Canine Parasites - Little Critters Veterinary Hospital - Gilbert, AZ

Little Critters Veterinary Hospital

1525 N Gilbert Road Suite #C-101
Gilbert, AZ 85234


Canine Parasites

Welcome to the Canine Parasites page at Little Critters Veterinary Hospital, Gilbert, AZ. This comprehensive resource is dedicated to educating pet owners about the various internal and external parasites that can affect dogs. Understanding the impact of these parasites is crucial for maintaining your pet's health and well-being. Our page covers a wide range of topics, from common parasites like fleas, ticks, and mites, to internal threats such as heartworms, roundworms, and tapeworms. We provide insights into the symptoms, risks, and prevention strategies for each type of parasite, emphasizing the importance of regular check-ups and preventative care. At Little Critters Veterinary Hospital, we are committed to helping you protect your canine companions from these unwelcome guests, ensuring they lead happy, healthy lives. Dive into our page to learn more about how to safeguard your pet against these common yet preventable health issues.


Parasites can be both internal and external and the type of potential parasites will vary from one region to another. As an example we see few fleas in Arizona because of our hot and dry climate, but areas higher in humidity often have severe flea infestations requiring year round preventatives.

External Parasites: Include fleas, ticks and mites.

Fleas: These are blood sucking organisms that will feed on your pet’s skin and can be seen moving or jumping through the fur. They can be any place on the dog, but are often present around the face and neck. Fleas will also infect the environment with eggs and larvae. Some pets have an allergy to the flea saliva and become extremely itchy with only a small number of fleas present. Heavy infestations of fleas, especially on small pets, care result in severe anemia. If fleas are crunched and eaten by the pet they can transmit tapeworms – an internal parasite infection. Many products are available for flea control and prevention. The best control involves treating both the pet and the environment. Environmental control should include cleaning and vacuuming all carpet, washing all bedding and spot treating as needed. Also, good flea control requires the use of a product that is both an adultacide (kills adult fleas) and also an insect growth regulator (prevents the development of immature fleas). Many variations exist on how the medication is delivered to the pet. Topical products such as Advantage, Revolution, or Frontline are commonly used and require the placement of a few drops to the skin once monthly. Ingestion of a pill such as Capstar, for treatment and prevention is also available. And lastly, a long acting injection ( lufenuron) is available. Older means of treating external parasites include a variety of insecticides in a dust, dip or shampoo. These insecticides are often carbamate, organophosphate or pyrethrin based and can result in toxicity if used improperly.


  • Fleas infect both the pet and the environment
  • Treatment of the environment and the pet is required to eliminate infestations
  • Fleas can transmit tapeworms to dogs and cats and can also cause anemia and allergies.
  • Flea control should include a product that kills adults and also inhibits development of immature stages (insect growth regulator).


Many different types of ticks are present and the type found in your state may vary from other states. Ticks are small, round, brown, blood sucking insects that will bite the dog and stay stuck on the skin at that location. You will not see them moving quickly as fleas do. With heavy infestations ticks may be seen crawling in the environment, often up walls to ceilings. Also, on heavily infected dogs numerous bumps will be felt when the pet is stroked. Ticks cause numerous diseases such as Lyme disease and E. canis/ tick fever and many others. In Arizona the most common problem we see is tick fever (E.Canis infection) and skin infections, but anemia can also occur especially with puppies that are heavily infested. Often treating the pet is enough to eliminate infection, but if the yard or house is also heavily infested, regular spraying will be needed. Commonly used products for ticks are similar to those discussed above for fleas, with many of the products serving a dual purpose. For more information on tick fever please see my Arizona page.

