Wednesday, October 19, 2016

Halitosis in Cats

Halitosis in Cats

            Cats are well known for being exceptionally clean animals.  They take pride in their appearance, grooming constantly to remove any offensive odors that might make them detectable to both predators and prey.  Occasionally, however, cats do emit a foul odor.  Although there are several possible reasons for a cat to be malodorous, as a cats-only veterinary practitioner, I find that halitosis, i.e bad breath, is the most common cause of fetid felines.

 Periodontal disease – inflammation of the tissues surrounding the teeth – is by far the most common cause of stinky breath in cats.    Periodontal disease is initiated by a build-up of plaque, the sticky bacteria-laden coating on the tooth surface. As the immune system responds to the plaque, the gums become inflamed.  Gum inflammation is called gingivitis, and is the first stage of periodontal disease.  Bad breath often accompanies the gingivitis. As inflammation progresses, the second phase of periodontal disease – periodontitis – occurs.  Periodontitis is a condition where both the soft tissues and the bony tissues are affected.  Cats may develop receding gums, bone loss, and continuing halitosis.  If not removed from the tooth, plaque mineralizes into tartar (also called calculus) in a few days.  Calculus requires professional removal by your veterinarian. 

            Although periodontal disease and gingivitis tend to develop as cats age, gingivitis can occur in cats as young as 6 months.  These cats often have little or no calculus accumulation.  We call this condition “juvenile-onset gingivitis”, and it is a common cause of halitosis in kittens.  The exact cause of this condition is unknown, but genetics is suspected to play a role, since purebred cats, especially Abyssinians, Siamese, and Persians are predisposed.  If left untreated, these cats may develop significant periodontal disease early in their adulthood.  Daily home oral care is recommended in cats with juvenile-onset gingivitis to avoid future dental problems.

            Infections or abscesses can cause foul odors from the mouth.  Tooth-root abscesses are common in cats, usually resulting in facial swelling near the site of the affected tooth.  Tooth-root abscesses need to be lanced and drained by your veterinarian, and the affected tooth is likely to require extraction.

            Ulcers in the mouth can result in halitosis.  The calici virus is a common cause of feline upper respiratory infections.  Although sneezing, runny eyes, and a snotty nose may be seen in affected cats, an ulcer on the tongue is the classic finding in cats infected with calici virus. 

            Sadly, tumors of the oral cavity are not uncommon in cats, and halitosis is a frequent accompanying symptom.  The most common feline oral tumors are squamous cell carcinoma and fibrosarcoma.  As these tumors grow, a portion of the tumor may become infected or necrotic (non-viable), leading to an unpleasant smell from the mouth.  Early detection and aggressive treatment are essential for therapy to be successful.  Unfortunately, by the time most cats are showing clinical signs of their oral tumor, the condition has already progressed to a point where treatment isn’t possible. 

            Disorders of oral origin aren’t the only cause of halitosis in cats.  Systemic illnesses, such as kidney disease, can lead to bad breath in cats.  The role of the kidneys is to filter toxins from the bloodstream, creating urine in the process.  As most cats age, they eventually begin to show signs that their kidneys are weakening.  These signs may include excessive thirst, increased urination, poor appetite, weight loss, and vomiting.  As the kidney dysfunction progresses, cats may develop a condition called uremia, literally “urine in the blood”.  Uremia generally refers to cats with severely elevated toxins in their bloodstream.   Uremia results in a characteristically foul odor from the mouth.  The smell differs from the bad smell caused by dental disease.  As one of my colleagues once indelicately put it, cats with uremic breath smell like “something died inside their mouth.”   A crude description, but I can attest to its accuracy.   Cats with severe uremia will sometimes develop ulcers in their mouths, often on the sides of the tongue.  These ulcers contribute further to the halitosis.

