Saturday, November 11, 2017

Blood Transfusions in Cats

Most people have some familiarity with the concept of a blood transfusion, perhaps by donating blood to the local Red Cross, or possibly as a recipient during a hospital stay.  Thankfully, most cat owners have very little experience with transfusions when it comes to their cat.  Transfusions are infrequently performed in general veterinary practice, however, as cat owners become more willing to pursue state-of-the-art veterinary diagnostics and therapeutics for their beloved companions, advanced procedures such as blood transfusions are becoming more commonplace. 

Topeka, our hospital cat and blood donor.
There are several reasons why a cat might require a transfusion, with anemia (a decreased amount of red blood cells) being by far the most common.   Some veterinary clinics have a pet “hospital cat” that lives at the clinic and earns its keep by occasionally functioning as a blood donor in those rare times of need.  For years, my hospital employed “Topeka”, a black and white domestic shorthaired cat who, besides providing us with years of joy and affection, saved many lives by donating her red blood cells to desperately anemic fellow felines.

Blood donors should be healthy adult cats of agreeable temperament (for easy handling and restraint), preferably in the age range of 2 to 8 years.  Ideally, the cat should weigh 5 kg (11 lbs) or more, be shorthaired, and be of lean body stature.   The donor’s PCV (packed cell volume, a measure of the percentage of the blood that is comprised of red blood cells) should be greater than 35%. (The normal range for a typical cat is 29 to 48%.)  The cat should test negative for the feline leukemia virus (FeLV), the feline immunodeficiency virus (FIV), toxoplasmosis, and mycoplasmosis (a red blood parasite).  Blood should not be collected more than once every 4 to 6 weeks from an individual donor.  

In a general practice setting like my own, transfusions are performed using whole blood, because that’s what we obtain from Topeka, our donor.  However, the ability to fractionate whole blood into its component products has made it easier to treat a variety of conditions if a blood donor isn’t readily available.  Veterinarians now have access via veterinary blood banks, local emergency clinics, or referral centers, to fresh or stored whole blood, packed red blood cells (pRBCs), fresh-frozen plasma (FFP), and platelet products. 

Blood is sterilely collected into commercially prepared blood bags containing an anti-coagulant.  The blood can be used immediately, or it can be stored in a refrigerator for several weeks until needed.  As noted above, fresh whole blood can also be separated into its component parts.  Whole blood contains everything: red blood cells, serum proteins, clotting factors, and platelets.  Because the most common reason for a transfusion is severe anemia, packed red blood cells (pRBCs) may be a more appropriate product.  The advantage of using pRBCs is that you are administering the same amount of red blood cells as that found in a unit of whole blood, but it is in a much smaller volume, making it safer for animals with concurrent heart or kidney disease. 

Cats have specific blood types, similar to humans: Type A, Type B, and Type AB.  Unlike humans, there are no type O cats.   The majority (99%) of cats in the United States are type A.  Type B is less common.  In Europe, Japan, and Australia, higher percentages of cats with Type B blood are found.  Some breeds of cats (for example: British shorthair, Devon rex, Cornish rex, exotic shorthair, Abyssinian, Japanese bobtail, Persian, Himalayan, Somali, and sphinx) have a higher percentage of Type B blood.  Although purebred cats are most likely to be Type B compared to non-purebred, it is interesting to note that Siamese cats are reported to be 100% Type A.  Cats with blood Type AB are extremely rare.  In 29 years of veterinary practice, and having performed countless blood typing procedures, I have still not encountered a type AB cat. 

The Rapid Vet H Blood Typing Test.  Both cats here are Type A.
Transfusing blood products into a cat isn’t a benign procedure.  The feline immune system can react dramatically to blood components, with life-threatening consequences.  The serum of cats with Type A blood possesses antibodies that react against Type B red blood cells.  Conversely, the serum of cats with Type B blood possesses antibodies against Type A red blood cells.  In Type A cats, the amount of antibodies they have against Type B blood is relatively low, so accidentally giving Type B blood to a Type A cat will typically result in a mild reaction, with the transfused Type B red blood cells undergoing attack and destruction by the immune system of the recipient within 2 to 3 days.  However, the amount of anti-A antibodies in the blood of a Type B cat is very high, and administering even a small amount of Type A blood into a Type B cat can cause acute, dramatic destruction of the transfused red blood cells, resulting in a potentially fatal transfusion reaction.  It is therefore imperative that blood typing be performed before any transfusion is undertaken.  To be even safer, it is advisable to perform an additional procedure called crossmatching to further minimize the risk of a transfusion reaction.  A detailed description of crossmatching is beyond the scope of this article, but it involves mixing donor red blood cells with serum of the recipient (major crossmatch) and mixing donor serum with recipient red blood cells (minor crossmatch) and observing the reaction.

