What is that bump? - Cutaneous mast cell tumors in cats

Just like any cat that comes through our front doors, Mr. A and Mr. B get wellness exams periodically. On February 7, one of our technician discovered a small, raised bump on Mr. B's hock.

Since new bumps on a cat should be looked at to ensure that they are not cancerous, we had Dr. Demos give Mr. B a thorough exam and take a sample from the mass with a needle. This is called a Fine Needle Aspirate (FNA), and can often give us a good preliminary idea of the kind of lump we are dealing with.

Once we had a sample of the mass, the images we saw under the microscope showed this:

 Very dark-staining cells filled with small granules and lots of small granules in the background. These are mast cells.

Mast cells

 Mast cells can easily be compared to other abnormal cells, like these white blood cells, called lymphocytes, that are abnormal due to the presence of a cancer called lymphoma.

Lymphoma

 Since we were suspicious of a mast cell tumor, we scheduled Mr. B for surgery to remove the mass. He fasted prior to surgery, and then was given preliminary pain medications. We anesthetized him and shaved and scrubbed the surgical site. Even though the lump was quite small, the surgery was very delicate, because the hock is an area with prominent blood vessels and tendons, and has very little fat.

Once the mass was removed, we placed it in formalin to send to a pathologist for analysis. Even though we have a good idea what the mass is before we remove it, we like to confirm it with the experts, and also have the mass checked to ensure that we removed all of it. This is done by measuring the "margins" around the edge of the abnormal tissue.

"Clean margins" (a ring of completely normal tissue around the mass) mean that the mass is less likely to recur. If the margin of normal tissue around the mass is too small, there increased risk of the mass re-occurring. The need to have clean margins around the mass is also the reason that you may notice the area where a mass was removed is often quite a bit larger than the mass was, originally. In some areas, such as the leg, face and tail or the top of the head, where there is not a lot of extra skin, it may be very difficult to create good margins for a mass without risking the integrity of other parts of the body. This is why it is a good

After surgery, we placed Mr. B in a cage, to ensure that he was fully recovered before we let him run around. Usually recovery from a short surgical procedure like a skin mass removal takes just a few minutes from the time that the anesthetic gas is turned off. In Mr. B's case, he was sitting up and asking for post-surgical treats within about 10 minutes.

First, Mr. B fasted for his surgery. He was not very excited about that.

Next, we set up for surgery.

We placed Mr. B under anesthesia, intubated him and shaved and prepped his surgical site.

Post-surgery, we cleaned the sutured incision site, and let Mr. B recover on his warm water blanket.

Mr. B completed his recovery in a cage, and then enjoyed a post-surgical meal. His eyes are very dilated from the pain medication we used. It made him VERY happy.

What is a Mast Cell? Mast cells are a normal cell type found in the body that is involved in various functions including the immune system, wound healing, allergies and inflammation. The granules that they contain are really little sacs that carry important chemicals such as heparin, histamines and antimicrobial chemicals.They are developed in the bone marrow and disperse throughout the body to the skin, connective tissues and the lining of the abdominal organs such as the stomach and intestines.

Despite their beneficial activities in the body, sometimes, mast cells go bad. Mast cells play a big role in anaphylactic reactions (the kind of serious allergic reaction many people experience due to bee stings). Also, in addition to forming mast cell tumors, they can also be involved in autoimmune diseases. In humans, mast cells have been implicated in rheumatoid arthritis.


About 20% of all skin tumors in cats are mast cell tumors, and these types of tumors occur less frequently in cats than in dogs. About 90% of cutaneous mast cell tumors in cats are benign, and excision (surgical removal) is the cure. Mast cell tumors in the internal organs are a different matter.

Once we had sent in Mr. B's mass for biopsy, we received the following report from the pathologist a few days later:

Microscopic Description	Small left hock skin mass contains a dermal solid proliferation of minimally pleomorphic small neoplastic mast cells. Mast cells efface adnexal structures. One mitotic figure per 10 high power fields is seen. Tumor free margins measure approximately 1 mm.
Microscopic Interpretation (Biopsy)	Cutaneous mast cell tumor
Comments:	Histologic features of this skin tumor are consistent with a benign dermal mast cell tumor. Cutaneous mast cell disease accounts for approximately 21% of all feline skin tumors. Grading scheme similar to canine mast cell tumors has not been developed for feline neoplasms. Mitotic count (over 5/10 HPF) is the only criteria that has prognostic significance in determining benign from malignant (Vet. Pathol 2010; 47(4); 643-653). Neoplasms with high mitotic rate may have concomitant increase in mast cell pleomorphism.

