We have recently had quite a few reports of people finding worms on their pets, not just tape worm larvae on their bedding from ingesting fleas, but actual worms found protruding from the surface of their pet’s skin. So, this month we are just going to go over a few more types of worms or parasites. I know it’s everybody’s favorite gross topic!! Next month, we will be sure to talk about something cute and cuddly!
A parasite is any living thing that lives in, on, or with another living thing or host and depends on the host for its food and shelter. Some parasites depend on a host for their entire life while other parasites depend on a host only during a certain part of their life. Many worms are parasites that can infect dogs, cats, horses and other animals. Some of these worms may also infect people.
Dr. Gabbard has what I call a “Scary Specimen Collection”. Often in the spring we find cuterebra larvae that are kept for show and tell. The Cuterebra fly is a large non-biting fly that looks like a bee and lays its eggs on rocks or vegetation located near the openings of rabbit or rodent burrows. Some reports have suggested that eggs can be found in garden mulch that has been obtained near such areas. The rabbit or wild rodent are the normal hosts and can pick up these eggs on their coats and ingest them during grooming. Cats and dogs may also be exposed in the same manner. Eggs hatch once they are exposed to warm body temperatures of their cat or dog host. The larva migrates to an area under the skin of the pet, typically on the head, neck or trunk. A cyst or thick capsule is created under the skin as the larva grows. A circular breathing hole may appear as an open wound. There is often fluid drainage from the opening and if the pet has a long-hair coat, you may notice an area of matted hair that appears to irritate the pet causing excessive grooming at the site. Removal or treatment of the cuterebra should be performed by your veterinarian so the larvae can be removed in one piece. It is important not to squeeze it. You may cause damage to the larva and release harmful chemicals into your pet’s circulation. Your pet can experience repeated and chronic infections if any part of the larva is left behind. Limit your pet’s exposure to areas around rabbit and wild rodent nests or burrows to avoid Cuterebra infection.
Myiasis is the term used to describe a maggot infestation. Maggots are fly larva that feed on necrotic and dying tissue. Pets confined to the outdoors with situations in which their skin remains moist are more likely to be exposed. This includes pets with draining wounds, urine or fecal stained hair coats, or bacterial skin infections. This applies especially to weak and debilitated pets (for example: a female dog just giving birth to a litter of pups could have very moist bedding as an outside dog). The majority of maggots found on pets are larva from blowflies. The blowfly lays many eggs on decaying, infected or inflamed tissue. In warm moist weather, the eggs hatch within 24 hours. The cone shaped larva uses its specialized mouth parts to lap up liquids and pierce the skin. After feeding and maturing for 5-7 days, the maggots leave the animal and enter the soil. Then, adult flies emerge a few weeks later. Some maggots only invade dead or dying tissue but some do not know when to stop and start feeding on healthy tissue causing extensive damage.
One of our clients reported finding a worm in her dog’s water bowl and the same type of worm had been found on the floor in vomit. Horsehair worms can be found in streams and other still waters such as puddles, ponds, bird baths, toilets, pet dishes, sinks and domestic water supplies. They may occur in knotted masses or as a single worm. These long, thin, brown to blackish worms can measure 1/25 inch in diameter and may reach 1 foot or more in length. Water-inhabiting insects such as mosquitoes and tadpoles ingest the preparasitic larvae. When horsehair larvae are ingested by these organisms, they enclose themselves in a cyst like structure in the host’s body cavity and remain encysted as this initial host develops into an adult. If an insect such as a grasshopper, cricket or beetle consumes the first host with an encysted horsehair larva, the worm emerges from the cyst and completes its development in the second host. About three months after the horsehair worm parasitizes a host, the host is compelled to seek out water. When the host enters the water, the mature worm emerges. Adult worms are free-living in water and don’t feed but they can live many months. They can spend the winter in water or mud and the cycle repeats itself the following spring. Although these worms may look harmful, they are not parasitic to humans, pets or plants. Domestic water supply systems should be filtered, chemically treated, and inspected for necessary repairs, especially when the homeowner discovers horsehair worms in wash water, bathtubs or sinks. Morever, it isn’t unusual to find horsehair worms in the home in such places as shower stalls or toilets where crickets may die and worms emerge into the water. Prevent nuisance insects such as crickets, which are known hosts, from entering the home by caulking or sealing entryways.
Another one of our clients reported that there was a worm coming out of her dog’s leg. At first we thought she must be mistaken. When she arrived for her appointment, to our surprise, there was actually a worm embedded in the patient’s leg. We carefully removed said worm and submitted it to the state lab where it was speciated as a Dracunculus worm. A Dracunculus worm is a species of roundworm found mainly in the connective tissue beneath the skin of the legs. They are known to infect raccoons, minks and other animals including dogs in North America. Female worms can reach 10 feet in length. (Yes…we said 10 FEET!!) Male worms are tiny in comparison at around 0.6 inches long. These worms can produce skin ulcers on their hosts. When the ulcers touch water, the worms stick their heads out of the wounds in order to birth their long, thin-tailed larvae. The larvae then develop inside of another host, the water flea. Dogs can also become infected when they drink contaminated water or eat another host, such as a frog. Signs of a Dracunculus worm infestation include swollen tracks under the skin and crater-like red ulcers on the skin’s surface. These infections are rare, but have occasionally been found in dogs that have been around small lakes and shallow, stagnant water. Veterinarians treat the infection by carefully and slowly extracting the parasites. Antiparasitic drugs can also be useful. In parts of Africa, Asia, and the Middle East, a guinea worm (Dracunculus medinensis) is a well-known parasite of humans that may also infest dogs and other animals. We have heard reports of pet owners removing these parasites themselves as they are emerging from their pets leg and I cannot stress enough how important it is to have a veterinarian assist with the removal process.
Pelodera dermatitis is a rare skin worm infestation that causes a short-term skin infection caused by larvae of roundworms known as Pelodera strongyloides. These larvae are widespread in decaying organic matter and on wet soil. In most cases, animals are exposed to the larvae through direct contact with infested materials such as damp, dirty bedding. Animals with healthy skin are not usually at risk of infection. The sores usually appear on parts of the body that come in direct contact with the infested material such as the legs, groin, abdomen and chest. Often there is severe itching, scratching, skin redness, missing hair. Veterinarians can treat the condition and usually make a definitive diagnosis by examining a skin scraping under a microscope to check for worm larvae. So be sure your pet has a dry area with clean bedding.
Did you know?…..
Many people see the Universal Veterinary symbol (see left) and they think that it is a Snake wrapped around a stick. But did you know that it is actually supposed to be a Dracunculus worm? The worm emerges from painful ulcerous blisters. The blisters burn, causing the patient to immerse the affected area in water to cool and soothe it. The worm senses the temperature change and discharges its larva into the water. The traditional treatment was to slowly pull the worm out of the wound over a period of hours to weeks and wind it around a stick.