            Diabetes is a common glandular disorder in cats due to inadequate or improper secretion of the hormone insulin from the pancreas.  Insulin is required for the utilization of glucose, which is the primary source of energy in cats.  Cats with diabetes usually require twice daily injections of insulin to maintain proper blood glucose levels.  If the diabetes remains undiagnosed or untreated, cats will metabolize body fat into molecules called ketones, in a desperate attempt to provide energy to the body.  Ketosis is a veterinary emergency, and affected cats are usually very ill.  Cats in ketosis have a characteristic smell to their breath.  The odor has been described by some as being “fruity”, and by others as faintly resembling acetone, the main ingredient in nail polish remover.  Whether ketone-breath qualifies as being offensive, like halitosis, is debatable.  Interestingly, people vary in their ability to detect this smell in cats, and apparently, the ability to detect it is genetic.  Some people have the gene that allows them to detect ketones instantly, while others are oblivious.  Sadly, I cannot detect it.  A doctor who worked for me a few years ago could smell it a mile away. 

 And finally, it should be said that halitosis is sometimes in the nose of the beholder.  I have examined many cats brought into my office with the complaint of bad breath and upon examination, the cats were discovered simply to have, for lack of a better term, “kitty fish-breath”.  Their mouths were normal – no dental disease, no oral pathology of any kind – and they had no systemic illness.  Cat owners must simply realize that if you feed your cat stinky food, it may end up with stinky breath.  However, because there are so many significant medical conditions that can lead to halitosis in cats, it’s best to err on the side of caution and have any offensive oral odors evaluated by a veterinarian. 

Saturday, October 8, 2016

The Lymph Nodes - What Are They, and What Do They Do?

Body Parts – the Lymph Nodes

I’m sure you’ve heard of them, but do you really know what they are, or what they do?  I’m talking about the lymph nodes, important structures that we don’t think about much, but play a crucial role in a cat’s ability to fight off infections.

Lymph nodes are small, oval shaped organs that are dispersed throughout the body.  They are a part of the lymphatic system, a branch of the immune system that plays an important role in the development of the body’s immune response.  The lymphatic system consists of vessels that run throughout the body, in a similar fashion as arteries and veins.  Instead of blood, however, the fluid that flows through the lymphatic system is called lymph, which is rich in protein and white blood cells.  Cells of the immune system circulate throughout the lymphatic vessels in the body.  As lymph flows through these vessels, it passes through at least one set of lymph nodes, and often several sets, before ultimately emptying into the general circulation, where it mixes with blood.  The lymph nodes are the major sites in the lymphatic system where the immune cells gather.

The main job of the feline immune system is to protect and defend the body against harm by fighting off invading substances, which we call antigens.  When an antigen invades the body, it eventually encounters the lymphatic system, and eventually a lymph node.  Here, it stimulates a discrete population of lymphocytes (a type of white blood cell) in the node.  This causes those lymphocytes to multiply and transform, or become “activated”.  These activated lymphocytes mount an immune response to the antigen, for example, by producing antibodies that neutralize the antigen.  When the lymphocytes in the lymph node multiply, the lymph node becomes enlarged.   The medical term for enlargement of the lymph node is lymphadenopathy.  Us humans usually refer to this as “swollen glands”.   As a veterinarian, I perform hundreds of physical examinations every year.  Every veterinarian performs a physical examination in his or her own style, making sure to evaluate all of the body systems.  Assessment of the size of the lymph nodes is unquestionably a part of every veterinarian’s physical assessment.

Enlargement of the lymph nodes is often discovered as an incidental finding during physical examination of the cat.  Now and then, a cat owner brings the cat to the vet because of symptoms related to lymph node enlargement, for example, difficulty swallowing due to enlargement of the lymph nodes in the back of the throat.  Sometimes a cat owner will bring me their cat because they detected a lump, which turns out to be a lymph node, while patting or stroking the cat.

The age of the cat is important when considering the significance of lymph node enlargement.  Kittens and young cats are exposed to a variety of antigens early in their lives, and an increase in lymph node size is an expected response by the immune system.  As cats mature, lymph node size usually decreases and the nodes often become more difficult to feel in older animals.  However, in geriatric cats or cats that have lost weight due to illness, the loss of body fat around the lymph nodes may make the lymph nodes appear more prominent than expected, and are easier to feel.

