It is important to realize that each region of the country will have different parasite problems and potentially different prevention/treatment programs. Therefore, it is essential to involve a local veterinarian in all parasite control programs.

Internal Parasites:

1. Dirofilaria immitis

Tapeworms (Cestodes):
2. Taenia spp.
3. Echinococcus spp.
4. Spirometra spp.
5. Dipylidium caninum

6. Toxocara cati
7. Toxascaris leonina

8. Nanophyetus salmincola
9. Alaria spp.
10. Paragonimus kellicotti

11. Aelurostrongylus abstrusus

12. Ancylostoma spp.
13. Uncinaria stenocephala

14. Toxoplasma gondii
15. Cystoisospora spp.
16. Giardia
17. Cryptosporidium parvum**
18. Cytauxoon felis**

External Parasites:
19. Fleas
20. Lice
21. Mites
22. Ticks

Active Ingredient 
(Brand Name)


Carbaryl (Various)

# 19, 20, 22

Clindamycin (Antirobe)


Fenbendazole (Panacur)


Fipronil (Frontline)

# 19, 22

Imidacloprid (Advantage)

# 19

Ivermectin (Heartgard)

# 1, 21*

Levamisole (Various)

# 1*, 11*

Metronidazole (Flagyl)

# 16*

Piperazine (Various)

# 6-7

Praziquantel (Droncit)

# 2-5,8-10

Pyrantel pamoate (Various)

# 6-7*, 12-13*

Selamectin (Revolution)

# 1, 6, 12, 19, 21

Sulfonamides (Various)


* Not labeled for use in these situations


**No effective specific treatment available

Clinical Signs:

  1. Internal Parasites: Signs of disease for the internal parasites are most common in young, very old, or diseased animals. Each infected animal, depending on the parasite or parasites it is infected with, will have different signs of disease. In general, most infections cause weight loss, poor hair coat, and failure to thrive. Some parasites can cause diarrhea, decreased appetite, poor conception rates, and fluid retention. Some animals infected with internal parasites show no signs of disease at all.

  2. External parasites: These infections can cause red/inflamed skin, hair loss, and severe pruritus (itching).

Disease Transmission:

  1. Internal Parasites: Many internal parasites are spread by oral ingestion of the infective stage of the parasite. This commonly occurs when infected animals are kept in overcrowded and/or dirty environments. Non-infected animals may become infected by ingesting feces that contain various parasites at certain stages of their life cycle. Some internal parasites are spread by biting insects that pass the parasite through the bite wound while taking a blood meal.

  2. External Parasites: These parasites are usually spread by direct contact from one animal to another or through a contaminated environment.


  1. Internal Parasites: Many of these infections can be detected using a fecal test. This is done by obtaining a fecal sample and sending it in to a local veterinarian for testing. See page D220 for more specifics.

  2. External Parasites: Actual parasites or the signs associated with infestations can often be observed upon routine examination of the animal. Special cultures, skin scrapings, and/or other testing may be necessary to determine what type of external parasite is causing problems.

Treatment/Prevention: Differences in treatment are based on the common parasite(s) encountered and geographical location. Because of this, the following are a few general suggestions. (It is highly recommended to consult the package insert and a local veterinarian for more specific information.)

  1. Each Month:
  1. Administer heartworm prevention. (ivermectin or selamectin)
  2. Administer flea and tick prevention in problem areas. Effective products include Frontline or Advantage.
  1. Every 3-12 Months:
  1. Administer additional parasite prevention/treatment for roundworms, tapeworms, and hookworms. The frequency of this treatment is based on the risk of recurring infections and the specific area where the animal resides.