Abscess and other wounds in cats


Retroperitoneal abscess

Question: Dear Dr. Mike,

I have a four and a half year old cat that was absolutely normal up to ten months of age when she was bitten by a dog. Her entire life changed after that. She sat almost immobile for about 10 days following the bite crouching in a corner and stopped jumping and playing. Slowly a lump was noticed around the site of bite, which was operated upon suspecting a hernia but was found to be a lipoma. Later she started developing growths over the thighs and abdomen, which was operated upon and diagnosed to be diffuse benign lipoma. The last surgery was about a year ago when she was spayed. She never conceived until then although she used to come on heat regularly. Now her weight is a little bit under control as we restrict her diet. No fat free diet is available over here. She also consumes lot of water and passes lot of urine. Time and again tests for diabetes are negative.

I am also enclosing the lab results of some investigations done on her in the last two years.

Feb 12, 2001

Alkaline Phosphatase 16.5MU/ml

Cholesterol 118mgs%

Creatinine 1.3mgs% S.G.P.T 65U/L

Total Proteins 9.2gms%

Albumin 2.9gms%

Globulin 6.3gms%

A: G Ratio 0.5

Aug 28, 2000

Creatinine 1.5mgs%

Random Blood Sugar 123mgs%

Total Count 24600/cmm

Neutrophils 78%

Lymphocytes 20%

Eosinophils 2%

Hb 16.8gms%

PCV 48.3%

The results of Aug 2000 were followed by a course of Cefazolin Injections for suspected infection (pyometra?) and spaying.

The above tests were carried out to rule out some systemic cause for her lipoma (like addison's) and were told that all the results were normal except for increased WBC count in the latter.

Presently she has a skin/subcutaneous tissue problem for the last four months. Over the right hip region at the root of the tail, there are multiple holes with serous discharge. She has been on oral or parenteral antibiotics continuously for the same for the last three months. As long as on antibiotics the holes are closed and the discharge reduced but stopping the medicine for a single day will aggravate the condition the next day. Though her feeding is normal when not on medicines, her activity comes down and she tends to gain weight. She was given the following drugs for the last three months.

Oral Ampicillin+cloxacillin 15days

Inj Cephalexin 10days

Oral Ciprofloxacin 15days

Oral Pefloxacin 15days

Oral cefadroxil 15days

Inj Cefazolin 10days

Presently the vet has prescribed oral cefuroxime to be given on alternate days. All dosages have been given adequately as per vet's advice.

Is there any other alternative in the form of drugs or surgical intervention? Doesn't prolonged antibiotic therapy have adverse effects? Do the investigations reveal anything? Do you suggest any other tests? How do I manage her weight problem other than exercising? And how can I free her from her chronic infection?


Answer: Veena-

You didn't say where the bite wound was but if it was over her back or flank I would worry about a retroperitoneal abscess with the draining tracts and history of elevated white blood cells counts. Often, when there is a persistent infection there is an increase in the immature neutrophils (band neutrophils) in the blood stream but this is not always the case. It does make this possibility a little less likely but with the clinical signs it still has to be considered. The high total protein is probably indicative of high globulin levels, which include the antibodies manufactured to fight off diseases. High globulin levels also occur in chronic disease, for this reason.

Retroperitoneal abscesses are infections that occur between the peritoneum, which lines the abdominal cavity, and the muscle layer above it. This seems to be a hard area for the body to deal with infections due to a lack of blood supply, so they can become very chronic. In many cases, antibiotics alone will not resolve the problem. We have seen this problem infrequently in our practice (and I can't remember a cat with the problem but I think it can occur in them). The drainage usually occurs right where the hip and flank meet but in cats drainage often seems to occur at some distance from the inciting cause so it just seems possible that this is the problem.

These abscesses are sometimes visible on X-rays or through ultrasound examination. If there is a foreign body (like a piece of the dog's tooth) visible on the X-rays the location should be carefully noted since it can be really hard to find a foreign body during surgery to drain these abscesses. In one study reporting on retroperitoneal abscess in dogs it was noted that it took up to five hours to find the foreign body during some of the surgeries (Dudley Johnson, 1990, Compendium on Continuing Education). We have seen these abscesses as the result of non-absorbable suture material used during spay procedures but this is an unlikely cause since recognition of this problem has pretty much led to the discontinuation of the use of these materials for spays.

