The problem: Topical issues
“Every year around late summer, just as I am starting some serious training, my spaniel spends half the day itching. Antihistamines don’t work.”
Regrettably, it is most likely that your dog is suffering from a seasonal pollen allergy (SPA). While humans that are affected by hay fever sneeze, wheeze and get red, runny, itchy eyes, our canine companions suffer with itchy skin.
Seasonal pollen allergy
SPA is caused by an inherited predisposition to develop hypersensitivitymediated skin disease against environmental allergens. Quite why it occurs, we do not know. After all, there is no benefit to the body mounting such an extreme reaction to harmless pollens.
The chemical reactions that result in itching, or pruritus, are complicated and rather bewildering. Suffice to say that SPA is associated with the dysregulation of cytokine production and aberrant T-cells, which results in the release of inflammatory substances, including histamine and interleukins. Unfortunately, the process of histamine release is different in dogs compared with humans, hence the lack of efficacy of common over-the-counter antihistamines. A defective epidermal barrier can also be demonstrated in affected dogs, so that allergens are able to ‘stick’ – consider, as analogies, the loss of the non-stick surface of a frying pan or the potential damage to an unwaxed car.
And the culprits are?
Common problematic pollens include wheat, couch grass, dockens and sweet vernal. Early onset SPA (in March and April) indicates the involvement of tree pollens, especially birch and alder. In May, June and July, grasses are implicated, while in June, July and August, flowering weeds are often the cause.
What do you see?
Typical clinical signs include inflammation and itching of the face, ears, feet, perineal region and the tummy. There is often brown saliva staining of the feet, which is caused by the deposition of saliva during licking, and there is excoriation, hair loss, increased pigmentation (especially in chronic cases) and skin thickening. Recurrent, bilateral ear and eye infections are common (so allergies should always be considered when these occur). Dogs will be restless and disturbed by head shaking, face rubbing, foot licking and scratching, making concentrating on training difficult, as you have found.
Who is affected?
Around 10% of UK dogs are affected by SPA and it is most common in West Highland
Vet’s advice Neil McIntosh SG’s gundog health expert
white terriers (and, increasingly, in French bulldogs), but labradors, spaniels and golden retrievers figure highly, too. Careful dam and sire selection is very important, as a familial history of the condition makes it far more likely to be seen in offspring. There is a theory that there is a link between month of birth and the development of SPA, as dogs born during the pollen season can be sensitised to pollens in the first few months of life. It is, however, extremely uncommon for it to be found in dogs under a year old, except in shar peis (and I haven’t encountered many of them in field trials).
What happens next?
Part of the problem is that scratching becomes a way of life. An affected individual’s scratch threshold (the level of itchiness that instigates physical scratching) becomes very low, so that there is an excessive scratch response to even minor irritation. Scratching causes further damage to the skin surface, promoting secondary infections with bacteria and yeasts, such as staphylococcus and malassezia. (To further compound the issue, some dogs then become allergic to these bugs). It gets worse, of course, as many SPA-affected dogs will go on to develop other allergies; 30%, for example, will be allergic to the ubiquitous house dust mite, Dermatophagoides farinae.
Treatment options
Glucocorticoid steroids: usually in the form of oral prednisolone.
They are cheap, but they are also immunosuppressive, especially at higher doses, and side effects are common. These include (take a deep breath) increased thirst, urination and appetite, panting, skin infections, urinary tract infections, intestinal bleeding and iatrogenic
Cushing’s (thin skin, pot belly, muscle weakness and calcium deposition in the skin). Side effects are proportional to the dose used and sudden cessation of steroid treatment can be dangerous. Oclacitinib: trade-named Apoquel, it is a powerful, synthetic janus kinase inhibitor. It reduces cytokines, mentioned earlier, which are responsible for turning on itching at a cellular level. Ciclosporins: there are a number of available ciclosporins, which are immunosuppressive agents, costly and reserved for non-responsive cases. Lokivetmab: relatively new and available as a monthly injection called Cytopoint, this has rapidly become my treatment of choice. It is not a drug but a protein, which is a caninised monoclonal antibody that targets a chemical called interleukin-31. Put simply, interleukin-31 is an important mediator of itching and inflammation in allergic skin disease and Cytopoint inactivates it. The response is rapid and convincing.
“Part of the problem is scratching becomes a way of life”