Common Parasites in Dogs


  • Fleas are a small, brown/red, flat-bodied insect with large legs used for jumping.
  • The most common flea is Ctenocephalides felis.
  • Flea bites cause your pet to be itchy and uncomfortable.
  • Animals can get fleas by going outside, OR they can be brought into the house on clothing or other animals.
  • Check animals for fleas by looking for fleas or flea dirt (small specks of “dirt” on your pet’s skin that turn red when placed on wet paper towel).
  • There are many appropriate products for treating fleas, and it is important to treat all animals in the household. Prevention of infestations involves up-to-date use of preventative medications. Contact your veterinarian to determine which product is right for you.


  • Ticks are small, brown arachnids (having eight legs) with no antennae.
  • Many species of ticks can impact dogs. The species present in New Brunswick include the black-legged tick, the American dog tick, and the moose/winter tick.
  • Ticks can transmit a number of diseases, including Lyme disease.
  • Animals most often get ticks when walking through areas with grasses or shrubs.
  • Check animals for ticks by looking at their skin and running your fingers through their fur.
  • If a tick is found on your dog, it must be removed. It can be done at your veterinary clinic or at home. If you are unsure how to remove a tick safely, please contact your veterinary clinic for directions.
  • Prevention of ticks involves up-to-date use of preventative medications. Talk to your vet to determine the right product for you.


  • Demodex are small mites not visible to the naked eye.
  • Demodex mites are present in small numbers on all dogs, most of which never experience related problems.
  • In some dogs that experience immunosuppression (of various causes) these mites can overpopulate and cause skin disease characterized by bald spots +/- scaly skin.
  • The skin disease caused by Demodex mites is not contagious.
  • If your dog is displaying any signs of skin disease, please contact your veterinarian to determine the appropriate course of action.


  • Heartworms (Dirofilaria immitis) are long, thin worms that live in the heart and large arteries.
  • Heartworm infection can cause damage to the heart, lungs, liver, and kidneys.
  • Signs of heartworm infection may include coughing, shortness of breath, and weakness.
  • Heartworm is transmitted through mosquito bites.
  • Screening tests for heartworm can be performed as part of annual wellness and/or if an infection is suspected.
  • Further diagnostic testing may be indicated.
  • The appropriate treatment plan will be determined by your veterinarian. Treatment consists of multiple medications and strict rest.
  • Prevention of heartworm can be achieved by the use of heartworm preventative medication.

Please contact your veterinarian to determine the right product for you.

Written by: Dr. Nicole Mann, DVM