Once the compatibility of the donor and the recipient has been confirmed, the transfusion can be performed.  Initially, the blood should be administered slowly.  If no adverse effects are witnessed after 30 to 60 minutes, the rate of administration can be increased.  The rate depends on the urgency of the cat’s condition.  Cats that are in shock from acute blood loss require rapid blood administration.  Cats with cardiac disease are at risk of fluid overload and congestive heart failure, and may require a much more judicious rate of administration. A typical transfusion is completed in 4 to 6 hours.  The goal of the transfusion, in most cases, is to increase the patient’s PCV sufficiently to reverse the signs of anemia.  A reasonable aim is to achieve a PCV of 20%, although this isn’t always possible.

My beloved Crispy
[I have personal experience with blood transfusions not only as a veterinarian, but as a cat owner. Two years ago, my 14 year-old cat Crispy underwent surgery to remove an intestinal tumor.  Immediately post-surgery, Crispy became alarmingly pale and was very slow in waking from anesthesia.  A quick in-house test revealed a dangerously low red blood cell count (PCV of 12%) and a transfusion was going to be needed if she was going to have any chance of recovery.   Although 99% of domestic shorthaired cats in the U.S. are Type-A, I quickly checked Crispy’s blood type right after surgery, and to my shock and dismay, she was a very definite Type B.  Frantic calls to the first two nearby emergency clinics were futile; they only had Type A blood on hand.  Miraculously, the third referral center had two units of Type B packed red blood cells stored in their refrigerator.  A harrowing 20-minute taxi ride ensued, with my anesthetized cat on my lap, her endotracheal tube still in her windpipe.  Thankfully, the emergency staff was ready and waiting, and her transfusion began immediately upon arrival.  She woke up from anesthesia a tense 40 minutes later.  (Catnip subscribers may remember this case, which I described in detail in the article “When Doctor Becomes Client” in the July 2015 issue of Catnip). ]

Although blood transfusions are infrequently performed in general practice, the increased availability of feline blood and blood products and the willingness of cat owners to pursue more advanced care for their pets has made this often life-saving procedure more common.  By transfusing a patient only with the blood component that is needed, knowing the blood types of the donor and recipient, and performing a crossmatch right before the transfusion, most transfusions can be performed safely and effectively.

Tuesday, August 8, 2017

Helping Your Veterinarian Make the Diagnosis

Helping Your Veterinarian Make the Diagnosis

A successful examination begins with the owner

            If you think about it, being a cat veterinarian is not very different from being a pediatrician. We can’t ask our patients what’s wrong. We just have to figure it out.
Nowhere is the role of a cat owner more important than at the veterinarian’s office, where a good history can sometimes mean the difference between life and death.

            Veterinarians are faced with a variety of diagnostic challenges on a daily basis. The ability for a veterinarian to obtain a detailed and complete history is our most important diagnostic tool. When accurately interpreted, this information lays the groundwork for a logical diagnostic and therapeutic plan, which may prevent unnecessary
diagnostic testing and needless discomfort to the patient and cost to the owner. After briefly discussing the primary complaint, veterinarians try to obtain both objective and subjective information when gathering the history. Examples of objective data include the signalment, the environment, diet and medical history.

            The signalment consists of the cat’s age, breed and gender, including the reproductive status, i.e. whether the cat is neutered or spayed. This is basic and important information. Certain illnesses tend to strike cats at certain age ranges. For example, hyperthyroidism is a glandular condition that causes cats to lose weight despite a ravenous appetite. It’s an old age disease, rarely striking cats under the age of eight. A 13-year old cat with weight loss and excellent appetite warrants a blood test to evaluate thyroid function. A four-year-old cat with the same signs would be more likely to have something else, such as inflammatory bowel disease or pancreatic insufficiency. Even if you’re not sure of the exact age, an accurate approximation can be very useful for a veterinarian. Certain breeds are predisposed to certain conditions and knowing the breed can help veterinarians choose proper diagnostic tests. Persians are prone to polycystic kidney disease; Ragdolls and Maine Coons are susceptible to hypertrophic cardiomyopathy. Veterinarians must not be misled by clients who tell their veterinarian that their cat is a Maine Coon, only to discover that it’s a domestic longhair that, “looks just like the Maine Coon in the magazine.” Gender provides important information as well. A female cat straining to urinate is likely to have cystitis. A male cat straining to urinate could have a urinary obstruction, something that can be life-threatening if not treated promptly. Unlike age or breed, there’s very little guesswork when it comes to determining gender. Just lift the tail and take a look!