It also seems possible that a hernia was actually present and was just difficult to identify and that the present problems are a complication of the hernia. I can recall several times when I was unable to identify a hernia during surgery that was later found to be present. I have also had hernias form in areas in which I didn't think there was a wound and therefore didn't look for one. Bite wounds can cause a lot of damage below the surface without penetrating the skin so this is always a possible problem.

There may also be a problem with infection of the bones (probably of the spine) in this region that could be new or could be due to the original wounds. Bone infections often lead to draining tracts in the overlying tissue and drainage from the tracts is often controllable with antibiotics but returns quickly when they are discontinued.

If it is possible to culture the bacteria in the wounds and to get a sensitivity test done to help decide which antibiotic to use that might be helpful. I think that I would want to open the wounded areas again (or at least the new ones) and look for hernias, draining tracts, abscesses and foreign bodies, but that would depend some on the actual appearance of the draining tracts.

We have used antibiotics long term in a number of patients. Sometimes this does cause problems but most of the time it doesn't, as long as the antibiotics used are relatively safe, such as the cephalosporins which have been used so far.

I realize that surgery probably isn't an appealing choice and I wish I could think of a better option.

Mike Richards, DVM



Abscesses are a common problem in cats. It is hard to say why cats develop abscesses more frequently than other domestic species but there are several plausible reasons. A bite from a cat wound is more likely to become infected than a bite from most other species due to the bacterial residents of cat mouths. Since cats bite each other fairly frequently this is certainly one reason for the high number of abscesses. This situation is exacerbated by the tendency for cat bite or scratch wounds to have small entry wounds but to cause damage subcutaneously which becomes infected after the small skin wound is already healed. Cats also are prone to immunosuppressive viral illnesses such as feline immunodeficiency virus and feline leukemia virus which makes infected cats more likely to suffer an abscess after a wound.

Most abscesses start out as cellulitis, which is infection of the tissues under the skin. In some cases it is possible to prevent abscess formation by early detection of the presence of cellulitis. Signs of early infection may include lameness, localized pain, lethargy or reluctance to eat. If your cat exhibits any of these signs and your vet can determine that cellulitis is present early administration of an appropriate antibiotic may prevent abscess formation.

After a brief period of cellulitis, an abscess forms. The cat's body attempts to fight the bacterial infection by forming a capsule around it and flooding the capsule with a large number of white blood cells. This collection of white blood cells and bacteria is commonly referred to as pus. I f the cat is really successful at walling off the infection there may be a small abscess. If the cat is less successful at dealing with the initial infection the abscess may be very large. In this case the abscess may cause the skin over the abscess to die. The skin usually turns black and becomes very hard to the touch after it dies. It will fall off eventually if left in place but it is better to remove the dead skin to allow healing to occur faster and to ensure that the abscess can be properly treated. Abscesses that occur around the base of the tail are very prone to causing skin sloughing. Early aggressive treatment is best when there is pain or swelling around the base of the tail.

Abscesses are generally treated by opening them up to allow them to be adequately cleansed with an antiseptic. Abscesses can be very painful. If a cat will not allow an abscess to be opened due to the pain it may be necessary to use an anesthetic agent so that the abscess can be properly treated. If there is dead skin over the abscess is should be removed as well. It surprises many clients that this can often be done without an anesthetic agent, since the dead skin has little or no feeling. The live edges still have nerve endings and many cats do object, though. After the abscess is cleaned most vets will prescribe antibiotics. There is a wide variation in the way antibiotics are used by veterinarians in the case of abscesses. In general it is possible to treat most abscesses with ampicillin or amoxicillin since the majority of abscesses are caused by bacteria that are susceptible to these antibiotics. Once started the antibiotics should be used for at least three days and it is important to use appropriate dosages. It is not usually necessary to use antibiotics longer than seven days and it is often appropriate to use them for three to five days only.

Some abscesses do not respond to standard therapy. Almost every veterinarian who treats cats has run across an abscess that seems impossible to cure. If this happens there are a number of possible causes. It is usually a good idea to culture the abscess site in this case. If the bacteria involved can be grown and identified it helps a great deal. If the bacteria can be grown on a culture plate it is possible to try to kill it with a number of antibiotics and pick one that works -- at least on the culture plate. If it appears that a new antibiotic is necessary that may be enough to cure the problem. Sometimes that isn't enough to cure the abscess, though.