Prevention is best and there are many safe and effective products available today 

1. Bravecto - A single tablet that last for 3 months

2. Revolution - A once monthly topical 

3. Frontline - A once monthly topical 

Mites (Mange/Skin)

Two types of mites are Sarcoptes (scabies) and Demodex mange mites:

Both types of mites infect the skin of the pet and cannot be seen with the naked eye. They will cause varying degrees of alopecia (hair loss) and pruritus (itchy skin). Typically sarcoptes is thought of as the infectious mange mite spreading easily between dogs, causing severely itchy skin, and even biting humans. Demodex is typically described as the non-infectious mange mite. Pets with demodex are often young dogs with an immature immune system that has allowed a increased number of mites to develop and cause disease. Typically, just a few spots of alopecia are seen, but generalized (whole body) infections can occur and are often seen with very immunosuppressed pets. Diagnosis of both mites occurs by scraping the pets skin with a blade coated in mineral oil and applying it to a slide for microscopic viewing. Demodex is vary easy to diagnose in this way, but scabies can be very difficult to find on a skin scraping and suspected pets are often treated empirically. The topical product, Revolution, is affective at treating scabies, but Demodex is more difficult to treat. Pets with demodectic mange are typically treated with regular Amitraz dips over several weeks until negative skin scrapings occur. The prognosis for both types of mites is good with the possible exception of generalized demodex. Always remember that for most diseases there are a wide variety of possible treatments. My attempt here is to name some of the more common treatments and those which we use at our hospital, however many other medications may be equally effective and all treatments should be discussed with your veterinarian

Internal Parasites

Internal parasites are a large and varied group of organisms that live in various organ systems within the animal. Many, but not all, parasites are located in the intestinal tract but some can also be found in the lungs, urinary bladder, kidneys, heart and other organ systems. Veterinarians will typically look for internal parasite infection by performing a fecal examination with a fecal float. This test mixes feces with a solution that allows eggs in It is important to understand that even if you don’t see worms in your pet’s feces they may still be infected. The parasite may be located in areas other then the gastrointestinal tract or they may not be shedding (laying) eggs yet. Either of these situations would result in a false negative fecal float examination. Because of the potential for a false negative fecal exam and the high incidence of infection in puppies and kittens, most veterinarians will routinely deworm all young pets. Additionally, some of these parasites may pose a health hazard to humans and children in particular which further necessitates a prophylactic deworming program. There are a small number of cases reported in the U.S. each year of children infected with roundworms (called visceral larval migrans) and hookworms (cutaneous larval migrans). Therefore, all puppies and kittens should be dewormed by a veterinarian. It is important that a veterinarian deworm the pet to ensure that the correct drug, dose, and frequency is given. One type of medication will NOT kill all types of worms. Your veterinarian will need to determine what your particular pet is infected with to determine the best treatment.

A few of the internal parasites of dogs & cats include:

1. Nematodes

a. Roundworms

  • Toxocara canis
  • Toxocara cati
  • Toxascaris leonine
  • Baylisarascaris procyonis (raccoons)

Roundworms are a common parasite of puppies and kittens and they can be transmitted to children from the environment (fecal-oral transfer). The roundworm eggs are passed in the pet’s feces and become infectious in the environment (yard). Once in the environment the ova or eggs live for extended periods of time and remain infectious. This organism is very difficult to eliminate from the yard. Therefore, it is recommended that all puppies and kittens complete a deworming program that will kill this parasite. Many medications are effective against this parasite. Most infected animals show no sign of disease. However, some puppies will have a pot-belly from the mass of worms and intestinal blockage is also possible.

b. Hookworms

Anclystoma caninum

Uncinaria stenocephala

Hookworms are another common parasite of dogs and cats. They live in the intestines and eggs are passed in the feces. Severe infections can cause anemia (low red blood cell count) in young animals. The medications effective against roundworms are also effective against hookworms.

c. Heartworms:

Dirofilaria immitis

A parasite that is transferred to the dog or cat by the bite of an infected mosquito. The immature stages of the parasite then travel the pet’s body for about 6 months finally reaching the heart where they infect the pulmonary artery (large blood vessel form heart to lungs) and right atrium of the heart. Heavy infections lead to heart failure. This parasite is most common in areas of the country with high mosquito populations but is thought to be spreading throughout the country. Several cases occur in each year. Theses worms are large worms that can live several years in the heart. If a dog is infected the worms can be killed but the pet may still have problems due to the dead worms in the heart. It is extremely inexpensive and easy to prevent this parasite with a number of products that can be given once monthly. A couple of common products (among the many available) include Revolution applied topically to the skin between the shoulders once monthly and Heartgard chewable pills given once monthly. The medications commonly given to puppies and kittens for roundworms and hookworms do not kill or prevent heart worms. However, both Heartgard and Revolution in addition to other preventatives do include a gastrointestinal dewormer to kill roundworms and hookworms and thus serve a dual function.

