How much fur does a cat shed?

Question

Is there any known estimate of the total mass of fur shed by a cat over a year? I can find some anecdotal estimates that full regrowth can be achieved over 8 to 12 weeks, but that does not give me any answer with regards to the actual mass.

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Some precisions:

• The answer certainly depends on the cat size but also type of hair, and environment. Cat owners easily observe that shed amounts vary depending on, for instance, current temperature (the animal gets a lighter fur in summer, and denser in winter). It is possible that the growth rate varies with temperature. As such, there cannot be a simple answer valid for all cats, but that does not mean that the question is unanswerable, only that the answer will consist in multiple data points. It's like a question about the height of a human: not all humans have the same height, but it is not totally meaningless to talk of averages.

• Cats are neither photosynthetic nor nuclear-powered. As such, the carbon atoms found in the fur keratin can only come from their food intake (excluding water). Basically, if a cat east 200g of food per day, then it cannot shed more than 200g of fur per day on average, or 73 kg over a year. But I really expect the figure to be a lot lower than that.

• I find unsubstantiated claims that an average cat may have 20 to 40 millions of hair, with an average thickness of about 20µm, and can grow back a complete coat in "8 to 12 weeks" (if shaved). Assuming an average length of 4 cm per hair, and that hair density is close to that of water, then the total fur weight (under these assumptions) would be 250 to 500g and the beast could produce such an amount 5 times per year, leading to a total of up to 2.5 kg over a year.

  This estimate is based on totally unscientific figures that could be off by a large amount. Moreover, if the growth rate varies depending on conditions, then chances are that a fully-shaved cat will have a higher growth rate, and a non-shaved cat will settle for a lower growth rate and thus shedding amount.

Thus, I am trying to find some better sources for data so as to get at least ballpark numbers. Basically, are we talking about 100g, 1kg, 10kg per year or so?

Answer 1

This is much too varied to give an even halfway accurate answer. Even if we disregard differences between breeds of cat and hair length, this can vary on a personal level.
Other than that, even if we were to somehow keep an eye on cats so we could count this, the fact that cats self-clean is going to throw a wrench in the numbers. You're never going to get an accurate measurement of hair loss since they ingest and digest hairs too.

I have two sister cats. Born in the same litter, sharing the same father (guaranteed). They were both sterilized. It took one of them three times as long to regrow the fur on their belly. 1,5 weeks versus 5 weeks.

Similarly, although both cats are now in a shedding phase, there is a notable difference in the amount of hair that sticks to your hand when you pet them. This may be related to the fact that their fur feels different (one is a bit more bristly, the other has a very silky fur).

Keep in mind, these cats are about as equal as you can get: same age, same parentage, all food is shared, same environment, similar lifestyle. And there is still a 200% increase in hair growth speed.

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Without trying to be facetious, I think there's only one way to answer this:

1. Observe the cat for a while. Wait until its fur stays of a consistent length (should apply to pretty much any cat in the long-term). Call this state the "equilibrium".
2. Completely shave the cat.
3. Observe how long it takes for the cat to regrow its fur back to the previous observed equilibrium.
4. Count all the hairs on the cat (good luck).

Now you can calculate an average shedding rate:

avg_hairs_shed_in_a_day = hair_count / days_to_regrow_fur

Logically, if a cat is able to regrow its entire fur in e.g. 100 days, that means that it must shed an amount equal to its fur coat in 100 days in order to stay at an equilibrium.
If it was shedding more, the cat would eventually go bald. If it was shedding less, its furriness would increase over time.

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But due to the vast amount of factors involved in hair strength/hair growth; we can't really answer this question unless we perform this experiment on every breed of cat in almost every variable condition.

I don't have the time for that.

Answer 2

A guesstimate is that a cat with medium length of fur has about 10% of its body weight as fur.

Every hair in this fur is replaced once a year +/- two months. A long haired cat has two types of fur: a short haired undercoat made of thin hairs and a long haired overcoat made of thicker hairs.

The longer hairs do grow for a longer time, but they do not grow as dense as shorter hairs do (in number of hairs per square CM of the cat's skin).

So short to medium length fur is just one single type of fur--it is just undercoat(not totally correct but close to it). Long haired cats have both undercoat and overcoat.

I am not able to back any of this up so this is what I personally think about a cat's fur.

Here is a link about the fur of cats and dogs. It does not solve your question, but it is still interesting. Christy.b provided this link to another question I had, so credit to her for this.