Tuesday, September 23, 2014

New hope for canine allergies

My next patient was Scratchie the pit bull.  It was Scratchie’s sixth visit this year for itchy, infected skin.  His “seasonal” allergies now extended from spring through fall, and our various treatments hadn’t seemed to give the poor guy much relief. 

Statistics show that 10% to 15% of dogs have allergies, but sometimes it seems closer to 75% in our practice.  That’s because when pollen levels start to go up in the early spring, itchy dogs start filling up the appointment calendar until frost.  Most allergic dogs can be controlled with topical treatments and oral medications, but for some unfortunate critters, that just isn’t enough to keep them from being miserable.  Those patients usually need immunotherapy, in the form of allergy shots. 

Before beginning allergy shots, the dog must first be tested.  That requires a trip to the dermatologist for intradermal testing or a visit to our hospital for blood testing. Once the test is done, a serum is made specifically for that dog, using small amounts of allergens (the proteins that cause the dog to itch).  The patient periodically receives injections with gradually increasing amounts of allergens until a maintenance level is reached.  

Although immunotherapy has very good efficacy, this option hasn’t been popular with owners for a number of reasons. The cost of going to the dermatologist and having the skin testing done is one drawback. Then there is the issue of having to inject your dog -- not a great option if either owner or pooch is needle-shy.
Some dogs can have adverse reactions to the serum. Allergy shots can take months to start working. Finally, it can be difficult to remember to give the injections at certain time intervals.

But now there’s a better way to deliver allergens to our patients:  sub-lingual immunotherapy.  The procedure is simple.  First, we draw blood from your dog and send it to Heska Veterinary Diagnostic Laboratory.  The serum that is formulated from the allergens is then administered by drops given in the mouth instead of by injection. 

About half of dogs receiving allergy immunotherapy will have an excellent response, about 25% will have a so-so response, and about 25% will have no response at all.  When sub-lingual immunotherapy first came out, there was skepticism over whether the drops would be as effective as injections.  It turns out that not only do they work just as well, in many cases they work better!  In fact, dermatologists often find that dogs that fail to respond to injections have success with sub-lingual therapy.  Many dermatologists are using oral therapy from the get-go almost exclusively now.  

Besides its good efficacy and the no-needle thing, there are more advantages. There is much less chance of anaphylaxis (a severe and life-threatening allergic reaction) with the oral drops. Even dogs who had anaphylaxis with the injections tolerate sub-lingual immunotherapy.  The drops, which are delivered by a pump, are easy to administer by the pet owner.  With injectable therapy, mold serum must be injected in a syringe separate from the pollen serum, but with sublingual therapy the two can be combined in one vial.  And the sublingual treatment seems to work slightly faster than the injections.  Heska says it takes three to four months to see a response, but many dermatologists say they see a reduction in scratching more quickly than that.  With either method, though, it’s best to expect to see results during the next allergy season, so pet owners need to plan ahead. 

A disadvantage for some clients is the frequency of administration.  Allergy injections are usually given every one to three weeks, but sublingual immunotherapy requires twice-daily administration. However, some pet owners prefer the routine of giving medication every day and find themselves forgetting to give an injection every few weeks, so that isn’t an obstacle for them.    

If the cost of allergy testing and immunotherapy worries you, consider dogs like Scratchie.  Each time he visits, there is a professional fee plus the cost of oral and topical medications, and occasionally lab fees for cytology or culture.  Such a visit can range from $50-$275.  The cost of serum-testing a dog is around $140, and it’s a one-time expense. A vial of sublingual serum, which lasts five months, costs $105.  I realize that isn’t an inconsequential amount, but if the therapy prevents multiple visits to the animal hospital, you will have come out ahead.  Not only that, but you’ll get a better night’s sleep when your allergic dog stops licking, head-shaking, and thumping his leg against the floor while scratching all night!

Sunday, September 14, 2014

A new look at neutering

The recommendation to spay and neuter all dogs is the standard of care, but recent evidence has thrown new light on that dogma – at least for two breeds.   

Two studies from the University of California-Davis School of Veterinary Medicine have taken the veterinary world by surprise.  The research was based on 13 years of health records from UC-Davis for neutered and non-neutered male and female Labrador and golden retrievers between 6 months and 9 years of age.  The most recent study, published in July of this year, compared 1,015 goldens with 1,500 Labs.  Those two breeds were chosen because of their popularity, similar size, and comparable behavioral characteristics.

