Parvovirus

I have recently treated a couple of cases of parvovirus and have had a few scares where the owner suspected parvovirus, so I thought it would be a good idea to discuss the virus and how we can prevent and treat the infection.

Parvovirus, as its name implies, is a virus that attacks rapidly dividing cells in dogs.  Two such areas where cells like this occur in the body are the gastrointestinal tract and bone marrow.  The virus attacking these areas leads to severe diarrhea, vomiting, and a decrease in white blood cells (which usually help to fight off infection).  Without treatment a majority of dogs will die from dehydration and infection.  Even with treatment, some animals may not survive.  It hits puppies particularly hard as their immune system is not fully developed and their ability to fight infection is low.  Un-vaccinated adults can also become infected, but may respond to treatment better since their immune system is usually fully developed.

The virus is picked up when a dog ingest infected soil or other contaminated materials.  It is a very hearty virus and can live in the environment (even harsh conditions) for over a year, so may be prevalent in areas of heavy dog traffic.  After the virus is ingested it replicates in the lymph nodes and then escapes into the bloodstream eventually ending up in the intestinal tract and bone marrow.  Infected dogs will typically have acute cases of vomiting, diarrhea, inappetence, and weakness.  In many cases, blood will be seen in the diarrhea or even the vomit.  Most vets have a good bed-side test for parvo that uses a rectal swab and gives a result in less than 10 minutes.

Because it is a virus, there is not much we can do besides provide supportive care to the pet while the virus runs its course.  Supportive care usually involves hospitalization with fluids, antibiotics, vitamins, nutritional support, and pain management.  If finances allow and it is available, some veterinarians will also treat with plasma that is rich in proteins and electrolytes.  In addition, some vets are using an anti-viral medication called Tamiflu (used against human influenza cases) to help treat parvo cases.  The medication does nothing against the parvovirus, but likely helps prevent the secondary infections that are seen with the cases.  Unfortunately, even with the most aggressive supportive care some dogs may not survive the infection.

The good news is there is a good vaccine to help protect against the virus.  Vaccinations typically start around 6 weeks of age and are given every 3-4 weeks until 16 weeks.  Then, the vaccine is boosted at a year of age.  The parvo vaccine is typically part of the "distemper vaccine" series which includes multiple viruses.  Prior to 6 weeks puppies have some protection if they were able to ingest enough colostrum (mother's milk for the first 24 hours).

So the moral of the story is to make sure that your pet starts vaccinations at 6 weeks of age to prevent this aggressive disease.

Glaucoma

What is Glaucoma?

Put simply, glaucoma is an increase in the pressure inside the eye.  The big question is what is causing the increased pressure.  Before talking about this, let’s talk a little about the inside of the eye.  The eye can be divided into structures in front of the lens and behind the lens.  The globe of the eye behind the lens has a chamber that is filled in with a thicker material called vitreous humor.  In front of the lens the eye contains a thinner material called aqueous humor.  Eye pressures are the pressure inside the aqueous humor.  The aqueous is produced by the ciliary epithelium next to the len.  It then flows forward from the posterior chamber through the iris opening into the anterior chamber and then finally drains out through the trabecular meshwork into the aqueous plexus (and back into the blood stream).  The production of aqueous and its drainage is typically well regulated, but when the production exceeds drainage, pressures rise and glaucoma results.

 What are the clinical signs of glaucoma and how is it diagnosed?

When pets have glaucoma you can notice a number of different signs including redness of the eye, abnormal blood vessels on the eye, different sized pupils, squinting, pawing at the eye, and vision problems.  The diagnosis of glaucoma is fairly straightforward and involves measuring the pressures of the eye and documenting an increased eye pressure.  Most veterinarians have a tool called a Tonopen that accurately and quickly measures eye pressures.  The eye is first numbed; then the Tonopen is pressed against the eye multiple times and records the pressure.  Normal pressures for dogs and cats are between 10-25 mm Hg.  Individual pressures above this confirm glaucoma or a major difference (>8 mm Hg) between pressures in either eye may indicate a problem. 

What causes glaucoma?

The causes for glaucoma can be divided into two major categories: primary versus secondary.

