Canine leptospirosis is caused by an order of bacteria called spirochetes-slender, spirally undulating bacteria. There are at least four species of the leptospira bacteria (or serovars) that can infect dogs: canicola, icterohemorrhagiae, grippotyphosa, and pomona.
Leptospira are found in wild and domestic animals. The bacteria are spread in the urine, often making their way into water sources and remaining infective in the soil for up to six months. Rats, pigs, raccoons, cattle, skunks, and opossums...
Swelling is just one sign of ear problems in dogs. Other symptoms include scratching or wiping the ear against things, head shaking or tilting, odor, discharge, redness, scabs or crust, balance problems, walking in circles, odd eye movements, and hair loss around the ear.
The most common causes of ear swelling in dogs include:
Ear mites. Microscopic parasites that feed on the wax and oils inside your dog's ear, mites are behind most ear problems in puppies and young dogs, though they can happen to any dog, regardless of age.
A serious mite infestation can completely block your dog's ear canal with the coffee-grounds-like debris of the mites. Complications may include ear hematomas -- in which blood vessels rupture from intense scratching and head shaking -- or serious infection.
To treat ear mites, your dog may need a gentle ear cleaning, prescription medication, or insecticidal eardrops. Since ear mites are contagious between cats and dogs, all the pets in your household should be treated. Follow your vet's instructions about how long to treat and when to recheck.
Ear hematomas. These are firm, swollen masses on the inside of your dog's ear flap. They occur when a blood vessel within the ear flap ruptures and bleeding occurs between the tissue layers. Sometimes caused by head shaking or scratching because of ear mites or an infection, hematomas can also be the result something foreign stuck inside your dog's ear.
Treatment for an ear hematoma includes a veterinary exam to find out the cause of the hematoma and draining of the blood to prevent ear deformity and scarring. Surgery is usually necessary to prevent the ear flap from filling up with blood again.
Inner or outer ear infections. These can also cause ear swelling in dogs, as well as discharge, odor, and discomfort. Infections can be the result of a dog bite, a foreign object in your dog's ear, polyps, allergies, water in the ear, and other problems.