When to Spay or Neuter a Chihuahua: Wait for Growth Plate Closure

The short version: wait until your Chihuahua's growth plates have closed. Not a birthday. Not a guess. Closure.

For most Chihuahuas that is around 12 to 14 months. That is what we see in our own dogs. It varies by dog, and the only way to know is to look.

Ask your vet for an X-ray to confirm the growth plates are closed before you schedule surgery.

What a growth plate is

A growth plate is a band of cartilage near the end of a long bone. It is where the bone gets longer. When growth is done, the cartilage turns to bone and the plate closes.

Sex hormones are the signal that tells the plates to close. Estrogen does this in both males and females. Take those hormones away early, and the plates stay open longer. The bones keep growing. In a 1991 study, puppies neutered early had later growth plate closure and longer leg bones than intact puppies (Salmeri et al.).

Why this matters in a Chihuahua

The Chihuahua knee (stifle) is a small joint with almost no margin. Patellar luxation is the most common orthopedic problem in the breed.

Whether the kneecap tracks right depends on the length and angles of the femur and tibia. Those are set when the growth plates close. Change that timing, and you change the geometry of the joint. Limbs that end up the wrong length put uneven wear on the joints for life.

A large UK study found that neutered dogs, females, and dogs below their breed's average weight each had higher odds of patellar luxation (O'Neill et al., 2016).

Hormones, Cushing's, and diabetes

When the ovaries or testicles are removed, a hormone called luteinizing hormone (LH) rises and stays high for life.

• The adrenal glands are left under constant LH pressure. That chronic demand is tied to Cushing's disease.

• High LH also appears to act on the pancreas. That is tied to diabetes, separate from weight gain (Kutzler, 2020).

• Population studies agree: neutered dogs had 2.54 times the odds of Cushing's in a study of 21,281 dogs. Neutered males had higher diabetes risk than intact males in a UK study.

This is not just something we read. We keep lifetime health records on our dogs. The ones altered too early show up more often among our orthopedic cases, and among Cushing's and diabetes cases.

Other changes with early alteration

• Urinary incontinence in females is more common with early spay.

• Weight gain is easier when metabolism drops before adult weight. Extra weight makes a bad patella worse.

• Less muscle. Sex hormones build muscle.

What we are not saying

You may read that early spay or neuter causes cancer. That research was done mostly in Golden Retrievers and Labradors. The 2020 UC Davis study of 35 breeds found risk varies by breed, and small breeds did not show the same pattern.

We will not claim a cancer risk the Chihuahua data does not support. Our reasons are bone, joints, and hormones.

Her first heat: please text us first

Most girls have their first heat between 6 and 9 months. This is when most owners panic and book the spay. A heat cycle is not an emergency. It lasts about 2 to 3 weeks.

• Use a doggie diaper or belly band. We make custom ones sized for Chihuahuas.

• A heating pad on low under her bedding helps with cramping.

• Keep her leashed outside, every time.

• No dog parks, daycare, or intact males for the full cycle.

• Foul discharge, lethargy, heavy drinking, or fever are not normal heat. That is a vet visit now.

If you want to alter and keep the hormones

• Ovary-sparing spay (females): the uterus comes out, the ovaries stay. No pregnancy, no pyometra, hormones kept.

• Vasectomy (males): he keeps his hormones and cannot sire puppies.

Not every practice offers these. Ask. We can help you find one that does.

Where your vet fits

Your vet may have a reason to recommend a different timeline for your dog. We want to hear it. Ask one question: "Can we confirm the growth plates are closed before we schedule this?"

FAQ

What age should I spay or neuter my Chihuahua? There is no set age. Wait for growth plate closure, confirmed by X-ray. For most Chihuahuas that is around 12 to 14 months.

Does early spay or neuter affect a Chihuahua's knees? Early alteration delays growth plate closure and changes bone length and angles. The Chihuahua stifle has little margin, and patellar luxation is the breed's most common orthopedic problem.

Is early neutering linked to Cushing's or diabetes? Removing the gonads keeps LH high for life, which is tied to adrenal and pancreatic disease. Neutered dogs show higher Cushing's odds in large studies.

What do I do when she comes into heat? Manage it with a diaper, leash, and no contact with intact males. Text us. Do not rush the spay.

Is there a way to sterilize without losing hormones? Yes. Ovary-sparing spay for females and vasectomy for males.

Sources

• Salmeri KR, Bloomberg MS, Scruggs SL, Shille V. Gonadectomy in immature dogs: effects on skeletal, physical, and behavioral development. JAVMA, 1991;198(7):1193–1203. Read it

• O'Neill DG et al. The epidemiology of patellar luxation in dogs attending primary-care veterinary practices in England. Canine Genetics and Epidemiology, 2016;3:4.

• Kutzler MA. Possible relationship between long-term adverse health effects of gonad-removing surgical sterilization and luteinizing hormone in dogs. Animals, 2020;10(4):599.

• Carotenuto G et al. Cushing's syndrome: an epidemiological study of 21,281 dogs. Open Veterinary Journal, 2019. Read it

• Mattin MJ et al. Diabetes mellitus in dogs in UK first-opinion practice. Veterinary Record, 2014. Read it

• Hart BL et al. Assisting Decision-Making on Age of Neutering for 35 Breeds of Dogs. Frontiers in Veterinary Science, 2020. Read it

• Von Pfeil DJF, DeCamp CE. The Epiphyseal Plate: Physiology, Anatomy, and Trauma. Compendium.