That’s why my team came to me recently and asked me to discuss differences in some of the most common tests for pet parasite detection. Through their conversations with clients, my team has learned that the typical pet owner has a limited understanding about parasites and detection tests, even though we consider those subjects fairly routine in our veterinary work. So let me shed light on what we know—and what you need to know as a pet owner.
Diseases that are transferred through bites generally are tested for with a blood sample. Mosquitos and ticks take a blood meal, allowing them to transfer disease to our pets in the process. Deep, penetrating bite wounds inflicted on one cat by another also can introduce infected saliva into the blood stream of the bitten animal.
Some of the diseases that can be detected from a blood sample include: heartworm, tick diseases such as Lyme disease, feline leukemia and feline immunodeficiency virus (FIV). Blood samples for these let us know if the animal’s immune system has been exposed to disease and has mounted a response. When we look at the blood under a microscope, we sometimes can even see organisms in the blood cells or circulating in the blood stream.
Heartworm disease is particularly confusing to pet owners. Mosquitos introduce the heartworm larvae to a pet when taking a blood meal. The larvae then migrate to the blood vessels around the pet’s heart. They mature and reproduce in the blood vessels. But while we typically look for worms in pet feces, heartworm disease is different. We look for this disease in the blood.
Anyone who has raised a puppy or a kitten is probably familiar with the worms found in feces. That’s because intestinal parasites, or worms found in the GI tract, have developed numerous ways to spread in pets. Intestinal parasites can spread to puppies and kittens from their mothers through the placenta, through milk when they are nursing and through eggs shed in feces that contaminate the young animals’ environment.
This is why we recommend deworming all puppies and kittens at two, four, six and eight weeks of age and then starting them on a monthly parasite preventative. Mom and babies should be dewormed on the same schedule. This helps to prevent further contamination of the area where the puppies and living. Adult dogs and cats that have been dewormed also can be re-infected by ingesting eggs from a contaminated environment, eating another animal that has parasite larvae in its tissues or ingesting feces from an infected animal.
One of the misconceptions I hear often is that a pet doesn’t have worms because the owner hasn’t seen any in the animal’s feces. But what these owners don’t realize is that veterinary clinics must check stool samples for worms using a microscope. The miniscule adult worms attach to the lining of the stomach and intestines, where they lay eggs. In general, only if there is an extremely high number of worms would a pet owner see an adult worm with his or her unaided eye. When we check for worms we identify the eggs using the microscope. Then we use the size and shape of the eggs to identify the type of worm or worms present.
We typically recommend annual testing to keep pets healthy and to identify and treat diseases early. The more information and the better understanding that owners have, the more they can advocate for proactive, healthy choices for their pets.