Snake Morphs and Inherited Problems: Wobble, Kinks and Lethal Genes

Quick answer

Colour and pattern in snakes are produced by genes that do more than colour. In some morphs, that is exactly the problem.

Morphs are inherited colour and pattern variants. Most are harmless. A small number carry neurological or structural problems that come with the gene and cannot be bred out of it, and a few combinations kill the embryo before it hatches.

This matters when you buy, when you breed, and when a snake starts corkscrewing its head and you need to know whether you are looking at genetics or at a disease that will kill it.

• Spider ball pythons show a head wobble to some degree. It is part of the gene, not a husbandry fault or a sign of illness.
• Some genes have no viable homozygous form, which is why certain pairings produce dead eggs.
• Kinked spines, duckbilled heads and infertility are documented in specific ball python combinations.
• Neurological signs that appear later in life, and that get worse, are not morph wobble. They need investigating urgently.
• The single most useful question to a seller is which genes are in the animal, not what the morph is called.

Decide in 60 seconds

Why a colour gene can affect the nervous system

Colour and pattern in a snake come from pigment cells that form early in development, in a band of tissue called the neural crest, and then migrate outward to their final positions.

The neural crest is not only a pigment factory. The same population contributes to parts of the nervous system and other structures. A mutation that alters how those cells develop, survive or migrate can therefore change more than colour.

This is not unique to snakes. The pigment linked deafness of white cats, of some dog breeds and of white marked ferrets works the same way. In snakes the visible outcome is different, but the biology is the same.

What this does not mean.

It does not mean all morphs are unhealthy. The great majority of colour and pattern genes in captive snakes carry no known health effect at all, and a normal looking wild type snake can be just as prone to husbandry disease as any morph.

The problem is specific genes, and they are known by name.

The documented ones

The same pattern exists outside snakes. In leopard geckos, the enigma trait is associated with a neurological syndrome, and the lemon frost line has been linked to skin tumours arising from pigment cells. If you are choosing any reptile by appearance, look up the specific gene rather than the marketing name.

Telling morph wobble from disease

Watch the head at rest and during a feed. Morph wobble is a tremor and a loss of head control; it does not change how the eyes look or how the animal breathes.

This is the part that matters clinically, because the two look superficially similar and lead to completely different actions.

Morph linked wobble.

Present from hatching or from the first weeks. Non progressive over years. Fluctuates with arousal: worse when the snake is stressed, excited, hungry or feeding, and often barely visible when it is settled. The snake feeds, grows, sheds and behaves normally otherwise.

Disease.

New onset in an animal that did not previously do it, or a steady worsening. Look for the accompanying signs: regurgitation, weight loss, stargazing that persists at rest, an inability to right itself when turned over, abnormal shedding, mouth lesions, or breathing noise.

Inclusion body disease in boas and pythons is the classic example, and it can appear long after purchase. Severe mite infestation, overheating, head trauma, septicaemia and neurological infection all belong on the same list.

The test that separates them in practice.

History and progression, not appearance. If you cannot say with certainty that the animal has always done this, treat it as disease and get it examined.

Living with a wobbling snake

Most wobbling snakes do well. The adjustments are small and specific.

Feeding.

The main practical risk is a missed strike. A snake with poor head control can strike short, strike past the prey, or grab itself. Offer prey with long tongs, feed in a container with room to manoeuvre, and stay to watch.

Never leave live prey with any snake, and particularly not with one that may misjudge a strike. A rodent left with a snake that has failed to kill it can inflict serious wounds.

Enclosure.

Keep climbing opportunities low and landings soft. Avoid tall stacked decor that a snake with poor coordination can fall from. Secure hides so they cannot shift and trap the animal.

Handling.

Short, low sessions over a supported surface. Stress makes the wobble worse, so a snake that is corkscrewing during handling is telling you the session should end.

Breeding.

Do not. Wobble genes are passed on with the colour, several combinations are lethal in the egg, and a hatchling with a kinked spine has a poor life ahead of it. Some organisations have already taken a position on this: the International Herpetological Society banned spider ball pythons from its shows in the UK.

The failure modes of the usual advice

"Good husbandry will fix the wobble."

It will not. Temperature, hydration and supplementation are worth getting right for every snake, but a gene linked wobble is structural. Owners who chase it through husbandry changes usually end up cycling through setups while the animal stays the same.

"Wobble is just cosmetic, it does not affect the snake."

Mostly it does not, and many affected snakes live full lives. But a snake that cannot control its head during a strike is at real risk of injury, and severe cases can struggle to feed. Treat it as a management requirement rather than as nothing.

"The breeder said it grows out of it."

It does not grow out of it. Some animals appear better as adults because they are calmer and better handled, and that is a change in arousal rather than in the gene.

"It is only a problem if you breed it."

Breeding makes it a problem for a new generation, but the animal in front of you still has it. Both things are true.

"Any wobble means inclusion body disease."

The reverse error. A spider hatchling that has always wobbled does not need an emergency workup. What it needs is an accurate record so that a genuine change is recognised later.

"A pretty morph is a healthy morph."

Appearance carries no information about the gene behind it. Two animals that look identical can carry different combinations, and the trade name will not tell you.

What the vet will want to know

What never to do

Do not breed an animal with a known lethal or deforming gene combination.

Do not leave live prey unattended with any snake, and least of all with one that has poor head control.

Do not assume a new neurological sign is the morph.

Do not house a wobbling snake with other snakes. Cohabitation is a poor idea generally and worse for an animal that cannot judge a strike.

Do not buy on a photograph. Ask for movement, feeding and a spine you have felt with your own hand.

When to get help

A snake with a lifelong wobble that eats, sheds and holds its weight needs management rather than treatment. One that has changed needs a vet.

Contact a reptile experienced veterinarian promptly for any neurological sign that is new or worsening, for stargazing that persists when the animal is undisturbed, for an inability to right itself, or for repeated regurgitation.

Contact them within the week for a snake that is missing strikes or failing to feed, for a spinal kink that appears to be affecting movement or shedding, and for any shed that is repeatedly incomplete in a reduced scale animal.

Before you buy, take the time to write down the genes and look each one up. This is the one health problem in snake keeping that is entirely avoidable at the point of purchase.