worried about my guinea pig

Question
I rescued two 5 month old guinea pigs just over a week ago- was told they were both males and I noticed both seemed to have mites.  They are being treated by the vet with Ivomectin (just had the 2nd treatment today) but one is much worse than the other and I have seen no improvement.  It has sores and squeals in pain when it scratches.  Today the vet gave him an anti-inflammatory /antibiotic injection to try to soothe it, but I've noticed no difference yet.  I have not handled them much yet as they are very scared and not used to being handled, and also their skin is sore and I don't want to put them through any more pain until they are feeling better.  The thing is, when I went to put one back in it's pen- the Abyssinian with the worst case of mites, I noticed its belly is very swollen and I cannot see any obvious male genitalia.  The other pig is definitely a male.  I am worried it is a female who is pregnant- not easy to tell as it has a lot of fur- if it is, 2 vets have missed this!  But they have only looked at its skin.  They are due to go back to the vets in a couple of days' time- do you think I can leave it until then or should I take them back sooner?  I am worried as he/she is not fully grown yet and not in the best of health, in addition to the stress of being moved to a new home, going to the vets etc and then today being given an injection.  Can you give me any advice?  I am very worried for its health and that of any possible babies, and how soon they might arrive.

Answer
Hi Donna

Firstly, well done for rescuing the 2 pigs.

In terms of the skin, it does take 3 doses sometimes before the skin shows signs of improvement, but a stronger anti-mites dose/drug may be needed if things dont improve.

Take a look at the link below which tells you how to sex piggies. The main way to tell if the pig is pregnant is to weigh it each day and if there is more than a couple of ounces gain then pregnancy is a big possibility.

Pregnancy lasts 63-72 days approximately but its very difficult to say how long has passed but if you can feel babies moving inside her then you are in the latter stages.

Some people find that teatree oil helps sooth the skin so you could try this.

Andy

http://www.diddly-di.fsnet.co.uk/Sexing-Guinea-Pig.htm

PS When you go back for the third dose, make sure they vet weighs your pigs as the correct dose depends on their weight. Please keep me posted and write back anytime you need. I have had lots of experience of mites.