The researchers picked several cancers (lymphosarcoma, hemangiosarcoma, mammary cancer, and mast cell tumor) and three joint disorders (hip dysplasia, cranial cruciate ligament tear, and elbow dysplasia) and compared the incidence in neutered and non-neutered dogs of both breeds.  The neutered dogs were grouped into four categories, according to the age at which they had been altered.  

It turned out that non-neutered males and females of both breeds had a 5 percent rate of one or more joint disorders.  But in Labs, neutering before 6 months of age doubled that rate, to 10 percent.  More alarming, the golden retrievers that had been neutered before 6 months of age had 4 to 5 times the incidence of joint disorders compared with non-neutered goldens.  The joint disorders found to increase in male goldens were hip dysplasia and cranial cruciate ligament tears, while lab males had more cruciate tears and elbow dysplasia. 

Lead investigator Dr. Benjamin Hart at UC-Davis says,  “The effects of neutering during the first year of a dog’s life, especially in larger breeds, undoubtedly reflects the vulnerability of their joints to the delayed closure of long-bone growth plates when neutering removes the sex hormones.”  In other words, we’re messing with Mother Nature!

Regarding cancers, the data also uncovered significant differences between the breeds.  The cancer rate of both breeds when they weren’t neutered was 3 to 5 percent, except in male goldens, who have an 11 percent cancer rate. Neutering didn’t have much effect on the cancer rate of male goldens.  However, in female goldens, neutering at any point beyond 6 months increased the risk of some cancers to 3 to 4 times the level of non-neutered females.  But that was true only for goldens; neutering female labs only negligibly increased their cancer rate.  According to Dr. Hart, “The striking effect of neutering in female golden retrievers … suggests that in female goldens the sex hormones have a protective effect against cancers throughout most of the dogs’ lives.”  Mother Nature again. 

What does all this mean?   Should we stop neutering our dogs to prevent joint disease and cancer?  Before sweeping changes are made, the limitations of the studies must be discussed.  First of all, they compared Labs with goldens; no other breeds were studied.  Comparing goldens with German shepherds probably would yield vastly different results. Even within a breed, there were significant differences based on gender.  To get solid data, hundreds of studies would have to be done, not just on a breed basis, but also on a gender basis.  

When I started practicing veterinary medicine in 1977, the unwavering recommendation almost every veterinarian made was to neuter all dogs at 6 months of age.  I don’t think compliance was nearly as good then as it is today.  I remember many male dogs coming in with prostate problems, perianal tumors, and perineal hernias, all conditions associated with not being neutered.  Spaying a female of any breed before her first heat has been associated with a lowered risk of breast tumors; performing surgery on unspayed dogs to remove breast cancer and infected uteruses was a frequent occurrence back then.  I rarely see those medical problems today; it’s likely that the early neutering of pets from shelters has had a big influence on preventing them.

The two studies looked only at the risks of neutering those breeds, but not at the benefits.  Neutering a female golden, for example, elevated the risk of one or more cancers three- to fourfold.  But not spaying dogs of all breeds causes the above-mentioned breast cancer and infected uteruses, as well as messy heats and the risk of overpopulation.   You might prevent joint disease in your male Lab by leaving him intact, but in addition the problems I listed above, the compromise might be aggression, wandering, marking in the house, and, again, unwanted puppies.  

So now we veterinarians and our clients are faced with a quandary:  to fix or not to fix.    I think it’s wise to discourage neutering in goldens and Labs before 6 months of age, and 12 months is even better.  I also think a discussion is warranted with the owners of other large-breed dogs, whose joints are more vulnerable when they are altered early.  As far as never neutering, we need more data before we make a blanket recommendation across all breeds.  For the owners of Labs and goldens, we can discuss the risk-benefit ratio with you, but the decision as to whether to neuter will ultimately be yours.   

Sunday, September 7, 2014

Rodenticide toxicity: The perils of poison

A couple of years ago, I noticed a sprinkling of dried mouse droppings on the desk in my basement.  I cleaned them up and, except for setting traps in the basement, pretty much accepted the occasional debris as an unavoidable nuisance.  That changed on the day I arrived at the desk to find that fiberglass from the nearby wall had fallen on it, sodden with mouse urine and feces. Ewww!  I decided to go after the little vermin with a vengeance.