As noted above, stimulation of the immune system by invading antigens is a common cause of lymph node enlargement.  Sadly, cancer is an equally common cause.  The cancer can arise from the lymph node itself.  This is called lymphoma, and is the most common cancer found in animals.  Cancer arising in other parts of the body can also spread to the lymph nodes.  This is called metastatic cancer, and the cancer is said to have “metastasized” to the lymph nodes. 

Figuring out the cause of lymph node enlargement may require a variety of tests, including blood and urine analysis, x-rays, and ultrasound.  Ultimately, a definitive diagnosis often requires obtaining a sample of cells from the node itself.  This is usually achieved either by aspiration cytology or by surgical biopsy. Aspiration cytology is a procedure in which a needle, attached to a syringe, is inserted into the lymph node.  Suction is applied to the syringe so that cells from the lymph node are sucked or “aspirated” into the hub of the needle.  The contents are then sprayed onto a microscope slide and are sent to a laboratory for interpretation.  The advantage of this procedure is that it’s non-invasive and inexpensive.  A disadvantage is that the aspirate may not yield enough cells to make a diagnosis. Biopsy of the lymph node is the definitive test in evaluating lymph node enlargement.  Depending on the size and location of the node, either the entire node is removed (this is called “excisional biopsy”), or a small piece of the lymph node is removed (“incisional biopsy”).  The specimen is evaluated by a pathologist.  Treatment is based on the biopsy results: infections are usually treated with antibiotics; cancer is treated by chemotherapy, surgery, radiation, or a combination of these.

Monday, September 26, 2016

Cytauxzoonosis in Cats

Cytauxzoonosis in Cats

Also known as “bobcat fever”, this hard to diagnose, hard to treat (and hard to pronounce) blood parasite spells bad news for cats.

            In 1987, during my senior year at the University of Florida College of Veterinary Medicine, the teaching hospital began seeing a few puzzling cases of acutely ill cats.  All of these cats had fevers, were lethargic, and refused all food.  All of the cats were anemic, and most were jaundiced.  Sadly, despite aggressive treatment, all of the cats died within a week of hospitalization.  After much investigative work, a diagnosis was finally elucidated. These cats had succumbed to cytauxzoonosis, a parasitic blood disorder.

             Cytauxzoonosis is a life-threatening blood disorder caused by the parasite Cytauxzoon (“site-awk-zo-an”) felis.  It used to be considered a rare disease, confined to a small geographic area.  The first reported case was in Missouri in 1976.  Since then, the geographic range has progressively expanded, and has now been confirmed in domestic cats in 17 states. (See Sidebar 1) The organism has been documented in bobcats from Pennsylvania and North Dakota, although no domestic cats have been reported with the disease there.  For many years, cytaxzoonosis was reported in North America and South America, but in recent years the infection has also been documented in Europe (in the south of Spain, in France, and in Italy.)

            Cats acquire the illness through the bite of a tick, specifically the lone star tick.  The tick picks up the parasite from bobcats, which are the reservoir host.  Bobcats, when infected with Cytauxzoon felis, develop only mild clinical signs of illness.  The bobcats recover, and then become persistent carriers.  When a tick feeds on an infected bobcat, the tick acquires the pathogen. These ticks can bite and infect other bobcats, or they can bite a domestic cat instead, which leads to severe illness and often death.  All felids are susceptible to infection; cytauxzoonosis has never been described in a non-felid. 

            Because ticks transmit the disease, it should be no surprise that infection is far more likely in cats that go outdoors, especially in rural areas where tick contact is more common.  Cats of any age and either sex may be infected, although young adults are more commonly affected.  Most infections occur between April and September. 

