Greater Ammi Poisoning in Cats

Greater ammi (also known as Ammi majus or 'bishop's weed') is a flowering plant that originates in North Africa. Nowadays, the plant is commonly grown in temperate and tropical gardens around the world thanks to its pretty, lace-like flowers and the screening effect that its long stems can provide at the edge of borders. However, the greater ammi is surprisingly poisonous, with its seeds especially being a source of dangerous toxins. Unlike with many other poisonous plants, it is the secondary complications caused by greater ammi poisoning that pose the greatest threat to the health of the affected animal.

Whilst some of the symptoms of greater ammi poisoning are quite noticeable, the more dangerous aspects can be hard to spot. For this reason, owners should keep a close eye on the developments of symptoms so as to aid diagnosis and thereby ensure that treatment starts as soon as possible.

Vomiting

An hour or two after ingesting greater ammi plant matter, the cat will begin to display the classic signs of nausea, including aversion to food, a withdrawn and possibly irritable demeanor and gagging/retching. When the irritation to the digestive tract caused by the greater ammi proves too much, the cat will eventually start vomiting in order to void the contents of its stomach. At this point, the owner should be sure to provide plenty of fluids in order replace those lost as the cat is repeatedly sick. If this is not done, the vomiting can eventually lead to dehydration, which can in turn cause serious side effects.

Oral Irritation

Soon after the greater ammi has come into contact with the tissues of the mouth, the cat will begin to experience extensive physical irritation. This can manifest in several different ways, the first of which is general redness around the mouth and nose. Varying degrees of swelling can also be noticed, depending on the quantity and specific part of the plant that has been eaten. As such, this can range from slight puffiness around the lips and tongue, to inflammation of the whole face. Typically, the cat will begin drooling as they attempt to clear the toxins from their mouth. In some rare cases, this can prove to be extremely dangerous when the tissues of the throat are affected and begin to prevent the cat from swallowing and even close off the windpipe.

Photosensitivity

Perhaps the most dangerous symptom of greater ammi poisoning is the onset of photosensitivity. Owners may notice their cat secluding themselves to shaded areas outside or even preferring the relative darkness of a curtained room. This is because exposure to sunlight starts to irritate exposed tissues, causing blisters, boils, cracking, and even open wounds. This means that owners will need to perform a physical inspection of the cat by parting the fur in order to confirm the signs of photosensitivity. This cellular damage can be especially dangerous to the eyes, as with sufficient exposure to direct sunlight, the cat can develop burns and scar tissue that will potentially have a massive impact on their vision for the rest of their life.

Within the tissue of the plant are high concentrations of ‘calcium oxalates’. Calcium oxalates are crystallized structures that can dig into tissues like thorns, causing hgh degrees of irritation. These are responsible for the majority of the irritation to the mouth and digestive tract, provoking the swelling, salivation, and vomiting. Also present in greater ammi plants are copious amounts of bergapten, which is produced as a means of warding off herbivores that would otherwise attempt to incorporate the plant into their diet. Bergapten cannot be metabolized by most animals and as such is absorbed into the bloodstream, allowing it to move throughout the body. However, when exposed to direct sunlight the bergapten induces a chemical reaction in the surrounding cells, causing copious amounts of damage to the surrounding cells. It is this photosensitivity that makes greater ammi poisoning so dangerous.

When the cat is brought to the clinic, the vet will usually only need to perform a physical examination in order to identify the problem. This is due in large part to the distinctive symptoms of photosensitivity and irritation from oxalates. In some cases, the vet might also wish to take a sample of the cat's blood for further testing, in order to rule out the presence of an underlying condition. Owners should be mindful that the vet will also most likely have some questions regarding the progression of the cat's symptoms as well as their general living environment, so having some answers at the ready will speed up the diagnostic process.

At present, there is no specific remedy to counteract the toxins present in greater ammi plants. This means that the majority of the treatments administered by the vet will be focused on purging as much of the toxins from the cat's body as possible. The first step will most likely be to start intravenous fluid therapy, which will help flush the bergapten from the bloodstream as well as replace liquids that have been lost to vomiting. The second step will be to administer activated charcoal to absorb the toxins still lingering in the stomach. Finally, the cat will be left in a darkened room in order to properly recover whilst their photosensitivity subsides.

After returning home from the vet, the cat may have to continue to live in a low-light environment, so owners should dedicate a room to housing the cat in darkness whilst restricting their movements. The vet may also suggest feeding the cat yogurt in order to help move any lingering oxalate crystals out of the digestive system. Overall, the majority of cats will recover fairly rapidly from greater ammi poisoning if given the right treatment and the opportunity to recover. Most affected animals can expect to be back to normal in under a week as long as secondary complications do not appear.