I called my pest control guy, who strategically placed bait stations around my basement.  These were plastic mazes, the payoff being a chunk of anticoagulant mouse poison at the end of the tunnel.  Even though I don’t let my cats wander into the basement, I told him I was concerned that they could be exposed to the toxin if they happened to sneak down there.  He assured me that the point of the maze was to prevent pieces of the poison from being removed from the bait station.  The mice would help themselves to the toothsome treat and leave.  And then die.

One of my cats, a rapscallion named Cam, became an expert at lying in wait for the basement door to open and then streaking down the stairs.  One day I chased after him and found him licking a substantial chunk of grainy blue mouse poison. So much for “the mice can’t remove the poison from the bait station!”  The bait stations were taken out the next day.

Rodenticides can be grouped according to how they work.  The common ones we encounter in our practice are anticoagulants, which stop normal blood clotting.  Bromadiolone, chlorophacinone, difethialone, brodifacoum, and warfarin are examples of anticoagulants. 

We receive rodent poison-related calls at least a couple of times a month.  The situations are sometimes similar to what happened at my house.  The most recent one involved a dog that escaped through the front door, ran into a neighbor’s garage and began eating a pellet of d-Con that was on the floor.  In that case, the dog was lucky: The owner knew what had happened and was able to get treatment right away. The tricky thing about anticoagulant poisoning is that the pet owner usually has no knowledge of the exposure, and the symptoms can be delayed for up to five days.  By that time, the owner has probably forgotten that Fido disappeared into the neighbor’s shed for 10 minutes last week.  The pet is presented to us with physical manifestations that aren’t specific to any one disease or syndrome:  difficulty breathing, weakness, exercise intolerance, lethargy, lameness, coughing, vomiting, and shaking.  The pet owner might not notice more specific signs, such as bruising, pale gums, tarry black stools, or blood in the urine. 

Treatment for anticoagulants is supportive care, if indicated, and administering Vitamin K1 for two to four weeks.  If the owner actually sees the pet eat the stuff, inducing vomiting (in some cases) followed by activated charcoal might help prevent absorption.  A pet with more severe clinical symptoms may be in big trouble.  Bleeding from rodent poison is typically into the body cavities.  Massive blood loss into the abdomen and chest is common and is often the cause of death.

Warfarin – the same substance often prescribed for humans as a blood-thinning medication – is what’s known as a first-generation anticoagulant poison and requires multiple feedings to deliver a lethal dose.  Second-generation anticoagulants were developed when some resistance to warfarin was discovered in rodents, and those can be lethal after just one dose.  After March 2015, consumers will no longer be able to buy anything but first-generation anticoagulants or other rodenticides, but pest control professionals will still be able to use the more potent second-generation products.

According to Audubon Magazine, there’s no safe place or delivery system for second-generation anticoagulants. Poisoning can occur from direct ingestion, but there’s also something called “relay toxicosis”: after a rodent eats the poison, it gets weak and becomes an easy, tasty meal for other animals such as raptors and mammalian predators. That includes not only dogs and cats but foxes, bears, bobcats, mountain lions, and wolves, among many others.

Here are some sobering statistics:

  • In California, rodenticides showed up in 79 percent of fishers, 78 percent of mountain lions, 84 percent of San Joaquin kit foxes, and 92 percent of raptors.
  • In New York, rodenticides were found in 49 percent of 12 species of necropsied raptors. For great horned owls the figure was 81 percent.  Rodenticides are also blighting raptors in Australia, New Zealand, Ireland, and Canada.
  • In Great Britain, necropsies revealed the poisons in 92 percent of red kites, 91 percent of barn owls, and 80 percent of kestrels.     
  • Currently about 15,000 calls per year come in to the Centers for Disease Control from parents whose children have eaten rodenticides.
    Scientists and wildlife advocates recommend non-toxic pest eradication in most cases.  There are certainly situations in which rodents damage crops or homes, transmit disease, and even cause severe ecological damage (entire island ecosystems have been destroyed by rats).  But for the most part, use of second-generation anticoagulants should be severely limited, even for pest control professionals.  

    Got an infestation?  Search “non-toxic rodent control” on Google and you’ll get more than 300,000 results.  Find out about the habits of the pest, and its likes and dislikes.  Block entry points and remove any food and water sources.  This is called integrated pest management

    We are the guardians of our children, pets, and wildlife; don’t use weapons of mass destruction when a cherry bomb will do the job!

Monday, September 1, 2014

Get the most out of your pet's appointment: Can we talk?

