Pyometra Or Mammary Cancer

[jr_inoz]

I wonder if any research has ever been done to determine if a bitch's mother or grandmother suffered from Pyo if they have a increased risk of also contracting it? As it is different from cancer ect it could just be bad luck?

I have no research articles to back this up only what 3 different vets have told me - but Endometrial Hyperplasia is the pre-condition to developing pyo. (in bitches) -

My bitch had it and was the reason she couldn't carry a litter successfully to term. She didn't develop pyo - was desexed before she developed it but did have it. Whilst not necessarily a genetic condition - the chances of developing it have strong genetic links.

Interestingly - having just had a health scare - Endometrial Hyperplasia also develops in women and is the pre-condition to endometrial cancer and again, whilst not necessarily a genetic condition (you can have it with no previous person in the family having it) it your chances of getting it increase if other family members have had it.

There's no point in a bitch having any seasons if you aren't going to breed her. Each time she has a cycle there is the possibility that she will have a pyo. It also increases the chances of mammary tumors.

There is if you want it to grow and develop properly

This is something I don't understand completely that gets thrown around a whole lot. I would be interested in any research which has concluded that desexing at the standard 5-7 month age bracket has adverse effects on growth and skeletal maturity.

There was an article on DOL last year - and I cant find the link anymore - that clearly showed a high increase in hip displaysia in dogs of all breed who are desexed before maturity. The person who wrote the article was an honours student who, for her thesis, had gathered together all the peer reviewed research from around the world and collated the results. Was very good.

People say they won't take risks so automatically desex, but they are taking risks, those of increased risk of other diseases that are just less well reported or understood as higher occurrence in desexed animals. It is a case of knowing as much s you can and choosing the risks you think you can best manage. Neither option is risk free as research is starting to show us. For most people the convenience of desexing is compelling, and that is fair enough, but when it isnt the risk based decision isn't as clear cut as the average suburban vet would assert.

just what I would have tried to say, less eloquently.

[Rappie]

Ok, I've pulled the articles I have on mammary tumours...

Elise+Hudson: I actually have a textbook chapter that references the original article. The chapter is in Small Animal Clinical Oncology (2007), Withrow and Vail, pp619-636.

The statistics quoted for the risk of malignant tumours in desexed dogs (as compared to intact dogs) is:

0.05% if before the first oestrus, 8% after the first oestrus and 26% after the second oestrus.

(Reference quoted here is: Schnieder R, Dom CR, Taylor DON - Factors influencing canine mammary cancer development and post-surgical survival. J Natl Cancer Inst 43:1249-1261, 1969. Certainly not a recent article).

Other relevant points from the same chapter:

- late ovariectomy may reduce the risk of benign tumours

- one study in Beagles (can get reference if needed) showed a lifetime risk of 63% for development of any mammary hyperplasia or tumour and 23% for development of a malignant tumour

- suggestion that small dogs have a higher incidence of benign tumours compared to large breeds (25% malignant in small breeds as opposed to 58% in large breeds).

In another articles I have: (Effect of ovariohysterecomy in bitches with mammary neoplasms. Morris JS, Dobson JM, Bostock DE, O'Farrell E; Vet Record (1998) 142, 656-658).

- in bitches with benign tumours, OVH at the time of tumour removal did not influence the future risk of mammary tumours.

- in bitches with malignant tumours, OVH has no effect on progression of an established tumour, and even with removal of the primary tumours death occured in 60% of cases with invasive tumours within 2 years, and 24% of those with well defined tumours.

- the more malignant tumours do not have high degrees of oestrogen receptor positivity

- the strongest promotional effect of hormones is exerted in the first 1-2 years of life, the effect is lost after two or more cycles (this is referenced back to the Schnieder article above).