Coccidiosis

Coccidiosis is a disease of rabbits caused by a class of single-celled organism known as protozoa. Coccidiosis is caused by the Eimeria species of protozoa. Of the nine species of coccidiosis affecting rabbits, one affects the liver, and the other eight affect the intestines. Poultry and other animals are also susceptible to coccidiosis but are affected by different species. Older rabbits are more likely to be resistant and it is young rabbits that are most likely to be badly affected.

Medicated pellets containing ACS coccidiostat

Rabbit breeders often feed medicated pellets to prevent the intestinal forms of coccidiosis. They are called ACS pellets because they contain a ‘coccidiostat’ such as clopidol, robenidine, or salinomycin. However these are available only from feed merchants who have a pharmaceutical licence which allows them to sell medicated pellets.

Like all drugs, there is a risk of the organism becoming resistant. I also discovered when carrying out some research for a UK feed producer in the 1990s, that rabbit breeders were mixing ACS pellets with their normal mix, effectively halving the recommended dose.

Robenedine hydrochloride should be included in feed at a rate of 50mg-66mg (ppm) per kilogram feed and lower doses are known to be unreliable in controlling coccidiosis.

ACS pellets are toxic to guinea pigs and chinchillas so they are not found in pet shops. Most pet rabbit owners would not be able to obtain ACS pellets locally, other than via their veterinary surgeon.

Hepatic or liver form of coccidiosis

Hepatic (liver) coccidiosis in rabbits is caused by only one species, Eimeria stiedae. E. stiedae causes the bile ducts to thicken. The main symptom is growth retardation and it is rarely fatal, but in advanced chronic cases the rabbit can develop a ‘pot bellied’ appearance caused by enlargement of the liver. Treatment is with sulfaquinoxaline.

The symptoms of intestinal coccidiosis vary according to which of the eight eimeria species is the cause of the disease. Young rabbits tend to be more severely affected.

The various species

Of the eight species of coccidiosis affecting the rabbit’s intestines, E. coeciola (found in the ileum and caecum), E. irresidua and E. perforans (both found in the small intestine) only cause slight growth retardation. E. magna, which affects the ileum and the caecum, causes retarded growth and diarrhoea. E. media, (ifound n the jejunum), may cause slight diarrhoea or constipation. Rabbits affected by coccidiosis caused by the Eimeria species E. flavescens (found in the caecum and colon) and E. intestinalis (found in the caecum and ileum), will show symptoms of weakness, weight loss, loss or appetite and bad diarrhoea. Both of these can be fatal, as can the rarer form of Eimeria, E. piriformis. Treatment is with sulfaquinoxaline.

Oocysts – the egg form

Coccidiosis is spread through a rabbit eating the eggs (Oocysts) of the parasite which have been excreted by an infected rabbit. The oocysts can remain active for more than a year and thrive in warm, humid conditions. Common sources of infection are grass or green foods contaminated by infected wild rabbits.

Adult rabbits are often passive carriers of coccidiosis without showing any symptoms themselves. It can happen that a baby rabbit that is brought into a home where an apparently healthy adult rabbit is already in residence, develops diarrhoea, and the blame is laid on the place the baby rabbit came from or change in diet, when in fact it has picked up the disease from a symptom free carrier

Prevention and treatment

In addition to good hygiene and keeping the bedding dry, feeding from uncontaminated bowls and hay/salad racks, rather than allowing the rabbit to feed off the hutch floor, reduces the risk of the rabbit ingesting infected oocysts. If rabbits are allowed access to an outdoor run, moving the run around the garden reduces the number of oocysts they are exposed to. Strong ultraviolet light from the sun helps disinfect the ground and destroy the oocysts. Many commercial disinfectants have no effect on the oocysts but DuPont Animal Health have a disinfectant product, part of the Antec® range, specifically designed to tackle oocyts called OO-Cide.

Drug rotation

Rotating the drug used to prevent coccidiosis is recommended to help reduce the risk of resistance. The Institute of Parisitology in the Czech Republic is working on an attenuated vaccine for coccidiosis in rabbits, similar to that already in existence for poultry. The fact that coccidiosis is such a problem in the farming industry means that it is financially viable for companies to produce preventative veterinary products and treatments for poultry and large livestock.

Food additives

There are two food additives that are EU approved licensed veterinary products for inclusion in feed to help prevent coccidiosis in farm animals, Deccox (decoquinate) and Eimericox, a patented blend of herbal extracts including eucalyptus, fenugreek and boldo. In Zimbabwe, farmers use a particular type of aloe, Aloe excelsa, to protect their livestock against coccidiosis. A natural alternative used in the poultry and pigeon industry is natural oregano extract, which can be added to the drinking water and used for general hygiene purposes, or oregano oil, which can be mixed with vegetable oil to a suitable dilution and used on food.