1. Primary glaucoma typically means there is an inherent change (typically breed related) in the drainage angle of the eye that causes reduced drainage of aqueous.  A majority of these are caused by abnormal formation of the drainage angle of the eye that results in a narrower angle and poor drainage (closed-angle).  A smaller subset appears to have a normal drainage angle, but the drainage is still impaired (open-angle).  Breeds where primary glaucoma is common include Cocker Spaniels, Basset Hounds, Schnauzers, Beagles, Poodles, as well as many others.
2. Secondary glaucoma occurs when other eye problems occur that alter the drainage of aqueous.  This may occur if the drainage angle of the eye becomes blocked (due to inflammation, cancer, cyst) or the iris opening becomes blocked (lens luxation or chronic inflammation of the anterior eye chamber).  Long term treatment for this glaucoma is more about treating the primary cause while managing the secondary glaucoma.

How do we treat glaucoma?

The first question to ask when treating glaucoma is whether the eye is still visual, as this will determine what options are available for treatment.  Also, with secondary glaucoma, it is important to treat the underlying cause as this may ultimately fix the problem.

1. Visual Eyes: The first goal for visual eyes is to decrease the pressures as quickly as possible.  The longer the pressures stay elevated the better chance at long term damage to the retina and subsequently vision. 

1. Topical medications: Many topical medications are available that help decrease the pressure of the eyes.  With severe cases of glaucoma multiple medications are started that work in different ways.  In most cases of sudden, severe primary glaucoma a medication to open the drainage angle (latanoprost) along with medications to decrease aqueous production (dorzolamide) are used together.  An intravenous medication called mannitol may also be used that helps draw out some of the vitreous of the eye making more room for the aqueous.  Some eyes with glaucoma respond well to these medications and can be managed with just topical medications for a time.  However, a long term solution usually involves surgery.
2. Surgical options: These options are only available through a veterinary ophthalmologist and financial costs can be very high.  With primary glaucoma the recommendation will usually be a combination of two procedures.  The first is cyclophotocoagulation, which is a procedure that destroys part of the ciliary body (tissue responsible for aqueous production) with a laser.  This helps lower aqueous production.  In addition, some ophthalmologists will also recommend placing a shunt that drains the aqueous humor out into the conjunctiva.  Even with these procedures, topical medications may still be needed and complications can occur.

1. Non-visual Eyes: Once eye pressures have been high enough for long enough the retina will degenerate and the eye will become non-visual.  When this is the case, our goal is to make the pet comfortable (as glaucoma is painful).  If topical medications aren’t working, then a few procedures should be considered.

1. Enucleation: Removing the eye eliminates the problem of the high pressures and pain.  This procedure can be performed by most veterinarians; however, if a prosthesis is desired then an ophthalmologist may be needed.  Even without prosthesis, most owners are happy with the cosmetic appearance of an enucleation.

2. Intravitreal gentamicin injection: This procedure is only available for dogs and there cannot be inflammation present in the eye when performed.  Gentamicin is an antibiotic, but for this procedure is being used because it kills the ciliary body and decreases aqueous production.  It works in around 75% of dogs, but cosmetic changes (cataract, small eye, etc) may be undesirable.  It is typically used as an alternative to enucleation when cost is a factor.

What to do about the other eye?

In many cases primary glaucoma develops in one eye before the other; however, the other eye has the same changes that led to glaucoma in the bad eye.  Starting the other, non-glaucomatous eye on a topical medication can lengthen the time before that eye develops glaucoma.  The typical medications used are either dorzolamide (Trusopt) or timolol (Timoptic).

Ultrasound

Sorry about the lack of blogging recently.  With the summer, things have been a little hectic.  I wanted to take some time now to discuss a newer form of testing we have added to our clinics here in Champaign/Urbana.  We have recently started to offer ultrasound services at our clinic in Savoy.  Currently, these are limited to abdominal (stomach, kidney, liver, spleen, etc) imaging, but we hope to offer echocardiogram (heart) imaging in the future.

The question you might be asking is what is ultrasound and when might we need to use it for your pet.  Unlike x-ray, which uses radiation to take images, ultrasound uses sound waves that are directed towards organs and the machine listens for the sound reflections from these organs to make images.  So instead of just being able to evaluate the outline of the liver or intestines (such is done with x-rays), we are able to better evaluate the architecture of organs.

Above are examples of ultrasound images from the intestines of cat.  As you can see, we can observe the different layers of the intestines and effectively evaluate for any thickening of the bowel or possible obstruction.

You might ask what would be a good use for this form of technology?  There are many patients where ultrasound can be helpful.  I will just talk about a couple examples.

