rabbit litter box training and urinary health

​Dr. Isabelle Tancioni and I speaking at Bunnyfest 2023

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This year I was invited once more to speak at Bunnyfest, a wonderful annual event celebrating all things Lagomorph. Bunnyfest is a great way for people with companion rabbits to meet local rabbit savvy vets, other rabbit enthusiasts, learn about different rabbit products and resources, and participate in lots of fun activities. All while supporting the San Diego House Rabbit Society and the critical work that they do in saving rabbits and educating the public on proper rabbit care. 

On September 22nd 2024 it was my pleasure to give a brief presentation on rabbit litter box training and urinary health. Below you can find a summary of my notes for your reference.

 Overview

• Urinary Tract Anatomy and Physiology
• Urinary Tract Disorders (symptoms, diagnosis and treatment)
• Importance of litter box training

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Urinary Tract Anatomy and Physiology

1. Kidneys: Rabbits possess a pair of kidneys responsible for filtering metabolic waste products from the bloodstream and urine production. These organs are integral to maintaining fluid and electrolyte balance within the body.
2. Ureters: The ureters are tubular structures that transport urine from the kidneys to the urinary bladder.
3. Bladder: The bladder is a muscular sac that stores urine until it is excreted.
4. Urethra: The urethra is the duct through which urine is expelled from the bladder and out of the body.

Urinary Tract Disorders in Rabbits

1. Urolithiasis and Hypercalciuria
2. Kidney Disease
3. Urinary Incontinence
4. Hematuria
5. Urinary tract infection
6. Scrotal/Inguinal Herniation of Urinary Bladder
7. Psychogenic Polyuria and Polydipsia

Symptoms of urinary tract disease may include (but are not limited to)*:

• Inappropriate urination (please note, in intact rabbits, urine spraying may be a normal sexual behavior. females reach sexual maturity at 4-6 months of age and males can try to mate as early as 3.5-4 months) 
• Urinary incontinence
• Perineal urine scalding
• Hematuria (bloody urine)
• Stranguria (straining to urinate)
• Anuria (inability to urinate)
• Pollakiuria (frequent urination)
• Polyuria (increased urine volume)
• Polydipsia (increased water consumption)
• Non-specific symptoms (depression, anorexia, weight loss, lethargy, hunched posture, teeth grinding, weight loss, unkempt apperance)

*The above symptoms may be associated with other pathologies, not necessarily relating directly to the urinary tract e.g. endocrinopathy, liver disease, toxicity, cancer, coagulopathy, neuropathy. 

1. Urolithiasis and Hypercalciuria Sludge
Also known as uroliths, stones or calculi can form in the bladder, urethra, kidneys and ureters. Rabbits with hypercalciuria (high level of calcium in their urine) have bladder “sand” or “sludge”, this is caused by excess calcium in the body, which in rabbits is excreted in the urine. Stones and sludge may cause pain, urinary blockage, and other significant health issues, such as kidney disease. However, a small amount of sand in the bladder of senior rabbits in a common incidental radiographic finding. 

Predisposing factors:

• Nutrition, diets high in calcium (e.g. high calcium greens such as kale and dandelion, alfalfa, excessive vitamin or mineral supplementation)
• Anatomy
• Infection (rarely)
• Limited exercise
• Diet of free choice pellets
• Obesity 
• Musculoskeletal pain (e.g. Osteoarthritis)
• Neuropathy (e.g. Intervertebral Disk Disease) 
• Chronic dehydration

Treatment

• Dependent on location and severity of calculi
• If hypercalciuria and/or non-obstructive stones (kidneys or ureter) are present can treat medically (aggressive fluid therapy, manual bladder expression every 2-4 days +/- urohydropulsion- bladder catheterization and flushing)
• Minimally invasive endoscopic techniques (e.g. urethral calculi)
• Surgery e.g Cystotomy (treatment of choice for large bladder stones), nephrotomy (obstructive kidney stones)
• Dietary changes (treatment and prevention)
  • Decreasing dietary calcium, e.g. avoid veggies right in calcium such as kale and dandelion 
  • Increasing water intake- best offered in water bowl
  • Feed grass hay (not alfalfa)
  • Offer only a limited amount of plain timothy hay pellets
  • Discontinue any mineral or vitamin supplements
  • +/- weight loss

2. Kidney Disease
The most common cause of kidney disease in rabbits is Encephalitozoon cunicili (a microsporidian parasite), chronic kidney disease (CKD) in senior bunnies and urolithiasis.