            Gathering environmental history is a routine yet important part of a cat’s history. Free-roaming cats, or cats that stay outdoors, are at a much higher risk of getting into fights with other cats, which increases their risk of getting cat bite abscesses or acquiring feline leukemia or FIV. Free-roaming, or recently escaped, cats may have had access to toxins or have been subject to trauma, which is unlikely to occur with an indoor pet. Sometimes a travel history is important, although this is true more so with dogs than cats, because when cats travel with the owner to another part of the country, they are not usually let outdoors where they are at risk of running away or getting lost. Still, a travel history can be important, especially if the patient has been exposed to diseases endemic to certain regions but not prevalent in their normal environment.

            A dietary history is more than merely determining which type and brand of food you’re feeding your cat. Granted, knowing the type of diet (dry, moist, table food), the brand name, any types of snacks, the method of feeding (free-choice or individual meals) and the amount is important; but, veterinarians also want to know about your cat’s appetite and whether there has been any weight gain or loss. It’s helpful if you watch your cat eat. Complete or partial anorexia is a common reason that clients take their cat to the veterinarian. A client that notices that their cat only chews on one side of its mouth, or has stopped eating dry food and now will only eat canned food, is telling the veterinarian that oral pain or discomfort may be the source of the problem and that a thorough oral exam may be the only diagnostic test necessary to obtain the diagnosis.

            Reviewing the patient’s prior medical record can give valuable information to the veterinarian. If this is your first visit to this particular veterinarian, it is very helpful if you know your cat’s vaccination history as well as feline leukemia virus and feline immunodeficiency virus status. Medical records detailing the diagnosis or treatment of any prior or ongoing health problems are helpful, as the primary complaint may be a consequence of a prior medical condition. Once the above information is obtained, the veterinarian is ready to delve deeper into the primary complaint. The history surrounding the primary complaint tends to be more subjective and this information, obtained from observant, conscientious owners, can be a tremendous asset. Veterinarians know that some owners aren’t as observant as others. Our job is to encourage our clients to describe the cat’s problem from its onset so that an orderly chronology is obtained. Some of the things we’ll want to know are when the cat last seemed normal, whether the onset of the clinical signs was sudden (acute) or if it developed slowly over time (chronic) and whether or not the illness has responded to previous treatment. For example, an itchy cat that was treated with steroids and did not respond in the past is more likely to have food allergy (poorly responsive to steroids) rather then flea-allergic dermatitis (responds rapidly to steroids).

            Depending on what the primary complaint is, a veterinarian may delve even deeper, to further help characterize the problem and better formulate a diagnostic plan. As an example, if a client reports that their cat has diarrhea, the veterinarian may then ask whether there’s any blood or mucus in the stool, whether the cat has been straining in the litter box or whether the cat has had any accidents in the house. The more the client answers “yes,” the more likely that the diarrhea has originated from the large intestine. This narrows down the list of possible causes for diarrhea and helps the veterinarian formulate a diagnostic and therapeutic plan.

            Behavioral changes can be difficult for veterinarians to interpret. I’ve had many clients bring in their cat because he or she was acting differently, although upon further questioning, it became apparent that the cat wasn’t actually ill despite the difference in behavior. Cats who suddenly stop sleeping on the bed, even though it’s been their favorite sleeping spot for years, or normally vocal cats that have lately become more quiet, may indeed be acting differently, but these are more likely to be benign behavioral changes. Lethargy, hyperactivity, aggression, growling and urinating or defecating in inappropriate places, however, are behavioral changes that may indicate an underlying medical problem. When in doubt as to whether any apparently new behaviors are medically significant or not, it’s best to be on the cautious side and report everything to your veterinarian. With the advent of cell phones and the ability to quickly take a photo or a video, clients are encouraged to photograph or videotape any unusual behaviors or symptoms, as a video of a seizure, for example, or other odd behaviors can often serve as a valuable supplement to the client’s verbal description.

            Because our patients cannot talk, veterinarians must rely on you, the client, to speak for them. The more observant you are, the more information you can give us. This information can go a long way toward obtaining the proper diagnosis, allowing us to tailor a treatment plan to put your companion quickly on the road to recovery.

Friday, July 28, 2017

Inhaled Medications: Another Option for Medicating Your Cat

            Cats can be tricky to medicate.  Veterinarians know that it is difficult to medicate a cat consistently with a medication that is required twice daily, and almost impossible to administer a medication reliably and unfailingly three times daily.  Most veterinarians, when dealing with cats, try to strike a balance between efficacy and ease of administration, prescribing the most effective drug that can be given with the least frequency. 

