Sprengeri Fern Poisoning in Cats

The sprengeri fern (also known as 'Sprenger's asparagus') is a species of flowering shrub that is native to South Africa. At present, it can be found in various warmer climates as an ornamental plant in many gardens, favored for its hardiness and delicate appearance. In its home regions, however, gardeners commonly tend to regard the plant as an invasive pest. Pet owners should be aware that the sprengeri fern contains fairly harmful chemicals which, if ingested, can cause a variety of unwelcome health problems in a variety of animals, including cats.

It is fortunate that the symptoms of sprengeri fern poisoning are relatively visible, as although they are unpleasant for the affected animal, they provide the owners with ample time to respond to the problem and seek veterinary help. Owners should be careful to make note of as much information regarding the symptoms their cat displays as possible, as this will be of great help to the vet.

Vomiting

Within minutes of ingesting the sprengeri fern matter, the cat will begin to show signs of nausea, which will eventually give way vomiting. 

Diarrhea 

Around the same time that the animal begins to vomit, it may alse experience diarrhea as the sprengeri fern toxins irritate the intestines and the body attempts purge the contents of its digestive system. Sprengeri fern poisoning can sometimes cause a small amount of blood to be passed in the cat's stool, which may give the feces a darker coloration than usual.

Oral Irritation

Almost immediately after it has eaten the sprengeri fern, the cat will experience intense irritation of the tissues in its mouth. The toxins contained within the plant can also cause irritation and inflammation of the nose and throat. The most noticeable consequence of this is typically drooling, caused as the cat attempts to flush the irritant toxins out of its mouth by producing excess saliva. The cat's face can also appear red around the lips and nose, in some cases becoming so inflamed that the area becomes noticeably swollen. This swelling can also occur in the tissues of the mouth and throat, which in some extreme cases can cause breathing difficulties.

Dermatitis

Direct contact with the sprengeri fern toxins can also produce quite noticeable skin irritation. The resultant discomfort caused by this dermatitis will typically cause the cat to groom itself constantly with its tongue in an attempt to sooth the irritation. Owners will be able to directly observe dermatitis by parting the animal's fur to reveal a reddish rash. However, it is worth bearing in mind that the cat will typically be unwilling to be touched, as this can exacerbate the irritation in a localized manner.

The sprengeri fern contains large amounts of substances known as 'sapogenins'. These are one particular offshoot of the family of chemicals known as 'saponins', which are produced by a large variety of plants across the globe. The primary function of saponins is to act as a deterrent against being eaten by grazing animals. Some saponins accomplish this by reducing the animal's ability to properly metabolize foodstuffs, causing them to forgo eating the plant in favor of more nutritious forage. Other saponins (such as sapogenins) have a more direct effect, producing digestive upset and other unpleasant symptoms in an effort to ward off predators. The mechanism by which the sapogenin accomplishes this is by acting primarily as an irritant, which causes the vomiting, diarrhea and oral inflammation. The toxin also directly damages cells once it has been absorbed into the body, thereby producing the aforementioned dermatitis. 

When the cat has been brought to the clinic, the vet will rely primarily on a physical examination of the cat in order to verify the symptoms and diagnose the problem. The physical exam may be followed with imaging scans (such as ultrasound), which can yield more detailed information about the state of the internal organs. However, it is still important for owners to be able to provide accurate information regarding the cat's symptoms and their progression. This information can prove invaluable for the vet and, in conjunction with a blood test, can help narrow down the root cause of the problem.

Typically, the first thing a vet will do to treat a case of poisoning is to start the cat on a course of fluid therapy. This will intravenously introduce liquid into the cat's bloodstream, allowing the vet to both replenish any fluids lost to vomiting whilst simultaneously helping to remove toxins from the body. Secondary effects of the fluid therapy will be a quick regression of the dermatitis and a noticeable increase in the cat's energy levels. Although not it is not usually required, the vet may opt to administer a dosage of activated charcoal to the animal in order to absorb any lingering sapogenins. 

Sapogenin poisoning does not normally have any lasting effects due to its primary role as an irritant. This means that most cats will make a rapid recovery after receiving treatment. However, it may be prudent for owners to closely monitor their pet for several days after the incident by confining them to the house. This will both help to conserve the cat's energy, as well as allow a rapid response to any complications that should arise.