Allergies in your pet

 

The theory of allergies
Allergies are a disorder of the immune system.
There are many things involved in immunity. It can be divided into two main categories:
  • Positive Immunity is gained through exposure to pathogens. This can occur naturally, via exposure to disease, or artificially via vaccines.
  • Negative or non beneficial immunity can be considered autoimmunity or allergies. Autoimmunity is when the body accidently attacks itself, such as when it attacks its own liver or kidneys. Allergies can be considered non beneficial (or negative) type of immunity because the body mounts an abnormally high immune response to something which should not normally be harmful, causing disease due to the immune response.

Type of allergies: (nutrition, plants, pollens & parasites)

1. Nutrition:

In dogs and cats food allergies tend to be to proteins. There needs to be prior exposure to the protein to be able to develop an allergy to it. Allergies to preservatives are seen as a totally different scenario in dogs especially and present in a manner much more closely to those signs seen with drug allergies.

Food allergies cannot reliably be tested for with blood tests. The best method is via a period of feeding a diet which has been determined to be hypoallergenic (something the pet hasn’t been exposed to before) and then rechallenging with individual proteins. When determining the hypoallergenic diet it is important that all regularly fed foods be considered, as many have ingredients, especially proteins in common, so merely changing brands will do little to achieve the end goal. Common hypoallergenic foods in Australia include fish and kangaroo as a protein source. Potato or tapioca are often used as a carbohydrate source. Overseas, lamb is commonly used, but in Australia lamb is widely eaten by most people and meat eating pets so it is not suitable.

Some foods maybe labelled as ‘for sensitive skin’. There are many different types of these, and many are not suitable for an initial diet trial. They often contain a single protein source, which is great if you have determined that protein source is safe for your pet, and may also contain added extras such as omegas. The omega 3 and 6 fatty acids are not overly useful as a sole therapy in skin disease management but do have some anti-inflammatory effects on the skin by inhibiting small sectors of the complex allergy pathway in the body, and can be helpful for some pets.

2. Plants:

Allergies can develop to many things, with allergies to plants being very common. As a general rule allergies to plants can be divided into two general categories. For simplicity when we refer to plants in this article, we are including trees, grasses, weeds and shrubs etc.

Contact allergies
These types of allergies involve actually having to come into contact with the offending plant. They can develop at any age, including in the very old and young. Due to the need to come into contact with the plant, these allergies will commonly give a distinct pattern of areas of the body affected. These are the areas of the body with naturally less hair cover and those which tend to contact the ground. The feet and belly are the most commonly affected, although the muzzle (as a dog sniffs the ground) inside of the ear flap (whilst laying down) are also areas which can be affected.
Contact allergens should be understood to be a different thing to contact irritants. A contact irritant is something which could reasonably expect to cause a rash, burn or similar on anyone (i.e. an acid or in the case of plants, poison ivy). A contact allergen maybe perfectly fine for some people or pets to come into contact with (i.e. a grass) but will cause others great problems.

3. Pollens:

Allergies can develop to many things, with allergies to plants being very common. As a general rule allergies to plants can be divided into two general categories. For simplicity when we refer to plants in this article, we are including trees, grasses, weeds and shrubs etc.

Inhaled allergies (traditionally referred to as “atopy”)
Inhaled allergens are those which can blow in the breeze for kilometres, such as plant pollens. As such, these cannot easily be avoided. Depending on the severity of the allgeries and the region you inhabit (eg tropical, sub tropical, temperate) these types of allergies are commonly seasonal as different plants pollenate at different times of the year. Spring is certainly a bad time for many allergy sufferers as many plants pollenate at this time.
Allergies to inhaled allergens typically develop by 3 years of age in dogs, and are not commonly seen prior to 6 months of age. Therefore a very young or very old dog whom develops a skin problem for the first time, is less likely to suffer from inhaled allergies or ‘atopy’.

4. Parasites:

1. Fleas:

Fleas 

 
Fleas are an important cause of skin disease. Allergy to fleas can develop at any time in life. In some cases the diagnosis is not overly apparent as the pet has groomed the flea away before it can be seen by the pet owner and the signs the pet displays are not always the traditional itch about the backs, hind legs and tail. 
 
