Internal and external parasites can be a big annoyance for pets and their owners. With the help of the Cedarburg Veterinary Clinic, your pet can receive diagnosis, treatment and prevention for many parasites.

Heartworm Disease

Heartworm disease is caused by the parasite called Dirofilaria immitis. The adult form lives in the heart and major arteries of the lungs in cats, dogs and other mammals. An adult heartworm produces offspring, called microfilaria, which are picked up by feeding mosquitos and mature into larvae inside the mosquito. When a mosquito carrying D. immitis bites another animal, the larvae are deposited and migrate to the heart of the new host where they develop into adult worms. These adult worms will produce offspring, starting the life cycle over. 


Heartworm disease in dogs can cause difficulty breathing, coughing, vomiting, fainting episodes, exercise intolerance, weight loss, and death. Heartworm disease in cats can cause asthma-like symptoms, sudden death, or may not show any signs at all. Because these symptoms are similar to other diseases, a simple blood test is all that is needed to test for this potentially fatal disease. Always discuss signs and symptoms with your veterinarian before determining if your pet has heartworm disease.



Before treatment, we recommend completing a blood panel and urinalysis to check for organ function, and a radiograph of the chest and an EKG to check for potential heart conditions. Treatment for heartworm disease typically consists of two separate doses of a deep intra-muscular injection of immiticide that kills the adult heartworms. The injection typically can cause discomfort for around 3 days. Your pet will be hospitalized and observed for the duration of treatment. Your pet needs to have very strict exercise restriction during this time, as well as 4 to 6 weeks following the treatment. This means no activity that will increase the heart rate (running, jumping, playing). The pet should be monitored closely for coughing, gagging, lethargy, anorexia, rapid breathing, difficulty breathing, fainting, bloody nose and fever which can all be signs of treatment complications. A secondary treatment is needed to treat your pet for young circulating heartworms at which time your pet will stay at the clinic for the day. The total cost for pre-treatment testing and treatments could exceed one thousand dollars, therefore prevention is much more cost effective and safe for your pet than treating the disease.


There is no available treatment for feline heartworm disease at this time, therefore monthly heartworm prevention is advised. If a cat becomes positive for heartworms, it is recommended that monthly prevention is given in hopes that the adult heartworms will die off without complications.


It is difficult and dangerous to treat heartworm disease when there are adult worms in the heart. It is much safer to prevent heartworm disease than it is to treat. Prevention comes in many forms including chewable tablets, soft chewable medicated treats, or topical liquids absorbed by the skin and are dosed once every month. A 6-month injectable heartworm prevention is now available. Yearly blood testing for heartworm disease is highly recommended to keep your pet healthy. Call the clinic to discuss your pet’s best options for preventing heartworm disease.

Intestinal Parasites

The most common intestinal parasites that infect dogs and cats are roundworms, hookworms, whipworms, tapeworms, coccidia and giardia. These parasites (minus tapeworms) are transmitted by your pet ingesting the eggs or cysts of the parasite which are commonly found in infected dirt or stool. These parasites will then travel through the digestive tract where they will live and thrive in the intestines. Hookworm larvae can also penetrate skin and travel through the bloodstream to the lungs, where they are coughed up, swallowed, and resume their life cycle in the intestines. Some pets can transmit certain parasites to their young in the womb or through nursing. Certain worms can sometimes be seen in the stool, but coccidia and giardia are not visible to the naked eye.

Laboratory diagnosis for these parasites is commonly done by evaluating a stool sample under the microscope after centrifugation and/or flotation. Most of these parasites are zoonotic, meaning they are transmissible from animals to humans. Be sure to practice good hygiene and wash your hands thoroughly after coming in contact with feces.

Tapeworms are flat, segmented worms that also live in the intestines. Segments sometimes break off and are seen in the stool. They often resemble rice grains or sesame seeds. Most tapeworm species do not pass directly to humans or animals from an infected stool, but rather require eating an intermediate host such as a flea, fish, rodent, or uncooked meat.


Depending on the parasite, symptoms can range from diarrhea, soft stool, blood or mucous in the stool, vomiting, weight loss, anemia, decreased appetite, dull hair coat, poor skin condition, pot bellied appearance, or no symptoms at all. Always discuss your pet’s symptoms with a veterinarian before determining your pet is infected with an intestinal parasite.


