Dog Allergies – Treatment With Steroids

Steroids such as prednisone, methyl prednisolone and trimacinolone bring relief to allergic dogs by decreasing inflammation.  At higher doses, they actually suppress the immune system.  Unfortunately, they also have many unwanted side effects because they effect so many body systems.  Dogs on steroids often have increased thirst, appetite and urinations.  They may also suffer with excessive panting, vomiting, diarrhea, gastrointestinal ulcers, pancreatitis, muscle wasting and liver problems. 

When I was in high school, I remember taking our dog in for an allergy shot.  The shot was actually a long–acting glucocorticoid (steroid) called triamcinolone.  Although this treatment brought him relief, I later learned it also has many dangerous side effects.  Early in my career, I saw a yellow lab who suffered from liver disease.  Her gums, eyes and other mucous membranes were actually yellow in color from bilirubin.  The dog had been on triamcinolone injections for most of her life to control her allergies.  Now at only 8 years of age, her liver failed.  Despite aggressive treatment, she did not survive. 

Because of the side effects, I reserve steroid therapy for dogs with severe cases of allergies and allergies that are  not responding to other treatments.  For these dogs, I prefer using a drug called Termaril P that is a combination of the antihistamine trimeprazine and prednisone.  This drug comes in a pill form.  The oral dosing gives better options if side effects should develop.  With an injection, once it’s in the body, that’s it.  My goal in therapy is to control the dog’s allergies and then get them off as quickly as possible.  That usually means the dog will be on the drug for about two weeks, starting with  a higher dose for about 3 days and then tapering off.  As a brief but important side note, tapering is critical.  Animals should not stop steroid treatment without a taper. 

Because intradermal or serum allergy testing and desensitization therapy are all expensive, some owners want to use steroids as a cheap alternative.  Because of the potential side effects, I strongly discourage this approach.  I think the risks associated with chronic steroid therapy far outweigh the benefit.  In my opinion, the best treatment is to remove whatever is causing the allergy from the dog’s environment.  If that is impossible, then pursue desensitization therapy.  As I said before, steroids should be the last resort because of their side effects.  Used properly, they are an excellent tool in a veterinarian’s arsenal but again, only in skilled hands after careful consideration.         

Dog Allergies – Additonal Tests

When working up a dog with allergies, I perform several tests to rule out other diseases before launching into a food trial, intradermal test or serum allergy test. In my experience, dogs with allergies often suffer with skin infections caused by bacteria and yeast.  Mange is a third common problem that can be misdiagnosed as allergies.  Here’s a list of the tests I use:        

1) Skin Scrape – Mange or infections caused by mites can look a lot like allergies.  The dogs are really uncomfortable and the constant scratching causes skin damage.  To check for mites, I scrape the patient’s skin with a sterile scalpel blade and examine the contents under a microscope. 

2) Skin Cytology – Dogs with allergic dermatitis often suffer with secondary yeast and/or bacterial infections.  In this test, a sample is collected, transfered to a microscope slide and examined for abnormalities.  Samples are collected in a variety of ways including dry skin scrapes with a scalpel blade, pressing the slide directly onto the skin or using cellophane tape.  Cotton swabs work well for ears.

3) Bacterial and Fungal Cultures – The skin is cultured to see what kind of organisms might be growing on it.  Again, this is to test for secondary yeast and/or bacterial infections.

4) Flea Combing – Flea bites cause horrible itching in dogs.  A special fine-toothed flea comb is used to find fleas on the dog.  It is a good way to make sure the flea control is effective.

5) Skin Biopsy – Full-thickness biopsies of the skin are sometimes needed to differentiate allergic dermatitis from other skin conditions. 

6) Blood Tests – Used to detect hormonal abnormalities that may cause skin problems.

As a veterinarian, I have to confess that dermatologic conditions can be vexing for everyone involved.  The animals suffer greatly, vets and owners can too as they struggle to uncover the true cause of the problem.  So, if you find yourself dealing with allergies or skin – hang in there!  The answers can be hard to find but the relief to the animal is rewarding. 

Dog Breeds – None Are Hypoallergenic

There is a myth that some breeds of dogs are hypoallergenic.  I wish this were true, but sadly it is not.  One common view  is that dogs with continuously growing coats like poodles and bichons are less antigenic than other breeds.  Although this has some conceptual appeal, there is no scientific evidence to support it.  