2. Demadex:
 
Demodex

 Demodex are a cigar shaped microscopic mite which is a common cause of skin disease in dogs. It can affect cats but is less common in our feline friends. Demodecosis is most common during the ‘juvenile’ and ‘teenage’ period when a pup is rapidly growing. It can vary in severity from small patches of hair loss to severe pustular or ‘pimply’ skin disease resulting in almost total baldness. It is important for demodecosis to be distinguished from allergies as confusing the two (they both can cause secondary skin infections and baldness) can have serious consequences. The medications such as steroids which are commonly used in allergy treatment can cause demodecosis to get worse. Demodecosis in older dogs can be due to an underlying immunosuppression, such as that caused by a hormonal imbalance.
Demodecosis can be diagnosed on cytology (the examination of scrapings and samples of skin and hair under the microscope) or by biopsies (small amounts of tissue sampled and sent to the lab for microscopic analysis). It is important not to guess about the presence of demodex mites as although it can be treated, the treatment can be involved and long term (months) in some cases, so you need to be sure about the need for treatment.

3. Scabies (Sarcoptic Mange):

 

Scabies

This is a contagious and zoonotic mite. This means it can be passed from human to pet and from pet to human readily. It is most commonly caught from contact with foxes, or from contact with areas used by foxes, although in some cases a cause is not found. Scabies is typically intensely itchy and can develop quite quickly. Scabies is most commonly diagnosed by taking scrapings from the skin surface and examining the obtained scale under the microscope. In some cases it can be difficult to find and a trial of therapy maybe instituted, as treatment for scabies only takes a few weeks. Scabies can be reasonably readily treated with a number of products, including oral liquids, topical ‘top spots’ and rinses.

4. Lice

 

Lice

Lice are less common in Australia these days as many of our commonly used insecticidal products readily kill lice. However, they are still found sporadically and can cause skin disease. Most good quality flea products will also kill lice. A common sign of lice can be a white flake, which if inspected closely ‘moves’. This should not be confused with the dandruff caused by many skin infections with bacteria or yeast which can cause the skin surface to flake off as it gets damaged.

5. Flies

Flies

Fly worry can cause more trouble in some pets than others. In dogs a traditional sign is crusting on the ear tips, which can be quite painful. Repellents should be used to prevent further fly bite or the dog should be kept inside in a screened environment. If your dog suffers from apparent fly worry, apart from instigating appropriate therapy it is important to check the lips, genital area and feet for any signs of disease, because a combination of disease in these areas can sometimes be a sign of more serious disease of other causes. In dogs, repellents containing a pyrethrin ingredient applied regularly (licenced for use on dogs) are usually the best. There are very limited options for cats as they do not tolerate most of the drugs which repel flies.
 
6. Ticks:
 
Ticks
 
The ticks we have in Australia can certainly cause various problems with skin, however the most important problem we have with ticks here in domestic animals is life threatening paralysis caused by Ixodes holocyclus. In horses and livestock cattle tick, Rhipicephalus microplus can cause substantial problems with hide damage and sores. Various diseases can be carried by ticks, although the jury is out on if the most commonly known ‘lime disease’ actually exists in Australia, but the evidence is mounting.
 
Symptoms of allergies:
 
The symptoms of allergies can include:

- Scratching or chewing at the skin
- Rubbing of the face into the carpet or furniture
- Warm or red skin on any part of the body, including ears
- Raised pimple like spots on the belly
- Hair loss
- Dry or flaky skin
- Recurring ear or skin infections

Although some symptoms are more suggestive of one type of allergy (such as hair loss and chewing over the rump and base of the tail in the case of flea allergies), the type of allergy cannot be determined by the symptoms alone. Also, some of the symptoms listed above may be due to diseases other than allergies, such as bacterial infection, fungal infection, parasites, pain or autoimmune diseases.

If your dog displays these symptoms, it is important to seek veterinary advice so that tests can be run to diagnose your dog’s condition, and the correct treatment can be provided. 
 