Medications that come in pill or capsule form are especially challenging, as many cats actively resist having pills put down their throats. Uniquely designed treats, such as “Pill Pockets” are available in some pet stores and veterinary offices. These are soft treats with a hole cut out of the center. Pills are placed in the center of the treat, and are then sealed inside by gently squeezing the sides. Some cats can be tricked into taking pills this way for months, although many catch on to the ruse and will eventually refuse to eat the treat.

Cat owners often find liquid medications easier to administer. Fortunately, a number of pharmacies now offer compounding services - they can convert medications traditionally available only in capsule or tablet form into other formulations, such as a liquid form, often adding chicken, liver, beef, and tuna flavoring if requested. While most cats do not like having any medication forced upon them, many find a tuna or chicken flavored liquid less objectionable and a few will take a flavored medication voluntarily.

A number of pill-hating cats will also resist liquid medication, regardless of the flavor. Transdermal medication (delivering drugs into the bloodstream via application of gels or skin patches) offers another option of medicating cats that simply refuse to take any medication orally. Some medications can be compounded into a gel, a small amount of which can be spread on the inner surface of the ear.  The medication is then absorbed through the skin, into the bloodstream, allowing owners of stubborn cats to bypass their mouths completely.  While transdermal drug administration is becoming more commonplace in veterinary medicine, there are only a few drugs for which efficacy has been proven with this method.  Just because a drug can be formulated into a transdermal gel doesn’t mean that therapeutic blood levels of the drug can be achieved. 

            Inhaled medications present another option for medicating cats, however, the use of inhaled medications is limited to cats with respiratory ailments, most notably asthma.  Interestingly, veterinarians seldom prescribe inhaled medications because of the difficulty of administering oral medications to a cat.  Rather, inhaled medications are often given because of the reduced risk of side effects when using inhaled medications. 

Veterinary Technician/Cat Whisperer Gill Nunes demonstrates
how to administer inhaled meds to little Trinity.
            Asthma is the most common reason for prescribing inhaled medication in cats. The most effective long-term treatment consists of high doses of oral steroids.  Steroids attenuate the inflammatory response, reducing the severity of signs.  Steroids are given twice daily for several days.  Most newly diagnosed asthmatic cats will feel and act much better, at which point, the steroid dose is tapered slowly over several weeks.  Unlike dogs, cats are fairly resistant to the undesirable side effects of steroids.  A few cats, however, exhibit adverse effects from steroids, making treatment challenging.  Oral steroids cause water retention, which increases a cat’s blood volume.  Cats with heart disease may not be able to withstand the increase in blood volume, putting a strain on an already compromised heart and triggering congestive heart failure.  Oral steroids also oppose the action of insulin, and can cause a well-regulated diabetic to become poorly manageable.  Some cats may be pre-diabetic, and giving oral steroids can tip them over the edge into overt diabetes.  Inhaled steroids, when administered, exert their effects almost exclusively in the lungs.  Very little of the drug crosses beyond the lungs into the bloodstream, so systemic side effects are minimized. 

Be warned: not all cats will be as cooperative as Trinity. 
            Bronchodilators are drugs that reverse airway constriction, allowing the air passages to open.  Although most asthmatic cats can be managed with steroids alone, some require a bronchodilator in addition to the steroid.  Bronchodilators can be given orally, although an advantage of inhaled bronchodilators is their rapid effect, which may be lifesaving in severely asthmatic cats that are prone to acute asthma attacks.

            Both types of drugs are available for humans, as metered dose inhalers (MDIs).  Human adults quickly learn to coordinate the inhaling of the medication with the actuation (pressing) of the device, although this is much more difficult for children, and impossible for infants or cats.  An alternative was developed to allow children, infants, and cats to use the MDIs without having to coordinate their breathing.  A spacer – a plastic chamber roughly the size of the cardboard inner tube of a roll of toilet paper – is attached to the MDI, and a facemask is attached to the other end.   The spacer acts as a temporary storage area for the misted medication to sit, until the individual breathes it in. Cat owners are taught to attach the MDI and the facemask to the spacer, and then to actuate the MDI twice, filling the spacer with the mist.  The facemask is gently placed over the cat’s mouth and nose, and the cat is allowed to inhale and exhale 7 – 10 times with the mask in place.  The most popular device for inhaled medications in cats is the Aerokat (see pictures above)

             Inhaled steroids are the most potent inhaled anti-inflammatory drugs available.  Fluticasone (Flovent) is the most commonly used inhaled steroid.  As for bronchodilators, Albuterol (Proventil) or Ventolin) is the one most commonly used for asthmatic cats.