When abscesses do not respond to treatment with standard treatment and after identification of bacteria that can be cultured from the wound it is time to look for underlying causes or complicating causes. There are several things that cause abscesses to be difficult to treat. Feline leukemia virus infection or feline immunodeficiency virus infection can cause the immune system to fail to help clear up the abscess. Despite the "wonder drug" label, antibiotics often need the help of the body's natural defenses to cause a cure. Sometimes the infection is caused by an unusual organism that does not respond to the same antibiotics used for the most common bacteria found in bite wounds. Mycoplasma infections will respond to tetracycline antibiotics in most cases. Nocardiosis infections respond to sulfa/trimethoprim antibiotics used at two to three times the usually recommended dosages. Actinomyces infections may respond to very high dosages of penicillin. A newly recognized variety of bacteria, l-form bacteria, usually respond to tetracycline antibiotics. This form of infection may not be known to your veterinarian. It usually appears as an infection affecting multiple joints with several abscesses or draining tracts that does not respond to conventional therapy. The l-form bacteria can not be cultured in the same way other bacteria are so they are difficult to diagnose. Response to tetracycline may be the best "diagnostic" test available to the general practitioner since confirmation of infection may require examination of abscess contents with an electron microscope.

Abscesses vary in severity from a relatively minor problem that the cat's immune system will handle on its own to complicated, life threatening infections. It is best to treat them early, establishing proper drainage if at all possible, cleansing with an antiseptic and in most cases appropriate antibiotic therapy. Some abscesses are not going to respond to routine treatment methods and will require multiple visits and become very frustrating, both for you and your vet. If an abscess is not responding to treatment it is vitally important that you alert your vet and that you continue to work with your vet to resolve the problem. You may have to push a little for diagnostic testing or use of tetracycline based antibiotics to rule out l-form bacteria and Mycoplasma infections in chronic abscess situations since there is a tendency among veterinarians to continue to use broad-spectrum antibiotics in the face of resistant abscesses rather than switching to medications with a narrower spectrum of action such as the tetracyclines. It is probably not a good idea to use tetracyclines routinely since they do not work as well against the most common forms of infection as other antibiotics and because their mechanism of action makes them harder to combine with other antibiotic therapy to achieve a broader spectrum of action.

Neutering male cats greatly reduces roaming behavior and fighting associated with seeking mates. This also reduces the incidence of abscesses in male cats. It may be best to avoid the whole issue of abscesses by taking this preventative measure!

Mike Richards, DVM

Swollen Nose in Cat - possible abscess

Q: I have a nine-year-old neutered male Tabby cat. He is in generally good health, but has started sleeping A LOT -- almost all day every day for the past two days. I also noticed last night that the bridge of his nose is swollen until it looks like a Roman nose. It's also very warm there. I don't want to take him to the vet (and therefore save money -- we're on a tight budget) if it's something that will go away on its own. I don't want to sound callous, but money is tight in my family right now. Does this sound like something minor? I've never heard of it myself.

A: It sounds like your cat may have an abscess on his face over his nose. This would produce swelling and heat in the area. It is also possible that there may be a fungal infection (ringworm occasionally develops in raised lumps and this would be a common spot for that to occur), nasal infection can lead to swelling in the area just behind the nose, skin cancer is possible in his age range and trauma can do this as well.

It would be best to take your cat to your vet. It can be a lot less expensive to treat a problem early before it causes major problems. Since the possible conditions require different treatments, knowing which one to recommend really depends on being able to see and examine the cat. Your vet can do that for you. I really do think that recommending a trip to your vet is the best advice I can give.

If money is a temporary problem your vet may be willing to allow you to pay later or to hold a check for you until the situation gets better. It doesn't hurt to ask.

Mike Richards, DVM


Michael Richards, D.V.M. co-owns a small animal general veterinary practice in rural tidewater Virginia. Dr. Richards graduated from Iowa State University's College of Veterinary Medicine in 1979, and has been in private practice ever since. Dr. Richards has been the director of the PetCare Forum...