Genetic Defect and a Lost Pig


Guinea pigs can live a few days without food for a few days. It has been a few days since Cassius has given birth, and one of her babies was lethargic. One of Cassius’s piglets has some major issues though. It is blind. Most of the time, blindness isn’t that big of a deal, but in this case, it is a genetic defect called microphthalmia.

This means that the eyes in the socket are too small (or not there) and the pig can’t see. This usually means that breeding of a Dalmatian x Dalmatian color, or a roan x roan color. In these breedings, 1 out of every 4 pigs have major issues and are white. This pig isn’t white, and neither Ron nor Cassius are visibly roaned or dalmation. Ron is a red and white bicolor, and Cassius is mostly brown, with a bit of white and orange on her cheeks.


This is Cassius (Cass), my new 1.68 lb girl.

But freak births happen.

However, some recessive roaning can be in the genetic makeup. Somewhere?!? I don’t know, but this pig can’t see, nor get food or warmth. So, I humanely ended his life, leaving me with 16 baby pigs.


8 responses to “Genetic Defect and a Lost Pig

  1. It sounds like you may have something called a hidden roan which would lead to a lethal white baby or one with severe genetic deformities. Some roans only have a few roaned hairs that are barely noticeable. It is not recommended to breed from these animals so please do be very careful.

    I’m not suggesting you don’t know what you’re doing but I think you might find these websites interesting or useful. (I know some places can be a bit preachy and against breeding but these pieces have some quite good information if you get past that!)

    I hope this helps

    Best wishes


    • I have already read both of these websites. I searched both of the pigs for any sign of roaning. The baby pig also has hardly any white on him. Ron has 16 other offspring that were healthy, and Cassius had four in her last litter that survived with a solid boar. She will be moved in with another boar once she weans (though she has already rebred).


      • It is always good to share knowledge. The babies come out so well developed, that sometimes, I think flukes just happen. Even though it is a lethal gene thing, it must be dormant in other pigs too right? And then occasionally comes out. My knowledge of animal genetics is limited


      • From my knowledge, which may be considered limited also – I have kept guinea pigs for 12 years now and keep up to date on veterinary research. If you want to know about heart disease, URI’s, UTI’s, fatty lumps, eye or ear infections, brain damage, seizures, diets, etc then I’m your girl! But genetics it a bit sketchy for me – some carry the lethal gene and there is a 25% chance with every litter that they will have a deformed baby. As they age I believe the chance rises but I will double check when I get home and can look in my files. It’s something to be aware of at least. I believe the pregnancy diet can affect the health and genetics of the babies. What sort of diet are you feeding the Mother’s if you don’t mind my asking? I’ve never bred and only keep boys but I know that they are supposed to have alfalfa hay. That’s about it. Sorry for all the questions, I’m just curious! So many forums I go on are totally against breeding so it’s near impossible to study it and I’m one of those annoy people who always wants to know more!



      • So, I feed alfalfa pellets (for Guinea pigs), and they have an outdoor style tractor pen, so they have unlimited access to green grass. They also get free run of grass hay. Some of my guinea pigs also get spent brewing grains (majority of carbs washed out). Twice a week they get veggies high in vitamin c. Kale, collards, carrots, etc. Not a perfect diet, but I have no cases of obesity, malocclusion, or even unhappy pigs! Cassius is only 1 ish. This is her second litter.


      • That’s really interesting. I’ve heard grain is not recommending for piggies. How long have you been feeding it? What do this piggies think of it? Usually they’re pretty good judges of their own food and won’t eat things that aren’t good for them so if they eat it then it’s fine. I suppose it’s a cheaper option as well.

        Have you tried them with any herbs? Things like parsley are really a favourite with mine and good for them too.

        Also, I just started using the piggy poop as fertiliser on the parsley plant and it’s grown gigantic! Might be worth if you’re trying to make the best of everything using the poop like that, if you’re not already!



      • This group of pigs that Cassius is in has never received them. They eat it voraciously. Have been doing it for only a few weeks. I did extensive research on the nutrient content in spent grains, and it is high in fiber and protein, and has a similar nutrient content to pellets. I will be posting that soon. They fertilize the grass they eat with the poop, so it ends up back in their system. Will try herbs though

        Liked by 1 person

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