Following on from our recent post about the need for an oral source of vitamin C in
guinea pigs, I thought a blog discussing this topic in more detail would be useful.
Vitamin C is also known as ascorbic acid. It is needed for the growth and
repair of several different tissues in the body. It helps to form collagen. This is a
protein that contributes to the formation of skin, mucous membranes, tendons,
ligaments, cartilage and blood vessels. It is also important to help heal wounds and
maintain healthy teeth and bones.
A lack of vitamin C leads to a condition colloquially known as Scurvy.
Symptoms of scurvy can include poor wound healing, a rough coat, painful teeth
and/or bleeding gums (leading to poor appetite), weak painful bones, lethargy and
weight loss. In guinea pigs, in particular, it can also contribute to symptoms of cystitis
(a very common condition in guinea pigs) as it is a component of the mucous
membrane that lines the bladder.
Many animals are able to produce their own vitamin C by converting glucose.
An enzyme known as l-gulonolactone oxidase is needed for this process. Guinea pigs
are among a group of animals that lack this enzyme. This group also includes
capybaras, fruits bats, several reptiles and many primates (including humans). Since
this enzyme is lacking in these species they require a continuous oral source of
vitamin C to remain healthy.
The daily vitamin C requirements of a guinea pig are thought to be 10mg.
However, in times of disease or ill health this can rise to 30mg. Vitamin C is in many
vegetables that may be included in a guinea pigs diet. Vegetables that contain high
levels of vitamin C include bell peppers, parsley, spinach, kale and broccoli. Of
course there are also many fruits that contain vitamin C. Fruits should only be fed as
treats to guinea pigs due to the high sugar content.
Commercially available guinea pig food has added vitamin C. This is usually
in a stable form; however it will still degrade over time. Speed of degradation is
dependent on several factors, including exposure to sunlight, moisture and air.
Opened food bags should be stored in dry, airtight containers, out of direct sunlight to
preserve the vitamin C for as long as possible. The number of guinea pigs you have
will dictate the size of food bag you should purchase as you should aim for the bag to
be changed every 3-6mths depending on conditions. Although a bigger bag may be
cheaper per kg, if you only have a couple of guinea pigs a smaller bag is more
appropriate.
If vitamin C needs to be supplemented over and above these sources this can
be achieved in the form of tablets, or liquid. Use of tablets is preferential as if stored
correctly degradation of vitamin C is slower than in liquid. Liquid drops can be given
directly into the mouth or added to the water. Accurate dosing in the water is more
difficult as it is challenging to analyse how much the individual guinea pig is
consuming or the rate of degradation. Degradation of vitamin C is faster in water, but
is again dependent on factors such as sunlight and temperature. It is wise to change
the water very frequently if vitamin C is supplemented via this route and to offer fresh
water at the same time as the vitamin C can taint the taste and may result in reduced
water consumption.
Excessive supplementation with Vitamin C can also result in health issues.
Guinea pigs can suffer from an ocular condition know as osseous metaplasia or
heterotropic bone formation. It is thought that excessive levels of vitamin C can
contribute to the formation of these boney lesions. Excess vitamin C can also
contribute to gastrointestinal disturbances.
In summary it is important to remember that guinea pigs need a continuous
oral source of vitamin C. This can be provided in a variety of ways. The fact that
vitamin C will degrade over time should be considered when assessing if adequate
vitamin C is being provided. Over-supplementation should also be avoided.
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