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. Dipylidium caninum
3. Taenia spp.
4. Echinococcus spp.

5. Toxocara spp.

6. Nanophyetus salmincola
7. Alaria alata
8. Paragonimus kellicotti

9. Strongyloides spp.

10. Ancylostoma spp.
11. Uncinaria stenocephala

12. Trichuris vulpis

13. Spirocerca lupi
14. Giardia

External Parasites:

15. Fleas
16. Lice
17. Mites
18. Ticks


Active Ingredient
(Brand Name)
Susceptible Parasite(s)
Albendazole (Various)
# 8*, 13*
Carbaryl (Various)
# 15,16,18
Fenbantel (Drontal Plus)**
# 2,3,5,10,12
Fenbendazole (Panacur)
# 3,5,*8,10-12
Fipronil (Frontline)
# 15,18
Imidacloprid (Advantage)
# 15
Ivermectin (Heartgard)
# 1,5*,9,17*
Levamisole (Various)
# 13
Metronidazole (Flagyl)
# 14

Milbemycin oxime (Interceptor)


Piperazine (Various)
# 5
Praziquantel (Drontal Plus)
# 2-4,*6-8
Pyrantel pamoate (Various)
# 5,10,11
Selamectin (Revolution) # 1,15,17,18
Thiabendazole*** # 5,9

* Not labeled for use in these situations.

** Usually combined with praziquantel for treatment of these parasites.

*** Toxic doses of this drug may be required to achieve complete control.


(See the pages on Skin Disease for additional information on the external parasites.)

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

Disease Transmission:

  1. Internal Parasites: Many of the 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 often dirty environments. Non-infected animals ingest feces that contain various parasites. Some internal parasites are spread by insects that bite the animal and spread the disease 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.

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, such as Heartgard, Heartgard Plus, or Interceptor.
  2. Administer flea and tick prevention in problem areas. Effective products may include Frontline or Advantage.
  1. Every 3-12 Months:
  1. Administer additional parasite prevention/treatment for ascarids, tapeworms, strongyles, whipworms, and hookworms. This may include Drontal Plus. The frequency of this treatment is based on the chance of recurring infections and the specific area where the animal resides. See pages F770 and F998 for additional information on parasites.