Puppy Forum and Dog Forums banner

1 - 10 of 10 Posts

·
Registered
Joined
·
4 Posts
Discussion Starter #1 (Edited)
I have been reading online about different dog breeds and genetic diseases. Afterwards I began checking several forums to see what people are saying about breed diseases. I noticed on several forums if a mentioned breed have been known to have several diseases there seems to be an automatic assumption by some posters that the breed is in worse condition than a different breed with a lower number of diseases, but that is not automatically true.

Hypothetical situation - For example let’s say you are looking at two dogs, Breed-A and Breed-B. Breed-A is known to have 10 different diseases within the breed, but Breed-B is known to have 1. At first glance Breed-A may look worse if you don't go by any other information. Now you are given the information that 10% of dogs in Breed-A are afflicted with a disease, and 90% of the breed is clear, while 65% of Breed-B have that 1 disease, only 35% are clear of disease, then you realize Breed-B is actually in worse condition, while Breed-A is relatively healthy as a breed. Even if Breed-B were to suddenly only breed from the 35% clear, that would significantly reduce Breed-B’s genetic diversity (what little modern breeds have left) and endanger it to future new diseases due to new mutations. (Explanation - All living organisms have at least 1 copy of new mutant recessive genes that have the potential to cause disease, but rarely does in nature because most organisms rarely find a mate with the same new mutant gene in a large population. Most genetic diseases are recessive and need two copies within an organism to cause disease)
 

·
Registered
Joined
·
8,384 Posts
that's why you look for breeders testing what they breeding.. I purchased my GSD when there was an abundance of hip problems, short lives (it was 8 years at the time) was the main thing.. and I found a breeder who had been testing their dogs for 30 years and looking to breed into longevity. 13 GSDs from her lines all HD free, and they all lived well beyond 8 years old well ..... add 4 elderly GSDs I took in from other tested lines of breeders HD free lived long, and two show prospects from testing breeders again HD free lived long. There will always be problems in breeds, that is where the right breeder doing the right thing gives you the best chance for a good out come.
 

·
Registered
Joined
·
12,194 Posts
Yes, incidence is important, as is severity especially with HD. Some breeds have a high incidence of HD and it is crippling. Others have the same incidence but it is rarely crippling. So there are nuances. Some diseases are also impossible to test for, like cancer.
 

·
Registered
Joined
·
1,849 Posts
Specific example. Labradors are known to have had almost every disease in dogdom. They are the most common breed in the English speaking world . . . and pretty common elsewhere. Most every vet has seen a few Labs with hip dysplasia, maybe a case or two of elbow dysplasia, epilepsy, bloat, diabetes . . . and of course some cancer. If you take the time to dig up incidence numbers you'll find that Labs tend to be in the middle of the pack for incidence. In many cases, in the bottom third.
Common breeds with a lot of diversity, including pits, Labs, and GSD's, have reported cases of a whole slew of diseases. Doesn't mean those diseases are common in the breed.
 

·
Registered
Joined
·
6,658 Posts
Yes the frequency of disease is an important consideration.
Frequency refers only to the number of cases of disease, regardless of the population size or any other factors. 100 cases of cancer is a frequency.

What the OP is referring to is prevalence - the number individuals within a specific population that have a disease. 100 poodles with cancer would be prevalence, where poodles refers to well defined and specific population.

Incidence is a rate (so much include some measure of time, e.g. "per year") and only refers to new cases of disease that occur during a specified time period. In one year, 100 poodles were diagnosed with cancer, would be incidence. Incidence doesn't include cases of the disease that already existed before the time period is being measured, whereas prevalence does.
 

·
Registered
Joined
·
1,849 Posts
Frequency refers only to the number of cases of disease, regardless of the population size or any other factors. 100 cases of cancer is a frequency.

What the OP is referring to is prevalence - the number individuals within a specific population that have a disease. 100 poodles with cancer would be prevalence, where poodles refers to well defined and specific population.

Incidence is a rate (so much include some measure of time, e.g. "per year") and only refers to new cases of disease that occur during a specified time period. In one year, 100 poodles were diagnosed with cancer, would be incidence. Incidence doesn't include cases of the disease that already existed before the time period is being measured, whereas prevalence does.
I'm afraid this is one of those cases where different sources use different definitions. I think the OP used incidence to mean incidence rate...which a lot of people do.
https://www.health.ny.gov/diseases/chronic/basicstat.htm
"Incidence is a measure of disease that allows us to determine a person's probability of being diagnosed with a disease during a given period of time. Therefore, incidence is the number of newly diagnosed cases of a disease. An incidence rate is the number of new cases of a disease divided by the number of persons at risk for the disease. If, over the course of one year, five women are diagnosed with breast cancer, out of a total female study population of 200 (who do not have breast cancer at the beginning of the study period), then we would say the incidence of breast cancer in this population was 0.025. (or 2,500 per 100,000 women-years of study).
By this definition, an example of incidence rate would be 100 poodles newly affected per 100,000 poodle-years of study, or a 1/1000 probability, if the disease was random, that a given poodle would be newly affected in a given year.

