Hashish refers to the fibers of the cannabis plant, which have been ground into a paste before being heated, solidified and molded into a shape for consumption as a recreational drug. Although not usually harmful to humans, the chemicals present in hashish can prove extremely toxic to a variety of animals, including felines. In some cases, hashish poisoning can prove to be fatal for cats.

Once hashish has been consumed by a cat, the symptoms should begin to manifest themselves fairly rapidly. Owners should take note of the progression and characteristics of the symptoms, as this information can be of immense help to a vet when they are trying to diagnose the problem.

Hashish contains high concentrations of a substance called 'tetrahydrocannabinol', more commonly referred to as THC. The mechanism by which THC works is (in general terms) via creating an imbalance in the receptors in the brain. For humans, the effects of this imbalance can be quite pleasant, creating a euphoric state and can even be used to block out negative feelings such as pain and anxiety. For cats, however, this receptor imbalance can have a similar effect to a neurotoxin, causing a loss of control over motor functions and an inability to regulate bodily processes (resulting in vomiting, pupillary dilation, low blood pressure, and seizures). 

After the owner has brought the cat to a clinic, the vet will first perform a manual examination of the animal's body. This will allow them to observe the symptoms firsthand and rule out any other illnesses as being the culprit. It is at this point that they will usually wish to discuss the symptoms with the owner in order to get a chronological view of events. If relevant, they will want to discuss the cat's medical history. The vet might also wish to take a blood sample from the cat for laboratory testing in order to identify the specific toxin that is causing the problems.

Unfortunately, there is no direct remedy for hashish poisoning in cats. Because of this, the vet will likely pursue a strategy of mitigation in order to prevent further worsening of the symptoms until the THC is naturally passed out of the cat's body. The first step will be to either pump the cat's stomach or administer a dosage of activated charcoal to absorb the trace elements of THC that remain. Secondly, intravenous fluid therapy will be started in order to replace the fluids lost via vomiting and to 'flush' the toxins from the cat's body by provoking urination.

The severity of the reaction to THC varies from each individual animal to the next. Most animals can expect to make a full recovery within a few days, whereas others (mostly older animals) may require longer to get well again. The main facet of recovery from hashish poisoning is rest, so most vets will recommend limiting the cat's activity for several days in order to allow it to conserve its energy. Follow-up visits are generally unnecessary, though the presence of complications such as dehydration may require them.