The health of herbivores is determined by their breeding, diet and environment. 

Breeding

As with all animals bred for exhibition, the requirements of various pedigrees can lead to unwanted health issues emerging.  Some examples of problems caused by breeding are directly related to fatal genes such as those in roan and dalmation guinea pigs which can cause micro-opthalmia.  Other health issues can be down to 'type', such as the dental issues more common in lop rabbits.

Pets purchased from pet superstores may be unhealthy simply due to the poor conditions they and their mother were kept in.  The babies may have been weaned too soon, their mothers may have been malnourished, or they may develop infections due to the stress of being in a pet stire environment.

Animals from accidental matings, common in pet store bought rabbits where the staff cannot undertake to sex the animals correctly, may have health issues due to inbreeding.

Diet

One of the most common causes of dental disease and digestive disorders is the food we give them.  Obligate herbivores, they rely on an almost constant supply of plant material high in indigestible fibre to keep their constantly growing teeth ground down and their digestive system moving at the right speed.

Grains, starch, sugars (including molasses), and protein levels which are higher than the fibre levels can also cause the pH or acididty of the gut to change in favour of the bacteria which cause disease, rather than supporting the giood bacteria which help the animals digest their food properly.

Environment

Animals which are not allowed to display natural behaviour due to limitations in their environment will inevitably become stresed, thereby predisposing them to opportunist viral, bacterial, fungal and chlamydial infections which their immune systems would have been able to handle in an ideal environment.

Environmental distress can be caused by a number of factors;  housing which is too small, lack of exercise, being kept without a companion of their own species, poor hygiene, inadequate grooming, poor handling, poor ventilation, draughts, damp, excessive heat or cold, and threats in the form of larger animals, noise or flapping objects.

Diseases

Insects and rodents can carry some of the most serious diseases which affect small pet herbivores, especially rabbits.  All rabbit owners should vaccinate against myxomatosis and VHD as well as being vigilant in the warmer months with regard to fly-strike.

Rats and mice can contaminate open food cartons and loose hay, so it is as well to ensure all food containers are sealed, that hay is kept in a rodent-free area and that mice cannot enter the rabbit or guinea pig's hutch if kept in a shed, lean to or outdoors in the garden.