Predisposing factors:

• Infections (e.g. E. Cuniculi, P. multocida, Staphylococcus)
• Toxins, can cause acute kidney injury (AKI- e.g. certain antibiotics, long term non-steroidal anti-inflammatory therapy)
• Hypercalcemia
• Hypervitaminosis D
• Fatty degeneration in overweight rabbits (causes direct kidney and liver damage)
• Hydronephrosis (iatrogenic, secondary to tumor e.g. transitional cell carcinoma)
• Renal cysts (rare, usually inherited)
• Cancer (e.g. benign embryonal nephroma, renal carcinoma, renal adenocarcinoma, nephroblastoma, hamartoma and lymphosarcoma - rare)

Treatment Acute Kidney Failure:

• Aggressive fluid therapy

Treatment Chronic Kidney Failure:

• Long term subcutaneous fluid support
• +/- oral phosphate binder
• +/- antihypertensive therapy
• +/- Epipoetin alpha if anemic 
• Dietary changes (treatment and prevention)
  • Ensure adequate calcium:phosphorus ratios 
  • Decreasing dietary calcium, avoid kale and dandelion 
  • Increasing water intake- best offered in water bowl
  • Feed grass hay (not alfalfa)
  • Small amount of plain timothy hay pellets
  • Discontinue any mineral or vitamin supplements
  • +/- weight loss

3. Urinary Incontinence

Predisposing factors:

• Spinal fractures or dislocations (lumbo-sacral)
• Central nervous system lesions (e.g. E. cuniculi, Toxoplasmosis, larval migrans)
• Urinary calculi or hypercalciuria
• Ovariohysterectomy 

Treatment:

• If hormonal: Estrogen supplementation
• Daily cleaning of perineum
• Acupuncture and chiropractic care
• +/- topical treatment of dermatitis
• +/- non-steroid anti-inflammatories (if no underlying kidney disease) to control inflammation and pain
• +/- Litter box with easier access (if mobility affected)

4. Hematuria (bloody urine)
Rabbits can produce variably colored urine (from yellow to orange and even reddish-brown). This is typically caused by porphyrins in the diet (Porphyrinuria).  Antibiotics and ingestion of pine needles can produce higher urinary pigment levels. It’s important to differentiate porphyrinuria (benign condition) from hematuria (medical issue). A urinalysis is the diagnostic modality of choice in making this critical differentiation. Rarely, pigmented urine can  be associated with urobilinuria (due to an inherited or acquired disorder of the heme biosynthetic pathway).  

Bloody urine can originate from the urinary or genital tract. 

Predisposing factors for urinary tract bleeding:

• Urolithiasis
• Cystitis
• Bladder polyps (+/- bacterial infection with Enterocossus or Proteus species)
• Pyelonephritis (kidney infection)
• Kidney infarcts
• Disseminated Intravascular Coagulation (DIC)
• Lead Toxicity

Predisposing factors for genital tract bleeding:

• Cancer (adenocarcinoma)
• Polyps
• Abortion
• Endometrial venous aneurysm​

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5. Urinary Tract Infection (UTI)
Although less common in rabbits than in some other mammalian species, UTI’s can occur. 

Predisposing factors:

• Urine retention
• Urolithiasis
• Hypercalciuria
• Chronic dehydration
• Ascending infection from lower urinary tract
• Polyps

Treatment:

• Antibiotics
• +/- treatment of any other urinary issues e.g. urolithiasis

6. Scrotal/Inguinal Herniation of the Urinary Bladder
Male rabbits are at increased risk as they have open inguinal canals throughout their life. 
It typically presents as a unilateral swelling in the scrotum and/or inguinal region. In female rabbits a unilateral inguinal swelling is typically observed. Female rabbits can also evert their bladder through the urethra. These rabbits also often have urolithiasis and/or hypercalciuria. It's important to rule out herniation of other organs e.g. digestive tract, tumors. 

Treatment:

• Surgery (Herniorrhaphy)

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7. Psychogenic Polyuria and Polydipsia (PU/PD) 
​Healthy rabbits can drink ~20-130 ml/kg of water and produce ~20-100 ml/kg daily, this can vary based on their diet. Anything is excess of the above numbers would be considered PU/PD. 

Treatment 

• Psychogenic PU/PD is an uncommon diagnosis of exclusion. It is typically due to boredom and as such may improve with environmental enrichment. 

Diagnosis of Urinary Tract Disorders:
As you can see from the above information there is a lot of overlapof symptoms and pre-disposing factors with the various urinary pathologies. Some rabbits can even have multiple issues concurrently. As such, veterinarians typically start with baseline diagnostics  (Items 1-4 below), and move onto move advanced +/- more invasive diagnostic procedures as needed (and based on findings on initial testing). 

