FEEDING INNOVATIONS FOR SNAKES

In 2003, I had a reovirus attack my collection of snakes (Hoser, 2003a). Among the numerous symptoms of this was a reduced ability to digest food. As a result of this and a general push to reduce regurgitation risks in general, especially with smaller and younger snakes a number of innovations were tested with success. Some are given in this paper, so that other keepers may take advantage of these newly developed techniques.

In terms of ease and difficulty to digest food, the general trend is as follows in terms of difficult to digest and then easier at bottom.

The most commonly used kinds of food for captive snakes are as follows:

• Birds
• Mice
• Rats (of same size as mice)
• Lizards
• Frogs
• Freshwater fish

Within these groups there are obvious variations, such as different kinds of lizards presenting different skins and hence their digestibility varies accordingly.

Small skink lizards are the most commonly used lizards for food and they tend to be digested fairly easily.

In terms of mice, those small mice which have just grown long hair (known as "hoppers") are often difficult to digest and many keepers (myself included) have reported them as being somewhat difficult for some smaller snakes to digest.

For fish, saltwater fish tend to take a heavy fluid toll on snakes and hence are only recommended for healthy snakes, for which they pose no serious problems. Freshwater fish are therefore the fish of choice, if all things are equal.

Ill snakes that don't voluntarily drink should not be given saltwater fish as feeding such food to the snake may in fact exacerbate the ailment.

Most snakes will in fact eat and do well on all the kinds of food items listed above, even if they are not part of the natural diet.

Snakes that won't voluntarily take the given kind of food can either be force-fed or induced to voluntarily eat the said foods via a process known as scenting.

Scenting is when a preferred food it wiped over the other thereby making it smell the same and hence be attractive to the snake.

Dietary deficiencies may arise if a single kind of food is used, particularly fish.

For fish, it is usually a Thiamine deficiency if used exclusively over a long period (months). The symptoms include a general emaciation and eventually death by tremors and convulsions.

This risk can be avoided via use of alternative foods at the same time (say one in four feeds), or via adding vitamins to the food corpse, via tablet crumbs, injecting solution or even wiping a vitamin B fortified bread paste (yeast extract) over the food item.

All such supplementation should be done in extreme moderation as snakes are usually so small as to need only a small amount of supplement.

Frogs and lizards are known to be excellent sources of parasites and so are shunned by many snake keepers for this reason.

However the risk of parasite infection is reduced to next to nothing if the food items are held in a freezer for more than four weeks.

Bearing this in mind, it's worth having access to such food items (on hand), especially in terms of potentially difficult to feed small or fussy snakes.

Rodents tend to be the food of choice, but are also generally expensive.

They are also smelly and labor intensive to keep. That's why many snake keepers, myself included do not deal with live rodents and merely buy them in frozen.

In terms of young snakes that eat "pink mice" the cost of raising a litter can become huge. As a result alternatives are worth exploring.

In my case, it became expedient to raise large numbers of Death Adders (Acanthophis spp.) on fish instead of mice.

The fish could be caught in effectively unlimited numbers in a nearby pond using so-called "bait traps" baited with food scraps.

Species used are fish like Carp, Gambusia and so on, which are common in ponds and lakes worldwide.

Any species is appropriate save for especially spiny kinds or poisonous ones.

To provide further essential vitamins, every third fish was wiped with a scrape of Vegemite Yeast Extract and every fourth feed was a rodent tail or segment thereof.

Vegemite is an Australian brand, but there are similar versions elsewhere.

The tails or tail segments are routinely taken from all rodents fed to large snakes (as in adult mice and rats of any size this big or larger).

These are cut off the rodents before they are fed to the snakes.

In my situation all rodents are purchased dead and so, the issue of live food simply doesn't arise. Likewise there can be no cruelty involved in chopping a tail from a dead rodent.

Due to the limitless fish food available, Death Adders born at 15 cm long can be raised to three times that length within 8 months, whereupon they are large enough to be fed 1/2-grown mice without problem.

As it happens, these snakes can do this at about 25 cm long, but they are kept on fish longer simply due to cost and related considerations.

Rodent sellers generally charge similar prices for their rodents and so the best value for money is from the larger ones. That's why small rodents are generally avoided by myself as a food source.

By the stage that Death Adders (and other snakes) are taking 3/4-grown or larger mice, the feeding frequency is reduced to allow for the feeding of a sizeable number of snakes to be an affordable proposition.

