ear canal can become very swollen and inflamed causing narrowing of the ear canal. In these severe cases, affected dogs may need a course of steroids to reduce the inflammation and swelling.
Affected dogs should be re-checked and the ears should be re-examined again under a microscope to ensure that the dog is responding to treatment. Always consult with your vet for proper diagnosis and treatment.
- Lloyd DH, Bond R, Lamport I. Antimicrobial activity in vitro and in vivo of a canine ear cleanser. Vet Rec 1998;143:111-112.
- DVM360: A recurrent, painful ear infection
- Farca AM, Piromalli G, Maffei F, et al. Potentiating effect of EDTA-Tris on the activity of antibiotics against resistant bacteria associated with otitis, dermatitis and cystitis. J Small Anim Pract 1997;38(6):243-245.
- DVM360: Treatment of Pseudomonas otitis in the dog (Sponsored by Pfizer)
- Picture of pseudomonosa aeruginosa bacteria, Janice Haney Carr Content Providers(s): CDC/ Janice Haney Carr - This media comes from the Centers for Disease Control and Prevention's Public Health Image Library (PHIL), with identification number