Paracitology

Rabbit Parasitology

Rabbits (Oryctolagus cuniculus) are affected by a wide range of parasitic organisms, including ectoparasites (mites, lice, fleas, flies), protozoa (Eimeria, Giardia, Encephalitozoon), nematodes (Passalurus, Trichostrongylus, Strongyloides), cestodes (Taenia spp.), and trematodes (rare). The significance of these parasites varies depending on husbandry, geography, and management practices. Some parasites are of zoonotic concern.

External Parasites

Fleas (Ctenocephalides felis, Spilopsyllus cuniculi)

Etiology (cause)

Fleas may infest rabbits housed with cats, dogs, or in outdoor environments. The cat flea (C. felis) is most common; the rabbit flea (S. cuniculi) is more regionally distributed.

Clinical Signs

- Pruritus, scratching, alopecia, dermatitis - Flea dirt visible in fur - In severe cases: anemia in young rabbits

Treatment, Prevention, and Control

- **Selamectin (kitten Revolution®)**: Effective against fleas, ear mites, fur mites, mange mites (off-label in rabbits) - **Imidacloprid (Advantage®)**: Safe and effective spot-on flea treatment in rabbits ≥10 weeks old - Treat environment with insect growth regulators (lufenuron) and vacuuming to remove eggs/larvae - Avoid pyrethrin/permethrin products due to resistance and potential toxicity

• Reference:* Hutchinson MJ, Jacobs DE, Bell GD, et al. Evaluation of imidacloprid for the treatment and prevention of cat flea (Ctenocephalides felis felis) infestations on rabbits. Vet Rec. 2001;148(22):695-696. doi:[10.1136/vr.148.22.695](https://doi.org/10.1136/vr.148.22.695)

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Ear Mites (Psoroptes cuniculi)

Etiology (cause)

Highly contagious mite transmitted by direct contact or contaminated fomites.

Clinical Signs

- Thick crusts and exudate in ear canals - Head shaking, scratching, pain - Secondary bacterial otitis possible

Treatment, Prevention, and Control

- Selamectin or ivermectin (topical or injectable) are effective - Avoid mechanical debridement of crusts (painful and risks tympanic rupture) - Quarantine and treat all in-contact rabbits

• Reference:* Papini R, et al. Clinical efficacy of ivermectin against Psoroptes cuniculi in naturally infested rabbits. Vet Parasitol. 1997;68(1-2):149-153. doi:[10.1016/S0304-4017(96)01053-5](https://doi.org/10.1016/S0304-4017(96)01053-5)

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Mange and Fur Mites (Cheyletiella parasitovorax, Sarcoptes scabiei)

Etiology (cause)

- Cheyletiella parasitovorax ("walking dandruff") is common in pet rabbits - Sarcoptes scabiei rare but severe, zoonotic potential

Clinical Signs

- Scaling, dandruff-like debris - Alopecia, pruritus - Weight loss in severe infestations

Treatment, Prevention, and Control

- Ivermectin or selamectin effective for both - Environmental cleaning essential - Sarcoptic mange requires aggressive treatment and zoonotic precautions

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Lice (Haemodipsus ventricosus)

Etiology (cause)

A sucking louse occasionally found in outdoor rabbits.

Clinical Signs

- Pruritus, scratching - Pale mucous membranes in heavy infestations (blood loss)

Treatment, Prevention, and Control

- Ivermectin, selamectin, or imidacloprid effective - Environmental decontamination recommended

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Flystrike (Myiasis)

Etiology (cause)

Caused by blowflies (Lucilia sericata, Calliphora spp.) laying eggs on soiled fur or wounds. Larvae invade tissue.

Clinical Signs

- Visible maggots - Necrotic skin, foul odor - Shock, toxemia, rapid death

Treatment, Prevention, and Control

- Emergency: clip fur, remove maggots, wound care, systemic antibiotics - Prevent with strict hygiene, prompt treatment of diarrhea/urine scald - Commercial protectants (cyromazine, rear-guard products) can reduce risk

• Reference:* Thomas J, et al. Blowfly strike in rabbits: an emerging welfare concern. Vet Rec. 2013;172(19):502. doi:[10.1136/vr.f3039](https://doi.org/10.1136/vr.f3039)

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Protozoal Parasites

Coccidiosis (Eimeria spp.)

Etiology (cause)

- Multiple species infect rabbit intestine and liver (E. stiedae hepatic; E. intestinalis and others intestinal). - Fecal-oral transmission.

Clinical Signs

- Diarrhea, poor growth, dehydration - With hepatic species: hepatomegaly, jaundice, weight loss

Treatment, Prevention, and Control

- Sulfonamides (sulfadimethoxine, trimethoprim-sulfa) - Toltrazuril effective in some studies - Sanitation critical; sporulated oocysts resistant in environment

• Reference:* Pakandl M. Coccidia of rabbit: a review. Folia Parasitol. 2009;56(3):153-166. doi:[10.14411/fp.2009.019](https://doi.org/10.14411/fp.2009.019)

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Encephalitozoonosis (Encephalitozoon cuniculi)

Etiology (cause)

Microsporidian protozoan, transmitted vertically or via urine. Zoonotic.

