Category: “Cat Health”

HELP! My Cat Stopped Using the Litter Box

HELP! My Cat Stopped Using the Litter Box

Your cat stopped using the litter box — Now What???32675706_1.jpg

Help! My cat stopped using the litter box! Cats are fastidious creatures so it comes as a surprise to people that little Pickles is indulging in urinating or defecating outside the litter box. This undesirable behavior is difficult for people to deal with, particularly if she is using the flower pots, bed or the sofa as her toilet.

Yet, this is a common problem with indoor cats, particularly in multiple cat households. In fact, it is so common that we have coined a name for this behavior: Multiple Indoor Situational Stress Elimination Dysfunction or M.I.S.S.E.D. As the name denotes, this behavior is due to environmental stress and frequently occurs in homes with multiple indoor cats. However, it can also occur in homes with a single cat.

First things first, we can not emphasize this enough, before you make any decision about giving this cat up PLEASE have her/him checked out by your veterinarian. When a cat suddenly breaks the cat box habit there is often a medical cause. Although we have encouraged cat owners to follow through with a visit to their vet, many choose not to. Instead, they prefer to think that kitty is “angry” at them or “getting even” with them. Many of them give up on the behavior and instead bring the cat to a shelter (where it’s often euthanized) or they make the cat stay outside, decreasing their lifespan and adding more stress to the cat’s life.

Please be assured that your cat is NOT angry at you — cats do not have the ability to think in these abstract terms. They are creatures of the moment, they are reactive, they do not harbor resentments or hold grudges. It may APPEAR as if they do—but in reality what they are reacting to is YOUR emotions. OR they are reacting to their OWN momentary emotion.

Some physical illnesses may mimic behavior problems. One is Feline Urologic Syndrome (FUS). Both male and female cats are affected by this but male cats are particularly prone to urethral obstruction (due to their narrower urethra) than females. FUS occurs when crystals and small stones form in the bladder. These will nick and cut the linings of the urethra and bladder creating inflammation and pain. As these structures travel from the bladder through the urethra they can be caught in the male’s narrow urethra, creating an obstruction. This is a serious medical condition that requires immediate medical attention because obstruction can lead to kidney failure and death.

Cats with FUS will often indulge in continual licking or grooming of the area around the urethral opening. Due to pain and a constant full-bladder feeling, inappropriate elimination can occur. Some cats resort to urinating in the bathtub, the sink, the bed, or on the sofa. Some cats will vocalize their pain when straining to urinate. Others will simply “shut down” preferring instead to hide and avoid human contact.

Feline hyperthyroidism (an increase in thyroid gland hormone) can also appear as a behavioral problem. This condition causes increased thirst and appetite along with anxiety-like behavior. The cat may lose weight despite excessive eating. Increased thirst increases urine output and when accompanied by anxiety it can cause inappropriate elimination in felines. (This condition can also imitate gastrointestinal disease since the cat may experience vomiting and diarrhea.)

On the opposite side of the spectrum is hypothyroidism (a decrease in thyroid gland hormone). Hypothyroidism increases thirst and appetite. Again, this is accompanied with more urine output. However, instead of losing weight the cat gains weight and those extra ounces (or pounds) will often cause litter box problems. Furthermore, this condition leads to a lethargic cat who appears depressed. Hypothyroidism is often seen in older cats, so if your senior feline is experiencing these symptoms get her over to the vet for some tests. Both hypo and hyperthyroidism are treatable.

In sum, physical problems can be misinterpreted by humans as “behavior” issues. So, if your sweet little Pickles suddenly turns sour consider it a blessing in disguise, she might be telling you something.

VetExamOn the other hand, if Pickles received a clean bill of health from the veterinarian yet still persists in using furnishings, flower pots, or floors as a cat box the following check list might unearth the problem. Please keep in mind that these questions are not listed in order of importance.

1. Have you recently changed cat litter products?

A change in litter can create cat box aversion. Why? Because your cat is comfortable with the old brand and this new stuff smells and feels different. If you plan on switching cat litter do it a little at time: Place a small amount of the new brand in a clean cat box then top it off with a thick layer of the familiar litter. As Pickles uses the box the two brands will get mixed. Just keep adding more of the new litter and topping it off with less and less of the familiar brand. Pickles will adjust within 7 days, if not sooner.

2. Have you recently moved the cat box?

Cats simply will not tolerate switching cat box locations unless it is done gradually. Why? Well, think of it this way: if someone suddenly locked the bathroom door on you and didn’t tell you where the new bathroom was, what would you do? “Ah!” you say, “But a cat should be able to smell his way to the new location.” Not necessarily. Sure, cats have a keen sense of smell but they also have a stubborn sense of habit. If you need to change the location of the box, do so gradually. Move the box a few feet daily until it ends up in its new spot. Pickles will be much happier for it and so will you!

