Breeding for Longevity and Health

Okay, I’ve been mulling this post over for months now, trying to work how how to say everything I want. The fact is, what I’m going to say is going to offend some people, and there’s not a thing I can do about it, so I’m going to just forge ahead. In the interest of your time, I will place my main and most inflammatory points first. That way you can know if you’re going to pitch a fit and stop reading right away. Here goes:

You cannot breed for health without doing necropsies on your breeding stock.

You cannot breed for longevity without doing necropsies on your breeding stock.

Having rats who live a long time, without necropsies on the line, is luck and nothing more.

If you do not have a competent veterinarian who can perform a gross necropsy and give you information about it, you shouldn’t be breeding.

There. Still with me? Brace yourself – this is not going to be a fluffy post.

Like I said, I’ve been mulling this for a while. Two things kicked me into gear.

First off was looking at my “age cheat sheet,” posted on my rattery door while I was cleaning in there. I counted and I currently have 27 rats who are over 20 months of age. 16 of them are 24 months and over. One is 32 months, one is 34 months. Huh, I thought, maybe I should make that post I’ve been thinking about.

Secondly was this comment I received on one of my Virtual Mentor posts, the one dealing with temperament:

Your posts are so helpful as I try to learn as much as I can about rat genetics and breeding.

Could you please devote some ink to breeding for resistance to tumors and, especially, to that blasted scourge, mycoplasma? I know this presents a dilemma for breeders, since they may have a barnstorming bloodline well under way before the problem in the line becomes apparent and they find that, if they are going to do right by the fancy, they have to scuttle the whole line and start over with new stock. It’s heartbreaking, and it’s a real test of character for the breeder to do the right thing.

It seems the average life expectancy is increasing by leaps and bounds, and I credit that state of affairs to breeders’ efforts. However, breeding for a POSITIVE trait is fun; it’s NOT breeding in order to eradicate a NEGATIVE one that hurts.

I sure am tired of expensive tumor removals and worrying to death about mycoplasma. It’s a hard thing to bury a pet for which you may have paid $20 and to whom you are utterly attached, well before her second birthday, especially after a lifetime vet bill in the vicinity of $800. All the temperament in the world profits you nothing if you have to drop it in a hole and plant lily of the valley over it many years before you ought because the fancy is apparently willing to live with mycoplasma as a given. We should be outraged. We should work to eradicate it from the fancy within the next decade.

Sorry, bit of a ‘nam flashback there. I was really traumatized, though, by my girl’s death and horrified to find that it’s actually rather a standard end of life in many gorgeous and wonderfully sweet lines, even if one’s husbandry is immaculate.

What are your thoughts?

My thoughts are that rats die one of two ways: respiratory collapse and tumors. That is what 90% of the rats I have owned and handled since 1995 have died from. Rats have crappy immune systems, crappy respiratory systems, and they run through cell cycles so quickly that they stack up errors and build tumors.  My second thought is that I could not disagree more that temperament profits nothing if you have an unhealthy pet – I give them equal weight, because who wants a 4 year old rat that’s a nasty aggressive jackass? But I’ve expounded on temperament elsewhere, I’ll save this blog for trying to build a rat with a long, healthy lifespan.

You cannot eradicate mycoplasma. It simply is not possible. It’s just not. Mycoplasma is endemic in the rat population. The only way to get a mycoplasma-free rat is to deliver it in a sterile environment via C-section and then take it away from the mother to be handraised (or fostered on a myco-free rat who was handraised earlier) and never, ever let it be exposed to other rats. We carry mycoplasma in our own lungs, every rat in every pet store carries it, wild rats carry it, and every rat in every breeder population has it. Being “outraged” over mycoplasma will benefit us absolutely nothing.  What we need to do is to breed resistant rats who have less outbreaks of respiratory distress, and build up a population of animals who have a strong resistance to mycoplasma and other respiratory bugs.

And rats who get sick from anything – anything – often come down with respiratory symptoms, but the respiratory symptoms are NOT the underlying cause of the illness. A rat with a bruised liver, or a parasitic infestation, or a heart that isn’t pumping right will all show symptoms that look respiratory! Tip their immune systems over, challenge it, and the respiratory junk they carry around every day takes advantage of them.