            The most common presenting signs are poor appetite and lethargy.  High fever and jaundice are consistently seen.  Dehydration, rapid and/or labored breathing, rapid heart rate, pale gums, abdominal or generalized pain, increased vocalization, enlarged lymph nodes, and enlarged spleen and/or liver have all been reported. 

            In order to diagnose it, you have to first have it on your list of possibilities.  In endemic areas, veterinarians must suspect cytauxzoonosis for any acutely ill cat with a high fever and outdoor exposure during the spring, summer, or early fall.   Of the routine tests we perform on sick cats – a complete blood count, serum chemistry panel, urinalysis, x-rays – the complete blood count is the most useful diagnostic test.  Microscopic identification of the parasites inside the red blood cell confirms the infection.  The parasite has been described as “signet ring” shaped.  Unfortunately, a major limitation of this test is that the parasite may not be visible inside the red blood cells early in the disease.  Evaluating a blood smear every day increases the chances of finding the parasite, but it may be several days before the parasite is identified.  Initially, only a few red blood cells may be parasitized.  As the disease progresses, however, up to 50% of the red cells may become infected.

            There is a molecular test for that is very sensitive and specific for identifying infected cats, however, this test must be mailed out to diagnostic laboratory, and given the rapid progression of the disease, treatment should not be delayed while waiting for test results.

            Because 90% of cats infected with Cytauxzoon felis die from the disease (most within a week of onset of clinical signs), it is imperative to begin treatment in any cat suspected of having the disease, even if a definite diagnosis hasn’t been made.  Many antiprotozoal drugs have been tried.  Recently, the administration of the antimalarial drug atovaquone, in combination with the antibiotic azithromycin, has shown the best results, with 60% of naturally infected cats surviving.  Treatment is administered for ten days.  Supportive care is essential during the treatment period, because these cats are critically ill.  Intravenous fluids, pain medication, anti-nausea drugs, and aggressive nutritional support are important aspects of treatment, as these supportive measures keep the cat alive while the antiprotozoal drugs and the cat’s own immune system do their work.  Severely anemic cats may require a blood transfusion.  Cats fortunate enough to recover from the illness are apparently immune from ever getting the disease again, however, they may continue to harbor the parasite in their red blood cells for months or years.

            There is no vaccine for cytauxzoonosis, so prevention is based on tick control.  A recent study showed that a collar containing 10% imidacloprid/4.5% flumethrin (Seresto, Bayer) was effective for prevention of Cytauxzoon felis transmission.  In that study, two groups of cats (with and without a collar) were exposed to ticks that were infected with the organism.  None of the cats wearing the collar contracted the disease, while 90% of cats without the collar got infected. Although infected cats cannot transmit the disorder to other cats through physical contact, cats that have recovered from the disease may become carriers, able to transmit the organism to ticks, and therefore indirectly to other cats. It goes without saying that the most sensible way to prevent infection is to keep cats completely indoors, thereby eliminating tick exposure.

            An alternative to the atovaquone-azithromycin combination would be highly welcome, because atovaquone is expensive, tough to obtain, and difficult to administer. (Atovaquone is a thick, viscous, citrus-flavored liquid that must be given every 8 hours, and cats greatly resent being medicated with it.) Until a better treatment is discovered, however, the combination of these two drugs offers the best chance for survival and remains the treatment of choice for infected cats. 

Sidebar 1: States where cytauxzoonosis has been reported in domestic cats

West Virginia
North Carolina
South Carolina

Sidebar 2:  Clinical signs of cytauxzoonosis in domestic cats

Jaundice (yellow coloration to the skin and whites of the eyes)
Rapid breathing
Fast heart rate
Labored breathing
Pale gums
Abdominal pain
Lymph node enlargement
Enlarged spleen

Monday, September 12, 2016

Body Parts – The Intestines

We use the term intestinal fortitude to describe someone with “the courage to endure and go on.”  Well, I have a “gut” feeling that my readers will have the intestinal fortitude to read this blog post despite these bad puns, and that you’ll have no trouble “digesting” the information within. 