Many excellent and very safe products are no available to prevent heartworm infection in dogs. 

Options Include: 

1. Proheart6 - An injection that last 6 months

2. Revolution - A monthly topical product

3. Monthly oral heatworm preventative 

d. Whipworms

  • Trichuris vulpis

Whipworms are uncommon in our area of the country but occur with much higher frequency in warm wet areas such as the south. Whipworms can cause intermittent diarrhea in addition to other signs. Adults live in the cecum and eggs are passed in the feces.

e. Lung worms

  • Capillaria aerophilia

An infection that is uncommon in this area of the country. Adults live in the large airways and lay eggs that are coughed up and swallowed by the dog to pass in the feces. They may cause coughing and are diagnosed by a fecal exam or trans- tracheal wash.

f. Bladder worms

  • Capillaria plica

Adults live in the urinary bladder and eggs are passed in the urine. This worm is an uncommon parasite which may cause signs of urinary tract infection.

g. Stomach worms

  • Physaloptera

Another uncommon parasite that lives in the stomach and eggs are passed in the feces. Diagnosis is by endoscopy or fecal examination. Maybe a rare cause of vomiting.

2. Cestodes: Tapeworms

a. Dipylidium caninum
Dipylidium caninum

A tapeworm that lives in the small intestine and passes proglottids that are reproductive segments which contain eggs. Proglottids look like rice grains often stuck to the pet’s anus or found in bedding. It is important to remember that the pet can only get this parasite by ingesting a flea (commonly) or dog louse (uncommon). Therefore, the pet must also be treated for fleas.

b. Taenia pisiformis

A tapeworm carried by rabbits but NOT passed in rabbit feces. The dog must actually eat the rabbit to ingest this parasite. The diagnostic stage is again the proglottid which looks identical grossly to Dipylidium.

The above is just a sampling of tapeworms, in reality there are many different types. But the important thing to remember is that the many of the common puppy and kitten deworming medications do not kill tapeworms. If you find fleas or proglottids or know that your pet has eaten rabbits or rodents (mice) you should advise your veterinarian.

3. Trematodes: Flukes

Very uncommon in this area of the country but are seen in wet areas such as WA. Pets need to ingest the intermediate host of this parasite to become infected. Hosts include other creatures such as snails, crayfish, frogs, fish… Flukes can carry the organism responsible for Salmon Poising in the Pacific Northwest. These are not seen on standard fecal exams and often require special techniques to find them.

4. Protozoa

Many parasites are included in this group and some are common and other are very rare. Only a few of the more common protozoa are listed.

a. Coccidia

Very common in young puppies. Will cause diarrhea with or without blood and sometimes vomiting is also seen. Requires a fecal examination for diagnosis and is treated with a special antibiotic that also has a good spectrum for protozoa. Not all antibiotics kill this organism. You must contact your veterinarian for diagnosis and proper deworming. The typically deworming medications for young puppies will not eliminate this organism.

b. Giardia

A common organism found in dogs that have been playing in and drinking from ground water contaminated with feces. Fecal contamination of food can also be a source of infection. This parasite is infectious to humans and other animals. Pet’s and people with a weak immune system are particularly at risk. Diagnosis is by serology (in hospital test-kit available) or fecal examination. The infection can be treated by your veterinarian.

c. Toxoplasmosis

This is an infectious organism of cats that has been shown to cause spontaneous abortion in pregnant women. Cats become infected from eating infected rodents or raw meat. Not all cats are infected and not all infected cats will pass eggs in their feces. However, the general recommendation is that pregnant women should avoid handling the litter while pregnant. The best prevention of this is to keep your cats indoors to eliminate hunting and don’t provided raw meat. Diagnosis is by fecal exam or serology (blood testing).

    In conclusion, remember that parasitic infections are treatable conditions and with proper veterinary care your new puppy or kitten will NOT pose a health risk to you or your children. Part of caring properly for your new puppy or kitten must involve a visit to the veterinarian for examination, fecal and deworming.