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The progressive syndrome of acquired dental disease (PSADD)

Although congenital incisor malocclusion, trauma or cancer can cause dental problems, most cases of dental disease in rabbits are due to a progressive syndrome that is linked with an inappropite diet, especially muesli mixes. This is an acquired problem i.e. the rabbit was born with good dentition but developed problems later in life. The acronym PSADD is used to describe this Progressive Syndrome of Acquired Dental Disease. These images in this gallery show some of the characteristic pathological, radiological and clinical features of PSADD.

Appearance of normal lower cheek teeth

This image shows the left side of the oral cavity of an anaesthetised rabbit. The mouth is held open with a gag and cheek dilators. The tongue has been pushed to one side with a pair of curved scissors. A reflection of the teeth is mirrored on the scissors. The appearance of the cheek teeth can be seen. The enamel ridges that run across the centre of each cheek tooth form a series of vertical points. These are normal. The teeth are all the same height so the zigzag occlusal pattern is regular. The brown staining is from plant pigments.

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Normal incisors

These incisors are a normal shape and have smooth shiny enamel and no ridges. The tips are sharp. The tips of the lower incisors rest against the peg teeth behind the large upper incisors.

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Early dental disease-labelled

This image shows some of the characteristic features of early dental disease. There is apical elongation. The deree of apical elongation is not constistent in all the teeth. The yellow arrow points to an elongated root of a second mandibular cheek tooth that has perforated the mandibular bone and will be palpable as a swelling along the ventral border of the mandible. The blue arrow shows elongation of the maxillary cheek teeth that are filling the alveolar bulla. There is also evidence of enamel loss as the longitudinal lines of the central enamal folds in the mandibular cheek teeth are lost (green arrow)

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Enamel ridges on normal shaped incisors

This image shows the incisors that have a normal shape, length and occlusion but have deep horizontal ridges in the enamel. These can be felt when a thumbnail is run up and down the teeth. These ridges are indicative of enamel hypoplasia that cannot be caused by inadequate, or lack of, dental wear. Calcium and/or vitamin D deficiency are msot likely to be responsible.

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Mild epiphora

This rabbit has mild epiphora.There was no conjunctivitis and no pus could be expressed from the lacrimal sac by applying pressure to the medial canthus of the eye. Tears were overflowing down the face because the tear duct was blocked by the apex of the large upper incisor that was elongated.

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Acquired incisor malocclusion

This lateral skull radiographs shows a rabbit with incisor malocclusion as part of the progressive syndrome of acquired dental disease (PSADD). The change in the relative position and shape of the upper and lower incisors has resulted in the teeth failing to meet and wear against each other. The shape and position of all the teeth has altered. There is apical elongation of all the teeth. The pulp cavities in the incisors are small. The occlusal surfaces of the cheek teeth have lost their normal zig zag appearance. The enamel folds in the centre of the teeth are indistinct or absent.

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Elongated upper cheek tooth

This picture shows an elongated first upper cheek tooth. It was growing into the cheek and causing discomfort when eating. The crowns of the remaining upper cheek teeth are normal in length. Only the elongated tooth required shortening.

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Incisor malocclusion

Malocclusion develops when the upper and lower teeth fail to meet properly. In species, such as rabbits, with teeth that continually erupt and grow, malocclusion is a problem because the teeth are not worn down by contact with the opposing teeth so they become elongated and may grow into the gum.

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Mandible of rabbit with spurs on cheek teeth

This mandible of a rabbit with spurs on the cheek teeth shows the change in shape of the teeth and surrounding jaw. The bone is transparent. The teeth are curved along their entire length and the shape of the jaw has changed accordingly. The exposed crowns of the teeth are curved, rather than elongated, which is why the dental spurs are present. Apical elongation is evident and has resulted in swellings along the ventral border of the jaw. These changes are irreversible and cannot be cured by dentistry. Treatment can only be palliative rather than curative.

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Spur lacerating tongue

This rabbit was salivating profusely because a cheek tooth was so curved that the lingual edge of the tooth had formed a spur that was lacerating the tongue.

