Tuesday, February 7, 2012

Lump on Cats Belly (Part 1) - I Want To Hold Your Gland

Two weeks ago, I was presented with a very aggressive 15 year-old cat for evaluation of a “lump on the cat’s belly”, as noted in our appointment book. Emma had been adopted as a 3 year old by her owner.  She was eating and drinking well, was drinking water normally, vomited occasionally, and that’s about it.  No coughing, no sneezing, no diarrhea… no problems in general.

Emma was a handful.  She had to be muzzled before I could examine her.  I couldn’t examine her eyes or her teeth very well, as a result.  When I got to her belly, the owner showed me what she was concerned about.  It looked like there was some discharge coming from the last nipple on the left side.

When it comes to anything involving the mammary glands, veterinarians start to worry.

In dogs, mammary gland tumors are benign 50% of the time, and malignant 50% of the time.  And of those that are malignant in dogs, half of those are cured by surgery.  In cats, it’s a different story: 85% of them are malignant.  But I checked the gland, and as best as I could feel, there was no “mass” associated with this gland.  When you pressed on the gland, a yellowish/reddish discharge appeared, but that was about it.  All of the other glands were normal in appearance and in feel.

Because she was 15 years old, I recommended bloodwork just to make sure that no concurrent illnesses were present.  At this age, Emma was at increased risk for hyperthyroidism and chronic renal disease, and we needed to make sure that nothing was brewing.  I obtained blood (much to Emma’s annoyance), but was unable to obtain urine (much to Emma’s delight).

I didn’t end up treating the mammary gland, because I couldn’t feel any mass or tumor associated with the gland, per se.  I had expressed all of the discharge that was present in the gland, and it looked pretty normal by the end of the appointment.

Afterward, I was thinking about Emma, and I had second thoughts.  I thought that this could be an infected gland, and that I should have cultured the material from the gland, and perhaps started her on antibiotics while waiting for the results.  I made a note to call the owner the next day and have her bring the cat back in for me to do this.

The next day, however, the bloodwork came back, and to my surprise, all of the liver enzymes were significantly elevated.  I didn’t expect this.  Emma had no signs of liver disease, i.e. no weight loss, no decrease in appetite, no significant vomiting.

When liver enzymes are elevated in the cat, it suggests that something may be wrong with the liver.  Duh.  Unfortunately, that’s about all you can say from the bloodwork.  People have noticed patterns, for example, if the ALP is high but the GGT is normal, then hepatic lipidosis (“fatty liver disease”) goes higher on your list of differentials.  If the liver enzymes are high and the white count is high and there’s a fever, then cholangiohepatitis (infection or inflammation of the liver and bile ducts) goes higher on your list.  But these are not hard-and-fast rules.  To get a true diagnosis, there’s no way around it: you need to biopsy the liver.

I spoke to Emma’s owner and told her that I’d like to schedule ultrasound of the liver, and then obtain an ultrasound-guided biopsy.  While the cat is sedated for the biopsy, I’d recheck the mammary gland, and culture the discharge from the gland to see if there’s an infection.  I’d also put a drop of the discharge on some microscope slides, make some smears, and send them to the laboratory so that a cytologist could assess it.  The owner agreed to this.

A few days later, Emma was back, as grumpy as ever.  We sedated her carefully (using drugs that did not require any metabolism by the liver) and performed the ultrasound.  Emma’s liver was mildly enlarged, with a few nodular areas that the ultrasonographer thought were just “nodular hyperplasia”, something commonly seen in cats (and dogs) as they age.  He did think that the “echogenicity” was increased (i.e. the liver looked a little “denser” on ultrasound), suggesting that it was more likely to be infiltrated with cells – for example, inflammatory cells or cancer cells – rather than fat cells.  He then obtained two biopsy specimens.  When we dropped the specimens into the formalin jar, we watched as the specimens sunk to the bottom of the jar.  It’s a crude little test, but it does give some information: if the liver specimen is fatty, like you see with fatty liver disease, the biopsy specimens float on top of the formalin. The fat makes them buoyant.  If they sink to the bottom, the specimen is cellular.  These sunk, supporting his contention that the liver had a cellular infiltrate.

I then checked out the mammary gland.  Although there was no discharge present on the nipple, I was able to produce some by gently squeezing the gland. I cultured some of it, made some slides for cytology, and then woke Emma up and, a few hours later, sent her home.

The results of all of our tests?  Stay tuned for Part 2...

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