Depending on the pet and the parasite, most parasites are treated with oral or topical medications.


Since most intestinal parasites are transmitted fecal-oral, the best prevention is to keep your pet away from areas where other animals defecate. To prevent tapeworms, do not allow your pet to ingest rodents or wild animals, and keep your pet flea free. Tablets, chewable medicated treats, and topical liquids are available to help treat and control worm infestations. It is recommended to keep your pet on a form of prevention year round as intestinal parasites can infect your pet during the winter months. It is also recommended to check yearly stool samples, even if your pet is not showing signs of intestinal parasites. Speak with your pet’s veterinarian to help determine the best prevention method for your pet.

External Parasites

There are many types of external parasites that can infest our pets, the most common being fleas and ticks.


Fleas are small brown insects that feed on blood of warm-blooded mammals and birds. A flea’s life cycle involves living on the pet and in the pet’s environment, so treating for fleas once the pet has them can be a difficult task.

Flea Life Cycle

After taking blood from a host (typically cat or dog), the adult fleas will deposit eggs on the host which normally fall off as the animal moves and scratches. After they are left in the environment, in about 2-12 days the eggs will hatch into larvae, feed off the environment, and then spin into a microscopic cocoon. This cocoon will hold the flea larvae from one week to one year. Adult fleas will then emerge from this cocoon and start the life cycle over.

Treatment and Prevention

There are many products available to help prevent and treat fleas that typically come in the form of tablets or topical liquid treatment. Year round prevention is recommended as fleas can still live on wild animals and in household settings during the winter months. As mentioned in the flea life cycle (above), the flea spends time off of your pet, therefore it is imperative to treat your pet’s environment (i.e. your home) or your pet will continue to become infested. Speak with your pet’s veterinarian to find out more information.


Ticks are small parasites that attach onto a host (cat, dog, human, etc.) and engorge themselves with blood. They are typically found in wooded areas, tall grass, indoors living in woodwork, or anywhere that wildlife (such as deer, rodents, rabbits and birds) pass through (including mowed yards). Ticks can cause problems for their host including infection at the attachment site, anemia, and transmission of vector borne diseases. It is highly recommended that your pet is tested for these diseases yearly if he/she is exposed to areas where ticks are prevalent.

Tick Born Diseases

The most common diseases transmitted by ticks around this area include Anaplasmosis, Ehrlichiosis, and Lyme. When a pet acquires any of these diseases, there can be a variety of signs and symptoms that are discussed below, however many pets do not show any symptoms. This is another reason why a yearly blood screen should be completed.

Lyme, Ehrlichiosis and Anaplasmosis

Lyme disease (also known as Borreliosis), Anaplasmosis and Ehrlichiosis are caused by bacteria that is transmitted by ticks. The ticks typically pick up the diseases from wild animals like white-tailed deer and mice and transmit them to domestic animals (including dogs and cats). The tick must attach to the animal in order to transmit the diseases. Ixodes Scaluparis (also known as the deer tick) is the tick that most commonly transmits Lyme disease and Anaplasmosis. Rhipicephalus (or the brown dog tick) is the tick that typically spreads Ehrlichia.

Signs and Symptoms

Physical signs of these diseases can include but are not limited to rash, fever, joint swelling and pain, swollen lymph nodes, alternating limb lameness, fatal kidney disease, anorexia, bloody nose, permanent blindness, vomiting, diarrhea and death, however pets may not show any signs.


The best way to prevent your pet from acquiring a vector born disease is to prevent a tick from attaching. Products to prevent ticks from attaching are available in sprays, topical liquids and collars. Speak with your pet’s veterinarian to determine which prevention is best for your pet. Routinely complete an inspection of your dog’s body by looking under the hair for any ticks that may be present, especially after your dog has been outside. It is also highly recommended to complete a yearly blood screen for these diseases, especially if your pet is exposed to areas where ticks are prevalent.