In SI units, frequency is measured in units of time^-1 (i.e., per unit time, as in cycles/second). I don't think there is a different definition for frequency in epidemiology.

As I understand it, the OP meant precisely what he or she said: the number of diseases found in a breed. People often talk about this breed or that breed as having a high or low number of hereditary diseases. The number is simply a count of the number of diseases that have been reported for that breed. It's a pretty meaningless number. Very rare breeds often have very few diseases reported for them because most vets will never encounter them in their lifetime. That does not make the breed healthy.
 

·
Registered
Joined
·
6,658 Posts
I'm afraid this is one of those cases where different sources use different definitions. I think the OP used incidence to mean incidence rate...which a lot of people do.
https://www.health.ny.gov/diseases/chronic/basicstat.htm
"Incidence is a measure of disease that allows us to determine a person's probability of being diagnosed with a disease during a given period of time. Therefore, incidence is the number of newly diagnosed cases of a disease. An incidence rate is the number of new cases of a disease divided by the number of persons at risk for the disease. If, over the course of one year, five women are diagnosed with breast cancer, out of a total female study population of 200 (who do not have breast cancer at the beginning of the study period), then we would say the incidence of breast cancer in this population was 0.025. (or 2,500 per 100,000 women-years of study).
By this definition, an example of incidence rate would be 100 poodles newly affected per 100,000 poodle-years of study, or a 1/1000 probability, if the disease was random, that a given poodle would be newly affected in a given year.

In SI units, frequency is measured in units of time^-1 (i.e., per unit time, as in cycles/second). I don't think there is a different definition for frequency in epidemiology.

As I understand it, the OP meant precisely what he or she said: the number of diseases found in a breed. People often talk about this breed or that breed as having a high or low number of hereditary diseases. The number is simply a count of the number of diseases that have been reported for that breed. It's a pretty meaningless number. Very rare breeds often have very few diseases reported for them because most vets will never encounter them in their lifetime. That does not make the breed healthy.
I am an epidemiologist, you don't need to explain to me what incidence and prevalence are or how to calculate them. :)

Frequency, in an epidemiologic context, refers to simple counts, without any denominator.

ETA: You're correct in that frequency is not very useful and doesn't give a lot of information, but sometimes it's all that you have, either because it is the first time a disease or outcome is being described as a problem, or because there aren't any good ways to figure out what the denominator should be in order to calculate incidence or prevalence.
 

·
Registered
Joined
·
1,849 Posts
I am an epidemiologist, you don't need to explain to me what incidence and prevalence are or how to calculate them. :)

Frequency, in an epidemiologic context, refers to simple counts, without any denominator.

ETA: You're correct in that frequency is not very useful and doesn't give a lot of information, but sometimes it's all that you have, either because it is the first time a disease or outcome is being described as a problem, or because there aren't any good ways to figure out what the denominator should be in order to calculate incidence or prevalence.
Do you think everyone who reads this forum is an epidemiologist? Is the OP? I'll bet my booties, most of the audience is confused about definitions. I sure am. I can't believe frequency doesn't have time units. I looked it up on google and found an online course in epidemiology that gives five definitions for frequency, all with different units ... https://onlinecourses.science.psu.edu/stat507/02/measures

I don't think the OP meant a count of individuals, rather a count of diseases that have been observed in a breed. That doesn't fit any of the five definitions given in the online source above.
 

·
Registered
Joined
·
6,658 Posts
Do you think everyone who reads this forum is an epidemiologist? Is the OP? I'll bet my booties, most of the audience is confused about definitions. I sure am. I can't believe frequency doesn't have time units. I looked it up on google and found an online course in epidemiology that gives five definitions for frequency, all with different units ... https://onlinecourses.science.psu.edu/stat507/02/measures

I don't think the OP meant a count of individuals, rather a count of diseases that have been observed in a breed. That doesn't fit any of the five definitions given in the online source above.
That's why I defined them in a simplistic way. I can see how it can get confusing. I think we are having a disconnect in terminology.

The website that you linked to is using "disease frequency" to mean "disease occurrence". Usually, when a published study refers to the frequency of a disease, it is often referring only to simple counts without any denominator (what the link you provided calls "counts"). Otherwise they'll use the specific measure of disease occurrence being measured (prevalence or incidence).
 
1 - 10 of 10 Posts
Top