Hoppers are those mice which have matured sufficiently to develop hair, but are still very small.

These mice have proportionately more hair and less flesh than any other rodents.

The hair often irritates the digestive tract of snakes and as a result healthy snakes may regurgitate them.

This is particularly so with smaller snakes that have yet to get a digestive system large enough to digest these rodents with ease.

As a result, rats of the same size class are far more popular and many keepers will simply shun and avoid "hopper" mice.

Because of this, it's not uncommon for rodent breeders to have large quantities of hoppers at reduced prices for those willing to use them.

To reduce the regurgitation risk there are some steps worth taking.

Firstly the mouse can be soaked in warm water. This makes the rodent's hair sit down in the digestive tract and enables digestion to take place more quickly.

As a matter of course, a snake will drink after eating to enable the digestive solution to develop in the stomach. However by wetting the rodent first this process is sped up and hence regurgitation risks reduced.

A side-issue in relation to feeding wet rodents to snakes is the possibility of dirt or other substrate sticking to the rodent as it is being eaten. This too will irritate the snake and perhaps cause regurgitation. If particles sticking to the food is a risk, then the keeper should lay leaves or paper over the cage floor at the place of eating when it occurs.

Another problem with small snakes eating large food is the problem of breaching the shoulder region.

It's common for snakes to eat the head and neck and then to struggle with the shoulder region for some time.

When this happens, snakes may simply give up and spit out the rodent.

To circumvent this, if you remove the front legs, this resistance is removed and the snake will tend to feed on it's rodent more easily.

In some cases the same can be done to the rear legs, but as a trend this isn't necessary as they tend to fold back when eaten anyway.

The removal of front legs from a rodent must be done judiciously as to feed a snake a food item too large for it to digest is inviting trouble as in increasing regurgitation risk (see Hoser 2003b).

Young Death Adders and even smaller young from smaller snakes are commonly fed skink lizards by keepers.

While healthy snakes will generally digest skinks without problems, there are several ways in which digestion can be assisted and sped up considerably.

Skinks that are regurgitated by snakes tend to be undigested and the readily identifiable problem tends to be the fact the digestive juices are unable to breach the hardened outer scales. The result is that the lizard's innards decay before the snake digests the lizard. Hence the lizard becomes toxic and is regurgitated.

To combat this, it is worth cutting the lizard along it's length with a pair of scissors.

A 5 cm lizard may be cut every 0.3 cm on alternating sides, with each cut being deep enough to excise half the lizard's body. The cuts along the sides of the lizard will not be too great to allow the lizard to snap into half or break, but they will allow the ingested lizard to be readily penetrated by the snake's digestive juices.

Such a practice can reduce digestion time by up to 50% and of course this will greatly reduce regurgitation risks in cases where such may occur.

Lizards are of low nutritional value as compared to other foods used for snakes, but if readily available are useful. Cutting skinks allows them to be fed with greater frequency (or size) and allows keepers to achieve growth rates in young snakes otherwise only seen in snakes fed on fish or rodents.

Most snakes will drink of their own accord. A snake that won't is seriously ill.

Seriously ill snakes, including young Death Adders with reovirus won't voluntarily drink and may emaciate rapidly. Force-feeding these snakes is essential for continued survival, but an associated risk is regurgitation. For such snakes force-drinking may be advised. This is done via a small syringe, which is used to inject water into the throat of the snake. The snake is held with it's head highest and the body held downwards from there.

The water then goes into the snake under gravity and once the snake is replaced in the case, regurgitation of water is non-existent or only slight, assuming only a small amount of water is given to the snake. Force-drinking may be advisable immediately after force-feeding in sick or emaciated snakes.

To get a good indication of how much water should be force-drank, one may see how much water is drank by healthy snakes of the same size (by measuring intake from a predetermined level in a cage's water bowl, discounting for the effects of evaporation). The amount then force-drank to the ill snake (assuming it's the same size) should about 1/3 that drank by the other snake, no more. In theory the non-drinking snake will rehydrate sufficiently to get the energy to itself take the remaining amount of water needed for proper digestion of food from the water bowl in the cage.

Most times this is exactly what happens.

Hoser, R. T. 2003a. OPMV in Australian Reptile Collections. Macarthur Herpetological Society Newsletter 38 (June):2-8.

Hoser, R. T. 2003b. Notes on feeding captive death adders (Acanthophis antarcticus), including posturing behaviour in response to large food items. Herpetofauna 33(1):16-17.