The Truth about Feline Fix by Five: A Veterinarian’s Response to Common Concerns

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The Truth about Feline Fix by Five: A Veterinarian’s Response to Common Concerns

By: Philip A. Bushby, DVM, MS, DACVS

Some of the most common concerns regarding early-age spay/neuter in cats, are that it will lead to problems related to growth and development, and increased urinary obstructions. Dr. Philip A Bushby, United Spay Alliance Board Member and proponent of Feline Fix by Five, reviewed the research to separate fact from fiction:

Prepubertal castration does NOT predispose to femoral head fractures.

Normal bone growth is influenced by gonadal hormones and gonadectomy prior to growth plate closure will delay that closure.  There is, however, not any documentation of clinical significance of delayed growth plate closure in cats.  There are no studies documenting increased incidence of physeal fractures in cats sterilized before the cessation of growth. There are no studies documenting joint disorders in cats sterilized before the cessation of growth. Given that the traditional age of sterilization is 6 months there are millions of cats that have been sterilized prior to growth plate closure.  Clearly if the abnormal open or wide physis mentioned in the critique predisposes to orthopaedic problems someone would have discovered it by now.  

A case-controlled study evaluated the associations between early neutering, obesity, outdoor access, trauma, and feline degenerative joint disease.  The objective was to determine risk factors associated with the occurrence of mobility changes in cats.  The study “demonstrated that obesity, outdoor access and a history of trauma may predispose cats to developing owner-reported mobility changes associated with degenerative joint disease whereas neutering before 6 months of age appears to decrease that risk.1

None of the long-term studies document increased incidence of lameness, fractures, or other clinically relevant orthopaedic issues.,2,3  

Prepubertal castration does NOT predispose to urinary obstruction.

Several studies have documented factors which predispose to urinary obstruction.  Prepubertal castration is never identified as predisposing factors.

A retrospective, case-control study of cats with urinary obstruction conducted at the Hebrew University Veterinary Teaching Hospital evaluated, among other things, the predisposing factors for feline urinary obstruction.  The study did not identify early castration or the failure to extrude the penis as predisposing factors.4

A paper published in the Journal of Feline Medicine and Surgery in 2016 described risk factors associate with feline calcium oxalate urolithiasis.  The paper identifies several risk factors including increased calcium excretion, increased oxalate excretion, urine pH, decreased urine volume and identifies certain feline breeds that are predisposed.  The paper does not identify early castration or the failure to extrude the penis as predisposing factors.5

A case-control study published in 2006 identified risk factors associated with clinical signs of lower urinary tract diseases in indoor cats.  The paper did not identify early castration or the failure to extrude the penis as predisposing factors.6

Other studies have explored the relationship between prepubertal gonadectomy and health problems.  These studies have not identified any predisposition for urinary obstruction associated with prepubertal castration.7,8

Prepubertal castration does NOT predispose to orthopaedic problems.

Normal bone growth is influenced by gonadal hormones and gonadectomy prior to growth plate closure will delay that closure.  There is, however, not any documentation of clinical significance of delayed growth plate closure in cats.  There are no studies documenting increased incidence of physeal fractures in cats sterilized before the cessation of growth.  There are no studies documenting joint disorders in cats sterilized before the cessation of growth.  Given that the traditional age of sterilization is 6 months there are millions of cats that have been sterilized prior to growth plate closure.  Clearly if the abnormal open or wide physis mentioned in the critique predisposes to orthopaedic problems someone would have discovered it by now.  

A case-controlled study evaluated the associations between early neutering, obesity, outdoor access, trauma, and feline degenerative joint disease.  The objective was to determine risk factors associated with the occurrence of mobility changes in cats.  The study “demonstrated that obesity, outdoor access and a history of trauma may predispose cats to developing owner-reported mobility changes associated with degenerative joint disease whereas neutering before 6 months of age appears to decrease that risk.9

None of the long-term studies document increased incidence of lameness, fractures, or other clinically relevant orthopaedic issues.,10,11 

Footnotes: 

1 Maniaki E, Murrell J, Langley-hobbs SJ, Blackwell EJ. Associations between early neutering , obesity , outdoor access , trauma and feline degenerative joint disease. J Feline Med Surg 2021. DOI:10.1177/1098612X21991456.

2 Porters N, Polis I, Moons CP, et al. Relationship between age at gonadectomy and health problems in kittens adopted from shelters. Vet Rec 2015; 176: 572.

3 Howe LM, Slater MR, Boothe HW, et al. Long-term outcome of gonadectomy performed at an early age or traditional age in cats. J Am Vet Med Assoc 2000; 217: 1661–5.

4 Segev G, Livne H, Ranen E, Lavy E. Urethral obstruction in cats: Predisposing factors, clinical, clinicopathological characteristics and prognosis. J Feline Med Surg 2011; 13: 101–8.

5 Bartges JW. Feline Calcium Oxalate Urolithiasis: Risk factors and rational treatment approaches. J Feline Med Surg 2016; 18: 712–22.

6 Buffington CT, Westropp JL, Chew DJ, Bolus RR. Risk factors associated with clinical signs of lower urinary tract disease in indoor-housed cats. JAVMA 2006; 228: 722–5.

7 Porters N, Polis I, Moons CP, et al. Relationship between age at gonadectomy and health problems in kittens adopted from shelters. Vet Rec 2015; 176: 572.

8 Howe LM, Slater MR, Boothe HW, et al. Long-term outcome of gonadectomy performed at an early age or traditional age in cats. J Am Vet Med Assoc 2000; 217: 1661–5.

9 Maniaki E, Murrell J, Langley-hobbs SJ, Blackwell EJ. Associations between early neutering , obesity , outdoor access , trauma and feline degenerative joint disease. J Feline Med Surg 2021. DOI:10.1177/1098612X21991456.

10 Porters N, Polis I, Moons CP, et al. Relationship between age at gonadectomy and health problems in kittens adopted from shelters. Vet Rec 2015; 176: 572.

11 Howe LM, Slater MR, Boothe HW, et al. Long-term outcome of gonadectomy performed at an early age or traditional age in cats. J Am Vet Med Assoc 2000; 217: 1661–5.

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Dr. Philip Bushby is a board-certified veterinary surgeon. He currently holds the Marcia Lane Endowed Chair of Humane Ethics and Animal Welfare at Mississippi State University College of Veterinary Medicine, where he has served on the faculty for 42 years. For more than 20 years, his primary focus has been taking veterinary students to animal shelters in north Mississippi to provide basic wellness care and spay/neuter services.