3. Have you recently changed the type of litter box you are using?

Cats prefer the open box variety to a covered box. A lidded box might be a great gimmick for you, to a cat it looks suspicious. Their nature is to avoid being enclosed. Observe the bathroom habits of the outdoor feline, they go where and when they feel like it. They do not look for a place that provides them “privacy” and enclosed areas are avoided. The idea that cats need privacy is strictly a man-made one. Try removing the cover and see if that helps. Also, is the litter box the correct size for your kitty?

4. How many litter boxes have you provided for your cat/s?

The rule of thumb is to provide each cat one box of its own plus one. Why? Well, strangely enough cats sometimes prefer one box location to another depending on the type of elimination required. For example, some cats prefer to use one specific box for their bowel movements. This might appear strange but if you think about it some people are the same with their toilet habits! This one-box-plus-one rule is particularly applicable when the home is multi-storied. In which case you might consider placing a box on each level.

5. Does the cat have access to the litter box at all times?

Placing a cat box in the bathroom or closet might be ideal for you. But if a person is using the bathroom the door might be closed, blocking the cat from its box. A closet door might also be inadvertently shut. And, if this box happens to be the only box in the house a cat with the “have-to-go-now” urge will have a real problem.

6. Have you recently acquired a new cat?

MISSED syndrome is common in multiple indoor cat households. Cats will eventually adjust to a new housemate. But it takes time. Sharing the litter box with another feline is stressful, much the same as if you suddenly had to share your bathroom with another person. It takes some adjusting to. For one, the box could be occupied when Pickles wants to go. For another, there’s a new smell in there. Keep in mind that urinating and defecating is also a cat’s method to “mark” their territory. Added stress in multiple cat households can be avoided by simply providing multiple boxes in various locations around the home.

cat-in-a-box7. Have you recently placed a new mat in front of the litter box?

In our efforts to alleviate dust tracking we purchase “litter mats.” However, some of these mats are not cat friendly. When seeking a litter trap keep the cat’s comfort in mind. Surfaces with large grates can cause a cat to feel insecure. Other mats appear to resemble outdoor carpeting, with brittle plastic “fibers” that can poke into a cat’s paw pads. Still others may have the annoying habit of slipping on hardwood floors, a feature not appreciated by the feline. Litter mats need to be soft, pliable, and secure feeling. A grated mat is fine, as long as the grates are small enough for the cat not to notice. A “carpet” type of mat is also fine as long as it doesn’t poke into the cat’s paws.

8. Have you recently moved?

This question opens up a myriad of problems since cats by far prefer to keep things unchanged. Yet, in today’s frenetic world change will occur despite the cat’ s wishes. You can help Pickles acclimate to her new space by placing her in a small room with her box and food and plenty of hiding places. When she becomes comfortable with this new space let her out to explore her new surroundings, a little at a time.

One word of caution, do not try to “comfort” Pickles when she acts nervous and afraid. Instead, adopt a calm demeanor and whenever she is doing something positive, such as eating or looking out the window, take that opportunity to pet her. Your own attitude about the move will greatly affect the cat so make certain that you feel happy about it and try to convey that to her in your outward expressions.

9. Have you recently placed an “air freshener” near the litter box?

A nice smelling home is something that people strive for, not cats. Their noses are very sensitive and foreign odors can create confusion. The MISSED syndrome will often show up if an owner places a plug-in air freshener or some other perfumed device near the cat box. So avoid this practice.

10. Have you recently added a litter pan liner to your cat box?

Simply put, cats do not like smooth, slick surfaces. While kitty box liners are fine for humans they are nor appreciated by the feline. Why? It changes the feel and texture of the litter since the plastic bag is often pulled up, dislodged or wrinkled by the cat’s digging. The result is an unpleasant experience that can result in cat box aversion.

11. Have you recently added “litter freshener” to the cat litter?

Covering up stinky cat box odors is a common practice among cat owners. However, if you have never done this before the new smell in the box could create cat box aversion. Even if you have used these products before your cat may suddenly decide she doesn’t like it. Instead of adding perfumed products or even baking soda to the box try scooping more often or adding additional boxes.

12. How often do you scoop the box?

We live busy lives and scooping might not be our priority. But it needs to be. The outdoor cat has a wide bathroom selection, the indoor cat does not. She is stuck with what you provide. To reduce odors and encourage proper elimination it is suggested that the cat box be scooped a minimum of two times a day. (It is of course better if it is scooped more often.) Some cat owners do not scoop at all, instead they dump the whole mess out once a week, scrub out the box, refill it with clean litter and call it done. This is not conducive to good feline toilet habits.

Why? Well, let’s contrast a fully-loaded cat box to our own toilet habits. Let’s face it, when you go out to a restaurant or a ballgame you want access to a clean toilet. What happens when you open up the stall door and see a toilet that hasn’t been flushed all day? More than likely you will seek a clean stall. And so it is with the cat, only she doesn’t have another stall to choose from. So pick up the scoop and start scooping! You’ll have a cleaner, more sanitary house (remember kitty gets on the bed, the sofa, and the surfaces of your home) and both of you will be happy.

