Hepatic and Intestinal Coccidiosis in Rabbits

Coccidiosis in the rabbit is a contagious, lethal, aggressive and common rabbit disease caused by a parasitic protozoan Eimeria spp. There are two types in bunnies, the intestinal and hepatic coccidia.  

This parasitic infection affects rabbits all over the world with the younger ones more affected [1] as well as recently weaned ones with higher mortality and morbidity. This intracellular, single-celled parasite is host-specific with different species affecting domestic rabbits as opposed to hares (Lepus species).[2]

Finally, the infection is common in wild rabbits, with domestic rabbits showing the varying prevalence and the species that affect domestic bunnies are uncommon.

Transmission

Transmission is by oral ingestion of infective sporulate oocysts often found in this pet’s feces if it is infected especially if the sporulate oocysts contaminate their water and food.

These parasites have a direct lifecycle and it involves both sexual and asexual reproduction and they take about two weeks to be complete its lifecycle.

Once an infective oocyst is ingested, it ruptures due to the enzymatic effects (pancreatic and bile) together with the mechanical effect of the upper intestinal tract contradiction releasing sporozoites.

The sporozoites enter the epithelial cell, initiates asexual reproduction forming many merozoites and once the epithelial cell bursts, a larger number of merozoites are released and they invade new host cells.

The last merozoite generation forms gametes and begins reproducing sexually forming oocysts which then detach from the host cells and leaves the host.

Coccidia in rabbit’s symptoms

The symptoms noted will depend on the specific species of Eimeria involved, the number of oocysts ingested as well as whether it is hepatic or intestinal. Common symptoms you may notice include the following:

• Reduced appetite
• Depression
• Anemia characterized by pale mucous membranes that may be watery especially in younger rabbits but may not be present in older ones.
• Bloodstained stools with mucus threads
• Diarrhea
• Poor coat condition
• Retarded growth in young rabbits in case of this protozoan parasite cause effects to the liver and kidney
• Emaciation and retarded growth may also be a problem due to the malabsorption of nutrients inside the small intestines because of these protozoans erode the epithelial lining.
• Electrolyte imbalance - serum analysis reveals an increasing amount of potassium while chloride and sodium decrease, and this is often associated with diarrhea and dehydration.
• “Serum calcium, iron, copper, zinc, and glucose are usually slightly lower than in healthy animals and may indicate malnutrition due to intestinal damage, or secondary bacterial infection.” [3]
• Hematology studies indicate a reduction in total red blood cells and hemoglobin whereas the white blood cells and packed cell volume increase.
• In hepatic coccidia, there is an increase in alkaline phosphate, serum bilirubin, aspartate aminotransferases, alanine aminotransferase as well as gamma-glutamyl transpeptidase values.
• Enlarged abdomen and this animal being thirsty has been noted in hepatic coccidiosis

Having looked at the general symptoms, let us look at each of the two types of coccidia in rabbits before we look at diagnosis, treatment, and prevention.

Hepatic coccidiosis

This type is caused by Eimeria stiedae and the affected rabbits will have dilated bile ducts as well as an enlarged liver. Also, white nodules may be the primary macroscopic lesions.

The infection can be mild or severe with mild cases showing no symptoms while severe cases may lead to weakness, loss of appetite, no normal growth gain, diarrhea, and constipation at its advanced stages.

Blockage and severe liver damage may be noted since the Eimeria stiedae invade bile and liver cells and the disease can last for a longer time or cause death within 10 days.

Intestinal coccidia

In intestinal coccidiosis, these parasites attack the epithelial cells lining the intestinal walls and affects mainly weaned rabbits (aged between 6-20 weeks) with risk factors being a weak immunity, stress (including relocation stress), noise, poor hygiene, poor husbandry, and so on.

It can be very pathogenic, moderately pathogenic or non-pathogenic to slightly pathogenic considering weight gain, mortality rates, and diarrhea. The Eimeria ssp. are responsible for each of the three types are as follows:

• Non-pathogenic to slightly pathogenic - Eimeria media, Eimeria perforans, Eimeria exigua, and Eimeria coecicola
• Moderately pathogenic - Eimeria irresidua, Eimeria piriformis, and Eimeria magna.
• Very pathogenic - Eimeria intestinalis and Eimeria flavescens

Symptoms to expect

You will notice symptoms after 4-6 days after infection and they will include reduced appetite, dehydration, rough coat, dullness and so on. Sometimes, intussusception (one portion of the intestine being inverted in another) may occur.

In case of over 20% weight loss, severe symptoms including paralysis, convulsions, and death after a day may occur. Death is mainly due to dehydration as well as secondary infections.

Diagnosis

Diagnosis may present a challenge in asymptomatic pets (carriers). However, for the symptomatic ones, some clinical signs such as diarrhea, weight loss, enlarged abdomen, and dehydration may be an indicator.

Feces floatation tests may be used to determine the severity of this infection by looking at the number of oocysts per gram of feces. However, fecal matter examination may not distinguish these oocysts from Cyniclomyces guttulatus, a yeast that is specific for rabbits.

Necropsies can be used to tell where the disease is located such as in the large intestines, cecum, liver or small intestines.

In hepatic coccidia, impression liver smear that will be followed by direct microscopy may reveal the presence of oocysts.

Coccidia in rabbit’s treatment – sulfaquinoxaline or ponazuril

Your vet will prescribe antibiotics to deal with any secondary bacterial infection. Usually, anti-coccidial medication is effective in the early stages of infection (less than 6 days from the time of infection).

Hepatic coccidiosis may require administration of anti-coccidial medication such as sulfadimethoxine in water for 30 days or 20 days if in feeds to help reduce clinical signs.

On the other hand, the intestinal one requires antiprotozoals in water for 7 days and then repeated after 7 days to avoid reinfection. Sulfadimethoxine will often be recommended. However, amprolium, ponazuril, diclazuril, toltrazuril, and salinomycin may also be considered.

Successful treatment may still be accompanied by mortality and diarrhea for a few days and relapse may be noted after one or two weeks.  

Note that mild exposure may lead to life long immunity to the specific Eimeria species and not others.

Finally, the prognosis to expect depends on the severity of infection with it being good if treatment begins early and guarded in severe infections with signs of liver failure or extreme weight loss.

Coccidia in rabbits can be controlled by:

Prevention is the best way to manage this infection. This will revolve around proper hygiene and husbandry. Some of the ways include

• Avoid overcrowding as it causes stress and creates sanitation problems. Only breed these pets if you have enough space. Otherwise, you should consider neutering them.
• Consider late weaning to reduce weaning stress and keep healthy gut flora in kits. This will reduce the effects of coccidiosis infection.
• Ensure proper nutrition as it will produce healthy rabbits with more resistance to diseases including coccidia. Consider anticoccidial medicated feeds for weaning. For instance, the Robenz containing Shur-Gain’s 16% Medicated Rabbit ration is approved in Canada but should not be given to lactating or pregnant does. Hay is also very essential in promoting a healthy gut.
• Quarantine any new rabbit for at least 30 days to reduce the spread of this disease
• Clean and disinfect hutches and all items that your rabbit meets and discard any that cannot be cleaned or disinfected. Keep proper hygiene by regularly changing litter bedding and removing any soiled hay or littering boxes. Use disinfectants such as Hyperox, Profilm, Virkon, Virocid as well as detergents such as Biofoam, Biosolve, ProQuat, BioSentry EZ-Kleen, and so on while cleaning and disinfecting.