Some owners have cats that may vomit periodically or may be losing weight.  We start with blood work and don't find many changes.  The next step may be an abdominal ultrasound.  During the ultrasound we scan all the abdominal organs, but in this case would likely focus on the intestines and pancreas.  With the ultrasound we can evaluate the intestinal wall thickness and see whether it appears thickened.  If the intestine is thickened, we can determine which layer of the intestine is thick and then can make a list of diseases (inflammatory bowel disease, lymphoma, etc) that could be causing the problem.  We can also evaluate the pancreas to see whether any signs of pancreatitis are evident.

Another case that ultrasound may be helpful would be to evaluate elevations in a dogs liver values.  In older dogs elevations of liver values can be benign or could indicate the start of a more serious condition.  With ultrasound we can evaluate the structure of the liver and possibly get an aspirate or biopsy sample to evaluate for a more serious condition.

Ultrasound on a dog

The nice thing about ultrasound is it that it is a non-invasive procedure.  We only have to shave the underside of the belly (and possibly sedate your pet) to get good images and a possible diagnosis.  Like any test, it may not give us all the answers, but many times can give us a lot more information that can benefit your pet greatly.

Ultrasound image of a kidney

Please let me know if you have any questions.

Oh my gosh, is that a Tick?

Nothing creeps people out more than finding a tick on their pet (or themselves for that matter).  Because of pets hair it can be difficult to find ticks on your pets until they have been feeding for a few days and become engorged.  When this is the case we can get concerned because ticks do transmit several diseases that are transferred to animals after the tick feeds.  First, lets talk a little about the tick life cycle.  Ticks have 4 life stages: egg, larva, nymph, and adult.  Depending on the species this cycle can take a year to 2 years to complete.  The larva, nymph, and adults all can feed on mammals.

In Illinois there are numerous tick species, but the most common that may be encountered are the American dog tick, lone star tick, blacklegged (deer) tick, brown dog tick and winter tick.  Most species are active in the spring and early summer and then are more dormant throughout the rest of the year (however, ticks can be active any time of year when temperatures are above 45 degrees).  Ticks hang around on the tips of grasses and scrubs (not trees) and when the plant is brushed by a pet or person they crawl onto the host.  Using their mouth pieces they attach to the skin and feed on the blood of the host.  When they bite, ticks typically secrete saliva that has anesthetic properties, so the bite is not felt.  Ticks can feed for several days and become quite engorged prior to falling off.

Why is it important to try and prevent tick bites?  When ticks feed on blood, they can also transmit diseases to the host they are feeding on.  Common diseases that are passed include Rocky Mountain Spotted Fever, Lyme disease, Erlichia, Anaplasmosis, as well as other blood-borne pathogens.  Many of these organisms attack red blood cells, white blood cells, blood vessel lining cells and other cells in the body and can have serious, and possibly life threatening consequences.  So, it is much more advantageous to prevent attachment of ticks then to treat the diseases that may be passed along by a tick bite.  

How do you go about preventing tick exposure.  There are numerous products available that help repel ticks.  Many of the products are topical spot-on liquids that go on the back of the shoulder blades and last for around a month.  These products also typically protect against fleas.  Frontline and Advantix have been around for awhile and work fairly well.  Be cautious with using Advantix (dog only product) in a household with cats because it contains a permethrin which can cause problems (seizures, tremors) in cats.  Merial (the maker of Frontline) recently came out with another product called Certifect, which is the active ingredient in Frontline plus an added ingredient (amitraz) which helps repel ticks more strongly.  

There is also a very good product called Preventic, which is a collar containing amitraz that is put around the neck.  It starts working within 24 hours of application and lasts for 3 months.  This collar works very well and we don't see many side effects associated with it.  Occasionally, owners of pets with a Preventic collar may have a skin reaction when petting their animal.  Also, if ingested the collar can cause major issues, so if you have a pet who is good at getting collars off, this may not be the product for you.

What if you find a tick on your pet?  If the tick is not attached, simply remove the tick and dispose of it outside or in the garbage.  We will put them in alcohol to kill them prior to throwing them out.  If they are attached, then the tick should be removed.  Grasp the head of the tick as close to the skin as possible and pull straight out.  If you are not comfortable doing this, then contact your veterinarian and they can do it for you.  If the tick is engorged and you are in an area where ticks carry diseases (see above), then watch your pet closely for any signs of sickness (inappetence, lameness, lethargy).  Some veterinarians will start prophylactic antibiotics in this situation to treat tick-borne diseases.  Others may wait and suggest running tick-borne antibody titers in 8-12 weeks after exposure.

Ticks can cause huge problems, so it is best to prevent them in the first place.  Let me know if you have any questions.

So Many Choices...

