Extremely young pouch joeys need the high pouch humidity to help them retain moisture, but any moisture loss through the skin is made up for by suckling their milk which at this stage is very dilute. At this stage the immature kidneys cannot concentrate urine so there is a real risk of fluid loss through the kidneys. Passing dilute urine is potentially dangerous to the mother and young and, particularly in the dry conditions found in inland Australia, survival could be compromised but it doesn’t happen because the adult female ingests all waste produced by its in pouch young. This behaviour not only conserves water but also protects the young from bacterial infections in its gut; any bacteria in their faeces that enters the mother’s body induces an immune response in her and antibodies specific to that pathogen is later passed back to the joey in the immunoglobins of the milk.
A large percentage of joeys taken into care have reached the stage where they are able to regulate their own urine concentration. Some however, particularly pinks, may not yet have reached that stage so it is important that at every feed the bladder and bowel are stimulated to pass waste – don’t worry, you don’t have to mimic mums actions, gently stimulating the area between the uro-genital sinus and tail will cause the joey to begin to empty its bladder and bowel – but, failure to do this may end up causing urinary infections and/or constipation, both conditions are fatal if not treated. Stimulation can take place either before or after a feed but it is preferred that stimulation is after the feed, this way there is very little risk of bacteria being transferred to the mouth of the joey. Wash hands as soon as you have finished with the joey. If you have multiple joeys to feed then clean hands between each joey to ensure no bacteria can be transferred from one joey to another.
Always ensure the correct amount of formula is given at each feed, too much and you will end up with a joey that refuses to drink some or all of its allotted amount as it has an overloaded gut, maybe even a bloated gut – remember those delicious Christmas dinners; the ones where we just have to force in that extra cake or glass of wine? Remember how bloated and unwell we feel for hours afterwards? The joey will most likely also develop diarrhoea or at the least a much softer, runnier faecal consistency than normal. Either of these issues will quickly end up with the joey becoming dehydrated either from not taking in enough fluid or from the waste passing too rapidly through the body so the liquid component has not had a chance to be absorbed back into the body. Failure to address the situation immediately will impact on the joey and it isn’t unusual for a joey to end up dead, sometimes after a considerable time, simply because dehydration has not been corrected straight away.
There are several methods of re-hydrating, first the fluids can be given orally if the joey is willing to suckle, if dehydration is minimal and not caused by over feeding that has resulted in bloating, this may be the way to go; if dehydration has been estimated at up to 10% [when doing the pinch test, ie lifting the skin between the shoulder blades with your thumb and forefinger, the skin tents and is very slow returning to its normal position] then giving extra fluid sub-cutaneously [SC] is probably the preferred method, the warmed fluid is injected directly under the skin where it is rapidly absorbed into the body. It needs to be given by someone experienced in this method. I urge all carers to learn how to give fluids using this method or find a shelter who is willing to assist whenever necessary, remember you will not be able to hydrate the joey in one go. Critical dehydration requires intravenous fluid replacement [IV] this must be done by a veterinarian. Failing to hydrate any dehydrated animal will result in eventual, unnecessary death. Rehydrate over a period of 3 days. On day 1 offer the usual quantity of formula and 50% of the calculated required re-hydration fluid; on day 2 offer the usual amount of formula and 25% of the remaining replacement fluid amount, do this again on day 3. If the joey is refusing to take formula try electrolytes at alternate feeds.
To ensure our young animals remain healthy and well hydrated we generally offer 10% of body weight in formula over 24hrs, usually offering it over 5 feeds; 6 feeds if the joey is a small pink and 4 feeds if the joey is larger and spending a good amount of time out of the pouch. It has been my experience over 20+ years that young animals arriving for care will rapidly dehydrate if we offer much less than 10%, fluid over 24hrs, 8% often works well for most furred animals but pinks appear to dehydrate if not fed 10% and sometimes requiring more. Be particularly vigilant during the first few days to ensure the amount of formula you are giving is keeping the joey well hydrated.
It is also my preference to offer formula rather than electrolytes at each feed while also replacing the required amount of fluid SC to correct the dehydration.. An electrolyte replacer [Lectade, Vytrate, etc] is the preferred oral fluid if not using formula. For SC fluid use sterile 0.9% sodium chloride [saline]. Always warm to body temperature before use. I hope this is not too confusing. Call me anytime if you have any queries.
A friend recently asked if giving fluids SC hurt. Yes it does, but it is over very quickly. You need to prepare everything prior to taking the joey from its pouch, as soon as the joey is in position you begin injecting the fluid that has already been warmed and is already in the syringes, it is over in minutes with the joey put straight back into its warm bed. Far better than trying to force unwanted fluid orally over half an hour, maybe much longer, this is extremely stressful and can cause gut discomfort and maybe pain, later on. It may also result in a joey being reluctant to take the teat and suckle.