Page 941 - Veterinary Toxicology, Basic and Clinical Principles, 3rd Edition

Poisonous Plants of the Europe Chapter | 62 893

VetBooks.ir lesions identical to those caused by poisonous plants and cases are related to accidental ingestion of ornamental
plants rather that wild plants, particularly at certain times
thus must be ruled out. Therefore, an extensive differen-
of the year. Cats appear to be more sensitive than dogs
tial diagnosis must be initiated embracing physical exami-
nation, blood biochemical or serological evaluations, probably due to the tendency to chew on plant leaves.
possible postmortem evaluation and chemical or micro- Convallaria majalis and N. oleander have also
scopic evaluations of plants and/or animal tissues (Welch been commonly reported to cause severe and potentially
et al., 2012). A thorough postmortem examination, or nec- lethal cardiac disorders, and R. communis and Datura
ropsy, provides the most information needed to formulate stramonium cases were also frequently observed
a definitive diagnosis. (Gault et al., 1995).
Clinical signs are of prime importance to the clinician Small animal veterinarians must deal with a number
and toxicologist. Both the nature of the signs and their of potentially poisonous, commonly occurring, household
sequence of occurrence may be important. Loss of one or and garden plants (Table 62.2). In many cases, the client
more animals in a herd or a single animal at risk provides does not know name of the plant that the animal encoun-
an invaluable opportunity to increase diagnostic informa- tered. As indicated, veterinarians should familiarize them-
tion for toxicology. Lesions are often absent in certain selves with the most potentially toxic plants and their
toxicosis, and lack of lesions should correlate with the clinical signs (in clinic, farm, or field situations) and any
indicated clinical signs (Osweiler, 2011). naturally occurring dangerous plants in their area (Flood
and Fitzgerald et al., 2006).
The seasonal houseplants, such as poinsettia
Pets (Euphorbia pulcherrima) (Euphorbiaceae family), mistle-
The diagnosis of plant poisoning in dogs is not always toe and holly bring a greater potential for plant poisoning
easy because symptoms are rarely characteristic and treat- with the many beautiful live decorative plants brought
ment is often disappointing. The clinical signs of poison- into the home.
ing produced by ornamental plants certainly were not Mistletoe (Viscum album L) (Viscaceae family) has a
noticed in the past, either because the clinical examination long medicinal use history. All parts of the plant are poi-
was lacking or because symptoms that presented in the sonous. The concentration of viscotoxins (polypeptides)
poisoned animal were not sufficiently alarming to consult in European mistletoe varies with individual strains, but
or notify veterinarians. The frequency and severity of poi- the concentration of these compounds is relatively
soning are extremely variable. The toxicity of a given stable during the harvesting season (Schaller et al., 1998).
ornamental plant varies from one variety to another and In high doses, viscotoxins are cardiotoxic as a result of
from one organ to another, and it also depends on the the inhibition of papillary muscle function. Blood pres-
state of maturity. Animals react differently depending on sure is increased as are pulse and respiratory rates.
the species, age, health status before the poisoning, their Ingestion of high amounts of mistletoe may cause nausea,
sensitivity to the plant and the amount ingested, and vomiting, and gastroenteritis.
whether the plant has been macerated or not. It is difficult English Holly (Ilex aquifolium L.) (Aquifoliaceae fam-
to make a diagnosis of poisoning by an ornamental plant ily) plants are grown as ornamental plants. The red or
in view of the few symptoms and lesions presented by a black berries (Christmas holly) are attractive decorations,
sick animal. It is essential to identify the plant in the stool especially for pets. Polyphenols, saponins, triterpenes,
or vomitus to make a diagnosis by the symptoms corre- steroids and alkaloids have been extracted from Ilex
spond with those observed in similar cases previously. opaca. The compounds found in Holly are digitalis-like
The symptoms and lesions are varied; they predominantly cardiotonic and a saponin, which has hemolytic activity.
affect the digestive tract when the poisoning is benign The symptoms of poisoning are nonspecific and they con-
and the nervous and cardiovascular systems when poison- sist of abdominal pain, vomiting, and diarrhea. These
ing is serious. At necropsy of the intoxicated animal, gas- appear when large amounts of the fruit are ingested.
troenteritis lesions are often observed. For the previous
reasons, prevention must play an essential role. It is first
necessary to know the plants that are poisonous to pets Livestock
and avoid planting them in kennel areas or maintaining Livestock can be poisoned by many different plant spe-
them in the home. It is also necessary to ensure that ani- cies, but an analytically confirmed diagnosis is not always
mals receive a sufficient and balanced diet, corresponding easy, and most cases are only suspected following nec-
to their specific needs, and that they have regular daily ropsy and identification of leaves, stems, or pods in the
exercise. rumen. A diagnosis of plant poisoning can rarely be made
Generally, Liliaceae spp. and Araceae spp. are the by the clinical syndrome alone. Signs accompanied by a
major plant families involved in poisoning; most of the history of exposure to the plant are usually necessary.