With the start of Spring (and finally spring weather) it is always a good time to review heartworm and flea protection for your pet.

Heartworm disease is a parasitic infection that is passed by mosquiotoes when they feed on your pet.  Any pet is susceptable even if they don't spend a lot of time outdoors.  If you can imagine those warm summer nights sitting out on the porch (even if just for 5 minutes) and coming back in with what seems like hundreds of mosquito bites.  Well, those mosquitoes don't just feed on you and will look for any warm body to feed on; like your pet.  That being said, it is important that your pet (in particular dogs, but cats as well) be on a montly heartworm prevention.

Same goes for fleas.  You can see the previous post to get a more detailed discussion on fleas.  Basically, the moral of the flea story is it is much easier to prevent them than to treat your house after they have gotten out of control.  Fleas love to feed and love to multiply and if your pet is not protected they are a prime target for fleas.  Even if your pet only goes out for a short time (let's say to use the bathroom), that is long enough for a flea to hop on them and then come into the house and lay its eggs.  Because of this we recommend all pets be on a flea prevention.

Now that you know your pet should be on a heartworm and flea preventative, what preventative should you use?  Recently, it seems like there has been an explosion of different products available for prevention of heartworms and fleas.  Our clinic focuses on a couple of products that we believe work well. 

The first is a product called Trifexis.  The nice thing about this product is it prevents most of your major parasites all in one oral monthly tablet (Heartworms, Fleas, and Intestinal Parasites).  It is well handled by dogs with vomiting being the most common side effect.  We feel that it works very well for fleas; killing adult fleas in as quickly as 30 minutes.  The heartworm prevention in the medication is the same active ingredient as Interceptor, which has proven effective for a very long time.  The one downside with this medication is that it does not prevent against ticks; however, we have been adding in a Preventic collar in dogs at risk for tick exposure.

The other product or combination of products that we use is Heartgard and Frontline.  Heartgard prevents heartworm disease along with intestinal parasites.  It has been around for a long time and works very well.  It comes in a flavored tablet, so administration is easy.  Frontline is a topical flea and tick preventative (goes on the skin over the back).  It also has been around for a long time and works well, but you need to make sure that it is applied correctly.  It uses the natural oils of the skin to spread, so you have to make sure you do not bathe your pet or allow them to swim two days before or after application.  After that time it is water-resistant.  You also have to make sure that when applying the medication it get down to the skin and not just on the hair.  Both products are administered on a monthly basis.

There are numerous other products available, which likely are effective as well.  It is important that your pet be on one of these products as heartworms can be devastating to an animal and fleas not only are a nuisance, but can spread disease as well. 

Why a 1 year vaccine?

There are a few vaccines that we deem as "core" vaccines that are highly recommended in cats.  One in particular is a vaccine against the rabies virus.  Fortunately, in most area of the United States (Illinois included), rabies is not a huge problem and only few cases of rabid animals and very rare cases of human exposures are reported.  One of the main reasons for this is the implementation of rabies vaccines in our pet population, who can be carriers and propagators of the disease.  In areas were mandatory rabies vaccination of pets and wild dogs is not required (such as India) rabies is a huge problem with over 20,000 people killed each year.



You may say that my cat is indoor only, so I don't think they need to be vaccinated as they won't be exposed to any other potential carriers of the disease.  This may be true, but in our area the most common carrier of the virus are bats, which on occasion to get in the house and may cause exposure to your pet.  Because of this, the public health concern, and the fact that County laws requires it, we highly recommend that your cat be vaccinated against rabies.

Okay, now that we have decided that we should vaccinate your cat for rabies, what is the best vaccine to use?  There are a few vaccines available that are effective in protecting your cat from rabies.  The one that we recommend is the Merial PureVax vaccine.  This uses a recombinant canarypox-vectored vaccine technology.  Basically what that means is they take little snipets of the rabies virus' DNA and implant them into the DNA of a canarypox virus.  Once this is injected under the skin, your cat's body recognizes the canarypox virus as a foreign virus, so mounts an immune system response to fight off the virus.  In doing so, the body also mounts a response to the snipets of the rabies DNA, which gives your cat protection against rabies.  We rarely see side effects to the virus and are very happy with the results.  The one downside to this vaccine is that it is only labeled for protection for 1 year, so has to be boosted annually (as County laws are strict about following the labeled protection).