13. Have you recently changed your routine?

If your routine has altered this could affect your cat’s emotional state. Often when cats become anxious they express themselves in inappropriate ways such as yowling or resorting to urinating in other areas of the house. This is NOT a “get even” action, so please do not put that human emotion on your cat. Instead it is an outward expression of an inward turmoil. Consider it this way, your indoor cat is trapped in its environment, it can’t get in the car to “get away from it all,” nor can it take a vacation or have a group therapy session.

Instead its reactions are purely primordial: an increase in adrenal causes all bodily functions to speed up, including the bladder and the bowels. (This also applies to humans.) Consider the fact that the cat is not only pumping extra adrenaline into its system but it also has an instinctual urge to react to this physiological change by marking out a defined territorial barrier. Why? Because this is an animal’s method of preventing other animals from encroaching into its area. In this case, the cat’s actions are a defense mechanism. The best way to handle this is by using feline pheromone products, such as a Feliway plug in diffuser, that will produce a relaxed state of mind.

14. Have you recently added a new member to the household?

This falls under the heading of changing your routine so please see number 12 and also number 13 for the possible solution. If a new baby is added to the home follow the instructions for out of town visitors (Number 15) until the baby’s scent is established in the home, that will only take a few weeks. The same applies to any other new household members.

15. Have you had visitors from out of town?

This also falls under the heading of changing your routine with a few unexpected twists. Visitors bring with them excitement, strange smells, and different voices. They also bring into the home a new energy level. That is, the normally quiet atmosphere may become chaotic. The opposite may also occur. A chaotic household may become quiet because the family is out more often. Either way, the cat could react negatively.

One common reaction to visitors is the cat’s penchant for urinating in your visitor’s suitcase. It is an annoying occurrence, frequently followed by ruined clothes and voluminous apologies from embarrassed hosts. Is the cat defiantly stating his resentment of the visitor? The answer is, no! The cat is only reacting to the visitor’s powerful new scent. Cats do not understand the human’s approach to scent. We try to erase ours by bathing, using deodorant, and washing our clothes.

On the other hand, cats love their scent and faced with an overpowering scent they will add what they consider to be “good smells” onto the bad stuff — much the same way that you use an air freshener to erase foul odors. This situation can be prevented: simply ask guests to keep their door closed, their suitcase closed, and to please not leave their clothes in areas the cat has access to. And explain why. Better to be safe than sorry!


If your cat has MISSED:

1. Clean it up: Clean up the area as quickly as possible. Use a specifically designed enzyme pet product that will eliminate the odor, you don’t want PIckles to think the carpet is her new litter box. In addition to a thorough clean up, spray the area with a feline specific pheromone product such as Feliway twice a day.

2. Block it: Utilize a large plastic bag and secure it over the area to prevent her from returning to it. In the case of a sofa or a bed you can use a shower-curtain liner or purchase a tarp at your local hardware store. Make certain that you secure it in place so the cat can’t move it with her paws. You can also use boxes or any other structures that will block the cat’s access to the area. Or prevent access completely by closing the door.

3. Prevent it: To calm a nervous or anxious cat (due to a move or a new cat or new routine) utilize a plug-in pheromone product or spray. These pheromones send messages of happiness and contentment to the cat’s brain. Purchase Bach Rescue Remedy and place a drop of the essence on the skin of the inner part of each earflap four times a day. In addition, you can also mix a few drops of essence into the cat’s drinking water.comfort-zone-with-feliway-diffuser-48-ml-10

4. Stay calm: Don’t overreact or become frustrated or resort to yelling. This will only create more anxiety in the cat. Instead, try to remain calm and adopt as regular a routine as possible.

5. Give the cat plenty out outlets to get rid of extra energy or frustration: Providing little Pickles with a set schedule for physical activity (such as playing with cat fisher toys or strings) will give her an outlet for pent up energy and stress. It’s much like our way of taking a brisk walk when we feel frustrated or indulging in a good workout to relieve stress. Afterward, Pickles’ energy will be spent and she can relax and enjoy a good meal and a nap.

cat pole


Cat Litter – What’s safe?

Cat Litter – What’s safe?

Cat Litter: What is safe and What is Not?

The more indoor cats you have the more important cat litter becomes.

Finding just the right cat litter brand can be a real challenge for a cat parent. Naturally, you want to settle on the brand that both of you like. This can take a bit of experimenting. But there is more to the cat litter question than just what works for you and your kitty. There is a question of health, not only your cat’s but yours.

Silicosis and the cat box connection?

While conducting research on the Dust Bowl, I came across something interesting. It was a disease called Silicosis. Silicosis is caused by chronic inhalation of silica. The tiny silica particles embed themselves into the lungs. They clog up the natural function of the lungs: the exchange of oxygen and carbon dioxide. Because the particles are so small the lungs can not clear them out. In other words, silica dust gums up the lungs. In turn the lungs become congested, filling with fluid, and eventually producing fibrosis and inflammation. The final result is chronic lung problems such as bronchitis, asthma, and lung tumors. Silica is found in sand, clay and soil. It is the prime component of clay litter.

