Pet and animal allergy

Where the allergen comes from

The common assumption is that pet allergy is a matter of touch — that the allergen is on the fur, gets onto the hands and reaches the face from there. That model produces a lot of hand-washing and very little relief, because it is the wrong one.

The allergens are proteins in an animal's saliva, urine and dander, dander being the microscopic flakes of shed skin. For cats, the principal allergen is produced by the sebaceous and salivary glands and spread over the coat when the cat grooms itself, so saliva is central rather than incidental. For dogs it is found in hair, dander and saliva. For rodents — guinea pigs, hamsters, mice, rats — the main source is urine, which is why their bedding matters so much. It is the dander rather than the hair itself that is mainly responsible for symptoms, which is the first reason a short coat offers no protection.

The route of exposure is inhalation. Dander becomes airborne as the animal moves, sheds and grooms, and settles onto furniture, carpets and clothing to be disturbed again later. Proximity to an animal, not contact with it, is what produces symptoms.

Why it turns up where there is no animal

Animal allergen travels, carried on clothes and shoes, and it is found in schools, workplaces, cinemas and on public transport where no animal has ever been. Someone reacting in a pet-free house is not imagining it.

Cat allergen is particularly persistent and notoriously difficult to clear. Horse allergen travels on clothing in the same way, which can affect people who have no contact with horses themselves. Occupational exposure is a recognised route too — vets, farmers, kennel and stable staff, and laboratory workers handling rodents.

There is no hypoallergenic breed

This is the question people most want answered, and the answer is unambiguous: there is no such thing as a truly non-allergenic dog or cat.

The breeds marketed that way are usually ones that shed less hair, which is not the same thing, since the allergen is in dander, saliva and urine rather than in the hair. A low-shedding dog still produces allergen; it simply leaves less visible hair about. Individual animals vary in how much allergen they produce, but that variation does not track breed in any way that can be relied on when choosing one.

Which animals

Cats and dogs account for most of it, cats more than dogs, and cat allergy tends to be the more troublesome of the two. Beyond those: rabbits, rodents of all kinds, birds, horses, and even reptiles such as iguanas. Pet bedding is worth naming separately, since hay and straw carry mould and mite allergen of their own.

What it causes

Usually allergic rhinitis — sneezing, a blocked or running nose — along with itchy, red, watering eyes. It can produce hives or worsen eczema on contact, and it is a significant trigger for asthma.

Because household exposure is continuous, symptoms are perennial rather than seasonal, which can make them hard to attribute. People often adapt to a background level of symptoms they have had for years and only notice the difference when they go away.

If the animal is staying

Most people are not going to rehome a pet over a runny nose, and advice that assumes otherwise gets ignored. What follows is what makes a measurable difference.

Keep the animal out of the bedroom, always. This is the single highest-value measure, and it is worth doing even when nothing else is. A third of each day is spent in one room with the face pressed into soft furnishings for eight hours of it, and that is where exposure concentrates. Keeping the animal off beds, sofas and cushions follows the same logic.

Air filtration is more use here than for most allergens. Animal allergen is carried on small particles that stay suspended for long periods, unlike house dust mite allergen, which settles quickly. That makes an air purifier a more reasonable proposition for pet allergy than for dust mite — the benefit is still modest, but it is aimed at something that is actually in the air.

Vacuum with a good filter, and have someone else do it where possible, or at least have the cylinder emptied by someone without the allergy. Damp-dusting lifts less into the air than dry dusting, and hard floors can be washed rather than vacuumed.

Wash pet bedding hot, and keep it out of the bedroom along with the animal.

Washing hands after contact is sensible and worth doing — it just is not the main event, and it will not compensate for a cat that sleeps on the pillow.

Where a visit to a house with animals is unavoidable, taking an antihistamine beforehand is a reasonable precaution, provided any asthma is well controlled first.

If the animal goes

Rehoming is sometimes the right decision, particularly where a child has poorly controlled asthma driven by the animal. Anyone making it should know that improvement is not immediate: cat allergen in particular lingers in carpets, soft furnishings and mattresses long after the cat has left, and it takes sustained cleaning and often replacement of the worst-affected soft furnishings before levels drop substantially.

Expecting relief within a week and not getting it has led people to conclude, wrongly, that the animal was never the problem.

Treatment

A pharmacist can advise without an appointment. Non-sedating antihistamines — cetirizine, loratadine, fexofenadine, acrivastine — help with sneezing, itching and a running nose. A steroid nasal spray is more effective for a blocked or persistently runny nose and, since exposure here is year-round, is used continuously rather than seasonally; it needs days to weeks of daily use to work properly. Antihistamine eye drops deal with the eyes directly. The fuller picture is under managing allergies.

Where asthma is involved it needs managing as asthma, with its own review and action plan, rather than as an extension of the allergy.

Immunotherapy

Immunotherapy is available for animal allergy but the threshold is higher than for pollen or house dust mite. It is considered for moderate to severe allergy with a clear effect on quality of life, and it is reached by GP assessment and referral to an allergy specialist.

The clearest case for it is occupational — someone whose work requires contact with the animal they react to, where avoidance would mean changing career.

Getting it confirmed

Perennial indoor symptoms can come from animals, house dust mite or mould, and the sensible measures differ depending on which. Testing read alongside the history is how they are told apart, and worth having before any decision as consequential as rehoming an animal.

A GP is worth seeing where symptoms are not controlled by over-the-counter treatment, where sleep or school is affected, where asthma is involved, or where a decision about a pet is being weighed and the cause is not certain.