Advanced Health Check Guideline: A physical assessment of the pet rat

This guideline incorporates a more advanced method, along with the basic health check, of physically assessing your pet rat.

Rats often don’t exhibit sign of illness until they are well into a medical emergency. It is important to check your rat often for any medical abnormalities.

Any time that you handle your rat is an opportunity to check it for problems. Awareness of your rat’s physique and behavior will help you see any changes that indicate the need for a trip to the veterinarian.

Health checks are easier if your rat is a willing subject. It is helpful to get your rat used to being checked and to being held on its back.

Emergency situations should be managed and the rat stabilized before proceeding with a total physical assessment. How you begin your assessment should be no different for a rat than it would be for any victim of emergency. Treat the life threatening event first remembering to follow the ABC’s of emergency care by assessing their Airway, Breathing and Circulation.

For rats that are elderly or debilitated the health check should begin with the areas or systems most affected, and the rat should be permitted short rest breaks during the health check in order to minimize any stress to the animal.

*A note for veterinarian: because a rat may often be or become hypothermic when sick, injured, or debilitated, it is important to place a towel (or warmed towel) on a cold, metal, exam table before placing the rat on the table.

Weight

1. Female adult: average weight: 225 to 400 grams
2. Male adult: average weight: 250 to 550 grams
   Slight variation in average weights may occur among strains of rats and be normal.

   Abnormal: chronic weight loss, rapid/acute weight loss, rapid/acute weight gain, gradual weight gain often indicates developing obesity.
   
   Weight is an important factor, and weight loss can often be a first indicator of developing illness in the rat. It is also an important factor when determining the correct dosage to be used should your rat require any medication for illness.

Temperature

• Normal: 37.5 to 38 degrees centigrade
  Tympanic membrane thermometer can be used safely and accurately. If attempting to do a rectal temperature, it is advised to use a flexible thermometer with careful minimal insertion, while the rat is calm, to prevent injury.

  Abnormal: hypothermia, hyperthermia.
  
  Get to know what your rat’s normal temperature “feels” like so you can recognize when the rat is too cool to the touch or fevered.

History

The following should be considered when determining health status of your rat.

1. Age of rat
2. How long you have had the rat and previous background
3. Additional cagemates and their health status
4. Housing conditions
   1. cage size and type, is the rat allowed supervised free-range time
   2. cage hygiene (cleaning frequency and type of cleaning agents used)
   3. litter type
   4. bedding type and type of detergent used for washing
   5. environmental temperature, humidity, and periods of light and dark provided in room
5. Watering System (water bottles or bowls)
6. Diet
   1. type
   2. amount offered
   3. frequency given
   4. how much consumed at each frequency
   5. if supplements or vitamins
7. Has the rat had previous illness, taken medications, or currently on medications?

Head

1. Behavioral/Neuro: Alert, bright-eyed, inquisitive, explorative, aware of surroundings, carries head in normal position. Swaying of head can be a normal behavior in many rats, due to their poor vision, and aids in perception. Arching (lordosis), skittish when touched on the back, and vibration of ears in the intact female rat is normal behavior during estrus.

   Abnormal: Lethargy, agitation, restlessness, circling in relation to illness. The absence of movement of facial whiskers (vibrissae). Jerking/seizures, paresthesia, paralysis. Biting in an otherwise docile rat, abnormal permanent one-sided tilt to head.
   

2. Eyes: Symmetrical, clear, bright, pupils equal and responsive. Eyes should be free of discharge (porphyrin: rust-colored tears), crusting, or cloudiness in the cornea or in the lens.

   *Note: That cloudiness in the lens can be a common finding in older rats.
   
   Abnormal: Red or yellow discoloration of sclerae, cloudiness, ulcerations, protrusion/swelling, enophthalmia (small recessed eye), microphthalmia (small eye), sunken eyelids.
   
   Bulging eyes may be indicative of SDAV infection, tumors, or an abscess behind the eye.
   
   *Note: Porphyrin can be distinguished from blood as it will fluoresce when using a Wood’s lamp, and blood will not.

3. Ears: Clear, no obstruction, pink: no paleness or cyanosis.

   Abnormal: Discharge, odor, growths/protruding mass, crusting, or hardening of pinna (tips of ears). It is important to smell the ears when doing health checks as this can be one of the signs of ear infection. In addition ear infections can many times be accompanied by a head tilt.
   