Clinical Signs

- Head tilt, ataxia, seizures - Ocular lesions: phacoclastic uveitis, cataracts - Chronic renal disease

Treatment, Prevention, and Control

- Fenbendazole (20 mg/kg PO daily for 28 days) - No complete cure; management and supportive care important - Prevent by testing and culling carriers in breeding colonies

• Reference:* Wasson K, Peper RL. Mammalian microsporidiosis. Vet Pathol. 2000;37(2):113-128. doi:[10.1354/vp.37-2-113](https://doi.org/10.1354/vp.37-2-113)

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Giardia spp.

Etiology (cause)

Flagellated protozoan, occasionally infects rabbits. Fecal-oral spread.

Clinical Signs

- Often asymptomatic - Soft stools, weight loss, poor growth in some cases

Treatment, Prevention, and Control

- Fenbendazole or metronidazole may be effective - Sanitation and water hygiene are key

• Reference:* Read CM, et al. Giardia duodenalis: genetic diversity and zoonotic potential. Infect Genet Evol. 2004;4(1):13-25. doi:[10.1016/j.meegid.2003.11.001](https://doi.org/10.1016/j.meegid.2003.11.001)

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Helminths (Worms)

Pinworms (Passalurus ambiguus)

Etiology (cause)

Common rabbit intestinal nematode, usually subclinical.

Clinical Signs

- Perianal irritation, restlessness - Rarely diarrhea

Treatment, Prevention, and Control

- Fenbendazole, oxibendazole, or pyrantel pamoate - Routine deworming not required unless clinical

• Reference:* Gregory MW, Catchpole J. Oxyuroid parasites of the rabbit. J Helminthol. 1989;63(3):253-260. doi:[10.1017/S0022149X00009325](https://doi.org/10.1017/S0022149X00009325)

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Strongyloides spp.

Etiology (cause)

Occasionally infects rabbits in tropical/subtropical environments. Larvae penetrate skin or are ingested.

Clinical Signs

- Diarrhea, weight loss, dermatitis - Rare in intensive rabbitries

Treatment, Prevention, and Control

- Ivermectin effective - Hygiene and prevention of contaminated bedding important

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Trichostrongylus spp.

Etiology (cause)

Grassland nematode occasionally infecting rabbits grazing outdoors.

Clinical Signs

- Gastroenteritis, diarrhea, weight loss - Anemia possible

Treatment, Prevention, and Control

- Fenbendazole or ivermectin - Avoid grazing on contaminated pasture

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Obeliscoides cuniculi

Etiology (cause)

Stomach worm occasionally reported in rabbits in North America.

Clinical Signs

- Gastritis, reduced feed efficiency - Often subclinical unless heavy burden

Treatment, Prevention, and Control

- Benzimidazoles (fenbendazole, oxibendazole) - Control with pasture management in outdoor systems

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Tapeworms (Taenia pisiformis)

Etiology (cause)

Dogs and foxes are definitive hosts. Rabbits are intermediate hosts; larvae (cysticerci) encyst in liver and peritoneum.

Clinical Signs

- Often asymptomatic - Heavy infestations: liver damage, weight loss, sudden death

Treatment, Prevention, and Control

- Prevent by controlling dog/fox access to rabbit areas - Praziquantel may be effective, though data limited

• Reference:* Wang CR, et al. Cysticercosis in rabbits: a survey in China. Vet Parasitol. 2006;135(3-4):335-339. doi:[10.1016/j.vetpar.2005.10.013](https://doi.org/10.1016/j.vetpar.2005.10.013)

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Trematodes (Flukes)

Rare in rabbits. Isolated cases reported with *Fasciola hepatica* and *Dicrocoelium dendriticum* in outdoor-grazing animals.

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References

• Hutchinson MJ, Jacobs DE, Bell GD, et al. Vet Rec. 2001;148(22):695-696. doi:10.1136/vr.148.22.695
• Papini R, et al. Vet Parasitol. 1997;68(1-2):149-153. doi:10.1016/S0304-4017(96)01053-5
• Pakandl M. Folia Parasitol. 2009;56(3):153-166. doi:10.14411/fp.2009.019
• Wasson K, Peper RL. Vet Pathol. 2000;37(2):113-128. doi:10.1354/vp.37-2-113
• Read CM, et al. Infect Genet Evol. 2004;4(1):13-25. doi:10.1016/j.meegid.2003.11.001
• Gregory MW, Catchpole J. J Helminthol. 1989;63(3):253-260. doi:10.1017/S0022149X00009325
• Wang CR, et al. Vet Parasitol. 2006;135(3-4):335-339. doi:10.1016/j.vetpar.2005.10.013
• Thomas J, et al. Vet Rec. 2013;172(19):502. doi:10.1136/vr.f3039