As a veterinarian, I see how serious allergies are for both the animals and people involved.  Consider the following example;  A family brings a reportedly ‘hypoallergenic’ breed of dog into their home.  Initially, the allergic child experiences mild allergy symptoms.  As time goes by, the symptoms become more severe until the family is forced to get rid of the pet.  Of course, the child feels terrible and view this turn of events as being their fault.  The dog is obviously traumatized when they lose their family.  The parents also feel guilty for bringing the dog into their home in the first place. 

So, I have more to write on the topic of allergies but wanted to take this moment to discuss the notion of breeds and hypoallergenic traits.  Clearly, this is a tough condition for everyone involved.
 

Dog Allergies – Intradermal Tests, Serum Allergy Tests And Food Trials

Once a dog has been diagnosed with allergies (allergic dermatitis), the next step is to determine the specific cause and remove it.  Dogs may develop allergies to a number of things, far too many to list here.  The most common causes I see are dust, corn, wheat, wool and grass, but it really depends on where you live. 

There are three different tests used to diagnose this condition. 

1.)  Intradermal tests (skin tests):  This test assesses the allergy antibody IgE in the tissues.  The patient’s side is clipped into a large square and minute amounts of the antigens commonly found where the dog lives are injected into the skin.  The reaction at each site is compared to a control area.  Although the test is very accurate, only a limited number of antigens maybe checked.   

2.) Serum allergy tests:  This measures IgE circulating in the blood.  A blood sample is all that is required.  The sample may be analyzed for many more antigens than the intradermal test.  Besides the antigens common to all dogs, there are regional screens that check for antigens from specific plants and other antigens specific to the area.  Although most of these panels offer food screens, the dermatologists I follow believe the results are not helpful.  They recommend a 12 week food trial with a hypoallergenic diet instead.    

Please note that with both the intradermal test and the serum test, medication such as steroids and antihistamines will interfere with the results by limiting the immune response.  Patients should be off of these medications to promote accurate test results.  Before withdrawing any medication, talk to your veterinarian as sudden withdrawal of steroids may trigger a life-threatening crisis. 

Also, some antigens are seasonal.  If your pet’s allergies are seasonal, perform the test during the time when your pet exhibits clinical signs.     

3.) Hypoallergenic diets:  The proteins in these diets are hydrolyzed into small fragments, unrecognizable by the immune system.  During the 12 week food trial, the dog must not eat anything else beside the prescription food, this includes treats and flavored medicine. 

 
References:

Hillier, A., Allergy Testing: Uses and Interpretation (VET-93), Western Veterinary Conference 2004 Proceedings.

Dog Allergies – History and Clincal Signs

With spring right around the corner, I thought it was time to do a series of blog posts on allergies.  Allergies may develop at any age but typically dogs start showing signs around two or three years of age.  The symptoms are usually seasonal at first and progress slowly over time.  The typical history goes something like this:  Owner notices that the skin on the dog’s abdomen or other thinly haired areas is reddened.  The dog seems more itchy than normal.  The owner seeks veterinary attention when the constant scratching keeps them up at night.  Symptomatic therapy brings the dog relief at first.  Eventually, the dog has symptoms throughout the year and requires a full medical workup to determine the cause of the allergies and optimal treatment strategies. 

Clinical signs vary greatly.  Here are some of the more common ones:

1)  Reddened eyes.
2)  Brown stained fur on paws from constant licking.
3)  Ear disease, especially recurring ear infections.  The inflammation caused by allergies changes the mucosa of the ear, predisposing it to infection.
4)  Excessive itchiness (pruritis) anywhere on the body including the anus.
5)  Diarrhea and less commonly, vomiting from food allergies.
6)  Stronge body odor.
7)  Dull, poor hair coat and reddened skin.
8)  Hot spots (localized areas of moist dermatitis caused by staph.)
9)  Behavior changes, these dogs are miserable.

 

Miniature Schnauzer – Common Blood Problem

This beautiful puppy is a Miniature Schnauzer named Heidi.  Schnauzers are a popular companion dog because of their energetic and affectionate personalities.  It is very important to keep this breed of dog fit like her owner’s do with Heidi.  Obese Schnauzers are prone to developing a blood disorder that may lead to serious problems.  What is the name of this possibly inherited disease?  What are the clinical signs? 

                                         

Diagnosis:  Idiopathic Hyperlipidemia

Unfortunately, Miniature Schnauzers are prone to hyperlipidemia which basically means too much fat in their blood.  In severe cases, the blood is thick and reminds me of a strawberry milkshake.  After it is spun down to separate the cells from the serum, the fat accumulates in a white clump.  It is disgusting! 