   *Note: Swelling near base of ear may indicate a Zymbal’s gland involvement (e.g., tumor, abscess). In some cases fur loss at the base of the ear may be present.

4. Mouth/Teeth: Aligned, yellowish tinge of teeth enamel in adults, gums pink: no paleness or cyanosis. No difficulty with appetite/eating.

   Abnormal: Misalignment, lost tooth, brittle pure white teeth, swelling, redness, pus, foul odor, persistent drooling/wetness around mouth, cyanosis or paleness of lips or gums.
   
   *Note: Incisors should be even, not too long, and not piercing the cheek or gum.
   
   Oral infections can be aggressive and need early medical intervention to be resolved. Be sure rat is able to eat.

5. Nose: Clear, air-movement in and out of nose freely, free of discharge (e.g., porphyrin: rust-colored drainage).

   Abnormal: Porphyrin (rust-colored) staining that remains around the nose, or is excessive. Noisy nasal breathing (e.g., snuffling).

6. Cheeks/Neck: No growths, swelling, or distention.

   Abnormal: Edema/swelling near cheeks below ear may indicate infection (e.g., abscess) or tumor. Swelling of neck may be indicative of SDAV infection, or if more localized, tumor formation.

Respiratory

• Breathing:
  Learn to spot symptoms of respiratory infections before they become advanced to the point of emergency intervention.

  Normal breath sounds in the rat are relatively quiet. Rats are obligate nose breathers and breathing is done primarily through the nose until there is respiratory compromise. The normal respiratory rate is 71 to 146 depending on size of rat.
  
  Abnormal: Wheezing, congestion, clicking noises (can also be present during sleeping). Labored breathing requiring the use of accessory (abdominal muscles) muscles to help assist breathing, retracting (a sucking in of the sides of the chest), gasping (open mouth breathing), sputum.
  
  Head tucking and extending accompanied by drooling can indicate choking.
  
  A rat with a respiratory infection often exhibits other signs that may include; discharge (e.g., porphyrin: rust-colored staining) from the eyes or nose, poor appetite, hunched posture, or puffed up fur (piloerection). The rat will need to be seen and treated by your veterinarian. Signs that appear to be respiratory related may also involve the heart.

Cardiovascular

• Heart: Normal heart rate in the rat is 250 to 493 beats per minute.

  Abnormal: slow heart beat, missed heart beats, rapid heart beat faster than normal rate.

Body

• Body contour: Carefully massage the rat’s body starting at head and working towards tail, including under forelimbs, area of mammary chains, abdomen, and along groin and hindlimbs with your fingers.

  Abnormal: Lumps, edema/swelling, enlargement of liver, spleen, kidneys, areas of sensitivity/pain, emaciation and or cachexia, loss of fat and or muscle mass, rashes, cuts, bite wounds, bruising.
  
  *Note: Detecting if lumps feel connected to the skin or are moveable under the skin, and whether painful versus non-painful, may be of help in determining whether the lump is a tumor, abscess or cyst.

GI/GU (gastrointestinal and genitourinary) Area

1. Abdomen: Soft, non-distended.

   Abnormal: Hard, bloated, distended, swollen, sunken.
   

2. Bowels: Feces formed, brown in color.

   Abnormal: Diarrhea, bleeding, rectal protrusion, lacking color, dry and flaking, unusually foul smelling.
   
   *Note: Constipation may be present in rats that are dehydrated.

3. Urinary: Clear yellow urine.

   Abnormal: Excessive urination may indicate diabetes, or glomerulonephrosis. Decreased urine, absence of urine, or dark concentrated urine may indicate dehydration, and or renal failure.
   Bleeding may indicate infection or stones. Hunched posture chewing on feet is indicative of pain and seen in instances of bladder stones.
   

4. Female exam
   • Vaginal: No discharge, no bleeding, no odor, no prolapse. Female rats do not menstruate!

     Examine your female rat’s vaginal opening for any discharge or blood. In a non-pregnant rat this could mean a problem such as: uterine infection (often mycoplasma), cysts, or tumor.

5. Male exam
   1. Penis: In healthy males the production of vesicular proteinaceous material is taken care of during normal grooming.

      Abnormal: Bleeding, odor, thick white plugs, paraphimosis, priapism.
      