Tumors are another thing we’re just never going to get rid of. The reason so much cancer research is done on rats is that they are little tumor factories. They go through a complete hormone cycle in 4 days – the same cycle we go through every month. Every four days, your rats go through a trough, buildup, peak, trough of hormones and cell cycling. That’s a TON of room for errors, especially as they get older, and especially with females, who are little breeding factories and are pumping so much effort into their breeding tissues (which, incidentally, includes most of their bodies. Mammary tissue stretches from the lower jaw and cheeks through the neck, down the belly to the tail and wraps around the sides. It is EVERYWHERE.) Again, what we need to be doing is breeding from rats who are resistant to tumors by keeping track of our lines and not breeding from rats who have tumors of any kind show up under 2 years of age, and completely shutting down breeding lines where highly heritable tumors show up.

Aha! I hear the cries starting! BVR has continued lines where rats have gotten tumors under 2 years! BVR has bred the sons and daughters of a rat who had to be euthanized for a tumor at 20 months! HYPOCRISY!

That is where necropsies come in.

Many types of tumors are not considered heritable, by laboratories for whom this is a very important matter. For us, whether or not a tumor is heritable may affect a few generations where we may or may not breed a single litter per generation. For a rodent lab, a rat with a tumor that throws off test results can result in hundreds of thousands of wasted dollars, man-hours, and rat lives. We may not like that these labs exist, but they are the most valuable tool in our veterinarian’s arsenal when it comes to heritability. If your vet doesn’t have contacts with these people, they should make some if they’re going to seriously assist you in increasing the health and longevity of your rattery lines.

Tumors should be sent off for pathology unless they are obviously recognizable. Yes, there are certain types of tumors that you can be 99% sure of what they are simply by where and how they are attached, the shape, the color, etc. If your vet doesn’t know these things they need to learn it, or you need a new vet.

There’s really no room for compromise when it comes to your vet. If you don’t have a vet who is dedicated to helping you improve the health of your stock – not just doling out antibiotics and slicing off tumors, but really improving your stock long-term – and if you are not personally dedicated to working with that vet to do the same thing, then you are wasting time and lives. This is not a “hobby” for dabblers. Get dedicated, or get out.

That means you are going to be willing to spend money on this stuff. In my opinion, as a rattery, it is 100% more important to spend money on a necropsy than it is on antibiotics. Curing or masking the symptoms of one rat helps that one rat. That doesn’t help your breeding program. To see so many ratteries who would move the moon to extend the life of one rat by a few months, but will not devote the time and money to then open that rat up and see the condition of their health boggles and infuriates me. We are breeders, we need to look to the long term!! Am I saying that you should neglect the health of your rats? Absolutely not! However, the health of your lines should be at least as important to you as a breeder as any individual rat! If it isn’t, go back to owning pets and stop breeding because you are a pet person and aren’t helping the fancy.

When I see a health note on a bridge page or in NARR that says something like “27 months, nothing to report,” or “24 months, died of old age,” or “18 months, died of choking,” and no other information I want to kick something. You know what that note tells me? Nothing. At all. If you do not open the rat up, you do not know what killed it. I don’t care if you watched it have a seizure. What was the inside of the body like? Did it have a seizure because it had a brain tumor? Did it have a respiratory attack that you mistook for a seizure? Have you ever personally watched a rat die of a respiratory attack (I have!) and do you know what that looks like, and how much it looks like a seizure or choking? Did you have a rat who dropped weight, looked hunched, was breathing heavily – but had a massive liver infection that so degraded the rat’s general immune system that they developed respiratory symptoms because they couldn’t keep on top of their inherent myco anymore?

Unless you open your rat up with a competent member of veterinary staff  you have no idea what was actually making your rat sick. Rats do not just die of “old age” – there was something wrong with them that killed them. Maybe there was nothing really specific – maybe it was just organ wear and tear and their little body just gave out. But maybe their heart was spongy and enlarged. Is that something you want to pass on to their children?

