At What Point Does Rigor Mortis Begin in Cats? The Complete Explanation

Cats' Rigour Mortis Start

Image Credit:Marchnwe

When a cat passes away, the corpse may begin to experience rigour mortis as soon as ten minutes or up to three hours later. 

A factor that can be used to determine when a cat died is rigour mortis

The cat’s body first stays somewhat warm before becoming hard, and this process can last up to eight hours. 

An unconscious cat is laying on the ground. 

At any time between eight and thirty-six hours following exitus, an animal’s body will continue to be stiff but start to get cold. 


Rigour Mortis – what is it? 

Rigour mortis, also referred to as postmortem rigidity, is a normal aging process that affects most species, especially mammals have a variety of muscle kinds. 

The chemical makeup of a live thing’s muscles changes when it dies, which is why they become rigid. 

on a green background, “rigour mortis”

This is how some creatures (including humans) might find themselves in abnormal and seemingly fixed positions for some time before their bodily components can realign themselves. 

One of the earliest obvious indicators of death is rigour mortis. 

After a cat passes away, its body may occasionally remain flexible for a few hours before its limbs and muscles become rigid. 

Cats’ Rigour Mortis Causes 

Death is the only recognized cause of rigour mortis because no other known mechanism can result in the same condition. 

phenomenon to the degree that it is pervasive and that it has an impact on living things. 

The muscles in a cat’s body contract in a manner reminiscent of when they were alive after they die. 

senior cat on bed 

Simply put, when a cell dies, there is an imbalance in the chemical reactions that normally take place between the muscle and many other cells, and a lot of calcium ions end up inside the muscle tissue. 

The muscle contracts as a result of this imbalance and an interaction between calcium ions and the myosin and actin filaments that make up the muscle itself. 

Rigour mortis gradually goes away because ATP (adenosine triphosphate), which is present almost everywhere in an animal’s body, eventually breaks down. 

The muscles are subsequently relaxed by myosin, which also expels the calcium ions from the cell.

Rigorous to deal with whether in people or animals, rigour mortis is a natural chemical reaction nonetheless. 

Rigour Mortis phases

There are four basic post-mortem stages that make up death, of which rigour mortis is but one. 

These four phases are known as: 

Pallor mortis (paleness of the skin brought on by a halt of blood flow) 

(A decline in body temperature) Algor mortis 

Rigour mortis (stiffening of the muscles and joints) 

Livor mortis, or lividity in the body’s closest to the ground area 

Cats' Rigour Mortis Start 2

Image Credit:Joe Cooke

Other stages of corpse decomposition (other than rigour mortis) include, in particular, the following: 



dynamic decay 

accelerated decay 


During the autolysis phase, rigour mortis takes place. 

When the body is still alive and the autolysis process is still in progress, rigour mortis occurs. 

Every other condition, starting with bloat, entails a process in which the animal’s body decomposes into a corpse and eventually a skeleton.

cat skeleton rendered in graphics 

Rigour mortis can only manifest in animals that have recently gone away because a skeleton is devoid of muscle cells and the same chemical and biological material that we find in a living body. 

In terms of its evolution and eventual elimination, rigour mortis only has six distinct stages: 

No rigour mortis is present. 

very little rigour mortis 

mild rigour mortis 

More severe rigour mortis 

Mortal rigours to the full 


How Long Does Rigour Mortis Take to Complete? 

Rigour mortis normally lasts 36–48 hours, however the number of hours it takes to complete the process depends on a number of variables. 

The factors that have a significant impact on how rapidly rigour mortis develops in cats include the cause of death, levels of muscular mass and fitness, as well as the body’s temperature and that of the environment. 

The duration of the rigour mortis process may also be decreased if the animal had an infection that may have contributed to their demise and if they were severely underweight or emaciated, for example. 

an underweight cat

After the cat has passed away for one to three hours, their body will still be relatively malleable. 

After that, it will gradually stiffen up until it becomes quite firm. 

There have been instances where pets’ bodies remained rigid for up to 72 hours after their deaths, despite the fact that most animals’ bodies regain their flexibility after roughly 48 hours. 

How to Determine the Length of a Cat’s Death 

Cats that are allowed to roam free in the great outdoors run the risk of being killed by larger predators like dogs, foxes, and mountain lions or by human traffic, which is a very unpleasant surprise for their owners. 

A cat owner may be able to determine whether their pet has been deceased for one or more days based on the degree of body deterioration. 

It is likely that they have been deceased for less than two days if they are in rigour mortis. The majority of pet corpses experience rigour mortis, which lasts for fewer than 50 hours. They might have passed away yesterday if the cat’s body is still rigid. 

Around 50 to 60 hours after exitus, decomposition starts to have an impact on the body as gas and other liquids produced by anaerobic microbial activity. 

Cats' Rigour Mortis Start 3

Image Credit:Alexander Andrew Halim

The cat may have been dead for longer than three or four days if their body, particularly their abdomen, appears elongated and they don’t appear to be smelling at all pleasant.