Breeding out allergies?

[sorraia]

Question 1: Can you selectively breed for improved respiratory health? What would you actually be controlling there... are specific allergies genetic, like to aspen? Strength of resistance to Mycoplasma bacteria in the respiratory tract? Sensitivity to dust IE overall respiratory heartiness?

It is possible to select for improved respiratory health, but it can take quite some effort, time (depending on the volume you are breeding for), and lots of records. What you are selecting for depends on what cause of the sneezing. It can be allergies - I once had a rat who sneezed on every bedding I ever tried except, believe it or not, alfalfa pellets. That rat also tended to have skin issues when fed certain foods. Other rats will sneeze due to irritants (i.e. dust). Other times it has to do with their over all health and immune system - a rat with a weaker immune system will more likely develop an infection, especially when exposed to irritants, and is more likely to succumb to that infection. It can also be environment - conditions that are too warm, too cold, too dry, or too humid.

In my experience: While I bred rats, I was selecting for respiratory health. Since I was breeding strictly for pets and not feeding them off at a young age, I was able to keep track of ALL individuals I bred and keep records on them, even after placing them in pet homes I would keep in touch with the new owners and keep updated on their health. If a particular lineage seemed especially prone to respiratory infection or sneezing, I stopped breeding from that line. If a particular rat seemed to have sensitivities before I bred it, I would remove it from the program and not breed it. If an animal developed sensitivities after I bred it, I would wait a little longer before breeding its offspring. I was also having rats necropsied to determine what condition their lungs were in at death, which helped determine how healthy their respiratory system was, but also helped determine if they had developed "silent pneumonia" (which had happened a couple times). Over the generations I saw less and less incidence of respiratory infection or irritation. Within just a few short generations I got to the point where my rats would only sneeze under stressful conditions: moving homes, "spring cleaning" when a lot of dust got stirred up, or major weather changes (such as from 100 degree summer heat to a sudden drop of 20+ degrees, rarely happens here, but sometimes does). By the time I stopped breeding rats, my animals were almost never sneezing. This program was a combination of selection against allergies, for stronger immune system, and for animals who handled stress better. During this time I also noticed an interesting trend: those animals with longer, narrower heads tended to be more prone to sneezing and sinus irritation (which would trigger sneezing) than those animals with shorter, broader heads.

Question 2: Short of keeping them on expensive substrate or trying to litter box train them and keep them on fleece, is there anything I can do to reduce the sneezes... it's quite distressing sometimes as I have grown fond of a couple of the little ratties. My sister gave me Baytril and Doxycycline but I am hesitant to medicate when the sneezing is the only symptom that any of them have shown.

I would avoid medicating unless absolutely necessary. Over the years I've seen an awful lot of people have to use stronger and stronger drugs to treat their rats with respiratory infections. I suspect part of this is because these "lower level" drugs have been thrown around and used so much. In my own personal experiences, Baytril doesn't even treat respiratory infection (I've even stopped taking my rats to those vets who prescribe Baytril). That experience is different from other people, so take it with a grain of salt.

That being said, a basic air purifier can help, because it will help reduce the amount of airborne dust in the air. Do not use an ionizer, but a basic hepa filter is helpful. Also look for bedding with the least amount of dust. I had good experience with using aspen (which is less expensive than a lot of other options), but had to stop using it because *I* developed allergies to it. I never used pine or cedar (the phenols in these can actually irritate the sensitive respiratory tissues in rats and contribute to sneezing and respiratory infection), though I have heard of people successfully using kiln-dried pine (not sure if they performed necropsies to see what the insides of the animals looked like after death, though). I don't know what the cost is, but I have seen horse bedding that's basically just shredded paper. I was given a bag of this once and it worked great, none of my rats had trouble with it (except the one super sensitive rat mentioned above). I've also used alfalfa pellets fairly successfully, but I suspect these will be going up in cost in the next year (if they haven't already).