Now, people have asked me, what is the point of necropsies? You can’t do anything about having bred from them or not at that point, and if you threw every rat out of the breeding program because they had a parent with a crappy necropsy, what would we have left? Yet these same people will record how many months a rat has lived and point at that as a reason to breed their offspring, without ever knowing what the actual health of the line is, and you can’t do anything about whether or not you bred a 32 month old rat, either. That is luck, if you have no concrete information to back it up.

A breeder I work closely with just lost a 28 month old rat. He’d been going downhill, having some respiratory issues, acting old and off. And hey, 28 months is pretty old, right? She could feel a lump in his abdomen, and assumed it was a tumor. Hey, old rats get tumors. And there was some flagging of this rat’s offspring in her mind, and maybe her records, about him getting that tumor. When he died and they opened him up, did they find a tumor? No, they found an extremely encapsulated abscess in his belly. Antibiotics might have extended his life, but no one gives antibiotics to a rat with a tumor, and abscesses aren’t genetic.  So what would have happened to her breeding program, and others who work with her and have that rat’s descendants, if the bridge page simply stated “28 months, abdominal tumor, respiratory issues.” We would all have been working off incorrect information based on guesswork.

Where necropsies become useful is with subsequent generations and copious record keeping. Granted, there are a few things you find on the necropsy which require immediate action. Certain kind of tumors are extremely heritable, as I’ve said, and should be an instant show-stopper. Most heart disorders. Certain other disorders like epilepsy. Those are the rats who you cut out of the breeding program, along with every direct descendant no matter how painful that is or how hard you will have to work to make up for it.

Suck it up, folks. This isn’t a fluffy hobby. These are real lives we are playing with, not toys. Breeding from a line you know has a high possibility of throwing rats who will get sick and die early is unethical in the extreme, especially if you are then passing those animals on to pet people. Pet people have to deal with our works-in-progress and mistakes all the time – don’t make it worse for them by raising the odds they’re taking home a ticking time bomb.  Want to breed animals for fun without worrying about health or placing sick animals? I got something for you.

However, most health concerns will not be an instant line-stopper. That’s where every necropsy you do in your breeding line gets recorded in as much detail as you can get. Breeder’s Assistant is amazingly useful for this, because it has a giant “health” section where you can record a lot of information, and if you want, you can set your pedigrees up to print you a “health” addition that contains flags you’ve specified. If you don’t have Breeder’s Assistant, use whatever you ARE using for record-keeping. Word and Excel can do a lot of the same things as Breeder’s Assistant, but the difference is that you have to do all the work to set things up yourself. Personally, I say spend the money on BA, it will pay you back in time saved.

Hand-written records aren’t good enough. I’m sorry, but you’re not going to be able to form a coherent picture flipping through a spiral notebook eyeballing pages and looking for important information. I suppose you could do as much with a handwritten book as you can with Word and Excel, but the difficulty of keeping coherent records ramps up monumentally and finding things becomes difficult, and the entire point of this is to have the information available to you.

After a generation, or two, or three of keeping detailed necropsy records on your breeding stock, you’re going to start to see patterns. A lot of “sudden death” where a rat looked ok or maybe had some respiratory symptoms and then died under 2 is actually heart disease – which you will NOT be able to determine without necropsies. Maybe you’ve got kidney disease or liver disease passing in a line. Maybe you didn’t really worry about some weird organ discoloration until you noticed the same thing in that rat’s grandchildren. Now what had previously been just pure, but essentially useless, information is forming a health picture for your bloodline. And if you never did those necropsies, maybe you still think your problem is just the blanket “respiratory issues” umbrella where we tend to stick all our rat’s health problems.

The RFL recently added to our Breeder Code of Ethics that we will have necropsies done on every rat in our breeding program to determine their health and the cause of death, or we won’t use their descendants in our breeding program. I could not be prouder to belong to that group, and I feel that this is really a push in the direction of true accountability and dedication in working to improve rat health and longevity.  We can make informed decisions, we can weigh our options and truly choose animals with less genetic health concerns and more resistance to the things that make our rats sick.

Guess what? Healthier rats live longer. The way we’re going to make our longevity better is to breed healthier rats. Man, that sounds so stupidly simple.  It really is.