Diagnosis:
 
The diagnosis of allergies can be complex and require several trials or tests. Some of these involve ‘home work’ and some testing in hospital. By far the majority of the allergy diagnostics can be undertaken at home.
 
In clinic diagnostic test:
  • Check for infection: secondary infection is common with allergies, but if not controlled, finding the underlying problem can be near impossible.
  • Check for microscopic parasites such as demodex or scabies mites.
  • Test for specific allergens via an intradermal skin test or a blood test. The skin test involves lots of little needles of allergens to the skin to see which ones swell and go red, while the blood test can measure IgE levels in the blood to various allergens. Where possible the skin test is considered the slightly better of the 2 tests, but is not available in all areas and can be affected by certain drugs.

Home work:
This should generally be undertaken in conjunction with the advice of a veterinarian to ensure it is done in a systematic manner.

  • Food allergy elimination trial- rule out food allergy as a cause of skin & ear problems.

Food allergies cannot reliably be tested for with blood tests. The best method is via a period of feeding a diet which has been determined to be hypoallergenic (something the pet hasn’t been exposed to before) and then rechallenging with individual proteins. When determining the hypoallergenic diet it is important that all regularly fed foods be considered, as many have ingredients, especially proteins in common, so merely changing brands will do little to achieve the end goal. Common hypoallergenic foods in Australia include fish and kangaroo as a protein source. Potato or tapioca are often used as a carbohydrate source. Overseas, lamb is commonly used, but in Australia lamb is widely eaten by most people and meat eating pets so it is not suitable.Some foods maybe labelled as ‘for sensitive skin’. There are many different types of these, and many are not suitable for an initial diet trial. They often contain a single protein source, which is great if you have determined that protein source is safe for your pet, and may also contain added extras such as omegas. The omega 3 and 6 fatty acids are not overly useful as a sole therapy in skin disease management but do have some anti-inflammatory effects on the skin by inhibiting small sectors of the complex allergy pathway in the body, and can be helpful for some pets.

  • Isolation trial. A dog should be bathed and then kept away from grass/plants for about 48 hours, then re-exposed to grasses and plants. If in the time off the grass the skin settled, and it deteriorated when re-exposed a contact allergy is likely. The more severe the problem the longer the period the skin may take to settle when removed from the allergen. The bath is used to remove pollens and other allergens from the coat, so they do not continue to cause problems during the test period. If the skin is severely infected then this can complicate the interpretation of results.
  • Flea trial- excellent flea control is important in all allergic cats and dogs, however some are particularily sensitive and a single flea once every few weeks can continue to cause itch long after it is gone. Implementing a very strict effective flea control regime can help to determine is fleas are an important part of the skin disease. Itchy animals will often groom fleas away during their ‘chewing’ and many pet owners are unaware of the problem.
  • General skin hygiene: regular bathing in soothing or antibacterial and antifungal shampoos and conditioners can be an important part of controlling allergies, in many cases this dramatically reduces or eliminates the need for stronger drugs.


Treatment:

There are many different treatment options depending on what allergy your pet has or if they have a combination of allergies.

1. Nutrtitional allergies require a life long strict non allergenic diet

2. Pollen & Pant  allergies (atopy) may require immunovaccines, medication therapy (cortisone, antihistamines, cyclosporin, medicated shampoos and skin barriers) plus religious parasite control

3. Parasites requires religious flea control in the affected pet and all in ocntact pets as well as strict environmental parasite control.

Immunovaccines
In the case of allergies, the body’s immune response can sometimes be tricked, by developing custom vaccines to the allergens the body is allergic to. By using very small doses of a tailor made vaccine the body can be taught to slowly become used to (desensitised to) the allergen.
The vaccines are usually given as small injections under the skin, typically once every 3 weeks. By using regular small doses via a different route (i.e. injection rather than inhalation) the immune system is tricked into getting used to the allergen. This is an option for dogs with multiple allergies, although is only available for certain types of allergies and should not be considered a complete solution for all problems.