25 Apr 2011
James Grierson discusses approaches to such cases, taking into account any neurological considerations.
Amber Carswell
Job TitleTail pull injuries frequently occur in conjunction with pelvic trauma, and are often accompanied by damage to the nerves supplying the tail, bladder, perineum and anus. Careful assessment, consisting of an accurate and focused neurological examination to grade the severity of the injury, provides the clinician with information on prognosis to help guide the client.
Accurate assessment of the perineal reflex is an important aspect of this neurological assessment. Appropriate bladder management in individuals with an inability to urinate either through regular expression or cystostomy tube placement, is an important part of management in the weeks following trauma. Surgical stabilisation of some tail pull injuries may reduce pain and discomfort associated with the injury, but has little effect on the ability to regain urinary function. Recent studies have shown that up to 80% of cats with a floppy tail will regain urinary function, so the prognosis is not always poor.
Tail pull injuries are frequently seen in general practice and often present the clinician with some challenging decisions.
The aim of this article is to provide practical advice for managing these injuries. Tail pull injuries in cats often occur in conjunction with pelvic trauma and can be accompanied by damage to the nerves supplying the tail, bladder, perineum and anus. This article looks at the initial assessment of these injuries, including the key parts of the neurological examination that can assist in prognosis.
The surgical management of specific injuries is discussed, as well as the short and long-term medical and surgical management options for the consequences of tail pull injuries.
In cats, the nerve roots of L4-S3 form the pelvic plexus supplying the hindlimbs, bladder, rectum and perineal region.
These nerve roots form the part of the cauda equina, running in the vertebral canal from L5 into the sacrum. The bladder is innervated by the sacral and pudendal nerves from the pelvic plexus and, as the function of the bladder is an important prognostic indicator, a knowledge of anatomy is relevant.
Types of injury that are typically seen include:
• sacrococcygeal luxation
• fracture between the second and third sacral fragment
• endplate fracture of the third sacral bone – endplates close around 18 months, predilection site for fractures
• luxation/separation of coccygeal vertebrae
The vast majority of injuries are secondary to road traffic accidents. Consequently, it is important to be aware that most patients will have concurrent injuries of the pelvis and/or hindlimbs. These concurrent injuries will need to be managed before knowing whether bladder function may return, and owners need to be fully informed at all stages as to the likely prognosis.
Regardless of the specific type of injury seen, traction to the tail base results in nerve root damage and the potential for myelomalacia of the sacral and caudal lumbar spinal cord segments.
It is easy to assume that a cat with a floppy tail can only be a tail pull injury, but this is not the case. Important differential diagnoses include:
• tail pull injury (traction injury to nerve roots)
• disc disease (compressive injury to nerve roots)
• lymphoma (compressive injury to nerve roots)
Spending time taking a thorough history – along with performing a complete physical examination, including neurological assessment – is essential. While lymphoma and disc disease are not common, they should be considered when a case doesn’t seem to quite fit the clinical picture. In these cases, where the answer is still unclear, further advanced imaging – such as CT/MRI – may be needed to achieve a definitive diagnosis.
Presentation can be variable, depending on concurrent injuries and the severity of the neurological involvement. Signs include:
• local hyperaesthesia
• flaccid tail paralysis
• swelling around the tail base
• dribbling urine
Key point: urine found in a kennel overnight is not indicative of urinary function. To be certain, the animal must be seen to consciously urinate in its tray or a corner of the kennel.
In the vast majority of cases, plain radiographs are sufficient in terms of imaging (Figures 1 and 2). Radiographs of this area are always best taken under general anaesthesia to facilitate positioning – don’t be tempted to cut corners with poor imaging. While the lateral view is often the most useful and informative, always take an orthogonal view, as there may be concurrent injuries. Remember to centre over the area of interest and, if the exposure or positioning is poor, have another go. In some cases, radiographs may look normal where the bones have displaced and returned to a normal position.
Performing a neurological examination is often thought of as quite daunting for most clinicians; the good news is that in these cases the examination is simple and generally easy to interpret. This is a key step in investigating and managing these cases and must include:
• motor and sensory function of the tail – easily assessed with pinch; work from caudally up to tail base
• motor and sensory function of the pudendal nerve (S1-S3) – perineal reflex
This involves stimulation of the perineal area to elicit contraction of the anal sphincter and flexion of the tail. Typically a haemostat is used to “tickle” the perineal area (Figures 3 and 4). Absence or depression of the reflex indicates a pudendal nerve or sacral spinal canal lesion. An atonic anal sphincter and urinary incontinence are present in complete pudendal or sacral lesions.
Following neurological assessment, tail pull injuries can be categorised using a five-point grading system (Table 1). Using this grading scheme helps with defining a prognosis and advising clients. The clinician should remember that not all cats have read the textbooks and, therefore, this is used as a guide only.
A more recent and simplified scheme has been devised for assessing these injuries, based simply on the presence/absence of tail base pain sensation.
A haemostat is placed across the tail base to assess for deep pain (remember, you are looking for evidence of a pain response – not just a reflex twitch). In the study, there was 100% recovery within three days in all cats with pain sensation1.