It’s not just harmless dust….

Each time you pour clay cat litter into a cat box a puff of dust floats upward and streams throughout the room. You are inhaling these particles directly through your nose. As the litter dust floats throughout your home it is also inhaled by your family and other pets. Every time your cat uses the clay cat litter, digging into it, he stirs up more dust. Every time you scoop the litter pan you also stir up clay litter dust. Both your cat and you are inhaling large volumes of clay dust into your lungs. The clay cat litter dust floats throughout your home, ending up in the lungs of anyone who breathes.

It is a proven fact that exposure to silica dust is harmful, and clay cat litter contains the silica compound. Not only that, but exposure to clay cat litter dust puts people and animals at risk for such diseases called “Farmer’s Lung” and Mesothelioma Lung Cancer. The research is very clear that cats who are already suffering from lung problems have difficulty clearing clay cat litter dust from their lungs. It may not be the root cause of these lung problems but it certainly aggravates the condition. (Click on this link for a full report of this disease in cats…a-dust-in-cats/)

There are many natural alternatives to clay cat litter.

In addition to the health hazards of clay cat litter, there are the environmental factors. Strip mining is part of the process of obtaining raw materials to make clay-based litter. It robs the land of all vegetation, topsoil and it removes the first layer of dirt all the way down to the first rock layer. It destroys entire ecosystems. Despite major reclamation efforts the land and bio diversity it contained can not be re-established. Once a system is destroyed it remains destroyed. The bio diversity it once contained can not be replicated.

The evidence is clear: clay cat litter is linked to respiratory problems in cats. It is a potential health hazard to humans. It is an environmental concern, destroying entire ecosystems in the process known as strip mining. As responsible stewards of the earth and loving pet parents we need to think twice about bringing any clay cat litter products into our homes.

Thankfully, the alternatives to clay cat litter have grown. Now, there are many types of natural cat litter made from wheat, corn, paper, cedar and walnut hulls. The only clumping ones in this category are made from wheat, corn and walnut hulls. These materials are safe for cats of all ages. They are free from perfumes and dyes.Their natural enzymes destroy odors. They utilize natural materials that would otherwise be waste product such as corn cob, hulls and secondary wheat or corn that is a grade below food use. Best of all, they are biodegradable which means you can actually use them (after the cat feces is removed) in your flower garden as mulch.

Yes, it’s true, these litters are more expensive than clay cat litters. However, isn’t the health hazard of clay cat litter more expensive when you factor in the veterinary bills or doctor bills? Cost should not be the primary factor when choosing a product that has this much impact on you and your cat’s health. cat_napping

Respiratory Disease: Study on Silica Dust in Cats

Respiratory Disease: Study on Silica Dust in Cats

Reprinted with permission

Detection of Silica Particles in Lung Wash Fluid From Cats With and Without Respiratory Disease

Peter L. Borchelt, Ph.D.

Peter L. Borchelt, Ph.D.

Animal Behavior Consultants, Inc.
Brooklyn, New York

Structured Abstract

Objective: To identify characteristics of silica material from a variety of popular cat litters using electron-microscopy (EM) and x-ray spectroscopy (XS), and then apply these techniques to analyze tracheal washings (TW) and bronchoalveolar lavage (BAL) fluid to identify, characterize and quantify silica particles in cats with and without signs of lower airway disease.

Design: Prospective study.

Animals: Twelve client-owned cats; six with and six without clinical signs of respiratory disease.

Procedure: Samples of dust particles from four clumping and three non-clumping clay litters were submitted for EM and XS analysis. Six client-owned cats presented for evaluation of their respiratory disease underwent either an endotracheal TW or endotracheal BAL. Six healthy client-owned cats from a single household underwent a bronchoscopic BAL. Samples from each cat were analyzed cytologically, bacteriologically and by EM and XS. All cats used clay litter exclusively.

Results: Dust particles obtained from seven commercial cat litters have an identifiable appearance and elemental ratio (primarily aluminum and silica). The same pattern is observed in particles obtained from lung wash wash fluid of cats, and significantly more silica particles were obtained from cats with respiratory disease than cats without respiratory disease.

Conclusions: The most conservative conclusion from the present study is that silica may act as an airway irritant in those cats with airway disease and is not the initiator of a primary disorder.

Clinical Relevance: The higher numbers of silica dust particles found in cats with respiratory disease suggest an association, but it is unknown whether dust particles contribute to respiratory disease or accumulate because of interference with normal lung ciliary function.

Interpretive Summary
Inhaled silica dust has been implicated as a cause of lung cancer and other respiratory diseases in humans and several animal species. Electron microscopy and x-ray spectroscopy were used to identify and characterize dust particles from seven brands of commercially available clay cat litters and to identify, characterize and quantify particles in the lung wash fluid of six cats with and six cats without signs of respiratory disease. Dust particles from clay cat litter have an identifiable appearance and elemental ratio (primarily aluminum and silica) and the same pattern was observed in particles obtained from lung wash fluid. Significantly more silica particles were obtained from cats with than without respiratory disease. This suggests an association between presence of silica particles and respiratory disease, but it is unknown whether silica dust particles contribute to respiratory disease or accumulate because of interference with normal lung ciliary function.