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Spurs on very short crown

The rabbit in this image required dentistry every 3-4 weeks. The 3rd lower cheek tooth was so curved that it would grow into the sensitive mucosa under tongue. The spur was not a result of elongated crowns on the cheek teeth. All the crowns are short.

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Advanced dental disease

This lateral skull radiograph of a Netherland Dwarf shows the typical changes of the advanced stages of dental disease. There is apical elongation of all the teeth. The occlusal relationship of the upper and lower teeth is abnormal. The teeth have an amorphous structure rather than having a distinct pulp cavity and lines of enamel. The white line (lamina dura) that outlines the socket is irregular or absent. These teeth will be growing slowly or not at all. There is contact between the upper and lower teeth so they will have some function but the teeth are not good enough to bite through hay and other tough foods.

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Cheek teeth of rabbit with dental disease

This photo shows the inside of the mouth of a rabbit that is suffering from the progressive syndrome of acquired dental disease (PSADD). The shape, position and the structure of the teeth is abnormal. Although the teeth can be reshaped to remove the sharp edges, it is impossible to restore normal occlusion.

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Skull showing many of the features of PSADD

This skull shows many features of the progressive sundrome of acquired dental disease. The bone is translucent, indicating osteopaenia. The shape and structure of the teeth is abnormal. The jaws are deformed. Many of the teeth have broken. These changes are irreversible.

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Annotated skull showing features of PSADD

This skull shows many of the changes that take place during PSADD. The white arrows point to elongated apices of the cheek teeth. The blue arrows point to deformed sections of bone over curve roots of the teeth. The turquois arrow points to a poorly enamelled tooth with ridges on its surface, The green arrows point to loss of alveolar bone supporting the teeth. The yellow arrow points to translucent bone. The black arrow points to gaps where crowns have broken off some teeth and the red arrows points to deformed bone over distension of the maxillary sinus caused by onstruction of the nasolacrimal duct.

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Appearance of crowns in advanced stages of dental disease

This image of the inside of the mouth of a rabbit with dental disease shows the upper arcade of diseased teeth. They are discoloured and misshapen but are not causing any soft tissue damage. These changes are irreversible and will affect a rabbit's ability to eat hay. Corrective dentistry or a hay only diet will only add to the rabbit's problems. A soft diet of nuggets and soft leafy green foods will extend the rabbit's life.

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Skull of a rabbit with very advanced dental disease

This skull shows the change that take place in the teeth and bones of rabbits in the end stages of the progressive syndrome of acquired dental disease (PSADD). The crowns of the teeth have either broken of or are disintegrating. The apices of the teeth are long and the bone is very thin. A more detailed description of the changes can be seen on a copy of this image that has arrows on it to highlight the changes..

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Description of the features of advanced dental disease

This image of the skull of a rabbit in the advanced stages of dental diseases has had arrows added to highlight the changes that have taken place. The GREEN arrows point to the elongated, calcified apices that have penetrated the alveolar bulla into the orbit. These teeth are ankylosed into the bone. The BLUE arrow points to the apex of the second upper cheek tooth that has penetrated the zygomatic prominence of the maxilla, which is the place that an elongated apex of this tooth always appears. The BLACK arrows point to crowns that have broken off completely. The PINK arrows point to two teeth with remaining crowns: a peg tooth and part of the second lower cheek tooth. The peg tooth still has enamel is the only crown that looks relatively normal. The crown of the second cheek tooth has split and fallen apart. The RED arrows point to thin translucent bone, which is always a feature of skulls of rabbits with advanced dental disease.

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Advanced dental disease- crown loss

This image shows the inside of a rabbit's mouth in the most advanced stages of dental disease. The crowns have broken off the upper arcade of teeth and the gums have healed. The rabbit could only eat soft food such as soaked nuggets and banana.

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Mucosal (gum) flap

In some rabbits with advanced dental disease where the crowns of either the upper or lower teeth are short so they do not meet correctly, a gap can form between the teeth and a flap of mucosa may form (arrow). This flap can catch between the teeth and become ulcerated and sore. In this rabbit, there was also an inflamed area on the inside of the cheek that was associated with an abscess resulting from a penetrating injury from a dental burr. The crowns of the teeth had been taken down to gum level.

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