While this scheme is quite simplistic, it does provide a good starting point.
The prognosis for tail pull injuries is extremely variable, and it is a widely held misconception that if a cat has a floppy tail and cannot urinate, it may as well be put to sleep. In one study, 80% of cats presenting with tail pull injury recovered urinary function1. Unfortunately, a number of cases will have serious dysfunction that ultimately results in euthanasia. The important thing is to fully evaluate each patient first – if unsure, it is best to give it the benefit of doubt before proceeding.
Cats with only tail paralysis frequently recover after conservative and surgical stabilisation.
In cases with a paralysed tail, it is worth considering tail amputation to reduce traction on the nerve roots. An alternative is to wait six weeks and then perform amputation if motor and sensory function is not regained.
Surgical stabilisation is rarely considered for tail pull injuries. While surgery does have some benefits, it does not seem to have a significant effect on regaining the ability to urinate.
Benefits of surgery include:
• restoring the pelvic diaphragm
• preventing further neurological damage due to traction on nerve roots during the healing period
• improved return of motor function
• reduced long-term hyperaesthesia
Stabilisation of sacrococcygeal fractures and luxations can be performed, with the cat in ventral recumbency and using a dorsal approach. For sacrococcygeal luxation and endplate fractures, a suture sling is placed through the base of the spinous process of S2 and around the transverse process of the first coccygeal vertebra. For transverse fractures of S2 and S3, a suture sling can be placed between the dorsal spinous processes of S2 and S3. Readers are referred to surgical texts for a more detailed description of this technique2.
The degree of postoperative management required will be dependent on other injuries, but, more critically, on the cat’s ability to urinate. For animals that are unable to urinate, management is either medical or surgical.
For medical bladder management, manual expression of the bladder should take place at least three to four times per day to prevent over-distension and urinary infections.
Most bladders are easy to express due to lower motor neuron lesions of the pudendal nerve. Some cats show normal sphincter tone or reflex dyssynergia.
Placing a urinary catheter with a closed collection system is good for continuous drainage of hospitalised patients requiring short-term management.
Drugs for use with reflex dyssynergia include:
• phenoxybenzamine (0.25mg/ kg to 0.5mg/cat PO bid), which is used to relax the internal sphincter. It can cause miosis (small pupils) and needs to be used for five days before evaluating efficacy
• bethanechol chloride (0.1mg/kg to 0.2mg/kg PO q8h), which enhances bladder contractility and should only be given after urethral relaxation. Side effects include salivation, bradycardia, vomiting and diarrhoea, as it is a muscarinic agonist (reverse with atropine)
For surgical bladder management, placing cystostomy tubes is a relatively simple technique that can be very useful for longerterm management of cats with inability to urinate.
The basic surgical plan for cystostomy tube placement is:
• caudal mid-line laparotomy
• purse-string suture placed in ventral aspect of bladder towards the apex – 3-0 PDS or equivalent
• catheter advanced through stab incision in the body wall lateral to surgical approach
• catheter inserted into the bladder through a stab incision in the middle of the pursestring suture
• if a Foley is placed, a bulb is filled with water
• purse-string suture in bladder tightened
• bladder attached to body wall using four mattress sutures between the bladder wall and the transverse abdominal muscle
• the tube can be wrapped with omentum
• tube secured to skin using Chinese finger trap suture
• routine abdominal closure
Cystostomy tubes are generally well-tolerated by cats, but obviously they need to be kept indoors and confined to the house to avoid inadvertent removal.
Once you have placed a cystostomy tube or in-dwelling catheter, or you are expressing regularly, you need a plan for the patient.
Most texts quote allowing approximately three to four weeks for the return of urinary function. My preference is to try to give cats as much time as possible, and I will typically allow four to six weeks. Obviously, this is patient-dependent and some cats may not tolerate management of their bladder to allow this.
Following four to six weeks of bladder management, I hospitalise the cat and stop draining the bladder. It is important to monitor urination and bladder size carefully at this point. I would expect most cats that are going to regain bladder function to urinate within 36 to 48 hours.
Unfortunately, at this point, there will still be a number of cats that will not regain the ability to urinate. Options include euthanasia or a permanent cystostomy tube3. However, factors to take into account with the latter include:
• they are generally well-tolerated
• not ideal for very active/ outdoor cats
• complications will develop in about 50% of cases – most are manageable
• major complications include tube removal and chewing
• minor complications include infections, or inflammation around stoma.
Clinicians and owners need to be aware of a number of potential complications. These include:
• tail necrosis (which can occur after surgical or conservative management and necessitates amputation)
• faecal incontinence (rarely a problem due to functional intrinsic innervation of the colon and rectum
• constipation (occasionally seen and managed by dietary means, laxatives and enemas if necessary).
These cases are not as difficult to assess or manage as you might first think. The assessment is relatively straightforward and there are clear management paths to follow. In conclusion, I find the following points are useful:
• look out for the presence of concurrent injuries
• perform a thorough neurological assessment
• allow time before deciding if function will return
• be ready to manage concurrent injuries before urinary function returns
• keep owners aware of the prognosis.
