Understanding Cheyletiella mites in Rabbits and how to treat them

Rabbit farming in Kenya is increasingly becoming commercial as demand for the animals and their meat increases.

However, commercialisation of the trade does not match the production systems due to limited access to technical information, poorly designed, constructed and maintained rabbit houses, poor quality of animals and unavailability of artificial insemination.

Majority of rabbit farmers use non-conventional methods to treat pests, in particular, mange mite infestation. Mite infestation in rabbits is the second most prevalent disease affecting the animals after those of the digestive system. Mites are external parasites that cause a severe skin condition (mange).

A recent survey in Nyeri and Kiambu counties revealed that rabbit mange prevalence stood at 57.3 per cent. This implies that a rabbit farmer has a high chance of encountering mange.

There are three common mange mite species that affect rabbits across the country. First is the ear canker (Psorsoptic mange), whose clinical manifestation is infection of the ears leading to intense scratching, redness, crustiness on the inner and outer ear and ear canal, head shaking, foul smelling discharge and drooping of the affected ears.

Cheyletiella mites

Then there are the Sarcoptes and Cheyletiella mites. The former burrows in the skin of the rabbits resulting in severe scratching of the body while the latter is found in or on the fur of the animals and is normally referred to as the walking dandruff due to its presence on the fur of the affected animals.

Mange mites are a highly contagious condition and transmission of the parasites is through direct contact between infected and clean animals. Equipment used in rabbit production can also transfer the parasites from one farm or animal to another. Sarcoptes mites also affect humans, causing transient itching.

Factors associated with rabbit mites include purchase of initial/replacement stock, housing (design, construction and maintenance), feeding, production size, use of non-conventional methods, limited consultation of professionals and unavailability of drugs specially formulated for the parasites.

Purchase of initial/replacement stock

Buying stock from neighbors is one way of spreading mange mites. Therefore, one should buy the animals from certified breeders who have strict disease control measures. One such a breeder is the government farm in Ngong, which supplies rabbits at highly subsidised rates.

Housing (design, construction, maintenance)

Poorly lit and inadequately ventilated houses are a risk factor for mite infection. A good house should be made of welded wire mesh and be cleaned regularly. The recommended cubicle size for an adult rabbit or four weaners is 12x60x60cm and a 30x30cm nesting box next to the female cage. It has been demonstrated that regular removal of bedding materials and cleaning and disinfection of cubicles before introduction of a new brood helps control the parasite.

Feeding

Animals that are in poor body condition are normally susceptible not only to manage but also to other disease conditions. Most farmers feed their animals green matter, hay and some supplementation with concentrate feeds. The good news is that commercial feed formulations for pre-grower, grower/fattener and breeder rabbits are available in the market.

Lack of rabbit specific drugs/production size/use of non-convention treatment drugs

There are no chemicals specially registered to treat mites in rabbits. This has resulted in use of chemicals that are used to treat mites in larger animals like cattle, sheep, goats and dogs, a situation referred to as off-label drugs’ use. Rabbits are smaller in size thus use of these drugs, especially the injectable ivermectins, which are very effective in treating mange mites and whose dosage is 1cc for a 50kg body weight becomes tricky to measure a dose for a 3kg average body weight of a rabbit. The same challenge leads to use of non-conventional medications such as mineral paraffin, engine oil and ash. The effectiveness of some of these chemicals has not yet been confirmed.

The situation is complicated by the fact that rabbit farming is small-scale, with 40 per cent of farmers keeping utmost two rabbits; 45 per cent three to 10; 13 per cent 11 to 50 rabbits while only 3 per cent far more than 50. Such low numbers are not able to cover the cost of animal health service providers (AHSP) thus farmers diagnose diseases and treat the animals all by themselves.

To overcome these challenges, farmers are encouraged to form groups and have a contractual agreement with an AHSP, who can visit the group regularly.

The animals should be treated with research proven off-label drugs that include ivermectins, liquid paraffin and liquid paraffin/cabaryl (sevin) combination. The liquid paraffin is the same that is added into drinking water of day-old chicks to assist in digestion.

For ivermectin, it is injected at 400ug/kg body weight on day one and day 14. The advantage with this medication is that it controls mange mites and other skin parasites such as fleas and ticks. It also controls internal parasites such as worms. The drug is also environmentally friendly as it is injectable. The shortcoming of the drug is that it should be administered by a professional.

For cabaryl/liquid paraffin preparation, wet an infected area with 5-8 drops of liquid paraffin. Then dust the same area with cabaryl powder. Repeat this after a one day interval until 21 days. The disadvantage of this treatment is that excessive use of cabaryl can contaminate the environment. It is also laborious due to its prolonged application. The advantages include ability of the farmer to apply the medication and the fact that it is as effective as the injectable drug.

Finally, liquid paraffin alone can be used to treat mange mites by applying it on the affected area daily for 21 days. The disadvantage of this method is that the condition tends to recur after some time.

Dr Mwirigi is an animal production specialist based in Nakuru. [email protected]