Now we can be confident that the tumor was removed entirely, and that it was benign.

Mr. B is now strutting his stuff as usual, with lots of commentary on his healing progress. In 10-14 days, he can have his sutures out and in 6-8 weeks, his hair will have regrown, and no one will even see his scar!

We wonder whether Mr. B is asking for a matching shaved spot on his other legs.

Cat Friendly Practices - How Does this Help my Cat?

George, summer 2014

Semi-Feral Handling

Meet handsome George. He is a young cat that has lived outside for all or most of his formative years. He avoids direct human approach. But, he sort-of wants a home. Two lovely people took him under their wings and tried trapping him. After about 8 months of evading the trap, they finally caught him and brought him to us.

Having had minimal handling, he climbed the walls and bit and scratched out of fear and anxiety when the owners first tried to put him in a carrier to bring him in for neutering and vaccination.

After his first experience with us, which was a short stay in a boarding cage after his surgery, and minimal, gentle handling, his second visit went as follows:

First, he was allowed to acclimate to the sounds and smells of the hospital. We have Feliway diffusers throughout the hospital to help reduce anxiety.

Next, we approached with slow but deliberate motions. Making many small, unnecessary motions around a nervous cat can cause increased anxiety, since a fluttering hand may resemble the motions of a bigger predator or fluttering prey. Many times, when handling stressed, anxious or shy cats, "less is more".

Next, we undid the clasps on the carrier, and held a towel over the front of the carrier while we opened the door, removed it, and then simultaneously slid the top of the carrier off and slid the towel over George. Most of his exam was performed while he was under the towel, sitting in the bottom half of the carrier. This allowed him to feel comfortable and protected. The restraint used for him was gentle pressure on both sides of the body, just enough to keep him from darting out of the carrier, but no more.

Once as much of the exam was completed as could be done while he sat in the carrier, the technician tested his response by gently lifting up his front end. When he did not panic, she lifted his entire body from the carrier and placed him on the counter. The exam continued, and we were able to vaccinate him, as well. Additionally, once the exam was complete, we were able to brush out the fur on his back for a few minutes, until we could feel his muscles begin to tense. It may not look like the technician in this picture is paying attention to the cat, but often, staring at a cat can cause the cat to become anxious or feel threatened, so often, technicians rely more on the information the cat gives them through touch - tensing of muscles, small movements that project the cat's intentions. That way, the cat, who is already being closely inspected by the doctor, does not feel overwhelmed.

We placed him back into the bottom half of his carrier and he relaxed a bit, and we were able to comb him for another minute or two before he tensed again, signaling that he was thinking about fleeing. We carefully replaced the top of his carrier and the door, and gradually removed the towel, completing our work with this semi-feral cat without undue stress, and without anesthesia. We placed treats in his carrier to end the visit on a positive note. Our hope is that with each successive visit, he will become more and more tolerant of handling.

George, winter 2014

He badly bit one of his owners in his panic over being placed in the carrier to come to the hospital, that day, so it is our concern that he become used to the practice of traveling in the carrier to avoid future harm to his owners as they try to provide him with good medical care. We recommended leaving the bottom half of the carrier out in the house, possibly with intermittent food in it during the day and a blanket at night, so that he will become more accustomed to the sight and smell of the carrier. If the food is in the carrier all the time, he will likely still run when his owners approach the carrier. If the food only appears in small amounts when the owners walk over to the carrier, he may begin to run to the carrier in anticipation of special treats! We discussed placing a towel over him while placing him into the bottom half of the carrier, and then "re-building" the carrier around him instead of trying to to force him in through the doorway. Additionally, placing a mild sedative in his food prior to the exam may allow him to relax enough to be placed in the carrier.

Stay tuned to see how things go next month, when George will need a blood sample collected!