Clinical signs of hyperlipidemia include anorexia, lethargy, vomiting, diarrhea, neurologic problems including seizures, cloudy eyes from fat accumulation and abdominal pain if pancreatitis is present. 

Because hyperlipidemia is so common in this breed, I recommend routine annual blood work.  I also encourage owners to avoid high fat foods or treats and provide plenty of exercise for their dogs.  With treatment, these dogs can avoid the health problems hyperlipidemia causes and live a long, healthy life.   

Dog Covered With Ticks

Last summer, a woman found this dog wondering the streets of Phoenix.  Filthy matted hair covered his body and he smelled like garbage.    

When we removed his hair, a new problem emerged.  Ticks!  They covered his body.  It was the worst infestation I have ever seen.  We used a spray to kill the ticks and then removed them with slow steady traction.  As you may know, ticks carry a serious disease commonly referred to as “Tick Fever”.  What is the scientific name for the disease?  What are the clinical signs of this disease?  Scroll past the bowl of ticks to check your answer.

Diagnosis:  Ehrlichiosis

Ehrlichia is the causative agent in tick fever.  The organism is transmitted from animal to animal by ticks.  Once in the body, Ehrlichia invades the white blood cells.  Clinical signs of the disease are non-specific in the early phase: lethargy, anorexia and sometimes, a shifting leg lameness.  As the disease progresses, the gums turn pale pink to white, blood may be observed in the urine or feces, bruises may occur on the body and the animal struggles for breath.  Luckily for this little stray, he tested negative for Ehrlichiosis.

 

After three hours of work, most of the mats and ticks were gone.  Even though it hurt a little when the ticks were removed, he never tried to bite.  He sat on the floor and wagged his tail whenever anyone spoke to him.  At this point in time, he needed a break.  We placed  him in a run before tackling his face.  He ate, drank and curled up on a clean blanket.  Later that day, he went home with the woman who found him.  It was a happy ending to this a sad beginning. 

Raw Diets For Pets – The Freezing Myth

Recently, I’ve had several people ask me about raw pet diets commonly called BARF.  When I first heard about this diet, the letters stood for “bones and raw food”.  Now the marketing has changed to “biologically appropriate raw food”.  In these discussions, I have learned that many people believe freezing makes raw diets safe for their pets.  This is not true.  Given the buzz around raw meat diets, I feel compelled to alert everyone about the scientific findings on the topic.

According to Betsy Berry, Manager of the United States Department of Agriculture’s Meat and Poultry Hot line, “Freezing merely puts the bacteria in suspended animation.”   It does not eliminate bacteria.  Think of the recalls for frozen hamburger patties destined for human consumption.  In fact, freezing is the method of choice for storing bacteria in research settings!  Scientists have been able to culture bacteria after a millennium in the permafrost.   

Heat is one of the most commonly used methods to destroy bacteria in food and on inanimate objects. Remember passing a loop through the flame of a Bunsen burner to sterilize it in biology?  Autoclaves use a combination of heat and pressure to destroy pathogens on surgical instruments.  Milk is pasteurized and meat is cooked to an internal temperature of around 160 degrees Fahrenheit to destroy bacteria.  (The USDA/Food Safety and Inspection Service provides fact sheets on their web site for safe food handling.  Please refer to them for specific details on  handling different types of meat.)    

To make a raw diet safe, everything added must be free of pathogens.  Ideally, that means each piece of meat should be cultured prior to feeding to detect pathogens such as Salmonella, E. coli and Campylobactor.  I do not know of any commercially available BARF diet that guarantees pathogen-free contents.  In commercial raw diets tested in three Canadian cities, the Salmonella prevalence was 21%.  Also, do not confuse the term organic with pathogen-free.  Organic generally means without chemicals while pathogen-free means the product is free of pathogens.  In my experience, BARF made with human grade products has less contamination than the other grades of meat.  But the risk is always there.  That’s why posters at the butcher counter and menus warn about the inherent risks of consuming raw or undercooked meat products.  

Whether you feed raw diets or not, now you know the science. 
      
                                                                                             

Finley, R. et al., The Occurrence Of Microbiological Susceptibility Of Salmonellae Isolated From Commercially Available Raw Food Diets In Three Canadian Cities, Zoonoses Public Health, Oct. 2008;55 (8-10):426-9.

Inman M., Frozen Bacteria Repair Own DNA For Millennia, National Geographic News, 8/27/08.

Weese, J.S, Infectious Disease Risks Of Feeding Raw Diets, ACVIM 2006