Exposure to silica has been implicated as a cause of lung cancer and other respiratory diseases in humans, rats, mice and hamsters (1,2,3,4,5,6,7,8). Diseases caused by inhalation of silica include silicotic nodules, alveolar proteinosis, interstitial cell infiltrates and interstitial fibrosis (9). Pathological changes include diffuse fibrosis, nodular lesions, lymph node enlargement, and pleural fibrosis which together can result in airflow obstruction and impaired gas exchange (1,10). Inhaled silica particles initially are phagocytized by alveolar macrophages and can be.found in the respiratory mucus of affected patients (11). In addition, alveolar macrophages can leave the bronchial tract and translocate to the interstitium. When the silica laden macrophage dies, it incites an inflammatory reaction and pulmonary fibrosis, silicotic nodules and lymph node enlargement; respiratory failure ensues. Damage to the ciliary apparatus destroys the defense mechanism that functions to remove mucus, inflammatory debris, inhaled particles and infectious agents which colonize the airway. Through these mechanisms, chronic exposure to silica leads to respiratory failure (1,2,3,4,5,6,7,8) and impaired resistance to bacterial infections. In 1997, the International Agency for Research on Cancer classified silica as a human carcinogen (6).

In cats, respiratory diseases such as bronchial asthma, chronic bronchitis, viral, bacterial and pyogranulomatous pneumonia, and pulmonary neoplasia are commonly diagnosed (12). The incidence of primary lung tumors in cats is rare. It is estimated that 1-2% of the general cat population has asthma or chronic bronchitis, however, in some pure breeds, such as the Himalayan and Siamese it may be as high as 5% (13). Despite treatment, these problems may progress and can lead to life-threatening episodes and chronic respiratory disease. In the United States, the majority most of household cats are exposed to silica dust on a daily basis since more than 95% of cat litter is a form of silica (6). Although dusty cat litter has been suggested as exacerbating respiratory problems in cats, no research to date has demonstrated the presence of inhaled silica in airway secretions in cats or the presence of silica in primary lung tumors. The study reported here used scanning electron microscopy and x-ray spectroscopy (14) to analyze particles obtained from tracheal washings (TW) and bronchoalveolar lavage (BAL) fluid of 6 cats with and 6 cats without signs of respiratory disease. Respiratory secretions rather than lung biopsies were chosen to document the presence of silica because it is an accepted method in diagnosing human cases (11) and lung biopsies were not warranted for workup of the respiratory signs.

Materials and Methods:
Cats: TW or BAL fluid from a total of twelve client-owned cats was obtained. Six cats (4 MC, 2 FS, between 3-16 years of age, 3 DSH, 2 Abyssinians, 1 DLH) with lower airway disease were evaluated at the Bobst Hospital of The Animal Medical Center between October 1998 and December 1999. Six cats (4 FS, 2 MC, between 2-9 years of age, 3 DSH, 2 DLH, 1 Siamese) without respiratory disease were identified as controls and evaluated at Michigan State University Veterinary Teaching Hospital from November – December 1999. The six cats with respiratory disease used various brands of clumping and non-clumping clay litter. The six healthy cats used Premium Choice clumping clay litter exclusively.

The presence of respiratory disease was based on the clinical signs described by the owners, radiographic changes, physical examination findings and TW-BAL results. The absence of respiratory disease was determined by the lack of observed clinical signs by owners, absence of radiographic abnormalities, normal physical examination findings and BAL results.

TW and BAL Procedure: The determination of whether to perform a TW or BAL was made by the clinician or based on radiographic findings (15).

Cats with Respiratory Disease: Bobst Hospital of The Animal Medical Center.
Thoracic Radiology: Thoracic radiographs (lateral and ventrodorsal) were performed on each cat and evaluated by a single member of the radiology staff.

Endotracheal TW: The cats were anesthetized with intravenous ketamine and diazepam. A sterile endotracheal tube was passed through the larynx into the trachea avoiding oral cavity contamination. A sterile polyethylene tube was passed through the end of the endotracheal tube. One ml/kg (0.45 ml/lb.) of 0.9% saline solution (pH=5.0) was flushed through the tube and immediately aspirated. Washings were repeated when necessary to collect an adequate sample.

Endotracheal BAL: Bronchoalveolar lavage was performed in a standard method using an endotracheal tube. The cats were anesthetized with intravenous ketamine and diazepam for the procedure (16).