Inflammatory Bowel Disease vs. Irritable Bowel Syndrome: Which is affecting my cat?

INFLAMMATORY BOWEL DISEASE

What is Inflammatory Bowel Disease and what causes it?

Inflammatory Bowel Disease (IBD) is a chronic disease of the intestinal tract. In fact, IBD is not a single disease, but several conditions that result in the accumulation of inflammatory cells in the intestinal tract. These inflammatory cells are normal cells that occur in the body, but problems within the body cause these cells to congregate in the stomach or intestinal tract, causing thickening of the linings of these organs and decreasing the organs' ability to perform their normal activities: digesting food and absorbing nutrients.The thickened lining also decreases the body's ability to protect itself from harmful invaders like bacteria and viruses. The lining of the intestinal tract normally functions similarly to the skin in providing a protective layer between harmful infections and the rest of the body's vulnerable cells.

Normal intestinal anatomy - the villi absorb nutrients and pass them into the bloodstream for distribution throughout the body

Most of the time, the primary cause of IBD is unknown or "idiopathic", but chronic inflammation may be caused by diet, environment, parasite infection, immune health or the relationship between the body's immune system and the bacteria that inhabit the digestive tract. While food allergy may not be a primary cause of  IBD, it may be a contributing factor to the severity of the disease.

What are the signs of Inflammatory Bowel Disease?

Inflammatory bowel disease is generally a problem found in cats of middle age and older, but can affect cats of any age. Most affected cats have a history of recurrent or chronic vomiting and/or diarrhea.  During periods of vomiting or diarrhea, the cat may lose weight but is generally normal in other ways. As a rule, most affected cats eat well (or even have an increased appetite) and appear normal, though some cats may have decreased appetite.

Depending on which part of the digestive tract is affected, the cat may be more likely to vomit (stomach, duodenum) or have diarrhea or bloody stools (colon). Mucousy stools may also be a sign of IBD. However, a cat that vomits due to IBD may vomit after every meal, or only once or twice a month. Vomiting may be intermittent or cyclical. The cat may be more prone to hairballs that disrupt the digestive tract - either vomiting hairballs frequently, or by having his digestive tract become obstructed by a hairball. If the whole digestive tract is affected, the symptoms may not necessarily directly correspond to the areas most affected.

How is IBD diagnosed?

Ultrasound examination of a cat

Diagnosis of IBD can be complex, because the common signs (vomiting and/or diarrhea) are symptoms that can be associated with many diseases. Because IBD often is idiopathic in nature, your veterinarian will recommend diagnostics that will rule out more specific diseases, first, such as parasites, viral or bacterial infections, metabolic diseases and cancer. This may involve various blood tests, a stool examination and abdominal radiographs or ultrasound examination. The veterinarian may palpate or feel thickened intestines during the physical exam, or may see evidence of intestinal thickening on x-ray or ultrasound studies.

For most cats with IBD, bloodwork chemistries may be normal. If the liver and pancreas are involved (triaditis), then elevations of pancreatic or liver enzymes would be expected. In cases where the cat is having bouts of severe vomiting or diarrhea, electrolyte imbalances would be a common finding. Additionally, long-standing IBD may result in "protein-losing enteropathy". In a normal cat, a small amount of protein leaks into the intestine as nutrients are absorbed into the bloodstream. These proteins are normally digested in the intestine and then reabsorbed. When the intestinal tract is damaged, as in IBD, more protein leaks out than the body is able to reabsorb.

The only way to definitively diagnose IBD is to collect surgical biopsies of the digestive tract and submit them for pathologist review. The types of cells seen by the pathologist will determine whether IBD is present, and categorize whether the IBD is lymphocytic-plasmacytic (the most common), eosinophilic, neutrophilic or granulomatous in nature. 

Here is what the lining of a normal intestine looks like under the microscope. The areas within the boxes are what we are looking at, below.