Why do we use the 1 year vaccine over available 3 year vaccines?  The main reason that we do this is safety.  In the late 90's and early 2000's, the veterinarian community noticed an uptick in aggressive skin tumors call fibrosarcomas.  When looking at cats with these tumors they noticed that many of them were occurring over the shoulder blades where most vaccines were previously given (lots of loose skin here that made for easy administration).  Pathologists looking at these tumors under the microscope also noticed that they saw some foreign material that could be associated with previous vaccines.  Many vaccines use a slightly different technology for vaccines where a portion of killed virus is added with an adjuvant and injected under the skin.  The adjuvant is a caustic substance (usually not disclosed by the vaccine maker) that is meant to stimulate the immune system to react and subsequently react to the killed virus (which is typically too weak to stimulate the immune system itself).  It was hypothesized that the adjuvant was doing such a good job that it caused chronic inflammation in these areas that eventually would end up transforming into cancerous cells.



Planning for removal of large tumor on the back.

 These tumors are very aggressive and tend to metastasize (spread to other organs like the lungs) readily and without extensive surgery (sometimes removing parts of the scapular bones or chest wall) tend to grow back quickly (as soon as 2-3 months).  Even with extensive surgery these tumors can recur or spread and many cats don't make it longer than 1.5-2 years after they are diagnosed.

A cat after removal of a vaccine associated fibrosarcoma

In response to these tumors, a company switched to the canarypox vaccines and we have seen a declined in these tumors.  Because of a problem with a control group during testing of the vaccine, the vaccine was unfortunately denied a 3 year label, so we are stuck with the 1 year vaccine for the time being.  However, the safety of the vaccine (in my opinion) outweighs the inconvenience that may come with a 1 year vaccine.

Please let me know if you have any questions.

Food Allergies

Now that we have discussed environmental allergies, we should discuss other possible causes of itchiness in pets, in particular food allergies.

Does my pet have a food allergy?

Diagnosing a food allergy can be difficult with pets.  The only reliable way to judge whether a pet is having a reaction to food is performing a food elimination trial which can be cumbersome and lengthy, but if an owner is committed can be very rewarding.  If your pet has itchiness throughout the year and it tends to be around the feet and ears, then a food allergy should be strongly considered.  The allergies tend to start prior to a year of age, but can start anytime throughout a pets life (even if they have been on the same diet for a long time). 

Well, does my pet have a food allergy?

If you think your pet is allergic because they are itching a lot and go to the veterinarian’s office, they will likely ask you a series of questions to get a handle of what is going on.  There are some common criteria that food allergies fit into:

1.      Young age of onset: Most pets with food allergies start showing symptoms prior to one year of age.  In a dog who develops itchiness after 6 years of age with no history of previous problems, a food allergy should also be suspected.

2.      Time of year: A food allergic pet should be itchy during all times of year, since they are being constantly exposed to the allergen.  Some pets may show worsening symptoms during certain times of year because they have a concurrent airborne allergy.

3.      Response to steroids: Food allergies typically do not respond well to steroids.  In early stages of food allergies, the itchiness may improve.  If your pet once responded well to steroids and now doesn’t, then a food allergy should be suspected.

4.      Areas of itchiness: The typical adage for food allergies is, “ears and rears.”  That being said the distribution can be elsewhere including

5.      Concurrent gastrointestinal signs: Around 20% of food allergic dogs will also have consistent or intermittent gastrointestinal signs (vomiting or diarrhea).

We suspect my pet might have a food allergy, now what?

The “gold standard” for diagnosing a food allergy is an 8-12 week food elimination trial followed by rechallenging your pet with their previous food.  If your pet improves on the food trial and then symptoms reoccur after reintroducing their previous food, then a food hypersensitivity is diagnosed.  The offending agents in the food that cause problems are the proteins.  Common proteins that cause problems include beef, milk, lamb, wheat, corn, chicken egg, soy, chicken in dogs, and adding tuna and salmon to the list in cats. 

Prior to starting a food trial it is a smart idea to compile a list of foods that your pet has been exposed to in the past.  This includes any commercial dog diets, table scraps, treats, supplements, and drugs (particularly heartworm prevention).  We do not want to use a diet that has a protein source that your pet has already been exposed.  We also want to know whether your pet has unsupervised access outside as some pets forage outside and may be exposed to things that you may not know about.  Once we have a good idea about previous exposures we can make suggestions on foods for a food elimination trial.

What is a food elimination trial?

An elimination trial is a period of 8-12 weeks where a “hypoallergenic” diet is fed exclusively to your pet and their itchiness and skin issues are monitored and graded for improvement.  It is important that during this trial ONLY the chosen diet is being fed.  Your pet should not have any treats (table scraps, biscuits, popcorn, etc) during this time and any flavored medications (in particular heartworm preventatives) should be stopped (if during the summer a topical or unflavored heartworm prevention should be used).  