Sample Handling: For each cat, samples were submitted as either prepared slides of mucus secretions or in a sterile EDTA blood collection tubeboth a sterile EDTA blood collection tube for cytological analysis and in a Copan-Type Aimes culturette for submission for bacterial culture and sensitivity testing. All samples from theSamples submitted as slides from TW were stained with Wright stain and evaluated cytologically under light microscopy. All samples from the BAL were collected in sterileSamples submitted in EDTA tubes were first prepared using a cytospin technique prior to Wright stain and evaluated cytologically under light microscopy. All samples from the BAL were collected in sterile EDTA tubes and submitted to Idexx Laboratories (Totowa, New Jersey) for fluid analysis and cell count differential. Slides were also prepared using a cytospin technique and Wright stain for evaluation under light microscopy. Samples for bacterial culture were plated onto Maconkey Agar and Blood Agar and placed in Thiobroth and incubated at 37º C (98.6º F) for 5 days. Two mls of lung wash fluid from each cat was placed in a sterile non-citrated blood collection tube and stored at -70º C (-94º F) until analyzed by EM and XS.

Cats Without Respiratory Disease: Michigan State University Veterinary Teaching Hospital:
Thoracic Radiology: Thoracic radiographs (lateral and ventrodorsal) were performed on each cat and evaluated by a board certified veterinarymember of the radiologistradiology staff.

Bronchoscopic BAL: Control cats were anesthetized with intravenous propofol. Intubation was not performed; oxygen was delivered via an 8 french red rubber catheter advanced to the level of the carina. BAL samples were obtained by fiberoptic bronchoscopy (Olympus). The bronchoscope was advanced to the deepest level of fit (3.5mm diameter). A bolus of 10 ml Balanced Salt Solution (Baxter laboratory) was infused through the endoscope port. Coupage was performed and suction employed to collect the BAL sample in the sterile collection receptacle.

Sample Handling: Since cytologic examination (Michigan State University Clinical Pathology Laboratory) was performed on site immediately following the collection, preservative was not added to the sample. Slides were prepared using a cytospin technique and Wright stain and evaluated by a board certified clinical pathologistunder light microscopy. The BAL sample was also cultured for bacterial growth. Bacterial culture was performed on site (Michigan State University Department of Microbiology) immediately after collection. Samples were plated onto Maconkey Agar and Blood Agar and placed in Thiobroth and incubated at 37º C (98.6º F)for 72 hours. One ml of BAL fluid was placed in a 3 ml serum tube, stored at 4º C (39º F) , and shipped to The Bobst Hospital of The Animal Medical Center for EM and XS analysis in a manner identical to samples of cats with respiratory disease.

Electron Microscopy and X-Ray Spectroscopy
Dry cat litter dust from seven brands of cat litter was transferred to filters by passing the filter above each cat litter sample immediately after it was shaken vigorously in a vial. For each TW or BAL sample, 3 drops (approximately 30µl) of fluid were gently filtered in a dust-free environment onto a polycarbonate filter (pore size = 0.45µm). All filters were dried in a 60ºC (140º F) incubator for 24 hours, mounted on aluminum SEM stubs using double coated carbon tabs, and carbon coated at 70kv using a Denton Desk II carbon yarn coating system. Observations of all samples were made over a one month period using a Hitachi Digital Scanning Electron Microscope fitted with an x-ray Spectral Analysis System. Each stub was observed for about 1 hour and all particles containing silica found in each sample were photographed and the x-ray spectrum recorded.

Statistical Analysis: The total number of silica particles in each sample from healthy cats and from cats with respiratory disease were tabulated and the two groups compared using students t-test.

EM and XS Analyses
Dry Samples of Clay Litter Dust:
Photomicrographs and spectral analyses were obtained from dust samples from 7 popular brands of clay cat litter. The photomicrographs depict particles mostly in the 5-20µm size range and spectral analyses of all the litter dust samples indicated minor differences between brands of clay cat litter in the ratios of different elements (particularly aluminum and silica). These results provide a baseline for identifying clay cat litter particles in lung wash samples.

The cats without respiratory disease used Premium Choice clay clumping litter exclusively and a representative photomicrograph and spectral analysis is presented in Figure 1A and B.

cat liter 1A
Figure 1A

cat litter 1b
Figure 1BThe cats with respiratory disease used several brands of clumping and non-clumping clay litters (mostly Fresh Step) and a representative photomicrograph and spectral analysis is shown in Figure 2A and B.

cat litter 2a
Figure 2A

cat litter 2b
Figure 2BLung Wash Samples: The photomicrographs and spectral analyses of the lung wash samples from cats both with and without respiratory disease indicated that clay cat litter dust collects in lungs of cats. Representative photomicrographs and spectral analyses are presented in Figure 3A and B and 4A and B.

cat litter 3a

Figure 3A
cat litter 3b
Figure 3B

cat litter 4a
Figure 4A

cat litter 4b
Figure 4BThese data show that the identified particles in TW and BAL samples have a very similar appearance and x-ray spectrum as dust particles obtained from common brands of clay cat litter. Particles from two cats had higher aluminum peaks than observed from our the seven dry dust samples. These cats at one time used commercial litters which were not included in the baseline samples. A tabulation of the number of identified clay litter particles in lung wash samples for each group is shown in Table 1.

cat litter grid
1 All cats without respiratory disease underwent bronchoscopic BAL.Particles identified as other than clay cat litter (wool fibers, plant material, insect parts, diatoms) were excluded from the table. A statistical comparison between the two groups indicated significantly more silica particles among cats with respiratory disease as compared to cats without respiratory disease (t=4.7678, df=10, p<.000759).

