A gentle giant with a giant mass and a giant infection.


Many dogs experience Masses, which can potentially be located in any part of the thorax (esophagus, heart base, lung, trachea, chest wall, rib, mediastinum and thymus). If left untreated, your dog will experience continued swelling and discomfort which will eventually affect his/her well-being.

This is a case about a gentle giant with a giant mass and a giant infection.

Astro is a twelve year-old Great Dane who was seen for a mass on his thorax.

His owners noted it when it initially began to grow, but they were hesitant to have it removed due to his age.

When the mass reached about 8 inches in diameter, they brought him in to see if the mass could be lanced. A large amount of fluid was drained from the mass but it was still sizable afterwards.

As time progressed, the mass grew in size. It reached a point where it grew so fast, the tissue inside became necrotic, infected, and a draining tract formed.

A few rounds of antibiotics did not improve Astro's situation.

Astro continued to be healthy. He was showing some signs of arthritis, but was perky, alert and was eating well - despite the infected mass.

His owners decided to admit Astro to the hospital for removal of the mass. They elected to skip pre-surgical bloodwork because, regardless of the results, they wanted the mass removed.

By the morning of surgery, the draining tract was now 2 inches large and a cavitated area of dead, necrotic tissue could be visualized. It had begun to produce a foul odor due to infection setting in.

The mass was removed under general anesthesia. Astro was monitored closely and great care was taken to ensure minimal blood loss. A penrose drain was placed to encourage the surgery site to drain appropriately. The surgery lasted three hours, and Astro recovered nicely from anesthesia.

Astro was kept at the hospital overnight to be sure he was comfortable and did not lose excess blood post-op.

The next morning, a CBC was run and we discovered a white blood cell count of 64,000 (the normal count for a dog is under 17,000). This was one of the highest counts I have seen as a veterinarian!! Surprisingly, Astro was alert, perky and eating well for us, so we decided to send him home. The owners agreed to watch him closely and be sure Astro received ALL of his broad-spectrum antibiotics. Astro was at a high risk of becoming septic (infection of the blood that can be fatal).

Over the next week, Astro was in for a few rechecks. Some of the skin at his surgery site had died off. He received a few treatments to remove dead skin and a few more stitches were placed. His penrose drain was removed. Things were looking pretty good for Astro.

We saw him 14 days after surgery for removal of his stitches. At that time, the surgery site did not appear to be entirely healed. There was a fair amount of bloody, slimy discharge coming from the incision. We were very concerned that Astro had developed an infection that most of our antibiotics did not cure.

The incision was cultured, and it turned out to be infected with methicillin resistant staph pseudintermedius or MRSP.


MRSP in dogs is very similar to the MRSA we encounter in human medicine. It is a multi-drug resistant bacteria that responds to very few antibiotics. These few antibiotics, we call "last resort" antibiotics because they are very expensive, can only be given as injections, and can be harmful to the major organs in the body. There is also a HUGE concern that, if bacteria learn how to become resistant to these last resort drugs, there will be no other treatment options for infection in our patients.

Since Astro's only option was these strong antibiotics, he was placed on a 10 day course of them. Every day, Astro was given sub cutaneous fluids (to help nourish the kidneys) and injections of amikacin. We also applied a topical antibiotic (mupirocin) to the wound.

Over those 10 days, Astro was a healing machine! He remained bright with a great appetite. The surgery site began to dry up, scab over, and with the help of a few more stitches, he was 100% healed!!

How did this happen?

Due to the large amount of necrotic tissue and infection of the mass, and the several rounds of antibiotics given to Astro in the months leading up to surgery, there is a strong likelihood that the bacteria present on Astro's mass had become resistant to most antibiotics. Since we were never "clearing" Astro of the infection, there were remaining bacteria (after each round of antibiotics) that "learned" how to avoid death by most antibiotics. This (simple explanation) is one of the reasons that medical professionals are seeing more and more MRSP and MRSA - and why a lot of our first-line antibiotics are no longer working.

Astro was a special case; there was no way of knowing that this would be his outcome. However, "improper" use of antibiotics CAN be avoided on a daily basis. It is important for medical professional to heavily scrutinize prescribing antibiotics. It is also important for owners to follow the dosing schedule and finish all medication to be sure the infection is ENTIRELY cleared on/in an animal. Not every animal needs antibiotics, and the more our society can learn about the scary phenomenon of multi-drug antibiotic resistance, the more we can decrease MRSA/MRSP infection rates.

Four months later, Astro is still doing well. He is mass-free, infection-free and will sometimes let his "inner puppy" out to play! It was a long journey for this boy (and his amazing owners), and he has a beautiful battle scar to show for it!

To learn more about MRSP in pets, please follow this link