Mrs. Ernest’s forehead was creased in concentration as I tried to extract a medical history for Chunder, the little dog she held snugly in her arms.
“How long has Chunder been vomiting?” I inquired.
“Oh, let’s see, he’s 7 years old, so I’d say about six years.” (The intake information that our technician took said he’d started vomiting three days ago and had been fine prior to that.)  
“How often during the past six years has he vomited?” I asked.  “Once a day?  Once a week?  Once a month?” 
“Just a few times a year, usually after he eats grass or goose poop,” replied Mrs. Earnest. 
“So the recent vomiting episode — it says here that it started three days ago.  Is that correct?”
“Oh, no, he started vomiting two weeks ago.  He hasn’t felt well for the past month,” she answered.

If you think conversations like that are a rarity, think again!  They are a daily occurrence at animal hospitals everywhere.  And unfortunately, they can actually affect the quality of care. A concise, orderly history of your pet’s ills is imperative in helping us diagnose and treat your little buddy.  So how can you, as your pet’s guardian, help clarify your communications to your veterinarian?

We’ve all been told to write a list of our concerns when we visit our own physicians.  Lists are a big help for veterinarians, too, but pet owners need to prioritize the list and discuss the problem that is of the most concern to them at the beginning of the appointment.  Sure, I want to take a look at the minuscule lump (which took you five minutes to find for me), but first tell me about your pet’s decreased appetite over the past two months.  The lump can wait, or can be addressed at a later date. 

Before you take your pet to his veterinary appointment, sit down and chronicle the problem on paper — at home and in a quiet place.  When did your pet’s symptoms first appear?  For acute problems, that isn’t difficult to determine; it’s pretty hard to forget the six piles of diarrhea you had to clean up before your yoga class on Monday evening!  But the onset of problems that have been going on for a long time can be much more difficult to pinpoint.  It’s often useful to ask other family members when they noticed the first occurrence of said ailment.

The next thing to record is exactly what you noticed that was unusual.  It’s not helpful to say, “He’s just not himself.”  Why is he not himself? Make a list of specific things that aren’t normal:

  • He’s always eaten his meal in less than a minute, but now it takes him two hours to finish it.
  • He stopped getting up to greet me when I get home from work.
  • He stopped eating his favorite treats.
  • He started urinating in the house, which he’s never done before.
  • Suddenly he stopped jumping on my bed at night.

When you come to the office, bring your written history with you, and choose your cohorts wisely.  Unless the appointment involves life-or-death decisions, it’s best not to bring the entire family; a few of you will suffice.  Having several people chiming in with their opinions and contradictions isn’t helpful, which is another good reason to interview your family at home.  You don’t have to leave well-behaved kids at home, though.  In fact, parents often hush up kids who try to answer my questions, but I’ve found that children of many ages can offer valuable insight into their pet’s behavior.  They might also confess to having fed that pet a pile of greasy french fries!  

Veterinarians are trained to interview clients in a way that gives us the most useful information.  You might feel impatient when we ask seemingly inane questions, but there’s a good reason for us to delve into things that you feel are inconsequential:  They are important clues to us.  But there might be times when we don’t ask you about something you think is relevant.  Make sure you speak up:  “Let me tell you what else I’m seeing that I think may be important (or is unusual, worrisome, etc.).” 

An oft-quoted statistic in the veterinary community is that clients forget 85% of what we tell them by the time they get home.  If you aren’t absolutely clear about the doctor’s diagnosis or instructions, make sure you repeat them or ask questions:  “So are you telling me that Chunder needs x-rays if he’s not better in one week?  Are you saying that I should give him this medication until he feels better, or until it’s gone?  What exactly does ‘exercise restriction’ mean for my dog?”  And we don’t mind writing down our instructions, so don’t be afraid to ask us to do so.

It’s helpful to tell your doctor your expectations.  If your dog has been limping for the past two years and you want us to stop the limping, we need to know that.  You won’t be happy with us if we palliate the limp, which is probably the best we can do, when what you expect is a cure.   We’ll need to make sure your expectations are realistic, then decide on a common goal.  That’s especially important with serious problems, where simply improving your pet’s quality of life, rather than a cure, might be our goal.

Finally, don’t be afraid to tell us your fears.  Pet owners often are secretly afraid that we will find cancer, while we might be thinking that that diagnosis isn’t very likely.  Usually we can alleviate your anxiety with diagnostics, a good plan, and some calming words. 

Being a doctor is very much like being a detective.  Without good clues, obtained by our examination and your careful observations, we can’t solve the puzzle.  As the great Sherlock Holmes said: “Data! Data! Data! I can’t make bricks without clay."