Fluid therapy

Fluid therapy is an important part of critical care as well as being used for other situations for guinea pigs. The aim of fluid therapy is to restore blood volume and correct electrolyte and glucose levels and plasma pH.

Commonly isotonic (crystalloid) fluids are used. These fluids can be given in a variety of ways to guinea pigs, depending upon the situation they are required for.

Offering oral fluids (drinking water) is imperative and should be available at all times; this can be in a water bowl or a water bottle.

Blood transfusions are possible in guinea pigs, although certainly not common practice and accessing a blood donor and retrieving the blood donation is likely to be highly stressful to the donor guinea pig, so serious consideration needs to be made if this treatment option is selected.

The uses are vast, but fluid therapy may be used in guinea pigs for:

• Dehydration: fluids can be used to help restore hydration. Guinea pigs can be dehydrated for a variety of reasons and like rabbits may not show outward signs until the dehydration is in the more advanced stages. At this point the signs of skin tenting, sunken eyes, dry mucous membranes, etc will be evident; the severity depends on the percentage of dehydration. 
• Anorexia: any guinea pig who is not eating is also unlikely to be drinking and will dehydrate quickly, leading to gastrointestinal stasis, which is serious and can be fatal in some circumstances.
• Low blood volume (hypovolemia): a blood transfusion may be used in this situation, or if this is not available, a type of fluid may be used instead.
• During surgery to help support the kidneys and blood pressure: anesthetic drugs can decrease blood pressure, so fluids are given to ensure blood volume continues to be delivered to vital organs, such as the kidneys.
• Kidney disease: fluids can help to ‘flush’ the kidneys through and remove toxins from the blood when the kidneys are unable to. This palliative care can help to make the guinea pig feel better for the short-term.

Fluid therapy forms a vital part of a treatment plan and helps to save lives in many situations.

There are several ways in which fluids can be given to guinea pigs. Guinea pigs pose some challenges when opting for intravenous fluids as their veins are small and unlike rabbits, whereby a marginal ear vein can be used, only the veins in the front and back legs are readily accessible, and even then, it can be difficult to cannulate.

There are pros and cons for each route when used. The route will be decided by your veterinarian, based on what is best for your guinea pig. Common routes of fluid administration include:

• Oral: this is when fluids (water) are given into the guinea pig’s mouth or if the guinea pig is drinking, water can be offered in a bowl or water bottle. It may be difficult to get large amounts of oral fluids into the guinea pig and there is a risk that the guinea pig may choke on the fluids if they struggle. Guinea pigs are often highly stressed when handled and this method may not be suitable in nervous guinea pigs.
• Subcutaneous: injecting fluids into the subcutaneous layers of the skin (usually around the scruff of the neck) is a common way to give fluids to most mammals. Large volumes can be given over a short period of time and will be absorbed well, except in very ill guinea pigs where the fluids may not be absorbed as effectively. Also, guinea pigs have a large fat pad over the back of their neck. Injecting into this area can be extremely painful for them, so for that reason when injecting subcutaneous fluids, they should be injected further down their back and away from their neck, but even then, some guinea pigs may find this too painful and stressful, especially when repeated.
• Intravenous: these are fluids given directly into the vein, via a cannula. The cannula can be placed in one of the leg veins, although this is not always easy to achieve and some guinea pigs may not tolerate this, and if the circulation is poor or collapsed, it makes gaining intravenous access more difficult. Intravenous fluids are absorbed quickly, even in dehydrated guinea pigs. One of the advantages is that once the cannula is placed the guinea pig will not feel the fluids being given each time, so will not be as stressed as they would be when having subcutaneous fluids.
• Intraosseous: this is usually reserved for very ill guinea pigs whose circulation is collapsed, and it is difficult to place an intravenous cannula. This involves placing a cannula into the bone marrow and is usually performed under sedation or anaesthetic. Often, they are well tolerated, and fluids will be readily absorbed.

The risks from all routes of fluid therapy are far outweighed by the benefits. Guinea pigs may choke or aspirate on oral fluids, so care should always be taken not to overload the guinea pig and only give the guinea pig small amounts at once, to allow them to swallow what is in their mouth before more is given. The guinea pig should always be placed in a normal standing position and never laid on their back to minimize the risk. If the guinea pig is struggling and getting stressed, then oral fluids should be stopped, and another route tried.

Subcutaneous fluids, which are given repeatedly, may result in small areas of fur loss and soreness, especially if larger volumes are given and may make the guinea pig resent having their neck touched.

Intravenous and intraosseous fluids run the risk of infection at the site of the cannula. For this reason, extreme care will be taken by the veterinary team to ensure the site is kept as clean as possible, but this risk cannot be removed entirely.

Before asking you to give your guinea pig fluids at home, your veterinarian will have considered what is best for your guinea pig. Although it is not common for owners to be asked to deliver fluid therapy at home, and if your guinea pig requires fluids, they are highly likely to be admitted as an inpatient, whereby the fluids and other treatment can be given by the veterinarians and veterinary nurses, if your guinea pig is very stressed in a hospital environment then your veterinarian may suggest you do this.

There may be some other occasions, such as your guinea pig being on long term care, ie for kidney disease, when regular subcutaneous injections of fluid at home, can help to slow down the disease process and keep the guinea pig as comfortable as possible for as long as possible. If your veterinarian were to ask you to do this, they would demonstrate the technique with you first and if you are not comfortable doing this, then it is something you need to discuss with your veterinarian to see if there are any other possible options.

Subcutaneous fluids can be painful for guinea pigs, especially if the fat pad is not avoided and they need to have repeated injections of fluids. Placing a cannula into a vein for intravenous access is no more painful than giving an injection and cream to numb the skin can also be used beforehand so your guinea pig will not feel it, but still some guinea pigs do not tolerate the experience well.

Intraosseous cannulas need placing under sedation or general anesthesia, unless the guinea pig is in a collapsed and unconscious state and sedation would be too risky. In these cases, the guinea pig will not feel the cannula.

By and large, using fluid therapy far outweighs any risks and forms an essential part of treatment for your guinea pig, so always be guided by what your veterinarian feels is the most appropriate treatment.