1. Physical exam
2. Bloodwork: Hematology and serum biochemistry help to evaluate renal function. 
3. Urinalysis: to evaluate urine for presence of bacteria, inflammatory cells, blood, casts. If present, a urinary culture will be recommended
4. X-rays: may show bladder sludge, urinary stones and masses. Also important for evaluating size and shape of the kidneys (may be smaller) and evidence of osteosclerosis (increased bone density) and calcification of certain organs, common with chronic kidney disease.  
5. Ultrasound:  more sensitive than x-rays at evaluating kidney structure and other organs. 
6. CT Imaging: even more sensitive than x-rays and ultrasound at evaluating kidney structure and other organs. 
7. +/- Dynamic Computed tomography (CT) to evaluate glomerular filtration rate
8. +/- Intravenous pyelogram or renal schintigraphy (if renal calculi are present): to evaluate renal function
9. +/- Urinary stone analysis 
10. +/- E. Cuniculi panel
11. +/- Kidney Biopsy
12. +/- Blood Pressure Measurement: rabbits with CKD are prone to hypertension

Importance of litter box training
From a veterinary medical standpoint, having a rabbit that is trained to eliminate in their litter box is extremely helpful in monitoring for any changes in urine and fecal output, which are key in early disease detection and intervention. Other reasons for having a litter box trained bunny include:

• Preventing house soiling (common reason for animals being surrendered to shelters)
• Supports clean and hygienic environment. Litter boxes that are left unchanged for days on end can build up dangerously high levels of ammonia that are irritating to the rabbit's sensitive respiratory tract. A dirty litter box can also cause urine and fecal scald (when feces and urine accumulated on the rabbit's coat and literally burns their skin). 

Litter Training Box Tips

• Choose a box that's spacious enough for your rabbit to move around. A large or extra large plastic cat litter box works best.
• Make sure the sides of the box are low enough so your bunny can get in and out easily.
• It is helpful to put some of the droppings in the box.
• In households with multiple rabbits, provide one more litter box then the number of rabbits.
• Apart from medical causes, litter box avoidance can occur secondary to a fearful stimulus in the vicinity of the litterbox as well as  environmental changes (e.g. new animals or people in the home). 
• Place your rabbit in the box after meals and when they wake up, as these are common times for them to relieve themselves.
• Use paper-based (best) or aspen bedding. Avoid clumping cat litter, clay, or pine, as they can be harmful to rabbits. Compressed wood pellets can be an affordable option. 
• Place a large handful of hay at one end of the litter box over the bedding (the ‘kitchen end’), rabbits usually pass stool while they are eating.
• Place the litter box in a corner of the area where your rabbit spends the most time. Rabbits naturally tend to use corners for bathroom purposes.
• If your rabbit uses the box, reward them with a treat or gentle petting. Positive reinforcement helps them associate the box with good things.
• Accidents are normal, especially at the beginning. If your rabbit goes outside the box, gently place them in it and encourage them to use it.
• Keep the box clean by removing waste daily and changing the litter regularly. This encourages your rabbit to continue using it.
• If your rabbit is not spayed or neutered, consider this. It can significantly reduce territorial marking and help with litter training.
• If your rabbit consistently avoids the box, try different locations or types of litter to see what they prefer.

Please refer to the San Diego House Rabbit Society's website for additional information on litter box training.

If you are looking for a rabbit savvy vet, I am currently seeing bunny patients at the following veterinary hospitals:

• Feathers and Fur Animal Hospital:

​         (RHDV2 Vaccine Available)​​
         P: (619) 465-4600
         A: 7750 University Ave STE A, La Mesa, CA 91942

• Companion Pet Care 

         P: (760) 942-1220
         A: 222 N. Coast Hwy 101, Encinitas, CA 92024

References

• Reavill, D.R. and Lennox, A.M., 2020, "Disease Overview of the Urinary Tract in Exotic Companion Mammals and Tips on Clinical Management", Veterinary Clinics of North America Exotic Animal Practice, 23 (1), pp. 169-193. 
• Quesenberry, K., et al., 2020, "Ferrets, Rabbits, and Rodents- Section II, Rabbits, 16: Disorders of the Urinary and Reproductive System", Elsevier (4th Edition). Elsevier - OHCE.
• Brooks, E.E., 2024, "Kidney Disease, Chronic in Rabbits (Exotic Pets)", VINcyclopedia of Diseases.