Clinical Results
Cats With Respiratory Disease: The thoracic radiographs of five of the six cats had an abnormal bronchial pattern ranging in description from slight bronchial wall thickening to severe bronchial wall thickening and a marked miliary nodular interstitial pattern. In one of these cats (Number 8), scant pleural effusion was also noted. The sixth cat (Number 11) had moderate right and left ventricular enlargement and congested lung lobes in addition to a scant pleural effusion.

Four of the six cats presented for respiratory evaluation at The Bobst Hospital of The Animal Medical Center had TW performed and the remaining two cats had endotracheal BAL performed (Table 1). The cytological results of the TW demonstrated inflammatory cells including degenerative and non-degenerative neutrophils, lymphocytes, eosinophils and macrophages. The BAL fluid contained between 495 and 7970 nucleated cells per cubic millimeter which consisted primarily of neutrophils (range 59% of 495 cells to 96% of 7970 cells) and macrophages (range 38% of 495 cells and 2% of 7970 cells). These two cats had blue green material resembling hemosiderin in their macrophages. None of the six cats’ samples contained litter particles that were identified with light microscopy.

From four of the six cats (66%), bacteria was isolated from culture media; two positive culture results were from BAL samples and two from TW samples (Table 1). The organisms isolated included Pseudomonas stutzeri, Bordetella bronchiseptica and Pasturella multocida each as single organisms from three cats and one cat had three organisms isolated including Serratea marcescens, Pasturella multocida and a non-pathogenic alpha strep.

Cats Without Respiratory Disease: Thoracic radiographs were considered within normal limits for the age of each cat. Cytologic analysis of bronchoscopic BAL fluid from these cats showed that one cat (Number 2) was normal, three cats (Numbers 1, 3 and 4) showed mild eosinophilic inflamation, and two cats (Numbers 5 and 6) had a mixed population of cells. All cats’ BAL fluid contained blue green pigments assumed to be hemosiderin within the macrophages.

Four of the six cats (66%) had negative bacterial cultures. Pasturella sp. and alpha hemolytic strep were cultured for two cats (Numbers 3 and 6). Cat number 3 also cultured a gram negative bacillus which most closely resembles Bergeyella (weeksella) sp. This cat’s BAL cytology suggested oropharyngial contamination.

Respiratory disorders in cats are commonly diagnosed. Cats are known to develop chronic bronchitis, bronchial asthma and occasionally lung tumors. Respiratory diseases have many causes including bacterial, viral and fungal infections. In addition, it is known that airborne pollutants and dust particles can aggravate or initiate respiratory problems (17). Many occupational or industrial lung diseases in people are caused by inhaled dusts, including asbestos and silica (18). For example, one specific study suggests that there may be a relation between inhalation of a form of aluminum silicate and pulmonary fibrosis in workers who bagged this material for cat litter. (19). The clearance of these deposited particles from the lungs is by two major mechanisms: the mucociliary apparatus and the alveolar macrophage. Both of these mechanisms are impaired by silica dust deposition.

The normal function and operation of the mucociliary system is affected by pollutants and disease. They alter function by increasing the amount of mucus material and overwhelming ciliary motion by denuding the respiratory epithelium or by altering mucus composition to a more tenacious consistency (17). Regardless of mechanism, the result is mucus plugging of the airways, airflow restriction and loss of this important pulmonary defense. In the cat, it is known that asthma and bronchitis are associated with an increase of mucus volume, that respiratory infections (viruses and mycoplasma) may affect the degradation of substance P (a protein capable of causing airway constriction and edema) (13), and that eosinophils release cationic proteins from their granules which cause epithelial cell sloughing, ciliary stasis, and increased airway smooth muscle contraction (20). If the mucociliary system does not trap inhaled dust particles for clearance by the cough reflex, the particles will gain entrance into the alveolar region of the lung where the alveolar macrophage then takes over as the most important arm of the defense mechanism.

In man, the alveolar macrophages phagocytose the foreign particles, migrate to the small airway region where they become deposited on the mucus layer and are cleared by the mucociliary apparatus. In some cases, the alveolar macrophage migrates instead into the peribronchial tissue and deposits the dust there. If a dust is toxic, such as silica, the alveolar macrophage may be destroyed and a severe fibrosing reaction occurs in the lung where the dust accumulates. This results in dense collagen fibers around respiratory bronchioles, inside alveoli, and along lymphatics. Silica particles can also be observed within the nodules that are formed. These silicotic nodules are initially localized around bronchioles and arterioles. With advanced disease, the surrounding fibrosis destroys the lung tissue and the nodules enlarge and become confluent. Calcified perihilar lymphadenopathy may also occur (20).