Demodex are microscopic mites that are normal skin inhabitants, living in the hair follicles of healthy dogs and cats. With a healthy immune system, demodex are kept at a small number and do not cause the animal discomfort. When an animal has a decreased immune system (typically due to illness or stress), the body is unable to keep the mites from proliferating. Once the mites flourish and cause problems, the animal is considered diagnosed with demodectic mange (or demodicosis). Diagnosis is commonly completed with a physical exam, discussion with a veterinarian, and a small skin sample that is analyzed under a microscope. Additional laboratory testing may be required for secondary problems. Demodex are not transmitted from animal to animal, nor animal to human.

Clinical Signs and Symptoms

Physical signs of demodicosis include (but are not limited to) hair loss with possible secondary skin infections that appear red and crusty. Always discuss your pet’s abnormal signs and symptoms with a veterinarian.


Depending on your pet and the severity of the infestation, the veterinarian may choose a topical skin treatment, oral medication, medicated bath or a dip. Some pets may require additional laboratory testing and medication if other problems exist. Follow up checks should be completed and most likely include additional physical exams and skin scrapings to ensure the mites are being controlled.


Since demodicosis occurs when the animal’s immune system is lowered, it is best to complete yearly physical exams and vaccinations to help decrease the chance of your pet becoming ill. Do not allow your pet around other animals that are ill, and try to avoid stressful situations. If your pet has already been diagnosed and treated for demodicosis, there are topical medications that can control the number of mites living on your pet. Speak with one of our veterinarians to find out more information.

Ear Mites

Ear mites, also known as Otodectes cynotis/cyanotis, are very small parasites that live on the skin surface, most commonly in the ear canals. Ear mites are transferred from animal to animal by direct contact. Their entire life cycle from egg to larva to nymph to adult occurs on the host (cat or dog). Diagnosis is normally completed by microscopic examination of an ear swab.

Clinical Signs and Symptoms

Physical signs of an infestation of ear mites include formation of thick reddish-black wax in the ear, crusts that fill the ear canal, head shaking, ear twitching, and rubbing or scratching the affected ear(s).


Treatment starts by thoroughly cleaning the affected ear canals. Your veterinarian will prescribe the appropriate medication to kill the mites. Treatment may take several weeks.


Since mites are transmitted by direct contact, do not allow your pet to come in close contact with another animal that is infested with ear mites. Topical application of the appropriate product may help to treat and control ear mite infestations. Speak with one of our veterinarians for more information.


Often referred to as “walking dandruff”, cheyletiella is a mite that is highly contagious to other animals and can cause dermatitis in humans. They are transmitted by direct contact with an infected animal. Sharing objects, like combs or brushes, and bedding can also lead to infestation. Mites can live in the environment for up to 10 days. Diagnosis is made by taking samples of hair and dandruff and viewing them under a microscope. A mite or mite egg can sometimes be found on a fecal examination.

Clinical Signs and Symptoms

Typically animals with cheyletiella have severe dandruff. Some pets can have hair loss or a greasy coat, or have severe itching.


Depending on the severity of the infection, topical flea and tick preventions can be used to treat minor cases. In more severe infestations, medicated baths maybe indicated. Treating the pet’s environment is also suggested as the mites can live off of the animal.


Cheyletiella is contracted through direct exposure, so keep your pet away from animals known to have cheyletiella. Keeping your pet on a monthly flea and tick prevention will help avoid infestation. Do not share grooming items without disinfecting first.


Sarcoptes or scabies is a disease caused by a mite that burrows directly into the surface of the skin. It is transmitted by direct contact with an infected animal, and people can also be infected. Sarcoptes mites can live in the environment for a few days so items such as blankets, kennels, and brushes can lead to infestation. Diagnosis is made by taking skin scrapings and hair samples, then viewing the samples under a microscope. Occasionally mites can be found in fecal examinations.

Clinical Signs and Symptoms

Intense scratching, scabs and irritated/red skin are typical symptoms. The mites tend to be found on elbows, ears, and abdomen.


Depending on the severity of the infection, topical flea and tick preventions can be used to treat minor cases. In more severe infestations, medicated baths or dips may be indicated.


Because Sarcoptes is spread through direct contact, avoid exposure to animals that could be carriers. Using a monthly topical flea and tick prevention may help to avoid infestation. Avoid sharing materials that could transmit the mites without first disinfecting (grooming supplies, bedding, and crates).