The images towards the left show normal intestinal anatomy, while the images to the right show progressively more severe Inflammatory Bowel Disease (human). There is a decrease in the size and surface area of the villi, the thickness of the intestinal lining , and a general degeneration of intestinal anatomy.  Loss of structure = loss of function

Surgical biopsies can be collected via endoscopy or via exploratory surgery. Endoscopic biopsies are less invasive, but are limited because only the upper end of the GI tract can be sampled, and only superficial samples can be collected. Surgical exploration to collect biopsy samples allows full-thickness biopsies of multiple sites throughout the digestive tract to be collected. Additionally, since many cats that have IBD may also have pancreatitis or hepatitis (inflammation in the pancreas or liver), samples of these organs and abdominal lymph nodes can also be collected to ensure that there are no additional complicating factors to the disease.

The first method is a biopsy of the affected part of the stomach or intestine.  The preferred technique to to use a flexible endoscope which allows access to the lining of the stomach, small intestine, and colon.  If the site of inflammation involves any of these locations, a confirmed diagnosis is achieved.  Sometimes, the small intestine may be difficult to enter because of the cat’s small size; in these cases, surgical biopsy may be needed.  Fortunately, this is rarely necessary. The second method of diagnosis is a therapeutic trial involving administration of particular drugs, along with certain dietary changes.  Since not all cats respond to the same drugs, the trial may involve a series of a number of drugs and may take several weeks.  Also, different diets may be tried, depending on which part of the bowel appears most involved.  These diets include hypoallergenic, low residue, or high fiber foods.  The cat is monitored during the therapeutic trial for a decrease in clinical signs and, in some cases, weight gain.

Is IBD treatable?

Treatment for IBD is focused on controlling symptoms such as vomiting and diarrhea and promoting appetite and weight gain. Any complicating factors such as pancreatitis, parasite infection or other diseases should be treated accordingly. Treatment may involve a special diet, anti-vomiting or anti-diarrheal medications, steroids, pre- or pro-biotics, dewormers, omega-3 fatty acids, and B12 supplementation.

What is the prognosis?

Once the appropriate drugs or diet are determined, many cats are maintained on these for life, although dosages of the drugs may eventually be decreased.  Occasionally, a cat will be able to stop drug therapy at some point. Most cats do well for many years; others require alterations in therapy every few months.  Unfortunately, a few cats will ultimately become totally resistant to treatment.

There is a correlation between IBD and gastrointestinal lymphoma in cats. It is not completely clear whether IBD causes or progresses to lymphoma (the most common type of cancer in cats) over time, or whether the same problems that lead to IBD also cause GI lymphoma. Either way, untreated IBD in cats can cause malnutrition and eventual gastrointestinal ulceration and possible perforation of the bowel. Perforation of the bowel allows partially digested food and intestinal bacteria to leak into the abdomen causing severe systemic infection, sepsis and death.

IBD vs. IBS

Irritable Bowel Syndrome (IBS) is not the same as Inflammatory Bowel Disease (IBD). Irritable bowel syndrome is a psychosomatic response that causes hypermotility in the intestinal tract (things move through too quickly). The most common reason for this to happen is excessive stress or anxiety - a trip to the veterinary hospital, the addition of a new cat or new baby to the household, etc. A biopsy of the intestinal tract would look normal, because the problem is not with the intestinal tract itself, but with the nerve signals sent to the intestine that tell it what to do. Treatment of chronic irritable bowel syndrome is aimed at increasing fiber in the diet and controlling the cat's anxiety through environmental management and behavioral therapy. One-time bouts of IBS resulting from travel, visits to the veterinary hospital or other planned events can be averted by acclimating the cat to the carrier, using calming products, such as Feliway or anti-anxiety medications prior to travel or veterinary visits, or by choosing a veterinary office that is a certified Cat Friendly Practice. These hospitals generally have staff experienced with handling stressed cats, have separate waiting rooms, cages and exam rooms for cats and dogs, and may be better equipped to soothe your anxious kitty, preventing the onset of an IBS episode.

Additional Resources
Merck Veterinary Manual: Disease Profile: Inflammatory Bowel Disease 

All Feline Hospital: Inflammatory Bowel Disease 

Cornell Feline Health Center: Inflammatory Bowel Disease

WebMD: Inflammatory Bowel Disease

Wild Rose Cat Clinic Case Study: Tigger, and is it IBD or Lymphoma?