At mealtime, after your cat swallows, the food goes to the back of the throat (the pharynx), and then into the esophagus - the muscular tube connecting the pharynx to the stomach. It then enters the stomach where some digestion occurs, before making its way to the organ that is the focus of our column today: the intestines.

The intestinal tract is divided into two major portions: the small intestine and the large intestine. 

When food leaves the stomach, it enters the small intestine.  The small intestine is the longest portion of the gastrointestinal tract.  Expanded end-to-end, it is approximately 3 to 4 times the length of the cat’s body!  The small intestine is divided into three regions: the duodenum, the jejunum, and the ileum. 

The duodenum is the very first part of the intestine, and sits relatively stationary in the abdomen. The jejunum is the longest part of the small intestine and is free to move around, often occupying whatever unoccupied space available within the abdomen.  The ileum is the short, terminal portion of the small intestine. 

Digested food leaves the small intestine and enters the next portion, the large intestine.  We tend to use the term “colon” interchangeably with “large intestine”, but this isn’t entirely correct.  The large intestine actually includes the cecum, colon, rectum, and anal canal.  The cecum is a small pouch at the junction of the ileum and the colon.  It is analogous to our appendix.  The colon has thinner walls and is baggier than the small intestine. The last few inches of the colon is the rectum, followed by the anal canal – the short, terminal part of the gastrointestinal tract that is found just inside the anus.  For consistency, I’ll mostly use the term “large intestine”, but I’m mainly referring to the colon.
The small intestine is where most of the action occurs, digestion-wise.  After a little initial digestion and processing in the stomach, food arrives in the intestine where digestive juices from the pancreas, and bile from the gall bladder both empty into the duodenum through small openings in the duodenum wall. These enzymes and bile digest the food even further, breaking it down into smaller molecules which are absorbed from the small intestine into the bloodstream. Food then passes from the ileum to the large intestine. 

The large intestine is involved in the final phase of digestion.  The bulk of the water and electrolytes gets absorbed from the food, resulting in the formation of feces.  The feces then move into the rectum and anal canal where it is stored until defecation occurs.

As you might imagine, there are many disorders of the feline intestinal tract, and a discussing all of them would certainly be beyond the scope of this column.  Two common ailments, however, warrant a mention:  inflammatory bowel disease and colitis.

Inflammatory bowel disease (IBD) is a condition in which the immune system mounts an excessive inflammatory response, sending inflammatory cells inappropriately into the gastrointestinal tract.  Any part of the GI tract  - stomach, small intestine, large intestine – may be affected, although the small intestine is most commonly affected.  People mistakenly use the term “irritable bowel syndrome” interchangeably with IBD.  When inflammatory cells infiltrate the small intestine, a number of clinical signs may be seen.  The most common are poor appetite, weight loss, vomiting, and diarrhea.  These signs can occur singly, or in any combination.  Making the diagnosis of IBD requires ruling out other common causes of gastrointestinal inflammation, for example: parasites, food allergy, and metabolic disorders such as hyperthyroidism.  Routine lab tests tend to be normal in cats with IBD.  Ultimately, a definitive diagnosis requires obtaining biopsy specimens from the intestinal tract.  Corticosteroids are usually effective in controlling IBD in cats.  In fact, my own cat, Mittens, was diagnosed with IBD three years ago, and she has been symptom-free on medication.

Colitis is inflammation of the large intestine.  Cats with colitis often have diarrhea, occasionally with blood and/or mucus.  They show increased frequency of defecation, and may show straining to defecate.  Vomiting is a common sign.  A common cause of colitis is a sudden change of diet.  Stress is another trigger for colitis.  Cats are creatures of habit and like to have a consistent environment.  A new cat in the house, relatives visiting over the holidays, or a change in the owner’s work schedule can stress out a cat and induce colitis.  Most cases of colitis resolve spontaneously after a few days.  A prescription diet that is high in fiber is helpful in speeding the recovery. Stubborn cases may require medication in addition to a therapeutic diet.

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