Page 943 - Veterinary Toxicology, Basic and Clinical Principles, 3rd Edition

Poisonous Plants of the Europe Chapter | 62 895

VetBooks.ir animals by removing or preventing access to hazardous that have unlimited freedom. A dog with nothing to do
may resort to aberrant behavior, such as ingestion of any
substances, including toxic plants (Fowler, 1981). Very
available plant material(s). If these plants are poisonous,
old animals, with depressed protein synthesis due to
increased organ dysfunction may also suffer the same def- toxicity may result. Clay (1977) describes three instances
icit. Interactions with hormones at various ages may also of dogs poisoned by plants within their confined space.
be involved. Significant changes in the body composition
and regional blood flow occur as aging progresses, and
there is a steady decline in physiological function. Changes in Surroundings
New objects placed within the environment of a pet are
Sex novel and subject to a thorough investigation. During the
holiday season, new plants are often brought into the
There is differential toxicity for certain toxic plants
home, and some of them are potentially dangerous. When
between sexes. The sex differences in metabolism are
a family moves into a new home or goes on vacation with
mainly observed after puberty and are probably largely
its pet(s), new plants are often encountered.
related to hormonal influences.
Pets used to “star billing” in a household may feel
neglected when a new baby arrives and receives all the
Species
attention. In such circumstances, many pets resort to pica.
Some species are very susceptible to toxic plants, Illness of an owner may require “pet sitting” by others
whereas other are not. For example, rabbits are insensi- and thus initiate the same response (Fowler, 1981).
tive to the effects of Galega officinalis, and certain spe-
cies of birds can consume Cicuta spp. without toxicity
occurring. Marked differences among species metabolism Behavioral Abnormalities
of the same chemical compound exist. For example, cats
Behavioral abnormalities are increasingly being recog-
lacking adequate glucuronyl transferase form glucuro-
nized as specific clinical entities. A few behaviorist-
nides poorly and are therefore more susceptible to poi-
trained veterinarians are beginning to unravel some of the
soning by certain toxic plants. The cat is unable to
complex interrelationships of pet behavior and disease.
synthesize adequate amounts of taurine because of low
Ingestion of foreign materials is one such manifestation
activity of the decarboxylase enzymes involved in tau-
of deranged behavior. Plant poisoning may be a conse-
rine formation; the particular sensitivity of the cat is
quence of such behavior. The veterinary profession needs
heightened by its total dependence on taurine for bile
to distinguish the many minor exposures from the few
acid conjugation.
serious ones and to treat those toxic exposures appropri-
In ruminants, after a toxic plant is consumed, it will
ately. Such a task may be difficult because the plant
depend on the balance of many factors whether toxicity
involved is not easily identified. Even when it is known,
will be expressed. Some plant poisons are rapidly inacti-
predicting toxicity is difficult because of variation in
vated in the rumen by the microbiota, while other (poten-
plant toxicity, amount ingested, and animal/species sus-
tially toxic) compounds may be activated by the microbes
ceptibility (Fowler, 1981).
faster than they will be detoxified in the gut. Among the
toxic compounds that may be degraded in the rumen are
oxalates, pyrrolizidine alkaloids, essential oils, but also Plants
cyanides, seleniferous amino acids, digitalis alkaloids and
The following factors of plants are linked to toxicity:
caffeic acid among others.
The concentration of active ingredient varies among
Genetics and Strain different species of plants.
The entire plant can be toxic, but in some cases, parts
Within animal species, certain breeds or strains vary in
of the plant are responsible for toxicity (e.g., grain,
ability to detoxify toxic plants. For example, the
leaves, and fruit).
Dalmatian breed lacking uricase is less able to carry out
The active ingredient content can vary depending on
purine metabolism.
the state of plant development (e.g., G. officinalis
becomes toxic only after flowering).
Boredom Preservation procedures can destroy the active ingredi-
Both older animals and immature animals may suffer ents; e.g., drying can reduce toxicity (e.g., Cicuta spp.)
from apathy. Dogs, in particular, have problems resigning Herbicide treatments may increase the toxic principle
themselves to continuous confinement compared to others content and can make animals crave plants more.