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The Kidneys

The purpose of this article is really to clarify the importance of the kidneys to a rat's health, the prevelence of kidney decline, and what we as owners can do about it.

Why are kidneys important?

Just like in humans, a rat's kidneys are essential to their health. Their job is to clean the blood, removing waste so that it can be excreted from the body as urine. Over time, the kidneys become less efficient and this is called kidney decline. Eventually, the kidneys can fail completely.

Kidney Decline and Symptoms

When the kidneys decline, they don't do such a good job of cleaning the blood. The blood becomes more acidic as toxins get left behind, and this acidity stimulates the breakdown of muscle tissue. This is why kidney decline is often a cause of hind leg degeneration. Hind leg degeneration often starts with just a little bit of a waddling walk with the tail held low, it's not just the more extreme form we often think of, where a rat is unable to climb or even walk.

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This failure of filtration also leaves higher levels of protein in the blood. We can test this at home using a urine dipstick test meant for humans. (you can buy these online). The presence of any protein suggests a degree of kidney decline. The tests are sensitive to the concentration of protein - so if your rat passes a large amount of dilute urine, the presence of protein is more concerning than a small amount in more concentrated urine would be. I'd always advise having a vet check out any rat with protein in the urine or any symptoms of illness - but I do find urine tests a good way to monitor the condition at home, and to check those rats I feel are at-risk of kidney decline.

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Other signs of kidney decline can include gradual weight loss, thinning fur (exluding rexes), pale teeth and increased thirst.

Who is at risk of kidney decline?

Kidney decline is more common in elderly rats, particularly males. I have found it more common in my rescue rats, but as it's often age related it can often happen to well-bred rats by virtue of them living long enough for their kidneys to wear out! Kidneys are unfortunately a bit of a weak spot in rats generally. Overweight rats and rats on a diet that doesn't promote kidney health are also more likely to develop issues. I will go into more detail on the dietary influences on kidney health below.

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Diet, Prevention and Phosphorus

The kidneys remove phosphorus from the blood, along with other waste products. Rats need some phosphorous in their diet, but if they get too much and their kidneys can't filter the excess into urine, it builds up in the blood. Phosphorus in the blood can actually pull calcium out of the bones, causing weakness and making our rats more prone to injury. Combine this bone weakness with the clumsiness that hind leg degeneration can cause, and you can see why we need to be careful and consider the phosphorus in our rat's diet.

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Foods with high phosphorus are often very nutritious, and we just need to feed them in moderation rather than cut them out alltogether. This includes grains like wheat, oats and rye. It's often best to make sure you use other grains in your rats' food where you can, such as bulghur wheat, barley, corn and white rice. High-phosphorus protein sources include meat and fish. Better protein sources for kidney health are egg and soya. You can make these switches in your own home-made mix and fresh meals, and Rat Rations mixes are also designed with kidney health in mind. It's often well worth feeding your rats a kidney-friendly diet from adulthood, particularily if you keep males, as this can help to prevent issues by minimising the work the kidneys must do. Rats can actually lose 70-80% of their kidney function before showing symptoms, so prevention is well worth it as we may not spot issues arising until the kidneys are really struggling.

Omega 3 is a nutrient proven to help kidney function - this is in foods including flaxseed/linseed and oily fish. You can also buy omega oil or flaxseed oil online and drizzle this on food. I add flaxseed to the seeds portion of my dry mix and it has the added benefit of keeping their fur soft and shiny.

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Treatment

If your rat has kidney decline, evidenced by protein in the urine and symptoms such as hind leg degeneration, there are things that can be done. Firstly, make sure they're seen by a rat-savvy vet to confirm this is the issue. We can make the dietary changes talked about above as well. Ipakitine can be bought online, and it's a powder which is called a phosphate binder. This means it makes our rats actually absorb less phosphorus from their diet, meaning less for the kidneys to process and less in the blood. The vet can also prescribe ACE inhibitors such as Benazepril. There isn't much research on using them in rats, but some studies have found they can help dogs with kidney failure and I certainly have found Benazepril really useful in my own rats and have seen my rats thriving with kidney issues for longer when taking this medication. Rubenol is a rhubarb extract that can help the kidneys - this can be bought online.

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I do not recommend creating an easy cage setup for rats with hind leg degeneration, though it can be worth adding in a couple of extra perches and a lower hammock. Using the muscles helps to keep them strong, and an easy setup can really hinder enjoyment, quality of life and can lead to obesity in other cagemates (which has it's own associated health problems). If your rat is unable to get around at all, I would suggest you meet with a vet to discuss their quality of life.

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It's also important to be aware that Meloxicam, the most commonly used painkiller/anti-inflammatory for rats here in the UK, is not good for rats with kidney decline. Sometimes you may need to use it anyway, but your vet may give you other options for painkillers that will be more kidney-friendly.

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Rats with kidney decline can feel nauseous and this may put them off food they previously liked. It's helpful if you have several different options to disguise any medication in, in case they go off one of them. I either use some blended up fresh food, weight-up-baby (RatWarehouse) or Moo mix (RatRations). Complan is a great option for rats who don't need any additional help maintaining weight, as it's low calorie.

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Complications and End of Life

Kidney decline will eventually lead to kidney failure, which in itself can cause your rat to pass away. However, it is often possible to treat and slow the decline to the point where the rat may well pass of something else before the kidney decline turns to outright kidney failure. You can't reverse decline that has already occured, but treatment can really slow the progression of this disease. I will also add it's not possible to prevent kidney disease occuring entirely, but prevention will reduce the chance of your rats suffering from it.

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Kidney failure can cause seizures as well as urinary infections due to an incorrect pH as the kidneys no longer do their job well. Urinary infections can be painful and will require vet attention as well.

 

If your rat is struggling and no longer has a good quality of life, it is time to consider putting them to sleep. On a brighter note, I've had many rats with kidney failure over the years and the vast majority of them died of something else. It isn't a hopeless disease by any means, but it's always worth monitoring your rat's wellbeing and enjoyment of life. There's no need to keep them going for our benefit.

Case Study: Newt & Bard

Newt and Bard were what prompted me to write this article. They are 21 month old boys who I have had since birth. Their mother came to me heavily pregnant, and I raised them. I've always given a kidney-friendly diet and monitor my older boys pretty closely. As I said earlier in the article, it's not possible to completely prevent issues.

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They both began waddling slightly, and Bard's tail was always held low when he walked, in contrast to my younger rats who have their tails well away from the floor. I gave them both a urine test at home, which showed a moderate level of protein in Newt's urine, and high protein in Bard's. They were given Benazepril, which they have once a day with a pinch of ipakitine. I'm making sure to use egg, soya or fish as their protein source (fish for the Omega 3 although soya and egg are more kidney-friendly), and adding flaxseed or Omega oil to some of their fresh meals. At the time of writing, they are doing very well and have not declined, but Bard is definitely more affected than his brother. I am hopeful that they will continue to do well on their medication.

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Update: The boys are 26 months old now and still doing very well on medication, with only a slight decline in mobility. They are maintaining weight very well and are still able to access all of the cage and enjoy free roam.

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Other Resources (please click the names)

Ratwise Membership

Isamu Rat Care

Rat Guide

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