The consequence of parenchymal fibrosis is decreased lung compliance due to increased elastic recoil and the increased work of breathing. If small airways are involved, there is concomitant air flow obstruction. Pleural plaques can also be seen. Evidence supports a relationship between silicosis and lung cancer (21). Because of diminished function of the alveolar macrophages which have engulfed silica, humans are, in addition to the above problem, also predisposed to Mycobacterium tuberculosis infections (22).

In man, the likelihood that a particle within the lung will cause a respiratory problem is related to three important components of the particle: the composition of the particle, the deposition of the particle, and the total tissue burden of inhaled particles. Tissue burden relates to particle size, particle concentration in the inhaled airstream, duration and frequency of exposure, clearance ability at various levels of respiratory tract obstruction, and other factors. Two important host factors include genetic variability and the presence of respiratory disease at the time of exposure (1).

The present study in cats with and without lung disease was initiated to determine whether silica can be detected in airway secretions, and if so, to determine if a quantitative difference between groups could be found. It was found that cats with respiratory disease had a greater number of particles retrieved than those without lung disease. The questions that need to be answered are, (i) why did it accumulate more in cats with lung disease, and (ii) whether the presence of silica causes changes in cat lungs similar to those in man. It is suggested that cat litter induces pulmonary disease in workers who bagged aluminum silica used in cat litter (19). None of the cats in the present study had pulmonary function tests or post-mortems performed so no conclusion can could be drawn regarding alteration in pulmonary structure and function. The radiographic changes of cats with lung disease were not interpreted as consistent with pulmonary fibrosis, a common finding in radiographs from humans with silicosis. Some of the cats’ radiographs were interpreted as having a nodular pattern. This pattern may be consistent with mucus accumulation in airways and not necessarily the pulmonary silicotic nodules seen in humans. Radiographically, none of the cats had intrathoracic nodal enlargement, pleural placques, or calcification of their lymph nodes. None of the cats had pulmonary neoplasia.

The cats with an increased number of particles were not the oldest, those with the longest history of symptoms, those with the longest exposure, those with positive airway cultures, those with more severe signs, or those with the most inflammatory exudate. The cats with the greatest number of particles did not have a BAL performed versus a TW. In addition, the presence of hemosiderin-like particles in macrophages was noted only in those cats who had undergone BAL and may not represent hemosiderin but rather silica in the airways and its engulfment by macrophages. Hence, it is impossible to know from the present study whether the presence of respiratory disease and/or altered pulmonary defenses predispose cats to particle accumulation, or whether, as in man, silicosis predisposes to respiratory tract disease.

In man, exposure to fibrogenic dusts such as silica causes pulmonary dysfunction. Subsequent exposure to otherwise harmless substances then can cause the lungs to overreact and create a state of sensitization and asthma (23). Also in man, respiratory tract infections and the associated neutrophil recruitment causes denudation of bronchial epithelium, reduction of ciliary beating and stimulation of mucus secretion, all of which impair the pulmonary defense system (24). Chronic urban air pollutants affected the mucociliary clearance and pulmonary function testing in an experimental study on rat lungs (17). Perhaps in cats with lung disease, silica presence may further impair an already altered mucus clearance, incite a neutrophilic response and predispose the respiratory tract to hyperreactivity or infection. Although the number of particles of silica did not correlate with the degree of inflammation, cats with respiratory signs had a greater number of neutrophils in the lung wash fluid than did cats without respiratory disease.

The most conservative conclusion from the present study is that silica may act as an airway irritant in cats with airway disease and is not the initiator of a primary disorder. The increase in number of particles in the airways of cats with lung disease may reflect that an altered lung defense system was already present and further hindered by the presence of silica.

The authors recognize that only a small number of cats were evaluated in this study and that further research is necessary. The questions that need to be answered are, (i) why did silica accumulate more in cats with lung disease, and (ii) whether the presence of silica causes changes in cat lungs similar to those in man. Suggested future research should include pulmonary function testing that compares normal cats with no exposure to silica-based cat litter, normal cats with documented silica deposition in their lungs, and cats with respiratory disease and silica deposition. Post-mortem or histology is needed, as well as studies on ciliary apparatus motion and mucus composition. Additional studies should include the clinical courses of cats with respiratory disease that have access to alternative litter compared to control cats with continued use of clay litter.

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Figure and TableLegends

Figure 1A A representative photomicrograph of a silica particle from clumping clay litter used by the cats without respiratory disease.

Figure 1B An x-ray spectral analysis of the particle shown in Figure 1A.

Figure 2A A representative photomicrograph of a silica particle from clumping clay litter used by many of the cats with respiratory disease.

Figure 2B An x-ray spectral analysis of the particle shown in Figure 2A.

Figure 3A A representative photomicrograph of a silica particle from lung wash fluid of a cat without respiratory disease.

Figure 3B An x-ray spectral analysis of the particle shown in Figure 3A.

Figure 4A A representative photomicrograph of a silica particle from lung wash fluid of a cat with respiratory disease.

Figure 4B An x-ray spectral analysis of the particle shown in Figure 4A.