Canine Dewormer Efficacy Guide
A quick reference for veterinary students.
At-a-Glance Efficacy Chart
| Parasite | Pyrantel Pamoate | Praziquantel | Fenbendazole |
|---|---|---|---|
| Roundworms | |||
| Toxocara canis, Toxascaris leonina | ✔️ | ❌ | ✔️ |
| Hookworms | |||
| Ancylostoma spp., Uncinaria | ✔️ | ❌ | ✔️ |
| Whipworms | |||
| Trichuris vulpis | ❌ | ❌ | ✔️ |
| Tapeworms | |||
| Dipylidium caninum, Taenia spp. | ❌ | ✔️ | ✔️ |
| Echinococcus spp. | ❌ | ✔️ | ❌ |
| ✔️ Effective ❌ Not Effective | |||
Pyrantel Pamoate
Mechanism of Action:
Acts as a depolarizing neuromuscular blocking agent, causing sudden contraction followed by paralysis of the nematodes, allowing them to be expelled from the GI tract.
Notes for Students:
Very safe, even for puppies and pregnant animals. It does not kill the worms but paralyzes them. Does not treat tapeworms or whipworms.
Praziquantel
Mechanism of Action:
Increases the permeability of the membranes of susceptible worms to calcium ions, inducing strong contraction and paralysis, leading to detachment from the host's intestinal wall.
Notes for Students:
The drug of choice for treating most tapeworm infections. Often combined with other dewormers. Flea control is crucial for preventing reinfection with Dipylidium caninum.
Fenbendazole
Mechanism of Action:
Binds to beta-tubulin, disrupting microtubule polymerization in parasite cells. This inhibits cell division and nutrient absorption, leading to parasite death.
Notes for Students:
Broad-spectrum activity against common nematodes, Giardia, and some tapeworms. Treatment for Giardia and whipworms typically requires a longer course (3-5 days). Very safe.
Parasite Reference
| Parasite Type | Common Species | Characteristics & Clinical Relevance |
|---|---|---|
| Nematodes (Roundworms) | Toxocara canis | Large worms. Zoonotic potential (Visceral/Ocular Larva Migrans). Common in puppies. |
| Toxascaris leonina | Less common and less pathogenic. No zoonotic potential. | |
| Nematodes (Hookworms) | Ancylostoma caninum | Blood-feeding, can cause severe anemia. Zoonotic potential (Cutaneous Larva Migrans). |
| Uncinaria stenocephala | Less pathogenic but can still cause anemia. More common in cooler climates. | |
| Nematodes (Whipworms) | Trichuris vulpis | Causes chronic large bowel diarrhea. Eggs are highly resistant in the environment. |
| Cestodes (Tapeworms) | Dipylidium caninum | Most common tapeworm. Requires ingestion of infected fleas. |
| Taenia pisiformis | Requires ingestion of infected rabbits. | |
| Protozoa | Giardia spp. | Causes diarrhea and malabsorption. Often treated with Fenbendazole. |