Lop (floppy) eared rabbits are more likely than erect ('up') eared breeds to have potentially painful ear and dental problems that may ultimately affect their ability to hear and eat properly, finds a small observational study published in Vet Record.
These findings call into question the ethics of breeding and buying one of the UK's most popular types of pet rabbit, say the researchers.
Breeding animals for 'aesthetic' features that are linked to pain and discomfort is coming under scrutiny, but has mainly focused on dogs, they point out.
Some vets have voiced concerns that breeding for large floppy ears is associated with health problems that cause rabbits distress.
Anecdotal evidence indicates that lop eared rabbits (lops) are prone to ear canal narrowing and consequently reduced airflow and the build-up of ear wax. This may trigger ear infection (otitis) which can be painful and cause deafness.
The altered head shape of lops can also affect jaw and teeth alignment, potentially causing tooth overgrowth, pain, and eating difficulties.
But there has been no hard evidence to inform a debate about the ethics of buying and breeding lops, say the researchers.
To try and address this, they examined the teeth and ears of various breeds and ages of 15 lops and 15 erect eared rabbits in a rabbit rescue centre.
They also observed their behaviour, looking for signs of discomfort/pain, expressed as bouts of head shaking or ear scratching, and flinching or struggling when being examined, and checked their medical records.
The results confirmed that lops did indeed have much higher levels of ear and dental problems than erect eared rabbits.
They were 43 times more likely to have narrowed ear canals and significantly more likely to have a build-up of ear wax. And they were 15 times more likely to exhibit a potential pain response during ear examination.
Ear wax build-up was noted in the medical records of 14 of them, and repeated ear cleaning in nine. The equivalent figures for erect eared rabbits were 3 and none.
The lops were 23 times more likely to have diseased incisor teeth; 12 times more likely to have overgrown molar teeth; 13 times more likely to have sharp molars; and significantly more likely to have molar spurs--sharp points on the edges as a result of uneven wear.
Their health records showed that half of them (8/15) had dental abnormalities, and six had needed dental treatment, compared with none of the erect erect eared rabbits.
"The welfare consequences of a rabbit having lop ears include pain, as indicated by statistically significantly increased pain responses during examination of lop ears," write the researchers.
"Additionally, the higher frequency of signs consistent with [outer ear] otitis found in the lop eared compared with the erect eared rabbits, suggest potential for pain, [impaired hearing], or even deafness," they add.
This is an observational study, and as such, can't establish cause, and rabbits in a rescue centre may not be typical of pet rabbits in general, they point out.
Nevertheless, the findings confirm the anecdotal reports of vets in practice. And they conclude: "This brings into debate the ethics of breeding and buying lop-eared rabbits, as they may be more likely to suffer from these conditions, which can be painful and often chronic and recurrent."
Commenting on the findings, Daniella Dos Santos, British Veterinary Association President, said: "As well as being likely to suffer from ear and dental problems, lop-eared rabbits are also at increased risk of injury and prone to obesity, as for some, the length of their ears can restrict their movement. Sadly, vets tell us that all too often they're seeing clients who have chosen a pet with certain features without being aware of the serious health and welfare problems they may have as a result.
"It's critical that prospective owners think 'health over looks' when choosing a pet, as extreme features may come hand in hand with hereditary problems that can lead to serious health problems and be distressing and costly to treat. Vets are happy to give advice on how to find a happy, healthy pet and keep them that way."
Peer reviewed? Yes
Evidence type: Observational