World Journal of Gastroenterology: Inflammatory Bowel Disease in the Dog: Similarities and Differences with Humans

Pitch the Perfume and Toss The Talc: Reuniting Cats Following a Visit to the Vet

Reuniting cats following a visit to the vet

Steven J. Bailey, DVM, DABVP

2015

Traditionally, veterinarians have speculated that new odors on the cat returning home from the veterinary practice were a stimulus for antagonistic behavior between cats. I do not believe this is entirely true, and perhaps leads to clients (and professionals) further antagonizing these stressed cats by applying unnatural scents (perfumes and Baby Powder) with the intent to cover, mask, or replace other scents.

Cats have the ability to detect many more odors and pheromones than we people can even imagine. I have never appreciated that our feeble attempts to address these 'odors' has had any positive impact on feline behavior with respect to these homecomings. 

My perception of some of the causes has been:

- When a cat leaves a clowder of cats (even if the clowder is just a pair) it appears that they need to receive permission to rejoin. If this reintroduction is rushed and stressful, then antagonistic behavior is more likely to occur.

- The client's stress of bringing the cat to the veterinary hospital and then returning the cat to the home is undoubtedly perceived by the cat. Despite our efforts, cat owner’s actions don't always do a good job allaying feline anxiety. Often, we make it worse. Time and again, when clients are planning on a vet visit, cats hide from owners "even before they get the cat carrier out." Cats seem to have the ability to read us. They indeed have a ‘sixth sense’.

- The patient returning from a visit to the clinic has experienced a lot of stress. The cat may be experiencing pain from treatments or surgery; additionally the cat may have altered physiological reactions due to various administered drugs (even pain medications). The sympathetic nervous system is ‘turned on’ and they want to hide, fight, or flee. 

- Undoubtedly, new smells abound, but I suspect that fear pheromones, postural changes, facial expressions, eye contact, and other sympathetic reactions to the presence of other cats are far more important than simply the new scents acquired at the veterinary clinic. While friendly pheromones have been studied in cats, I am not aware that feline fear pheromones have been demonstrated in this species¹. On the other hand, fear pheromones have been demonstrated in other species (man, cattle, pigs, rats, & fish) so I expect they exist for cats². There is even a report suggesting that ‘feel good’ pheromones can have a negative effect in the face of preexisting antagonism³. Many of us in feline practice report that having a terrified cat in an exam room early in the day seemingly triggers previous relaxed cats to be reactive for the remainder of the day. I can’t imagine that adding new odors to a cat's coat will somehow negate the presence of fear pheromones.  I can imagine that the application of additional smells would serve as an additional stressor to both the cats returning home, and the others accepting them.

My recommendation to avoid anticipated antagonistic reunions is to isolate ALL potential  antagonistic cats to a separate environment (e.g. an isolated room). The returning cat is given free access to all the 'normal' inhabited regions of the home, while the others are confined to the ‘spare’ room.  Once the returning cat's behavior and physiology returns to normal, and fear pheromones have dissipated, then the other cats can be let out, one at a time.  Depending on how serious the antagonistic behavior is, this transition time could take 2 hours, or 2 days (or more?).  This time period also allows the owner's subliminal behavior to return to normal, and it creates a situation where the newly-isolated cats have to ask permission to be accepted back into the normally inhabited home environment. I believe we reinforce antagonistic behavior when the returning cat is isolated to the ‘spare’ room as this furthers the need for this (treated and stressed) cat to get permission before reuniting with the clowder.

If antagonistic cats are food motivated, then feeding them, or offering them a treat during reunions may be helpful as well. Cat nip has a variable effect on cats, and it will make some cats more aggressive so I would somewhat discourage this.

My opinion as a feline practitioner is we should not be trying to mask odors on our cats. Please pitch the perfume and toss the talc.

1.  Ogata N, Takeuchi Y. Clinical trial of a feline pheromone analogue for feline urine marking. The Journal of veterinary medical science/the Japanese Society of Veterinary Science 2001;63:157-161.

2.  Grandin T. Assessment of stress during handling and transport. Journal of Animal science 1997;75:249-257.

3.  Simpson BS, Papich MG. Pharmacologic management in veterinary behavioral medicine. Veterinary Clinics of North America: Small Animal Practice 2003;33:365-404.