horrible smell and discharge from cat

[falcon1529]

My 4 year old cat periodically gets a horrible smell and has a milky discharge from her rectum.  She's an indoor cat that won't even attempt to go outside even if the door is opened in front of her. Her sister/littermate lives with us too but shows no signs of these problems.  It seems to happen every couple of weeks and lasts for just a day or two. It seems to happen immediately after drinking milk (within an hour or two) but a couple of times it happened when she had no milk at all. She eats Purina Indoor Cat Formula and won't even try anything else.  Could this be a dietary problem, lactose problem or do you think there is cause for alarm?  We anxiously await an answer.

[Concernedkitty]

I also recently have noticed this about my female cat.  Indoor cat as well, totally.  She recently has smelled terrible from that area and her brother never does.  I thought it might be her inability to clean herself.  I am concerned.  I have not noticed any abnormalities in her stool.  They both have had worms a few times.  Not sure if that has anything to do with it.  

[falcon1529]

Thanks for your reply.  We're bereathing a little easier now that we understand what we saw and smelled.

[Aleda M Cheng, D.V.M., C.V.A]

She could have an anal gland problem, especially if the secretions have a very malodorous fishy-like smell.  Anal glands are scent glands on either side of the anus.  Normally a cat will express her anal glands daily when she defecates, and you will not smell anything extra.  Some cats lose control over when they can express their anal glands and they are expressed randomly, or not at all.  If they are cannot be expressed they must be expressed manually, or they can abscess.  Your veterinarian can do this for your cat.  They can also be expressed every two weeks as a maintenance to ensure that she does not express them randomly.  Anal gland problems can occur as a result of inflammation of that area from food allergy, IBD (inflammatory bowel disease), or unknown causes.  A lactose intolerance could effect the anal glands also.  Once expressed they can leak for a couple of days.  Switching to a hypoallergenic may help her, but it sounds like it would be very hard to switch her diet.  Your vet could help you out with the dietary switch since most hypoallergenic diets are prescription.