ONLY the “hypoallergenic” diet should be fed during this time.  If your pet has a food allergy and the diet chosen is the proper one for him/her, then you should only see improvement on the diet trial.  If your pet ever gets worse symptoms (AND you are sure that they did not receive any outside food source), then the food trial should be stopped and a different diet should be chosen.  Improvement are not always immediate, so we suggest giving a minimum of 8 weeks to see whether any improvement is noticed.

If your pet improves on the food and is doing significantly better, then we suggest following up with a “challenge” of their previous food.  Prior to starting the new diet, save some of their old food and freeze it for the challenge.  The “challenge” involves reintroducing the old diet.  If your pet has recurrence of the itchiness and skin issues (usually show up between 15 minutes after eating, but some can take as long as 2 weeks), then the food allergy is diagnosed and one of the protein sources from the old diet is the offending allergen.

What food should I use for the elimination trial?

There are a few routes that can be taken for the type of food used during the trial:

1.      Homemade diet: The home cooked diet is a simplified diet of one protein source (1 part) and one carbohydrate source (2 parts).  Although this is not balanced (minerals and vitamins), it is not meant to be fed long term and will not cause major problems if fed for the 8-12 weeks.  Protein sources currently available for home-cooking include kangaroo, camel, ostrich, emu, bison, elk, venison, rabbit, duck, fish, and whole chicken egg.  Carbohydrate sources can include oatmeal, quinoa, rutabaga, sweet potato, and white potatoes.  Ideally, a protein and carbohydrate that your pet has not been exposed to should be used.  This simplified diet eliminates any other food source and is very effective.  Once we have identified that your pet is food allergic (improvement on this diet), then we can seek out a commercial dog diet with similar ingredients that can be used or consult with a veterinary nutritionist to help balance the homemade diet so your pet will not be vitamin or mineral deficient.

2.      Prescription novel protein diet: These diets use a similar idea as the homemade diet as they use protein and carbohydrate sources that are novel.  Common ingredients include duck, kangaroo, venison, potato, green pea, or rice.  Companies offering these diet include Royal Canin, Science Diet, and Purina and these diets have to be obtained through a veterinarian.  The companies are very throughout about preventing cross contamination of foods during production and guarantee that the proteins listed are the only ones in the diet.  The advantages of these diets are the convenience of not having prepare the diet and knowing that there is no cross contamination.  The disadvantage is the price which typically run $33 for an 8# bag, $64 for an 18# bag, and $84 for a 28# bag. 

3.      Prescription hydrolysed diet: These diets are a little different in that instead of using novel proteins they process the proteins so they are very small and should not cause an allergic reaction.  They have similar advantages and disadvantages as the prescription novel protein diets.  Some pets do also have some gastrointestinal issues (mostly diarrhea) with these diets.

4.      Over-the-counter limited ingredient diets: These diets are similar to the prescription novel protein diets in that they use protein and carbohydrate sources not typically seen in commercial diets.  The disadvantage is that there may be some cross contamination during the production process that can leave small amounts of other common proteins (beef, chicken, etc) in the foods.  These proteins can be at high enough levels to continue to cause adverse skin problems.  The advantage is that they are typically cheaper than the prescription brand foods: $15 for 5# bag, $40 for #15 bag, and $58 for a 28# bag.  If choosing this option, I do like the Natural Balance Limited ingredient line.

Just because you start on one diet it doesn't mean that you have to continue on this diet forever.  You can use a prescription novel protein diet or homemade diet for the diet trial and if you see improvement, we can try to find an over-the-counter alternative that may do a similarly good job.  Using the prescription diet or homemade diet first at least makes cross-contamination from other proteins less likely and we can rule out a food allergy much easier.

I am not seeing improvement on the food trial, now what?

Please be patient with the food trial.  It can sometimes take 12 weeks to see a major improvement in skin issues with dogs on a new diet.  Try to make a conscience effort to grade your pets skin issues every 2 weeks.  You should see gradual improvement in itchiness over time if the food trial is working.  If there is ever a worsening of signs (AND you are certain your pet didn't get any other food and it is not the time of year for seasonal airborne allergies) then your pet may not have a food allergy or the diet being used is not appropriate.  Please contact your veterinarian to discuss things further.

Here is a website that discusses common pitfalls of food trials.