            Inhaled steroids and bronchodilators have been the standard of care for the treatment of asthma in humans, and while oral medications are still the initial method of treatment for asthmatic cats, inhaled medications offer another option for cats at risk for or experiencing side effects of oral medications, or for cats who refuse to allow oral administration of medication.


Wednesday, July 12, 2017

Cat Man Adieu

It’s been a little over a month since I retired.  I’m still finding it hard to get used to.  I overhear other people say, “I’m not working the rest of this week” or “I’m off for the rest of this month”, and I realize that hey, I’m off for the rest of my life. 

There are many things to adjust to.  I suppose the most noticeable thing for me is the silence.  As a veterinarian, I used to spend my day talking to clients during appointments.  If I wasn’t in an appointment, I was likely talking to a client on the phone.   If there were surgeries or procedures to perform, I’d be chatting with my staff in the treatment room before, during, and after the procedure.  My entire day was spent in some type of conversation.  In retirement now, I go through the day barely speaking a word to anyone.  Most days, the extent of my conversation is, “I’ll have the chicken salad club and an iced tea”, or “Can I have the venti green tea frappuccino?” (I’ve been saying that one a lot lately) I’m a social, outgoing person, and the curtailment of my conversation is the most striking difference in my day.

The lack of a set routine is probably the next most noticeable change.   My day was used to be pretty much the same: wake up, shave, shower, feed the cats, have breakfast, do a few household chores (laundry, dishes, litter box), and then descend into the hellish subway to work (thankfully only 5 stops), and then see appointments all day.  That routine is now gone, but being a creature of habit, a new pattern is starting to emerge to my mornings.  Sadly, I’m still getting up very early, because Mark (the hubby) still has to wake up at the ungodly hour of 5:20 a.m.   While he hops in the shower, I feed the cats and make breakfast for us both. (I’m getting very skillful and creative with omelets.) I complete a few more chores, and then I accompany him out the door at 6:30.  He walks to 14th Street to catch the van that takes him to work, and I peel away when we approach 27th Street and hit Planet Fitness.  Yes, I’m going to the gym for nearly 2 hours every single morning. 

Twice a week, I do a little grocery shopping at Fairway after the gym.  Otherwise, I come home, do a few more chores, shave and shower, read the New York Times headlines (delivered to my inbox every morning.  I’ve figured out how to work around their ten-article-a-month firewall), answer a few e-mails, and then confront the agonizing decision about where I’m going to have lunch.   As for my afternoons, they’re open.  Some days, I go to the mid-Manhattan library and either borrow some books, browse their books, or read a book that I’ve brought with me.  At least once a week, and sometimes twice, I catch the 1:30 movie at MoMA.  I’m a member, and so the movies are free for me.  These are usually old movies from the 30’s, 40’s, and 50’s, being shown as part of some actor/actress/director retrospective.  After the movie, I usually hang around and read in the sculpture garden.  Most of my afternoons are spent reading (and occasionally napping) in a park.   Some days (usually if I’m feeling a bit lonely or isolated) it’s Bryant Park.  Other days, it’s Madison Square Park (usually on days when I eat lunch at Eisenberg’s Sandwich Shop, because it’s close by).  Mostly, I head down to Tompkins Square Park.  It’s a little out of the way, but on weekdays it’s really peaceful and quiet, and I have a particular bench in a perfect, shady spot that is ideal for people-watching.  Rough life I lead, eh? 

I suppose the other major change since retirement is a so-called “lack of sense of purpose” that I’ve been warned about.  Two retirement books that I’ve read have mentioned this potential issue.   And yes, I can see how this can be an issue, and may end up being one for me in the future, given how strong a sense of purpose my career as a veterinarian had given me.   It so happens, this lack of a sense of “purpose” that I’m currently experiencing has actually turned out to be the most liberating and calming part of my retirement.  For 29 years, my purpose was to help sick animals become well, and help clients deal with all issues regarding their pets’ health, while mentoring students, interns and technicians along the way.  It was a huge responsibility (more on that in a future post).  Being free of all of that, for the moment, is a huge (we’re talking ginormous) weight off my shoulders.   Of course, at some point, the urge to do something more meaningful will be upon me, and I will pursue it wherever it leads (although I have a strong hunch that veterinary medicine won’t be involved), but for now, I really want to harken back to the days when I was a kid in Brooklyn and had the summers off.  I spent those summers playing stickball and stoop ball, riding my bike, and hanging out in the neighborhood park with my friends.  Forty-something years later, there won’t be any stickball or stoop ball, but I’m definitely on a mission to check out every little park in Manhattan.

Related Posts Plugin for WordPress, Blogger...