Distilled white vinegar has a high acidity level that makes it suitable as a household cleaner. When your pet comes down with a nasty case of the fleas, use that same vinegar to kill the fleas. This is a multi-step process that requires treating the pet in specific ways, as well as treating areas around your house where fleas may have laid eggs.
Pet food treatment
Feed distilled white vinegar to your pets by putting the vinegar directly into the water dish. Mix 5 ml (1 tsp) of vinegar into every 1 litre (1 quart) of water you use in the bowl. It may be helpful to mix a large batch in a jar or old water bottle and keep it on hand to refill the bowl. Shake the jar or bottle first, mixing the vinegar and water before pouring in the bowl. The vinegar works by slightly changing the chemistry of your pet and repelling fleas. Use the mixture even on pets that don't go outside, as other pets can bring fleas into your home.
Homemade flea spray
Dilute the vinegar in a water bottle, mixing equal parts water and vinegar. Spray the mixture in areas where you've seen fleas, including sofas and other upholstered furniture. Spray more of the mixture along skirting boards and around doors where the pests might enter your home. Also use the mixture on your pets' bedding and anywhere the pets sleep or lie.
Apple cider vinegar
Apple cider vinegar works in the same way as distilled white vinegar but has a lighter and fresher scent. Use a mixture of equal parts apple cider vinegar and cold water. Pour the mixture into a spray bottle and spray all over your pets. Apply an even layer of the vinegar mixture onto the pet's coat and let dry. Repeat the process every time the pet goes outside to kill any fleas on the coat.
Bathing your pets
Mix 1 litre (1 quart) vinegar and 3 litres (1 quart) of warm water in a large bucket. Place an old towel in the mixture and ring out the excess liquid. Lightly rub the towel over your pet's coat, making sure you reach all areas of the fur and skin. Keep dunking the towel back in the mixture and ringing out the excess as needed. The mixture soothes the animal's skin, kills fleas and helps repel other fleas.