      In males, particularly elderly males or those that have hindlimb issues, check the penis for discharge. (Occasionally you will need to inspect closer by very gently pushing back the sheath to make sure that there is no blockage, very gently cleansing if needed, and gently return sheath in place.

   2. Scrotum/Testes: Symmetrical.

      Note that anatomically the male rat has an open inguinal canals that permits the testicle(s) to migrate in and out of the abdomen.
      
      Abnormal: Missing testicle(s) not associated with neutering, cryptorchidism (testicle does not descend into scrotum), masses, lumps, bites, wounds.

Tail/Feet/Nails

1. Tail: Long, cylindrical, thick at base and tapers to a point, and has fine fur.

   Abnormal: Inflammation, sores, bumps, paleness, cyanosis. Concentric constriction on tail can indicate ringtail.
   

2. Feet/Nails: No paleness, cyanosis, injuries or wounds.

   Abnormal: Inflammation, raised red areas, open sores on bottom of feet (hind) can be indicative of bumblefoot, requiring treatment.
   
   *Note: Rats housed on smooth flooring may not effectively wear down the sharp points of their nails. Cautious clipping of the nail tips, avoiding the cuticle, may be needed.

Fur and Skin

1. Fur: Smooth, glossy (except in rex or nude), well groomed. Coarser texture of fur in males (neutered males may have a softer texture to their fur).

   Abnormal: Soiled, piloerection, hair loss unrelated to genetics, nits.
   

2. Skin: intact.

   Abnormal: Scratches, scabs, cuts, wounds, bleeding, lumps, rashes.
   
   *Note: Watch your rat’s behavior to see if it is scratching excessively.
   Check skin and fur for possible parasites. Fleas and lice are large enough to see. Lice nits can often be seen on the hair shaft. Mites, themselves, are harder to see or visualize; however, a characteristic scabbing around the rat’s shoulders and neck can indicate their presence.

Locomotion/Motor Movement/Posture

• Remove your rat from its cage and watch it walk. The walk should be symmetrical and without pain. Climbs without difficulty.

  *Note: Non-invasive tests for proprioception and mobility include “hopping” and “wheel-barrow” tests.
  
  For “hopping” test, place rat on a firm surface. Place hand under the chest for support and raise up the front of the rat, and with the other hand lift up and hold one hind foot. The rat will normally hop to one side to maintain balance.
  
  For “wheel-barrow” test, place rat on firm surface. Lift and gently hold up rat’s hind limbs and move gently forward like pushing a wheel-barrow. The rat will normally maintain balance and mobility by walking on its forepaws.
  
  Abnormal: Watch for trembling, limping, tilting, circling, weakness in the limbs, stiffness or knuckling in the digits of forepaws or hindfeet.
  A rat exhibiting any of these signs as well as: “hunched up” posture or lethargy can indicate an ill or injured rat.

Anywhere

1. Color:
   Check the extremities (feet, ears, tail, paws, etc.) for either pale or heightened skin color.
2. Odor:
   Sniffing your rat may help alert you to problems. Learn your rat’s “normal” odor. A “foul” smell may be indicative of infection. A sickly sweet smell could signal diabetes.
3. Hydration:
   • Visually inspect mucous membranes for color and moisture. Pink, moist membranes are seen in normally hydrated rats.
     
     Abnormal: dry mucous membranes can indicate dehydration. Mucous membranes appearing pale may indicate cardiovascular issues. Mucous membranes appearing engorged/dark “muddy” may indicate shock in the ill rat.

   • A “pinch test” can be easily performed to check for dehydration.
     Using two fingers take a little fold of skin on the rats back and lift it up (similar to the appearance of tent). When you release your fingers the skin should return to its normal position. If the skin stays raised, even for a few seconds, your rat may be dehydrated.

     *Note: Rats that are moderate to seriously ill may tend not only to reduce their food intake but their fluid intake as well. Measurement of weight loss should be monitored along with the use of a pinch test.

4. Injuries and Wounds:
   Visually inspect your rat’s body for bleeding, cuts, bites, scabs, rashes, and bruising.

5. Signs of Pain (Refer to charts on Signs of Pain in the Rat Guide).

Consultant

Advanced Health Check reviewed by Vanessa Pisano DVM

Resource:

1. Mader, D. (2010, October 3). Critical care techniques in small exotic mammals. International Veterinary Information Service. Retrieved March 2, 2011, from http://www.ivis.org/proceedings/sevc/2010/lectures/eng/Mader1.pdf