Farm to Pharma

MOST PASTURE GRASSES ARE FROM THE SAME FAMILY

The grass family, Poaceae, is very large and includes important crops such as wheat, rice, corn, sugar cane, and more. The family is subdivided into several subfamilies and those are further divided into tribes. The subfamily Pooideae – or Pooid grasses – is very important from an allergy perspective. The species in this large subfamily produce large amounts of windborne pollen. The pollen contains and releases potent allergens. In addition to the four species mentioned, the subfamily includes Meadow Fescue, Sweet Vernal and Red Top.

The major allergens of the temperate grasses have been well-studied and characterized in humans, and found to be similar for all the species in the subfamily.

GRASS ALLERGY IN ANIMALS

Canine sensitization to northern pasture grasses have been reported for several decades. Timothy and Sweet Vernal grasses are relevant aeroallergens involved in canine atopic dermatitis. Additionally, Perennial Rye pollen has been reported to elicit respiratory allergy in a few horses.

Feline allergies to pasture grasses are not as prevalent as in dogs. Both intradermal and serological reactions to pasture grasses range from four to twenty percent, depending on the allergen.

Below is the pollination chart for temperate grasses, pollinating from early spring through early summer.

Pigweed: Not Pig but Weed

Common Allergenic Species

► Short Ragweed – Ambrosia artemesiifolia

► Giant/Tall Ragweed – Ambrosia trifida

► Western Ragweed – Ambrosia psilostachya

► Slender Ragweed – Ambrosia tenuifolia

► Southern Ragweed – Ambrosia bidentata

Plant Characteristics:
Herb and shrub plants that range in size from a few inches to 7 feet
Leaf structure and appearance varies according to species; leaves are sometimes divided pinnately.
Leaf edges are smooth or toothed

Pollination:
Wind-pollinated, dispersing up to 400 miles from the point of origin.

From August into November in the United States and August to October in Europe.

The Amaranthaceae family is large and contains about 170 genera and over 2,300 species worldwide. Plants from this large family are found on almost every continent – save Antarctica perhaps.

Pollen from this large group is highly allergenic and there are similar cross-reactive allergens within the group.

Amaranthus leaves are edible and are a common vegetable ingredient in several regions of the world.

Cross-Reactivity
Pigweed and Carelessweed are distinct species of the genus Amaranthus. Extensive cross-reactivity among individual species of Amaranthus could be expected, as well as moderate or stronger cross-reactivity among other Amaranthaceae family members, which includes Russian Thistle and beets. A high degree of cross reactivity has long been reported between Pigweed and Lambs Quarters. In 2009 the Amaranthaceae family was redefined to include Chenopodiaceae species, based upon new findings of shared morphology and phylogeny.

In a retrospective study, North American canine sensitization rates for Spiny Pigweed were reported to be 15 percent. These data, however, must be interpreted loosely, given that the intradermal testing concentrations do not necessarily correlate with the current recommendations. Serology studies report canine IgE reactivity rates of 86 percent for Carelessweed. An additional retrospective study evaluated allergen sensitization in cats. Although the sample size is limited, a positive reactivity rate to Pigweed was reported to be approximately 31 percent in cats using intradermal testing and 30 percent using serology testing.