It always makes me laugh when I catch myself internally chastising itchy animals which are hurting themselves by constantly scratching .“Why doesn’t it just stop scratching?!” I ask myself. Then I think of my recent situation, where, as a keen but incompetent vet student, I was excited to get to scrub into surgery – which means having sterile hands. Hands scrubbed and gloved, I developed a rather inconvenient nose-itch. When facial contortions offered no relief, I sheepishly asked an ungloved vet nurse to scratch my nose for me. A bonding experience, some would say…
So just imagine the torment of a poor dog with itchy skin, trying to alleviate the irritation. The trouble is, scratching an itch stimulates the ‘itch-scratch cycle’. Essentially, when you are itchy, you scratch, and you stimulate a group of nerves (called “ultra-slow histamine-selective C fibres”) in the skin; these get all fired up and make the itch even worse. Excessive scratching will damage the skin’s integrity, leading to “self-excoriation” in animals; as horrible as it sounds, yes, this results in self-wounding. Scratching with dirty claws, mouths, or using walls and fences to scratch makes these wounds liable to infection. That’s one unhappy puppy or kitty!
What are the common causes of itching in dogs and cats
Did you know that the cat flea, Ctenocephalides felis, is the most common ectoparasite of both cats and dogs in the UK? These nasty blood-suckers feed upon your unsuspecting animal’s blood, and hop off when they are done feeding to hide away in your carpets and upholstery. Some cats may mount a hypersensitivity reaction to this, known as Flea Bite Hypersensitivity. The most common sign of this is miliary dermatitis (an allergic reaction characterised by lumps and scabs forming on the skin, usually around the head and neck). Cats are fastidious groomers, and may remove fleas with their rasp-like tongues, so even if you don’t see the nasty critters on Snowball, she may still have been bitten. Of course, dogs get bitten too, but are more likely to show more generalised itching and scratching.
Any animal can mount an immune response to ‘antigens’ (little proteins) found in the environment – that’s what an allergy is. In atopic dermatitis (AD or Atopy), the dog has a genetic abnormality making them highly predisposed to developing multiple hypersensitivity reactions to environmental antigens – that is to say, it elicits a huge and inappropriate immune response to many different substances in its environment. Cat can also become atopic, but it is rarer.
There are some common features seen in AD-sufferers: they are usually between 1 and 5 years old, live indoors, and get alopecia (hair-loss) and pruritus (itching) on the underside of their ear and their front paws/legs (dogs). Their groin, armpits (axillary region), and face may also be itchy and affected. Other presentations include skin thickening and darkening (hyperpigmentation) of some of the itchy skin and reddening. If you have a West Highland White Terrier, German Shepherd, Labrador, Golden Retriever or Staffordshire Bull Terrier, they are particularly likely to develop the condition.
Cutaneous Adverse Food Reaction
Again, this is a hypersensitivity reaction resulting in an inappropriate immune response causing itching, however, this time it is stimulated by food, not by the environment. Unlike Atopy, this may affect animals of any age. Dogs will present as itchy with reddened skin, whereas cats commonly get miliary dermatitis. They may present with ulcers as a result of skin-damage, caused by itching. Very occasionally there may be vomiting, diarrhoea or constipation associated with food allergies, but it’s pretty uncommon.
How do I know when my pet is itchy?
I know what you’re thinking – “When it’s scratching!” There are other signs too, however – for example, head-shaking. Whilst this is often thought to be caused by ear infections, it can also be a result of itching – some ear “infections” are actually allergic conditions! Reddening of the skin (erythema), is caused when the blood vessels dilate at the skin, stimulated by histamine. Foot-licking and face-rubbing may be dismissed as normal grooming behaviour – but saliva-staining on paws and gnawing may be tell-tale signs of an irritated animal. Over-grooming in cats may be thought of as a cat’s way to get the best barnet in town, but actually, it is commonly a result of agitation and itching.
A lot can be done for itchy animals, from flea control to highly effective and potent medications (such as steroids and cyclosporine), so don’t be afraid to consult your vet if you are concerned about your pet!