Category Archives: Dogs

Mast Cell Tumours

Mast Cell Tumours are aggressive skin cancers and common in dogs. They can look like anything: a patch of dry skin, a raised red itchy area, a wart or a lump.

Boxers and Staffordshire Bull Terriers have a higher than average risk of Mast Cell Tumours.  Other breeds affected include the Bull Terrier, English Bulldog and Sharpei but we see Mast Cell Tumours in all breeds.

Mast Cell Tumours release chemicals randomly, causing local redness, itch and swelling that comes and goes.

To diagnose a Mast Cell Tumour we take a sample of cells, stain them and examine them under the microscope.  Most Mast Cell Tumours contain characteristic granules that are easily recognised.  If we have any doubts we recommend removal anyway.

The lesion is removed with a wide excision because Mast Cell Tumours send out long microscopic fingers into the surrounding tissue.  It is sent to the pathologist who confirms the diagnosis, makes sure we have removed it all and grades it.

The grade of the tumour reflects how malignant the tumour is.  A low grade tumour is unlikely to have spread and, as long as the entire tumour has been removed, is unlikely to recur.

About 25% of all Mast Cell Tumours are higher grade.  They invade locally and can spread.  Without supplementary chemotherapy, the mean survival time is 18 weeks.

Chemotherapy is effective and median survival times are good.

Itchy Dogs

Many itchy dogs have the doggy equivalent of hayfever, which is called atopy.  A lot of dogs are allergic to flea saliva but only a few are allergic to food.

Common causes, or allergens, include pollen, grasses and dust mites.

Atopic dogs also have a poor skin barrier that allows the allergens to penetrate the skin and provoke the allergic reaction.

How does atopy affect my dog?

Dogs with atopy constantly scratch, bite, rub or chew themselves.  Itchy dogs don’t always scratch. They may rub their faces, flap their ears, or lick and chew their feet.

Some dogs scratch continuously but don’t damage their skin, whilst others quickly rub themselves raw. Recurrent ear infections are common.

Some dogs show signs of atopy as young as 3 months old, but usually it first occurs between 1 and 3 years of age. Initially most dogs will only be itchy during certain seasons, usually spring and early summer. As your dog ages, these itchy periods become longer.

As atopic dogs age, they become allergic to more things. Each dog has an allergenic load he can tolerate before he starts to itch. Exposure to one extra pollen or flea bite pushes him over the threshold into scratching or rubbing.

Diagnosis depends on the information you supply and examination of the skin. Tests such as skin scrapings and cytology rule out mites and secondary infections.

We may also rule out flea and food allergy by eliminating fleas and starting a dietary trial.

Skin testing by a specialist dermatologist will identify the allergens.

How to we treat atopy?

It is rare to cure atopy. We control it with a combination of strategies:

Improving the skin barrier:

  • Use shampoos without sulphates
  • Add essential fatty acids like Nutricoat, Megaderm, and fish oil to the diet
  • Apply sphingosines found in Nutriderm shampoo and conditioner,
  • Minimise bathing as much as possible

Avoiding allergens:

  • Vacuum carpeted areas frequently and minimise bedding to reduce dust mites
  • Keep your pet inside on windy days or when mowing

Treatments:

  • Cortisone offers immediate relief but can have serious side-effects if used long term
  • Atopica has fewer side-effects than cortisone and is often very effective but can be expensive in large dogs in the initial stages
  • Hyposensitization with repeated small injections of low doses of a combination of allergens chosen by a dermatologist on the basis of skin tests. These suppress the allergic reaction successfully in approximately 70% of atopic pets. Relief is not immediate and they usually require injections at least monthly for the rest of their lives. However in responsive pets hyposensitisation minimises the use of other medication.
  • Antihistamines such as Claratyne, Fexotabs, Claramax or Zyrtec are helpful in some cases but are rarely as effective as in humans.
  • Shampoos containing aloe vera and oatmeal may ease itchy skin

Skin allergies can be challenging to control and require a systematic approach to diagnose and treatment.  With commitment and care, most pets can enjoy a comfortable life despite ongoing exposure to environmental allergens.